CN103939805B - Low color temperature amber LED street light suitable for middle-aged and elderly people driving at night - Google Patents

Abstract

The invention discloses a low color temperature amber LED street lamp suitable for middle-aged and elderly people driving at night. The present invention adopts the combination of blue-light InGaN LED chips and amber fluorescent powder in a suitable ratio to construct this kind of low color temperature, while still having the high light efficiency and high color rendering performance of light-emitting diodes, and the high fog penetration of high-pressure sodium lamps. High-performance street lamps, replacing traditional high-pressure sodium lamp street lamps. Compared with traditional high-pressure sodium lamps, the present invention has higher luminous efficiency and color rendering index; compared with ordinary white LEDs, the present invention has lower color temperature and higher fog penetration performance, and will not cause biological clock disorder, causing The light pollution is relatively small, which is more suitable for middle-aged and elderly people with yellowing retinas to drive and walk at night.

Description

Low color temperature amber LED street light suitable for middle-aged and elderly people driving at night

technical field

The invention relates to a high-power LED street lamp, in particular to an amber high-power low-color-temperature LED street lamp with a color temperature between 1700K and 2700K.

Background technique

With the development of semiconductor lighting technology, LED has the advantages of high luminous efficiency, multiple colors, orientation, energy saving and environmental protection, high reliability, good color rendering, long life, easy control, etc., and has emerged to replace various traditional lighting source products. trend. Compared with the traditional high-pressure sodium lamp street lamp, due to the small size of the LED, the lens can be used to meet the uniform distribution of light spots on the road surface and improve the utilization of light energy. Therefore, it can achieve higher light energy utilization and uniformity than high-pressure sodium lamps. ; Due to the high light efficiency of LED, it has better energy-saving effect than high-pressure sodium lamp.

At present, white LEDs are mainly composed of blue LED chips and yellow phosphor powder. There are more blue light components in the low-wavelength band, so the color temperature is higher. Street lighting at night belongs to intermediate vision. Due to the Pukinye effect, the human eye is more sensitive to light in the low-wavelength band, and the intermediate vision light effect of white LEDs is higher than that of photopic vision. This feature of white LEDs was once considered an advantage by the lighting community. However, the recent use of white LEDs has increasingly revealed the problems of LEDs with more blue light. This kind of high color temperature, blue-rich LED lighting will have various side effects on the human body and vision; it will inhibit the production of melatonin in the human body, make it difficult to fall asleep and cause fatigue, and long-term use will cause biological clock disorders, which will lead to mental problems; Blue light LEDs will cause relatively strong nighttime glow pollution, which will have adverse effects on human life, nighttime astronomical observation, ecological environment, and the overall beauty of the night sky; The eyes of the elderly cannot better accept the light from this kind of blue-rich LED light source at night. The use of current ordinary white LEDs is not conducive to driving and walking at night for middle-aged and elderly people, and will reduce the safety factor of driving and walking at night. .

Contents of the invention

The purpose of this invention patent is to solve the problem that in the existing LED technology, LED has more blue light components, higher color temperature, more serious psychological and physiological side effects and light pollution, is not suitable for middle-aged and elderly people to drive and walk at night, and has insufficient fog permeability. Not suitable for road lighting problems at night. The present invention provides a low color temperature amber LED street lamp suitable for middle-aged and elderly people driving at night, including amber high-power LEDs, free-form surface lenses, light transmission covers, circuit boards, driving power supplies, heat dissipation structures and casings. The spectral design of amber high-power LED adopts indium gallium nitrogen blue LED chip to excite phosphor to emit amber light. The peak wavelength of blue light emitted is between 440nm and 460nm. The phosphor used is europium-doped amber phosphor or YAG yellow phosphor It is mixed with red fluorescent powder in a certain proportion, and its luminous peak wavelength is between 580nm and 600nm. In the light emitted by the amber high-power LED, the energy ratio of blue light is less than 10% of the total energy, and the energy ratio of amber light is greater than The total energy is 90%, and its color temperature is between 1700K and 2700K.

Further, the amber high-power LED has a 20% improvement in efficacy compared with a high-pressure sodium lamp street light, and an increase in equivalent color rendering by more than 50%. The equivalent color rendering index Rames is calculated according to the following formula:

γ refers to the color shift normalization parameter, which is determined by the ambient brightness, and Ra is the color rendering index under photopic vision.

Further, the amber high-power LED (1) meets the requirements of the human body clock, and the inhibitory effect on the production of melatonin in the human body during night lighting is more than 80% lower than that of LED street lights with a color temperature above 3000K, and will not cause the disorder of the body clock. The melatonin-suppressing effect (MMSI _A ) on humans during nighttime lighting was calculated by the following formula:

K ₀ and K _mes0 are the spectral luminous efficacy under photopic and mesopic conditions under night lighting, respectively; V(λ) and Vmes(λ) are the spectral luminous efficacy under photopic and mesopic lighting, respectively; S(λ ) is the spectral power distribution curve of the designed LED light source; S _A (λ) is the spectral power distribution curve of CIE standard A light source; C(λ) is the inhibition function of human melatonin by light of various wavelengths.

Further, the visible light scattering glow light pollution caused by the amber high-power LED is more than 1 times lower than that of ordinary white LEDs, and it has the strongest penetrating ability in rainy, foggy and hazy weather, which improves the visibility of objects when driving at night. Resolving power, the glow index MGVI _A in the visible light range is calculated according to the following formula:

V'(λ) represents the spectral luminous efficiency of the human eye under scotopic conditions.

Further, the light emitted by the amber high-power LED meets the visual requirements of middle-aged and elderly people due to the yellowing of the lens, and the transmittance to the lens of the elderly is higher than that of LED street lights with a color temperature above 3000K, which is suitable for the elderly to drive at night and Walking, the retinal brightness decrease effect index MLYIage caused by yellowing of the lens is calculated according to the following formula:

T _age (λ) and T ₂₅ (λ) are the average spectral transmittance of the lens of a certain age old people and 25-year-old young people.

Further, the europium-doped amber phosphor includes (Sr,Ba) ₂ SiO ₄ :Eu; the yellow phosphor includes Y ₃ (Al,Ga) ₅ O ₁₂ :Ce; the red phosphor includes (Ca , Sr) ₂ Si ₅ N ₈ :Eu, Ca ₂ Si ₅ N ₈ :Eu or Sr ₂ Si ₅ N ₈ :Eu.

The color temperature of the present invention is low (between 1700K and 2700K), and the high-power LED street lamp that emits light color is amber, and the glow pollution is also reduced with the reduction of the blue light component; The color is amber, which can be easily received by middle-aged and elderly people with yellowed lenses, thereby improving the ability to distinguish objects at night and allowing them to travel safely at night. And because the amber light has more components, it has less scattered glow and higher fog penetration than ordinary white LEDs. At the same time, compared with the traditional road lighting high-pressure sodium lamp currently used, the technology of the present invention still has the advantages of adjustable LED light spot design, high light efficiency and good color rendering.

Compared with the existing high-pressure sodium lamps commonly used for nighttime lighting, the amber high-power LED street lamp of the present invention has significantly higher light efficiency than high-pressure sodium lamps, better penetration of fog than high-pressure sodium lamps, and better color rendering performance than high-pressure sodium lamps. excellent. Simultaneously, compared with the existing white light LED, the blue light component of the emitted spectrum is lower in the present invention, and the color temperature is also lower. It has a lower inhibitory effect on the production of melatonin in the human body, and will not cause fatigue, difficulty in sleeping, and disturbance of the biological clock; moreover, it causes lower urban glow pollution than existing white LEDs. At the same time, because of the yellowing of the lens of the middle-aged and elderly people, the LED street lamp designed by the present invention is more suitable for the visual conditions of the middle-aged and elderly people when driving and walking at night than ordinary white LED street lights.

Description of drawings

Fig. 1 is the structure of amber high power low color temperature LED street lamp of the present invention;

Figure 2 is a comparison of the spectral curves emitted by the existing warm white, positive white LEDs, high pressure sodium lamps and amber high-power LEDs;

Figure 3 is the inhibition function C(λ) of various wavelengths of light on human melatonin;

Figure 4 is the average transmittance curves of the lenses of 25, 50 and 75-year-old people to visible light of various wavelengths.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

As shown in Figure 1, the present invention uses an indium gallium nitrogen blue light LED chip, is matched with an amber phosphor powder in a suitable proportion or an amber phosphor powder mixed with red and YAG yellow phosphor powder in a certain proportion, and is packaged into a new type of LED lamp. The color temperature is controlled at 1700-2700K, and then a free-form surface lens 2 and a light-transmitting cover 3 are arranged in front of the LED. Aluminum substrates, ceramic substrates or metal circuit boards are used, and heat pipes or fins, metal-based heat sinks 6 are used for heat dissipation, and aluminum Alloy or stainless steel shell 7 and controllable constant current power drive power supply 5.

There is a lamp circuit board 4 inside the shell 7, and an amber high-power LED lamp 1 is welded on the lamp circuit board 4. The peak wavelength of the blue LED chip is about 440nm, and the peak wavelength of light emitted by the amber phosphor is 580-600nm after being excited. . The front of the LED is equipped with a free-form surface lens 2, so that the light emitted by the LED becomes a batwing light spot distribution spread along the road surface, and then shines on the road surface through the light-transmitting cover 3. The circuit board of the LED lamp is an aluminum substrate, a ceramic substrate, a silicon substrate or a metal circuit board, and a metal-based heat sink is installed behind the board, and a cooling fin or heat pipe device is installed behind the heat sink.

Figure 2 shows the spectral distributions emitted by amber LEDs, warm white LEDs, positive white LEDs, and high pressure sodium lamps HPS. It can be seen from Figure 2 that the spectral curve of the light emitted by the amber high-power LED is relatively smooth, and the proportion of blue light is relatively low. The color temperature, color rendering index, radiant light effect and other parameters of the amber high-power LED can be designed from the spectral curve. Table 1 is a comparison of relevant parameters of the designed amber high-power LED, high-pressure sodium lamp, and existing warm white and positive white LEDs. In the table, 0.1cd/m ² , 2cd/m ² and >5cd/m ² correspond to the ambient brightness under the conditions of pedestrian walking intermediate vision, expressway driving intermediate vision and photopic vision respectively, and the correlation obtained under each environmental brightness The parameters are different.

Among these parameters, the equivalent color rendering index _Rames ^refers to the normalized equivalent color rendering index of the light source under the condition that the color resolution ability of the human eye decreases when the ambient brightness is reduced. Under visual conditions it is R _a . The calculation method of the equivalent color rendering index is shown in formula (1):

(1)

In formula (1), γ refers to the color shift normalization parameter, which is a parameter determined by the ambient brightness. For 0.1cd/ ^m2 and 2cd/ ^m2 environments, γ is 0.16 and 0.51, respectively.

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Table 1 Comparison of optical performance indicators of various light sources

It can be seen from Table 1 that the designed amber high-power LED has a lower color temperature, its chromaticity coordinates are close to those of high-pressure sodium lamps, and its equivalent color rendering index is better than that of high-pressure sodium lamps. Although the equivalent color rendering index is not as good as that of white LEDs, the equivalent color rendering index reaches 90 and 70 respectively under the nighttime conditions of brightness of ^0.1cd / ^m2 and 2cd/m2, which can fully meet the requirements of nighttime lighting color identification. need.

The amber high-power low-color-temperature LED street lamp of the present invention has relatively low inhibitory effect on the production of melatonin by the human body, and correspondingly has relatively low biological clock disturbing effect. The melatonin suppression effect of light of various wavelengths on the human body can be expressed by the suppression function C(λ), as shown in Figure 3. Therefore, under the unit light intensity, the melatonin inhibitory effect MMSI _A of the light source with unit brightness on the human body at night can be expressed by formula (2):

(2)

Among them, K ₀ and K _mes0 are the spectral luminous efficacy under photopic and mesopic lighting at night lighting, respectively; V(λ) and V _mes (λ) are the spectral luminous efficacy under photopic and mesopic lighting, respectively; S(λ) is the spectral power distribution curve of the designed LED light source; S _A (λ) is the spectral power distribution curve of the CIE standard A light source, which is defined as 1 for the biological clock disturbance effect on the human body under bright conditions.

Compare the MMSI _A of the amber high-power LED of the present invention with ordinary white LEDs and high-pressure sodium lamps under bright conditions (>5cd/m ² ) and mesopic lighting conditions (0.1cd/m ² , 2cd/m ² ) , and the results are shown in Table 2.

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Table 2 Comparison of melatonin suppression effects of various light sources

It can be seen from Table 2 that the amber high-power LED of the present invention has the lowest index of melatonin suppression under various brightness conditions, and will not have obvious inhibitory effect on the production of melatonin by the human body, and will not cause circadian clock disturbance.

The amber high-power low-color-temperature LED street lamp of the present invention has low glow pollution caused by it. Due to Rayleigh scattering and meter scattering, the light of blue-rich LED light sources will be scattered to the sky above the city by particles in the air, resulting in light pollution in the night sky and a decrease in the relative brightness of celestial bodies in the night sky, affecting astronomical observation and the overall beauty of the night sky. At the same time, this glow also has a negative impact on the ecological environment at night, affecting the physiological responses and structures of animals, plants, and the human body.

The evaluation index of night glow, MGVI _A , refers to the glow index that can be observed in the entire visible light range; the calculation of MGVI _A is shown in formula 3.

(3)

V'(λ) represents the spectral response intensity of the human eye under scotopic conditions. The MGVI _A of amber high-power LEDs, white LEDs and high-pressure sodium lamps were compared, and the results are shown in Table 3.

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Table 3 Comparison of glow pollution effects caused by various light sources

It can be seen from Table 3 that the glow pollution caused by the amber high-power low-color-temperature LED of the present invention is the lowest. At the same time, this also means that it has the strongest penetrating ability among the above-mentioned several light sources in the environment of rain, fog and haze, which improves the ability to distinguish objects when driving at night.

The glow pollution caused by ordinary white LEDs is relatively high, and in an environment with a lot of particulate matter, the penetrating ability is poor, and the ability to adapt to the weather is not strong, so it is not suitable for road lighting at night.

The lens of the human body will gradually yellow with age. As a result, the transmittance of the lens to low-wavelength (blue light) decreases, and blue light cannot be well presented on the retina. For middle-aged and elderly people, the brightness of rich blue light sources is actually much lower. Compared with the current white LED light source, the amber high-power low-color-temperature LED street lamp designed by the present invention is more suitable for middle-aged and elderly people to drive and walk at night. The lens spectral transmittance T _age (λ) is related to age, as shown in Figure 4. The effect of retinal brightness reduction caused by lens yellowing can be expressed by the age-related retinal brightness index MLYI _age , which is calculated by formula (4).

(4)

Table 4 lists the comparison of MLYI _age for various light sources.

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Table 4 Comparison of various light sources on the retinal brightness index of middle-aged and elderly people

It can be seen from Table 4 that compared with high-pressure sodium lamps, amber high-power LEDs have similar brightness to the retinas of middle-aged and elderly people, and neither of them has a significant decrease in brightness. However, for middle-aged and elderly people, especially those around 75 years old, ordinary white LEDs have a more obvious decrease in retinal brightness.

An embodiment of the amber high-power low color temperature LED street lamp of the present invention is composed of a blue-light indium gallium nitrogen LED chip that excites red Sr ₂ Si ₅ N ₈ :Eu and amber (Sr,Ba) ₂ SiO ₄ :Eu mixed phosphors; The measured color temperature of the amber high-power low-color-temperature LED street lamp of this embodiment is 1851K, and the color rendering index (photopic vision) is 40.1.

Another embodiment of the amber high-power low-color-temperature LED street lamp of the present invention is a mixture of red (Ca,Sr) ₂ Si ₅ N ₈ and yellow Y ₃ (Al,Ga) ₅ O ₁₂ :Ce excited by a blue Indium Gallium Nitride LED chip Phosphor composition. Wherein, the mixing ratio of the red phosphor and the yellow phosphor is 1:1. This amber high power low color temperature LED street light has a color temperature of 1842K and a color rendering index of 38.9.

The indicators of the two embodiments of the amber high-power low-color-temperature LED of the present invention are shown in Table 5.

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Table 5 Indexes of two embodiments of amber high-power low-color-temperature LEDs

The indicators of the amber high-power low-color-temperature LEDs from the two embodiments are similar. Install 108 1W high-power amber LEDs packaged in Embodiment 1 and Embodiment 2 on the circuit board, and package them into two 120W LEDs with a free-form surface lens, a light-transmitting cover, a driving power supply, a radiator and a casing. The amber street lamp has the advantages of low color temperature, good equivalent color rendering, low melatonin suppression level, strong fog penetration ability, less light pollution, and is suitable for walking and driving of middle-aged and elderly people with yellowing lens.

What has been described above and shown in the drawings are only preferred embodiments of the present invention. It should be pointed out that those skilled in the art can make some modifications and improvements without departing from the principle of the present invention, and these should also be regarded as belonging to the protection scope of the present invention.

Claims (6)

1. A low color temperature amber LED street light suitable for nighttime driving lighting for middle-aged and elderly people, including amber high-power LED (1), free-form surface lens (2), light-transmitting cover (3), circuit board (4), Drive power supply (5), heat dissipation structure (6) and housing (7), characterized in that: the spectrum design of the amber high-power LED (1) is composed of indium gallium nitrogen blue light LED chips to excite phosphor powder to emit amber light, emitting The peak wavelength of blue light is between 440nm and 460nm, and the phosphor used is europium-doped amber phosphor or YAG yellow phosphor and red phosphor mixed in a certain proportion, and its luminous peak wavelength is between 580nm and 600nm. In the light emitted by the amber high-power LED (1), the energy ratio of blue light is less than 10% of the total energy, the energy ratio of amber light is greater than 90% of the total energy, and its color temperature is between 1700K and 2700K. 2. The amber LED street lamp with low color temperature suitable for middle-aged and elderly people driving at night according to claim 1, characterized in that: the amber high-power LED has a street lighting effect that is 20% higher than that of a high-pressure sodium lamp, which is equivalent to The color rendering is increased by more than 50%, and the equivalent color rendering index Rames is calculated according to the following formula: γ refers to the color shift normalization parameter, which is determined by the ambient brightness, and Ra is the color rendering index under photopic vision. 3. The low color temperature amber LED street lamp suitable for nighttime driving lighting for middle-aged and elderly people according to claim 1, characterized in that: the amber high-power LED (1) meets the requirements of the biological clock of the human body, and is harmful to the human body during night lighting. The inhibitory effect of melatonin is 80% lower than that of LED street lights with a color temperature above 3000K, and will not cause biological clock disturbance. The melatonin inhibitory effect (MMSI _A ) of the light source on the human body when illuminated at night is calculated according to the following formula: K ₀ and K _mes0 are the spectral luminous efficacy under photopic and mesopic conditions under night lighting, respectively; V(λ) and Vmes(λ) are the spectral luminous efficacy under photopic and mesopic lighting, respectively; S(λ ) is the spectral power distribution curve of the designed LED light source; S _A (λ) is the spectral power distribution curve of CIE standard A light source; C(λ) is the inhibition function of human melatonin by light of various wavelengths. 4. The low color temperature amber LED street lamp suitable for middle-aged and elderly people driving at night according to claim 3, characterized in that: the visible light scattering glow light pollution caused by the amber high-power LED is two times lower than that of ordinary white LEDs. It has the strongest penetrating ability in rain, fog and haze weather, and improves the ability to distinguish objects when driving at night. The glow index MGVIA in the visible light range is calculated according to the following formula: V'(λ) represents the spectral luminous efficiency of the human eye under scotopic conditions. 5. The low color temperature amber LED street lamp suitable for middle-aged and elderly people driving at night according to claim 3, characterized in that: the light emitted by the amber high-power LED conforms to the vision of middle-aged and elderly people due to yellowing of the lens. It is required that the transmittance of the lens of the elderly is higher than that of LED street lights with a color temperature above 3000K, which is suitable for the elderly to drive and walk at night. The retinal brightness decrease effect index MLYI _age caused by the yellowing of the lens is calculated according to the following formula: T _age (λ) and T ₂₅ (λ) are the average spectral transmittance of the lens of a certain age old people and 25-year-old young people. 6. The low color temperature amber LED street lamp suitable for middle-aged and elderly people driving at night according to claim 1, characterized in that: the europium-doped amber phosphor comprises (Sr, Ba) ₂ SiO ₄ :Eu; The yellow phosphor includes Y ₃ (Al,Ga) ₅ O ₁₂ :Ce; the red phosphor includes (Ca,Sr) ₂ Si ₅ N ₈ :Eu, Ca ₂ Si ₅ N ₈ :Eu or Sr ₂ Si ₅ N ₈ :Eu.