In the 19th century, humans entered the era of electric lighting. After development, it is now the fourth generation of solid-state light source ----LED lighting era. Let's understand the knowledge related to LED lighting.

Noun explanation: LED is the acronym of Light Emitting Diode, Chinese full name "light emitting diode".

Depending on the semiconductor materials used, leds emit different colors, traditionally red, green, orange, yellow, blue, and so on. So it will be called blue LED accordingly. White light is composite light, so the so-called white LED is modulated on the basis of the above.

Basic parameters for lighting applications:

Luminous flux

Refers to the radiation power perceived by the human eye, that is, the ratio of light emitted by the light source. The unit is LW(lumens). The nominal luminous flux of a 40W ordinary incandescent lamp is 360lm, the nominal luminous flux of a 40W daylight fluorescent lamp is 2100 lm, and the luminous flux of a 400W standard high-pressure sodium lamp can reach 48000 lm.

Luminous efficiency

The ratio of luminous flux to electric power, usually lm/W. The luminous efficiency represents the energy-saving characteristics of the light source, which is an important indicator to measure the performance of modern light sources.

Luminous intensity and light intensity distribution

LED luminous intensity is to characterize its luminous strength in a certain direction, because the LED in different spatial angles of light intensity difference is a lot, followed by we have to understand the LED light intensity distribution characteristics. This parameter is of great practical significance and directly affects the minimum viewing Angle of the LED display device.

Wave length

For the spectral characteristics of the LED, we mainly see whether its monochromaticity is good, and we should note that the main colors such as red, yellow, blue, green, and white leds are pure positive. Because in many cases, such as traffic lights on the color requirements are more strict, but according to the observation of some of China's LED lights green blue, red for the deep red, from this phenomenon we have a special study of the spectral characteristics of LED is very necessary and meaningful.

Temperature

The light seen by the ordinary human eye is composed of the superimposed spectrum of seven colors of light. But some light rays are blue, some are red, and color temperature is a method specifically used to measure and calculate the color component of light. The unit is K. The color temperature of the light source is different, the light color is different, and the feeling is not the same:

<3300K Warm (white with red) stable and warm

3000-5000K middle (white) refreshing

>5000K Cool type (white with blue) cold

Color rendering index

The color rendering ability of the light source to the object is called color rendering, which is compared with the appearance color of the object under a reference or reference light source (incandescent lamp or painting light) with the same color temperature. There are two kinds of color rendering, loyal color rendering, can correctly represent the original color of the substance to use a high color rendering index (Ra) light source, its value is close to 100, the best color rendering. Effect color, to clearly emphasize the specific color, the performance of the beautiful life can use the method of adding color to strengthen the color effect. The use of low color temperature light source irradiation can make the red more vivid; The medium color temperature light source is used to irradiate the blue with cool feeling; The use of high color temperature light source irradiation, so that the object has a cold feeling.

Index (Ra) color rendering rating and general application

90-100 1A Excellent places that require precise color contrast

80-89 1B Places where correct color judgment is required

60-79 2 Common sites requiring moderate color rendering

40-59 3 Places with low requirements for color rendering and small color difference

20-39 4 Poor sites without specific requirements for color rendering