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Basic knowledge of LED
What is LED?
A lighting-emitting diode (LED) is a semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction of p-n junction. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or near-ultraviolet.
What is high power LED?
High power LED refers to a type of LED with a driving current of 350mA and above. Wisdom Science & Technology (HK) Co.,Ltd manufacture high power LED ranging from 1 watt to 300 watt.
What is forward voltage (Vf)?
Forward voltage (Vf) is the voltage across a diode for a given forward current.
What is lumens?
Lumens in an international unit that refers to the amount of light that a light source produces. For example, a 60 watt incandescent lamp provides about 800 lumens. A 1 watt LED provides 100-120 lumens and up.
What is phosphor?
Phosphor is an inorganic chemical compound processed into a powder and deposited inside the dome of an LED packaging. Phosphors are designed to convert the wavelength of light. LEDs use proprietary phosphors from the global leading company.
What is junction temperature?
A p-n junction is formed by combing N-type and P-type semiconductors together in a very close contact. The term junction refers to the region where the two types of semiconductor meet. The junction temperature refers to the temperature measured at p-n junction, which is also the core of an LED.
What is emission angle (2θ½)?
The emission angle refers to as the 2θ½ indicates how focused the light is when emitted from the LED. This angle is determined by measuring the angle from direct on-axis to the angle where light intensity falls to half of the on-axis intensity, and multiplying this difference by 2. The choice of viewing angle also affects the LED output intensity. LEDs are available in various emission angles.
What is CCT?
Correlated color temperature (CCT) is a characteristic of visible light that has important applications in lighting. The color temperature of a light source is determined by comparing its hue with a theoretical, heated black-body radiator. The kelvin temperature at which the heated black-body radiator matches the hue of the light source is that source’s color temperature.
What is CRI?
Color rendition index (CRI) is a quantitative measure of the ability of a light source to
reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
What is wavelength (λd)?
Light could be split into many colors. The colors produced by light are arranged in a precise array or spectrum. The order of color is constant, and each color has a unique signature identifying its location in the spectrum. The signature of color is the wavelength of light.
Why use LEDs for lighting?
1: Long life time.
2: Highly energy efficient.
3: Environmentally friendly – no hazardous materials.
4: No infrared or ultraviolet in beam output.
5: Vivid saturated colors without filters.
6: Small form factors for improved design flexibility.
What applications can LED be used for?
1: Architecture lighting.
2: Entertainment lighting.
3: Commercial lighting.
4: Residential lighting.
5: Emergency lighting.
6: Street lighting.
7: Refrigeration lighting.
8: Automotive lighting.
9: LCD display backlight.
10: LED display.
A lighting-emitting diode (LED) is a semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction of p-n junction. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or near-ultraviolet.
What is high power LED?
High power LED refers to a type of LED with a driving current of 350mA and above. Wisdom Science & Technology (HK) Co.,Ltd manufacture high power LED ranging from 1 watt to 300 watt.
What is forward voltage (Vf)?
Forward voltage (Vf) is the voltage across a diode for a given forward current.
What is lumens?
Lumens in an international unit that refers to the amount of light that a light source produces. For example, a 60 watt incandescent lamp provides about 800 lumens. A 1 watt LED provides 100-120 lumens and up.
What is phosphor?
Phosphor is an inorganic chemical compound processed into a powder and deposited inside the dome of an LED packaging. Phosphors are designed to convert the wavelength of light. LEDs use proprietary phosphors from the global leading company.
What is junction temperature?
A p-n junction is formed by combing N-type and P-type semiconductors together in a very close contact. The term junction refers to the region where the two types of semiconductor meet. The junction temperature refers to the temperature measured at p-n junction, which is also the core of an LED.
What is emission angle (2θ½)?
The emission angle refers to as the 2θ½ indicates how focused the light is when emitted from the LED. This angle is determined by measuring the angle from direct on-axis to the angle where light intensity falls to half of the on-axis intensity, and multiplying this difference by 2. The choice of viewing angle also affects the LED output intensity. LEDs are available in various emission angles.
What is CCT?
Correlated color temperature (CCT) is a characteristic of visible light that has important applications in lighting. The color temperature of a light source is determined by comparing its hue with a theoretical, heated black-body radiator. The kelvin temperature at which the heated black-body radiator matches the hue of the light source is that source’s color temperature.
What is CRI?
Color rendition index (CRI) is a quantitative measure of the ability of a light source to
reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
What is wavelength (λd)?
Light could be split into many colors. The colors produced by light are arranged in a precise array or spectrum. The order of color is constant, and each color has a unique signature identifying its location in the spectrum. The signature of color is the wavelength of light.
Why use LEDs for lighting?
1: Long life time.
2: Highly energy efficient.
3: Environmentally friendly – no hazardous materials.
4: No infrared or ultraviolet in beam output.
5: Vivid saturated colors without filters.
6: Small form factors for improved design flexibility.
What applications can LED be used for?
1: Architecture lighting.
2: Entertainment lighting.
3: Commercial lighting.
4: Residential lighting.
5: Emergency lighting.
6: Street lighting.
7: Refrigeration lighting.
8: Automotive lighting.
9: LCD display backlight.
10: LED display.
