TWI473303B - A way to reduce the LED color temperature and color coordinates drift - Google Patents

Description

A method for reducing LED color temperature and color coordinate drift

The invention relates to a method for reducing the color temperature of a LED and the amount of drift of a color coordinate, in particular, a phosphor-converted LED for controlling a dominant wavelength of a blue light emitter with a fluorescent powder to make a color expression Minimized by LED heat dissipation.

According to the LED light-emitting efficiency, it is easy to be affected by heat, especially in the case of high current or long time, the color performance will be unstable, and the color temperature will also rise. Common white LEDs usually use one or more kinds of phosphor powder, among which the phosphor powder It will be affected by heat and life, and the attenuation will reduce the efficiency, resulting in the change of light color of the output, which will result in unstable color of the LED lamp. In terms of comprehensive experience, the working temperature has a key influence on the luminous efficiency of the LED, and generally overcomes The most common way of LED luminous efficiency is to improve the LED heat dissipation efficiency and change the LED material to reduce its heat.

In view of the fact that the luminous efficiency of the conventional LED lamp is easily affected by heat, especially in the case of high current or long time, the color performance is unstable, and the color temperature is also soared, the inventors have introduced a method for reducing the color temperature and color coordinate drift of the LED. The method, in detail, is a phosphor-converted LED that controls the dominant wavelength of the blue illuminator with the phosphor powder, so that the color performance is minimized by the LED heat dissipation.

The invention relates to a method for reducing the color temperature and color coordinate drift of an LED, which is a phosphor-converted LED which is controlled by a dominant wavelength of a blue light emitter to match a phosphor powder, so that the color performance is affected by the heat dissipation of the LED. Minimized.

In order to achieve the aforementioned creative purpose, the present invention "a method for reducing the color temperature of a LED and the amount of drift of a color coordinate", which is caused by a change in the spectrum of the blue light, a red shift of the PW (peak wavelength), and a different absorption capacity of the blue light, which are converted by the heat. The principle of yellow light quantity change, CCT (correlated color temperature) change and color coordinate change, etc., the LED with the main wavelength of 400 to 470nm blue light illuminator with fluorescent powder can be tested, which can achieve the color temperature and color coordinates of the LED. Small effect.

The aforementioned fluorescent powder is an excitation spectrum (intensity vs. wavelength) having all the phosphors having a slope of zero or positive.

The aforementioned phosphor powder is YAG phosphor powder.

Therefore, the present invention can be said to be a practical and progressive creation, which is quite worthy of promotion by the industry and is publicized to the public.

The invention relates to a method for reducing the color temperature and color coordinate drift of an LED, which is a phosphor-converted LED for controlling the main wavelength of a blue light emitter with a fluorescent powder, so that the color performance is cooled by the LED. The impact is minimized.

In order to achieve the aforementioned creative purpose, the present invention "a method for reducing the color temperature of a LED and the amount of drift of a color coordinate", which is caused by a change in the spectrum of the blue light, a red shift of the PW (principal wavelength), and a different absorption capacity of the blue light. The principle of yellow light quantity change, CCT (correlated color temperature) change and color coordinate change, etc., the LED with the main wavelength of 400 to 470nm blue light illuminator with fluorescent powder can be tested, which can achieve the color temperature and color coordinates of the LED. Small effect.

Further, the fluorescent powder to which it is applied is an excitation spectrum (intensity vs. wavelength) having all the phosphors having a slope of zero or positive.

Further, the phosphor powder is YAG phosphor powder.

Referring to the first figure, overheating will cause the PW (primary wavelength) to shift red, as shown in the figure, Low pw is shifted to High pw.

Please refer to the second figure, the overheating will reduce the quantum efficiency of the phosphor powder, and will also reduce the conversion efficiency of the phosphor powder (so-called thermal decay), and the converted yellow light will be reduced, and the yellow spectrum will also be reduced. Will shift red, causing a decrease in B/Y (blue-yellow ratio) and an increase in CCT (correlated color temperature).

Please refer to the third-A diagram and the third-B diagram, which is the calculation method of the excitation ability. The above third-A diagram factor enhances the degree of yellow light, and if it can cause the yellow light to decline with the third-B diagram factor. If the two balance, the degree of color temperature and color shift can be minimized; thus, using a blue light emitter with a dominant wavelength of 420 to 460 nm and a phosphor powder can minimize the amount of color temperature drift.

Its calculation formula is as follows:

_{Power total = ∫ P barechip (λ} ) dλ

Excitation_ability =∫ P _excitation ( λ ) P _{barechip _ N} ( λ ) dλ

Please refer to the fourth figure, the experimental data of different peak wavelength bare crystals with different phosphor powder concentrations, the white LED will have different performance.

Please refer to the fifth figure for the case where the Ability of Excitation is greater than the degree of Thermal Decay.

Please refer to the sixth figure for the case where the Ability of Excitation is approximately equal to the degree of Thermal Decay.

Please refer to the seventh figure for the case where the Ability of Excitation is less than the degree of Thermal Decay.

The above description is only intended to explain the preferred embodiments of the present invention, and is not intended to limit the invention in any way. The changer should still be included in the scope of the intention of the present invention.

In summary, the present invention "a method for reducing the color temperature of the LED and the drift of the color coordinates" is indeed in line with the needs of industrial development in terms of structural design, practicality and cost-effectiveness, and the disclosed structural creation also has Unprecedented innovative structure, so its "novelty" should be undoubtedly considered, and the invention is more effective than the conventional structure, so it is also "progressive", which fully complies with the application requirements of the invention patents of the Chinese Patent Law. The stipulation is that a patent application is filed in accordance with the law, and the bureau should be reviewed at an early date and affirmed.

The first picture is a schematic diagram of the PW red shift caused by heat.

The second figure is a schematic diagram of the decrease in quantum efficiency and conversion efficiency of the phosphor by heat.

The third graph is a schematic diagram of the peak of the excitation spectrum and the degree of yellow light decline.

The fourth figure is a schematic diagram comparing the excitation ability and thermal decay degree of various main wavelengths with YAG phosphor powder.

The fifth figure is a schematic diagram of the deviation of the color temperature and color coordinates of the excitation ability from the degree of thermal decay.

The sixth figure is a schematic diagram of the excitation ability approximately equal to the offset of the color temperature and color coordinates of the thermal decay.

The seventh figure is a schematic diagram of the deviation of the color temperature and color coordinates of the excitation ability from the degree of thermal decay.

Claims (2)

A method for reducing the color temperature of a LED and a color shift of a color coordinate, which is a LED with a blue light emitter and a fluorescent powder, and the fluorescent powder is an excitation spectrum (intensity vs. wavelength) having all the phosphors having a slope of zero or positive, and the blue light The illuminating system is equipped with a blue illuminant with a peak wavelength of 400 to 470 nm and a phosphor powder; thus, the LED has a small drift of color temperature and color coordinates. According to the method of claim 1, the method of reducing the color temperature of the LED and the amount of drift of the color coordinates, the phosphor powder is YAG phosphor powder.