CN105449079B - A kind of adjustable color temperature White-light LED illumination light source - Google Patents

Abstract

The present invention relates to a white light LED lighting source with adjustable color temperature. The white LED lighting source with adjustable color temperature includes a blue LED chip fixed on a base, a yellow fluorescent powder, an encapsulating glue layer and a heat-sensitive coating. The yellow Phosphor powder is coated on the blue LED chip, the encapsulation adhesive layer is located on the upper side of the blue LED chip, the heat-sensitive coating is coated on the encapsulation adhesive layer, when the ambient temperature is higher than the thermal When the transition temperature of the thermosensitive coating is lower than the transition temperature of the thermosensitive coating, the thermosensitive coating is in a transparent state, and when the ambient temperature is lower than the transition temperature of the thermosensitive coating, the thermosensitive coating is in a scattering state. The white light LED lighting source with adjustable color temperature can realize the adjustment of low color temperature white light and high color temperature white light, and solves the problem that the existing LEDs are difficult to realize light color variability and adjustability.

Description

A white LED lighting source with adjustable color temperature

technical field

The invention relates to the field of white LED lighting, in particular to a white LED lighting source with adjustable color temperature.

Background technique

In recent years, LED lamps have been more and more used in the field of general lighting due to their advantages of energy saving, environmental protection, and high conversion efficiency. However, traditional LED lamps generally have a fixed color temperature when they leave the factory. To meet the lighting needs of different color temperatures, it is often necessary to properly replace LED lamps with another color temperature, which increases the cost and makes installation inconvenient. Therefore, it is necessary to develop a low-cost and more intelligent LED lamp with adjustable color temperature to meet the market demand.

A Chinese invention patent for an adjustable color temperature LED lamp and its color temperature adjustment method (CN101482232A) proposes a method for adjusting the LED color temperature, which is realized by designing a complex control circuit, mainly using the CPU to control the different color temperatures of the LED lamp group The luminance value of the LED lamp body changes the overall color temperature of the mixed LED lamp. Although this technology realizes the change of color temperature, it is realized by adding an external control circuit to control the LED lamp group, and does not involve the change of the LED lamp itself.

Contents of the invention

In view of the above technical problems, the present invention provides a white light LED with adjustable color temperature and lower cost, which is convenient to use.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a white LED lighting source with adjustable color temperature, including a blue LED chip fixed on the base, a yellow fluorescent powder, an encapsulating adhesive layer and a heat-sensitive coating. The yellow phosphor is coated on the blue LED chip, the encapsulation adhesive layer is located on the upper side of the blue LED chip, the heat-sensitive coating is coated on the encapsulation adhesive layer, when the ambient temperature is higher than the When the transition temperature of the thermosensitive coating is lower than the transition temperature of the thermosensitive coating, the thermosensitive coating is in a transparent state, and when the ambient temperature is lower than the transition temperature of the thermosensitive coating, the thermosensitive coating is in a scattering state.

Further, the ambient temperature is controlled by the current flowing through the white LED lighting source with adjustable color temperature.

Further, the thermosensitive coating is made of thermotropic cholesteric liquid crystal material.

Further, the transition temperature of the heat-sensitive coating is 45°C-55°C.

Further, the wavelength range of light emitted by the blue LED chip is 440nm-470nm.

Further, the yellow fluorescent powder contains at least one fluorescent material.

Further, the color temperature range of the low color temperature of the adjustable color temperature white LED lighting source is 2700K-3500K.

Further, the color temperature range of the high color temperature of the adjustable color temperature white LED lighting source is 3500K-6500K.

Further, the ambient temperature for making the heat-sensitive coating transparent is 55°C-150°C.

Further, the ambient temperature for making the heat-sensitive coating in a scattering state is -50°C-45°C.

Due to the adoption of the above technical scheme, the present invention achieves the following technical effects: 1. Since the present invention adopts a heat-sensitive coating, the heat-sensitive coating is coated on the encapsulation adhesive layer, when the heat-sensitive coating is In the transparent state, the transmittance of the yellow light emitted by the yellow fluorescent powder can be reduced, the reflectance can be increased, and the transmittance of the blue light emitted by the blue LED chip can be increased at the same time, so that the LED lighting source emits white light with a high color temperature; when the heat When the sensitive coating is in a scattering state, it can reduce the transmittance of the blue light emitted by the blue LED chip, increase its reflectivity, and at the same time increase the transmittance of the yellow light emitted by the yellow phosphor, so that the LED lighting source emits white light with a low color temperature. The problems of light color variability and poor adjustment existing in the existing LED are solved. 2. Since the heat-sensitive coating of the present invention is made of a thermotropic cholesteric liquid crystal material, by changing the ambient temperature, the conversion between the two states of the heat-sensitive coating can be realized quickly, and the LED lighting source can be realized Quick adjustment of low color temperature white light and high color temperature white light.

The thermotropic cholesteric liquid crystal material used in the thermosensitive coating has a helical molecular orientation arrangement structure, and this special structure makes the thermotropic cholesteric liquid crystal material have the characteristic of selective light scattering. When the external temperature increases or decreases, the pitch of the thermal cholesteric liquid crystal material will change, and the size of the pitch determines the characteristics of light transmission and selective light scattering of the thermal cholesteric liquid crystal material. Further, when the pitch changes, the peak wavelength of visible light reflected by the thermotropic cholesteric liquid crystal material also changes accordingly, so the liquid crystal material can transmit or reflect yellow light and blue light respectively at different temperatures.

Description of drawings

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

Fig. 1 is a structural schematic diagram of the adjustable color temperature white LED lighting source of the present invention;

Fig. 2 is a working principle diagram of the low color temperature white LED lighting source with adjustable color temperature according to the present invention.

Fig. 3 is a schematic diagram of the high color temperature working principle of the adjustable color temperature white LED lighting source of the present invention.

In the figure: 1-blue LED chip, 2-yellow phosphor, 3-encapsulation layer, 4-heat-sensitive coating.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention. It should be noted that, in the figure, marking and description of known structures are omitted, such as structures such as LED brackets, heat sinks, pins, and gold wires.

As shown in Figures 1 to 3, the present invention includes a blue LED chip 1 fixed on a base, a yellow phosphor 2, an encapsulation layer 3 and a thermosensitive coating 4, and the yellow phosphor 2 is coated on the blue LED On the chip 1, the encapsulation layer 3 is located on the upper side of the blue LED chip 1, the heat-sensitive coating 4 is coated on the encapsulation layer 3, when the ambient temperature is higher than the transition of the heat-sensitive coating 4 temperature, the heat-sensitive coating 4 is in a transparent state, and when the ambient temperature is lower than the transition temperature of the heat-sensitive coating 4, the heat-sensitive coating 4 is in a scattering state.

The present invention adopts a thermosensitive coating 4, and the thermosensitive coating 4 is coated on the encapsulation layer 3. When the thermosensitive coating 4 is in a scattering state, most of the blue light emitted by the blue LED chip 1 is reflected Returning to the yellow phosphor powder 2, more yellow light is generated through the excitation of the yellow phosphor powder 2. The heat-sensitive coating in this state can reduce the transmittance of the blue light emitted by the blue LED chip 1, increase its reflectivity, and increase the yellow light at the same time. The transmittance of the yellow light emitted by the phosphor powder 2 makes the LED lighting source emit white light with a low color temperature; when the heat-sensitive coating 4 is in a transparent state, most of the blue light emitted by the blue LED chip 1 can pass through, reducing the blue light High reflectivity, thereby weakening the yellow light emitted by the yellow fluorescent powder 2, so that the LED lighting source emits white light with a high color temperature, and improves the LED light color variability and adjustability.

In the above embodiments, the ambient temperature is controlled by the current flowing through the white LED lighting source with adjustable color temperature.

Specifically, the thermosensitive coating 4 is made of thermotropic cholesteric liquid crystal material. When the temperature of the liquid crystal material is low, the liquid crystal material is anisotropic, and the liquid crystal material is in a scattering state; when the temperature rises, the liquid crystal material melts and becomes isotropic, and the scattering disappears and becomes transparent. Since the thermosensitive coating 4 is made of thermotropic liquid crystal material, by changing the ambient temperature, the conversion between the two states of the thermosensitive coating 4 can be realized quickly, and the low color temperature white light of the LED lighting source can be realized. Fast adjustment of high color temperature white light.

The thermotropic cholesteric liquid crystal material used in the thermosensitive coating has a helical molecular orientation arrangement structure, and this special structure makes the thermotropic cholesteric liquid crystal material have the characteristic of selective light scattering. When the external temperature increases or decreases, the pitch of the thermal cholesteric liquid crystal material will change, and the size of the pitch determines the characteristics of light transmission and selective light scattering of the thermal cholesteric liquid crystal material. Further, when the pitch changes, the peak wavelength of visible light reflected by the thermotropic cholesteric liquid crystal material also changes accordingly, so the liquid crystal material can transmit or reflect yellow light and blue light respectively at different temperatures.

In the above embodiment, the transition temperature of the heat-sensitive coating 4 is 45°C-55°C.

In the above embodiment, the wavelength range of the light emitted by the blue LED chip is 440nm-470nm.

Specifically, the yellow fluorescent powder 2 contains at least one fluorescent material.

Further, the color temperature range of the low color temperature of the white LED lighting source with adjustable color temperature is 2700K-3500K.

Further, the high color temperature range of the adjustable color temperature white LED lighting source is 3500K-6500K.

Further, the ambient temperature for making the heat-sensitive coating 4 transparent is 55°C-150°C.

Further, the ambient temperature for making the heat-sensitive coating 4 in a scattering state is -50°C-45°C.

In the white light LED lighting source with adjustable color temperature in the above embodiment of the present invention, the blue LED chip 1 adopts blue gallium nitride (GaN) chip, the yellow phosphor powder 2 adopts yttrium aluminum garnet (YAG) phosphor powder, and the heat-sensitive coating The encapsulation layer 3 between the layer 4 and the yellow fluorescent powder 2 is polysiloxane, and the thermosensitive coating 4 is coated on the surface of the encapsulation layer 3 by using cholesteric liquid crystal material. Since polysiloxane has very good thermal stability and excellent conductivity to temperature changes, it is a preferred encapsulation material used in the present invention. The adjustment of the color temperature of the LED can be realized by switching the state of the thermosensitive coating 4 .

The state switching principle of the white light LED lighting source with adjustable color temperature in the above embodiments of the present invention is based on the characteristics of the thermally induced cholesteric liquid crystal material of the thermosensitive coating, the temperature can affect the pitch of the thermally induced cholesteric liquid crystal material, and the size of the pitch Plays a decisive role in light transmission and selective scattering. As the temperature changes, the thermal cholesteric liquid crystal can reflect visible light of different colors. By adjusting the ratio of the liquid crystal material and the mixture, the temperature sensitivity and the selection of the working range can be realized, and the effect of the present invention can be better realized.

The working principle of the above-mentioned embodiment of the present invention is described in detail below:

When the current passing through the LED lighting source is small, take 20mA as an example, its luminous state is shown in Figure 2. The gallium nitride (GaN) chip can excite the yttrium aluminum garnet (YAG) phosphor to produce warm white light, as shown in Figure 2 The arrow in the middle indicates the blue light emitted by the gallium nitride (GaN) chip, and the arrows on both sides indicate the yellow light emitted by the yttrium aluminum garnet (YAG) phosphor. Due to the low current operation, the temperature of the LED lighting source is relatively low , about 35°C, the heat reaching the thermosensitive coating 4 through heat conduction is not enough to convert the thermotropic liquid crystal material from the scattering state to the transparent state; in the scattering state, when the blue light encounters the liquid crystal material, it will be reflected back in large quantities to excite the yttrium Aluminum garnet (YAG) phosphors produce more yellow light, and yellow light can pass through the liquid crystal material smoothly, so the LED lighting source finally emits low-color-temperature white light with less blue spectrum.

When the current passing through the LED lighting source is relatively large, taking 80mA as an example, its luminous state is shown in Figure 3. The gallium nitride (GaN) chip can excite the yttrium aluminum garnet (YAG) phosphor to produce warm white light, as shown in Figure 3. 3 The arrow in the middle indicates the blue light emitted by the gallium nitride (GaN) chip, and the arrows on both sides indicate the yellow light emitted by the yttrium aluminum garnet (YAG) phosphor. Due to the high current operation, the temperature of the LED lighting source is relatively high. High, about 60°C. At this time, the heat generated by the LED lighting source is conducted to the thermosensitive coating 4, which can make the thermotropic liquid crystal material change from the scattering state to the transparent state; in the transparent state, the blue light emitted by the gallium nitride (GaN) chip It can pass through the liquid crystal material and emit outwards smoothly, while yellow light is suppressed, so the LED lighting source finally emits light with high color temperature white light with more blue spectrum.

The above embodiments are intended to illustrate that the present invention can be implemented or used by those skilled in the art. It will be obvious to those skilled in the art to modify the above embodiments, so the present invention includes but is not limited to the above embodiments. Any method, process, or product that conforms to the claims or the description of the specification, and conforms to the principles, novelty, and creative features disclosed herein falls within the protection scope of the present invention.

Claims (2)

1. A white LED lighting source with adjustable color temperature, characterized in that it comprises: a blue LED chip fixed on the base, a yellow phosphor, an encapsulation adhesive layer and a heat-sensitive coating, and the yellow phosphor is coated on the On the blue LED chip, the encapsulation adhesive layer is located on the upper side of the blue LED chip, the heat-sensitive coating is coated on the encapsulation adhesive layer, when the ambient temperature is higher than the transition temperature of the heat-sensitive coating , the heat-sensitive coating is in a transparent state, and when the ambient temperature is lower than the transition temperature of the heat-sensitive coating, the heat-sensitive coating is in a scattering state; The thermosensitive coating is made of thermotropic cholesteric liquid crystal material; The transition temperature of the heat-sensitive coating is 45°C-55°C; The ambient temperature for making the heat-sensitive coating transparent is 55°C-150°C; The ambient temperature for the heat-sensitive coating to be in a scattering state is -50°C-45°C; The blue LED chip uses a gallium nitride chip, and the phosphor uses yttrium aluminum garnet phosphor; When the current passing through the LED lighting source is 20mA, the gallium nitride chip excites the yttrium aluminum garnet phosphor to produce warm white light. Due to the working condition of small current, the temperature of the LED lighting source reaches 35°C, and reaches the heat through heat conduction. The heat of the sensitive coating is not enough to convert the thermotropic cholesteric liquid crystal material from the scattering state to the transparent state; in the scattering state, when the blue light emitted by the gallium nitride chip encounters the thermotropic cholesteric liquid crystal material, it will be reflected back in large quantities, Excite the yttrium aluminum garnet phosphor to produce more yellow light, and the yellow light is smoothly emitted through the thermotropic cholesteric liquid crystal material, and the final light emitted by the LED lighting source is white light with a low color temperature and less blue spectrum; When the current through the LED lighting source is 80mA, the gallium nitride chip excites the YAG phosphor to produce warm white light. Due to the high current, the temperature of the LED lighting source reaches 60°C. At this time, the LED lighting After the heat generated by the light source is conducted to the thermosensitive coating, the thermotropic cholesteric liquid crystal material is converted from a scattering state to a transparent state; in the transparent state, the blue light emitted by the gallium nitride chip is smoothly emitted through the thermotropic cholesteric liquid crystal material, The yellow light is suppressed, and the final light emitted by the LED lighting source is white light with a high color temperature and more blue spectrum. 2. The white LED lighting source with adjustable color temperature as claimed in claim 1, wherein the ambient temperature is controlled by the current flowing through the white LED lighting source with adjustable color temperature.