LED lamp capable of automatically compensating thermal state color point deviation

Abstract

The invention provides an LED lamp capable of automatically compensating thermal state color point deviation. The LED lamp comprises an LED light source and a compensation loop. The compensation loop is provided with a thermistor and a compensation light source in series, the thermistor is used for detecting the light emitting temperature of the LED light source, changing the resistance value of the thermistor according to the temperature change, and adjusting the light supplementing brightness of the compensation light source according to the resistance value change of the thermistor so as to keep the color temperature and the color point position of the light source output by the LED lamp basically unchanged before and after heating; by introducing the thermistor and the compensation light source, automatic compensation of color temperature and color point deviation after the LED light source is heated is achieved, the light emitting color quality of the LED lamp is improved, the price and cost of the compensation loop are low, and complex materials and processes are not needed.

Description

Technical Field

[0001] The invention relates to the technical field of LED light sources, and in particular to an LED lamp capable of automatically compensating for thermal color point deviation. Background Art

[0002] With the widespread application of LED technology in the field of lighting, the market has increasingly stringent requirements for the color quality of LED lights. However, after heating, the color temperature and color point position of existing LED light sources will shift, and the direction and distance of the shift of different types of LED light sources are different, resulting in LED lights showing different color temperatures and colors than when they are working normally, which will affect the visual effect of lighting, especially in occasions that require color consistency, such as commercial lighting, art exhibitions, etc. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an LED lamp that automatically compensates for thermal color point shift to solve the problems mentioned in the above background technology section.

[0004] The present invention is achieved through the following technical solutions:

[0005] An LED lamp that automatically compensates for thermal color point deviation comprises an LED light source and a compensation circuit; the compensation circuit is provided with a thermistor and a compensation light source in series, the thermistor is used to detect the luminous temperature of the LED light source, and changes its resistance value according to temperature changes, and the fill light brightness of the compensation light source is adjusted according to the change in the resistance value of the thermistor to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating.

[0006] Furthermore, when the thermistor is a positive temperature coefficient thermistor, the compensation light source is normally lit at an initial low temperature; as the temperature rises, the resistance value of the thermistor gradually increases, and the current of the compensation circuit gradually decreases, thereby reducing the fill light brightness of the compensation light source.

[0007] Furthermore, when the thermistor is a negative temperature coefficient thermistor, the compensation light source is basically dim at an initial low temperature; as the temperature rises, the resistance value of the thermistor gradually decreases, and the current of the compensation circuit gradually increases, thereby increasing the compensation light brightness of the compensation light source.

[0008] Furthermore, the compensation light source includes a monochromatic LED chip or a monochromatic excitation phosphor.

[0009] Furthermore, the LED light sources are arranged in a circular array with the compensation light source as the center.

[0010] Furthermore, the compensation light source and the LED light source are arranged at a distance of 1.5 mm to 5 mm.

[0011] Furthermore, the LED light source includes a substrate in a COB package form, and the thermistor is arranged near the substrate or the light-emitting surface of the LED light source.

[0012] Furthermore, the variation accuracy of the thermistor is ±0.05°C, and the B value is 2000K to 5000K.

[0013] The beneficial effects of the present invention are: an LED lamp that automatically compensates for thermal color point deviation, including an LED light source and a compensation circuit; the compensation circuit is provided with a thermistor and a compensation light source in series, the thermistor is used to detect the luminous temperature of the LED light source, and its resistance value is changed according to the temperature change, and the fill light brightness of the compensation light source is adjusted according to the change in the resistance value of the thermistor to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating. By introducing the thermistor and the compensation light source, automatic compensation for the color temperature and color point deviation of the LED light source after heating is achieved, thereby improving the luminous color quality of the LED lamp, and the compensation circuit has low price and cost, and does not require complicated materials and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. 4 is a circuit diagram of the compensation loop of the present invention.

[0015] Figure 2 This is a graph showing the wavelength variation of LED lamps, LED light sources, and compensation light sources as temperature changes when using a positive temperature coefficient thermistor.

[0016] Figure 3 This is a graph showing the wavelength variation of LED lamps, LED light sources, and compensation light sources as temperature changes when using a negative temperature coefficient thermistor.

[0017] Figure 4 It is a schematic diagram of the arrangement position relationship of the LED light source and the compensation light source of the present invention.

[0018] The above drawings include the following reference numerals:

[0019] 1. LED light source; 2. compensation circuit; 21. thermistor; 22. compensation light source. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Reference Figures 1 to 4 As shown, an LED lamp that automatically compensates for thermal color point deviation includes an LED light source 1 and a compensation circuit 2; the compensation circuit 2 is provided with a thermistor 21 and a compensation light source 22 in series, the thermistor 21 is used to detect the luminous temperature of the LED light source 1, and changes its resistance value according to the temperature change, and adjusts the fill light brightness of the compensation light source 22 according to the change in the resistance value of the thermistor 21, so as to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating.

[0022] When the thermistor 21 is a positive temperature coefficient thermistor 21, the compensation light source 22 is normally lit at an initial low temperature; as the temperature rises, the resistance value of the thermistor 21 gradually increases, and the current of the compensation loop 2 gradually decreases, thereby reducing the compensation light brightness of the compensation light source 22.

[0023] When LED lights emit white light, there will be a wavelength red shift phenomenon, that is, as the junction temperature increases, the wavelength of the LED light will change, usually manifested as a longer wavelength, that is, a red shift. This is because the temperature increase causes the bandgap width of the material to decrease, thereby increasing the wavelength of the device light. LEDs of different materials have different sensitivities to temperature, and their wavelength changes with temperature coefficients are also different. For example, when the temperature of InGaAlP series LEDs rises, the wavelength changes by about 0.1nm / ℃, changing to the long wavelength side.

[0024] Reference Figure 2 As shown, in order to make the LED lamp emit white light and use a positive temperature coefficient thermistor 21, the compensation light source 22 is a monochromatic LED chip or a monochromatic excitation phosphor that emits red light. Specifically, at the initial low temperature, the compensation light source 22 on the compensation loop 2 is normally lit. As the temperature rises, the resistance of the thermistor 21 increases, the current of the compensation loop 2 decreases, and the compensation light source 22 gradually dims to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating. For example, at 25°C, the color temperature reaches 3000K, and the color rendering index CRI reaches 80. When heated to 85°C, the resistance value of the thermistor 21 rises to an extremely high level, and the compensation light source 22 gradually dims, reducing the output of red light, so that the color point position no longer moves in the reddish direction, or moves very little.

[0025] Reference Figure 3 As shown, when the thermistor 21 is a negative temperature coefficient thermistor 21, the compensation light source 22 is basically not bright at the initial low temperature; as the temperature rises, the resistance value of the thermistor 21 gradually decreases, and the current of the compensation loop 2 gradually increases, thereby increasing the fill light brightness of the compensation light source 22.

[0026] When the LED lamp is made to emit white light and a negative temperature coefficient thermistor 21 is used, the compensation light source 22 is a monochromatic LED chip or a monochromatic excitation phosphor that emits green light. Specifically, at the initial low temperature, the compensation light source 22 on the compensation loop 2 is basically not bright. As the temperature rises, the resistance of the thermistor 21 decreases, the current of the compensation loop 2 increases, and the compensation light source 22 gradually becomes brighter to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating. For example, at 25°C, the color temperature reaches 3000K, and the color rendering index CRI reaches 80. When heated to 85°C, the resistance value of the thermistor 21 drops to an extremely low level, and the compensation light source 22 gradually becomes brighter, increasing the green light output. The green light provided will cause the color point to move in the green direction, and at this time they will cancel each other out, and the position will no longer move in the red direction, or move very little.

[0027] Because the compensation loop 2 will occupy the chip space of the LED, if the temperature of the LED light source 1 does not rise much during use, it will be more advantageous to use the compensation loop 2 with a positive temperature coefficient thermistor 21; if the temperature of the LED light source 1 rises very high during use, it will be more advantageous to use the compensation loop 2 with a negative temperature coefficient thermistor 21.

[0028] In practical applications, the design of the compensation light source 22 needs to be customized according to the thermal offset characteristics of the LED light source 1. For example, for an LED light source 1 that is easily offset to red, the compensation circuit 2 can be mainly composed of a green monochromatic LED chip or a monochromatic excitation phosphor; for an LED light source 1 that is easily offset to blue, the compensation circuit 2 can be mainly composed of a red monochromatic LED chip or a monochromatic excitation phosphor. The LED lamp of the present invention is mainly used in occasions that require high-precision color control, such as stage lighting, film and television shooting, museum lighting and other fields, providing a more stable and reliable lighting solution for these fields.

[0029] Reference Figure 4 As shown, the LED light sources 1 are arranged in a circular array with the compensation light source 22 as the center, so that a small number of compensation light sources 22 can be used to compensate for multiple LED light sources 1.

[0030] The compensation light source 22 and the LED light source 1 are arranged at a distance of 1.5 mm to 5 mm to achieve higher brightness and better light effect.

[0031] The LED light source 1 includes a substrate in a COB package form, and the thermistor 21 is arranged near the substrate or the light-emitting surface of the LED light source 1. Thus, the thermistor 21 can quickly and accurately identify the heat generated when the LED light source 1 emits light.

[0032] The variation accuracy of the thermistor 21 is ±0.05° C., and the B value of the thermistor 21 is 2000 K to 5000 K. This type of thermistor 21 has a high sensitivity, and the monochromatic excitation phosphor can be selected from CaGdAlO4:Er3+ / Yb3+ phosphor.

[0033] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An LED lamp that automatically compensates for thermal color point shift, characterized in that: Including LED light source and compensation circuit; The compensation circuit is provided with a thermistor and a compensation light source in series. The thermistor is used to detect the luminous temperature of the LED light source, and changes its resistance value according to the temperature change. The fill light brightness of the compensation light source is adjusted according to the change in the resistance value of the thermistor to keep the color temperature and color point position of the light source output by the LED lamp basically unchanged before and after heating.

2. The LED lamp capable of automatically compensating for thermal color point deviation according to claim 1, characterized in that: When the thermistor is a positive temperature coefficient thermistor, the compensation light source is normally lit at an initial low temperature; as the temperature rises, the resistance value of the thermistor gradually increases, and the current of the compensation loop gradually decreases, thereby reducing the compensation light brightness of the compensation light source.

3. The LED lamp capable of automatically compensating for thermal color point deviation according to claim 1, characterized in that: When the thermistor is a negative temperature coefficient thermistor, the compensation light source is basically not bright at an initial low temperature; as the temperature rises, the resistance value of the thermistor gradually decreases, and the current of the compensation loop gradually increases, thereby increasing the compensation light brightness of the compensation light source.

4. The LED lamp with automatic compensation for thermal color point shift according to claim 1, 2 or 3, characterized in that: The compensation light source includes a monochromatic LED chip or a monochromatic excitation phosphor.

5. The LED lamp capable of automatically compensating for thermal color point shift according to claim 1, characterized in that: The LED light sources are arranged in a circular array with the compensation light source as the center.

6. The LED lamp capable of automatically compensating for thermal color point shift according to claim 5, characterized in that: The compensation light source and the LED light source are arranged at a distance of 1.5 mm to 5 mm.

7. The LED lamp capable of automatically compensating for thermal color point shift according to claim 1, characterized in that: The LED light source includes a substrate in a COB package form, and the thermistor is arranged near the substrate or the light-emitting surface of the LED light source.

8. The LED lamp capable of automatically compensating for thermal color point shift according to claim 1, characterized in that: The variation accuracy of the thermistor is ±0.05°C, and the B value is 2000K to 5000K.

Images