CN114143930A - Method, medium and device for calculating color temperature of mixed light conversion of cold white LED and warm white LED - Google Patents
Method, medium and device for calculating color temperature of mixed light conversion of cold white LED and warm white LED Download PDFInfo
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Abstract
The application relates to the field of LEDs, in particular to a method for calculating color temperature of cold white and warm white LED mixed light conversion, which comprises the steps of collecting light source parameters of warm white light and cold white light, fitting the light source parameters into a regression formula, setting a target color temperature T, calculating CIE1960 chromatic values (Tu, Tv) of the target color temperature T, reading the current lamp panel temperature NTCTemp, substituting the lamp panel temperature NTCTemp into the regression formula to calculate intersection points (Cu, Cv) of a CW + WW vector and an isochromatic temperature line, and converting the intersection points (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into target CIE1931 chromatic values (Cx, Cy) for controlling PWM pulse ratio, so that errors between the target color temperature T and the actual color temperature CCT are reduced. Meanwhile, the application also provides a device for converting the color temperature by mixing the cold white LED with the warm white LED, which has the effect of smooth transition of the color when the color temperature is continuously adjusted.
Description
Technical Field
The application relates to the technical field of LEDs, in particular to a method, medium and device for calculating color temperature of mixed light conversion of cold white and warm white LEDs.
Background
The mixed light of cold white light CW and warm white light WW LEDs is a model commonly used in the current lighting lamp, and because the mixed light of cold white and warm white LEDs is in a straight line expression mode on a CIE1931 chromaticity space coordinate diagram and is different from a black body radiation locus curve in a curve expression mode, as shown in figure 4, the mixed light is the black body radiation locus curve in the CIE1931 chromaticity space coordinate, and the color temperature is adjusted by using an empirical rule in a traditional color temperature adjustment mode, so that the CIE1931 chromaticity values (x, y) after the mixed light fall near an isochromatic line of a target color temperature, but the pulse ratio of light sources with different color temperatures is different and is not suitable for the empirical rule, but the empirical rule is not enough to be applied to various LED mixed light technologies on the current market, and the problem that the color temperature adjustment is not in accordance with the reality occurs frequently.
Disclosure of Invention
The problem that the color temperature is not matched with the reality by the rule of thumb is solved. The application provides a method, a storage medium and a device for calculating color temperature of mixed light conversion of cold white and warm white LEDs.
In a first aspect, the present application provides a method for calculating a color temperature of a cold-white and warm-white LED mixed light conversion, including the following steps:
s1: collecting warm white CIE1931 chromaticity values (WWx, WWy) and luminous flux WWY of the warm white at different lamp panel temperatures, fitting the data into a first regression formula WW, collecting cold white CIE1931 chromaticity values (CWx, CWy) and luminous flux CWY of the cold white at different lamp panel temperatures, and fitting the data into a second regression formula CW;
s2: setting a target color temperature T, calculating CIE1960 colorimetric values (Tu, Tv) of the target color temperature T through a blackbody radiation formula, and calculating a slope m1 of an isochromatic temperature line of the CIE1960 colorimetric values (Tu, Tv) of the target color temperature T;
s3: reading the current lamp plate temperature NTCTemp, substituting the current lamp plate temperature NTCTemp into the first regression formula WW to calculate a first CIE1931 colorimetric value (WWx, WWy), and substituting the current lamp plate temperature NTCTemp into the second regression formula CW to calculate a second CIE1931 colorimetric value (CWx, CWy);
s4: converting the first CIE1931 chromaticity values (WWx, WWy) into first CIE1960 chromaticity values (WWu, WWv), and converting the second CIE1931 chromaticity values (CWx, CWy) into second CIE1960 chromaticity values (CWu, CWv);
s5: calculating a linear slope m2 of a CW + WW vector of the first CIE1960 chromaticity value (WWu, WWv) and the second CIE1960 chromaticity value (CWu, CWv);
s6: calculating the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line, wherein the calculation formula is as follows:
b1＝Tv-m1×Tu；
b2＝CWv-m2×CWu；
Cu＝(b1-b2)/(m2-m1)；
Cv＝m1×Cu+b1；
s7: and converting the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 chromaticity value (Cx, Cy) for controlling PWM pulse ratio.
By adopting the technical scheme, the light source parameters of warm white light and cold white light are collected and fitted into a regression formula, then the target color temperature T is set, the CIE1960 chromatic values (Tu, Tv) of the target color temperature T are calculated, then the current lamp panel temperature NTCTemp is read, the lamp panel temperature NTCTemp is substituted into the regression formula to calculate the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line, the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line is converted into the target CIE1931 chromatic value (Cx, Cy) for controlling the PWM pulse ratio, the color temperature is not required to be adjusted through an empirical rule, and therefore the error between the target color temperature T and the actual color temperature CCT is reduced.
In some embodiments, step S7 specifically includes the following steps:
converting the intersection (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 chromaticity value (Cx, Cy) for controlling PWM pulse ratio;
calculating an actual color temperature CCT of the target CIE1931 colorimetric values (Cx, Cy) through a color temperature conversion formula, and calculating an error between the actual color temperature CCT and the target color temperature T, wherein the color temperature conversion formula specifically comprises the following steps:
n＝(Cx-0.332)/(Cy-0.1858)：
CCT＝-437×n^3+3601×n^2+6861×n+5514.31。
by adopting the technical scheme, in the process of calculating the intersection point of the isochromatic temperature line of the target color temperature T and the CW + WW vector, because the process of data fitting is involved, an error exists between the finally calculated actual color temperature CCT and the target CIE1931 chromatic value (Cx, Cy).
In some embodiments, the CIE1931 chromaticity values and luminous fluxes of the warm white light and the cold white light at different lamp panel temperatures are collected through the integrating sphere in step S1.
By adopting the technical scheme, when the integrating sphere is used for measuring the luminous flux, the measuring result can be more reliable, and the integrating sphere can reduce and eliminate the measuring error caused by the shape and the divergence angle of the light and the responsivity difference of different positions on the detector.
In some embodiments, the regression formula is re-established by excluding noise from the collected data after collecting the data for warm white light and cool white light in step S1.
By adopting the technical scheme, the regression formula is established by eliminating the noise of the collected data after the data of the warm white light and the cold white light are collected, and the improvement of the precision of the regression formula is facilitated.
In some embodiments, the slope m1 of the isotherm of the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T calculated in step S2 is specifically: calculating the adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) of a target color temperature T by a blackbody radiation formula, calculating the straight line slope m of the adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) and the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T, and calculating the reciprocal of the straight line slope m to obtain the slope m1 of an isotherm.
By adopting the above technical scheme, calculating the slope m of the straight line adjacent to the CIE1960 chromaticity values ((T +1) u, (T +1) v) and the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T is equivalent to calculating the slope of the tangent line of the blackbody radiation curve at the point, and calculating the reciprocal of the slope m is equivalent to obtaining the slope of the normal line of the blackbody radiation locus.
In some embodiments, in step S3, the current lamp panel temperature NTCTemp is read by the temperature sensor.
Through adopting above-mentioned technical scheme, through temperature sensor can be comparatively convenient read current lamp plate temperature NTCTemp.
In some embodiments, the formula for exchanging the CIE1931 chromaticity value to the CIE1960 chromaticity value in step S4 is:
u＝4x/(-2x+12y+3)；
v＝6y/(-2x+12y+3)。
by adopting the technical scheme, since the isotherm in the CIE1960 diagram is perpendicular to the blackbody radiation locus, the conversion of the CIE1931 chromaticity value into the CIE1960 chromaticity value is beneficial to calculating the correlated color temperature.
In some embodiments, the formula of the straight-line slope m2 of the CW + WW vector of the first CIE1960 chromaticity values (WWu, WWv) and the second CIE1960 chromaticity values (CWu, CWv) calculated in step S5 is:
m2＝(CWv-WWv)/(CWu-WWu)。
by adopting the above technical solution, the slope formula can be used to directly calculate the linear slope m2 of the CW + WW vector of the first CIE1960 chromaticity value (WWu, WWv) and the second CIE1960 chromaticity value (CWu, CWv).
In a second aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the computing method as described in any implementation manner of the first aspect.
In a third aspect, the present application further provides an apparatus for converting color temperature by mixing cold white and warm white LEDs, including:
the illumination module comprises warm white light, cold white light and a PWM pulse module for adjusting the color temperature ratio of the warm white light and the cold white light;
an input module including a display device for inputting a target color temperature T;
and the color temperature control module is used for reading a target color temperature T, calculating and obtaining target CIE1931 colorimetric values (Cx, Cy) through the calculation method of the first aspect, and controlling the PWM pulses to adjust the color temperatures of the warm white light and the cold white light through the target CIE1931 colorimetric values (Cx, Cy).
By adopting the scheme, the target color temperature T with any numerical value can be input through the input module, and the error between the actual color temperature CCT calculated and output by the color temperature calculation method disclosed by the application and the target color temperature T is small, so that the illumination device has the advantage of smooth color transition when the color temperature is continuously adjusted.
The embodiment of the application discloses a method for calculating color temperature of cold white and warm white LED mixed light conversion, which comprises the steps of collecting light source parameters of warm white light and cold white light, fitting the light source parameters into a regression formula, setting a target color temperature T, calculating CIE1960 chromatic values (Tu, Tv) of the target color temperature T, reading current lamp panel temperature NTCTemp, substituting the lamp panel temperature NTCTemp into the regression formula to calculate intersection points (Cu, Cv) of a CW + WW vector and an isochromatic temperature line, and converting the intersection points (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into target CIE1931 chromatic values (Cx, Cy) for controlling PWM pulse ratio, so that errors between the target color temperature T and actual color temperature are reduced, and the problem that the color temperature is not matched with the actual color temperature through an empirical rule is solved. Meanwhile, the application also provides a device for converting the color temperature by mixing the cold white LED with the warm white LED, which has the effect of smooth transition of the color when the color temperature is continuously adjusted.
Drawings
The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the application. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.
Fig. 1 is a schematic flowchart of a method for calculating a color temperature of mixed light conversion of cold white and warm white LEDs according to an embodiment of the present application.
Fig. 2 is a schematic block diagram of an apparatus for converting color temperature by mixing cold white and warm white LEDs according to an embodiment of the present application.
Fig. 3 is a representation of a CIE1931 chromaticity space coordinate diagram of a method for calculating a color temperature of a cold white and warm white LED mixed light conversion disclosed in an embodiment of the present application.
Fig. 4 is a CIE1931 chromaticity space coordinate diagram in the prior art.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described in further detail with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 is a schematic flowchart illustrating a method for calculating a color temperature of mixed light conversion of cold white and warm white LEDs, to which an embodiment of the present application may be applied, and includes the following steps:
s1: collecting warm white CIE1931 chromaticity values (WWx, WWy) and warm white luminous flux WWY of warm white light at different lamp panel temperatures, fitting the data into a first regression formula WW, collecting cold white CIE1931 chromaticity values (CWx, CWy) and cold white luminous flux CWY of cold white light at different lamp panel temperatures, and fitting the data into a second regression formula CW.
In a preferred embodiment, in step S1, the CIE1931 chromaticity values and luminous fluxes of the warm white light and the cold white light at different lamp panel temperatures are collected through the integrating sphere, the light source collection is usually performed by long-time collection in the integrating sphere, and in the collection process, the warm white light and the cold white light are collected at regular intervals, and the interval is changed according to different integrating times of different light source types. When the integrating sphere is used for collecting light source data, the measuring result can be more reliable, and the integrating sphere can reduce and eliminate measuring errors caused by the shape and the divergence angle of light and the responsivity difference of different positions on the detector.
In other embodiments, the light source signal acquisition device such as an LED tester or a distribution photometer may be used to acquire the light source signal of warm white light and cold white light.
In a preferred embodiment, after the light source data is collected in S1, the regression formula is established by excluding the noise of the collected data, specifically, the standard deviation of the data may be calculated first, then blank data is excluded by numerical calculation, and finally the regression formula is obtained.
The first regression formula WW in this embodiment is specifically:
WWx＝-0.000136*NTC_Temp+0.4673；
WWy＝-0.000067*NTC_Temp+0.4171：
WWY＝-0.4942*NTC_Temp+532.24。
the second regression formula CW in this embodiment is specifically:
CWx＝-0.000120*NTC_Temp+0.3202：
CWy＝-0.000165*NTC_Temp+0.3364；
CWY＝-0.5590*NTC_Temp+488.40。
wherein, NTC _ Temp is the temperature of the lamp panel.
In other embodiments, suitable light source regression equations may be used depending on the accuracy requirements.
S2: the target color temperature T is set, CIE1960 chromaticity values (Tu, Tv) of the target color temperature T are calculated by a blackbody radiation formula, and a slope m1 of an isochromatic temperature line of the CIE1960 chromaticity values (Tu, Tv) of the target color temperature T is calculated.
In black body radiation, the color of light varies with temperature, and black bodies exhibit a gradual change of red, orange-red, yellow-white, blue-white. The color of light emitted by a light source appears to be the same as the color of light emitted by a black body at a temperature, which is referred to as the color temperature of the light source. To improve the CIE1960 chromaticity space, also known as CIE1960 UCS, which is designed to improve the non-uniformity of the CIE1931 chromaticity space, the CIE defined the uniform chromaticity space coordinates, CIE1960 is mainly used to calculate the correlated color temperature, wherein the isochromatic temperature line is perpendicular to the black body radiation locus curve.
In a preferred embodiment, the slope m1 of the isotherm of the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T calculated in step S2 is specifically: calculating the adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) of the target color temperature T by the black body radiation formula, calculating the straight line slope m of the adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) and the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T, and calculating the reciprocal of the straight line slope m to obtain the slope m1 of the isotherm.
By calculating the slope m of a straight line adjacent to the CIE1960 chromaticity values ((T +1) u, (T +1) v) and the TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T corresponds to calculating the slope of a tangent line of the blackbody radiation curve at that point, and calculating the reciprocal of the slope m corresponds to obtaining the slope of a normal line of the blackbody radiation locus, i.e., the slope of the isotherm.
An example of the calculation is as follows:
the CIE1960 chromaticity value of the color temperature 3000K is calculated to be (0.25056823, 0.34758903) by a black body radiation formula;
the CIE1960 chromaticity value of the color temperature 3001K is calculated to be (0.25053285, 0.34757553) by the black body radiation formula;
calculate 3000K and 3001K chroma normal slopes:
m1＝-1/(((0.34757553-0.34758903))/((0.25053285-0.25056823)))＝-2.6 2082518。
in other embodiments, the accuracy of the calculated m1 may be improved by reducing the difference between the neighboring color temperature and the target color temperature.
S3: reading the current lamp plate temperature NTCTemp, substituting the lamp plate temperature NTCTemp into a first regression formula WW to calculate a first CIE1931 chromatic value (WWx, WWy), and substituting the lamp plate temperature NTCTemp into a second regression formula CW to calculate a second CIE1931 chromatic value (CWx, CWy).
In a preferred embodiment, in step S3, the current lamp panel temperature NTCTemp is read by a temperature sensor.
S4: converting the first CIE1931 chromaticity values (WWx, WWy) into first CIE1960 chromaticity values (WWu, WWv), and converting the second CIE1931 chromaticity values (CWx, CWy) into second CIE1960 chromaticity values (CWu, CWv).
Since the isotherms in the CIE1960 chromaticity diagram are perpendicular to the blackbody radiation locus, converting the CIE1931 chromaticity values to CIE1960 chromaticity values facilitates subsequent calculations.
The formula for converting the CIE1931 chromaticity value into the CIE1960 chromaticity value is as follows:
u＝4x/(-2x+12y+3)；
v＝6y/(-2x+12y+3)。
s5: the slope m2 of the straight line of the CW + WW vector of the first CIE1960 chromaticity values (WWu, WWv) and the second CIE1960 chromaticity values (CWu, CWv) is calculated.
Wherein, the formula for calculating the slope m2 of the straight line of the CW + WW vector of the first CIE1960 chromaticity value (WWu, WWv) and the second CIE1960 chromaticity value (CWu, CWv) is:
m2＝(CWv-WWv)/(CWu-WWu)。
s6: calculating the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line, wherein the calculation formula is as follows:
b1＝Tv-m1×Tu；
b2＝CWv-m2×CWu；
Cu＝(b1-b2)/(m2-m1)；
Cv＝m1×Cu+b1：
wherein b1 and b2 are intercepts.
S7: converting the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 chromatic value (Cx, Cy) for controlling the PWM pulse ratio;
wherein, the conversion formula of the CIE1960 chromaticity value to the CIE1931 chromaticity value is as follows:
x＝3u/(2u-8v+4)；
y＝2v/(2u-8v+4)。
in a preferred embodiment, S7 specifically includes the following steps:
converting the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 colorimetric value (Cx, Cy) for controlling the PWM pulse ratio, calculating the actual color temperature CCT of the target CIE1931 colorimetric value (Cx, Cy) through a color temperature conversion formula, and calculating the error between the actual color temperature CCT and the target color temperature T, wherein the color temperature conversion formula specifically comprises the following steps:
n＝(Cx-0.332)/(Cy-0.1858)；
CCT＝-437×n^3+3601×n^2+6861×n+5514.31。
an example of the calculation is as follows:
the target CIE1931 chromaticity value is (0.4369, 0.4041) when the target color temperature T is 3000K calculated through the above steps, 2999.7K is calculated through the color temperature conversion formula, and the error between the actual color temperature CCT and the target color temperature T is 3000K-2999.7K ═ 0.3K.
Fig. 3 shows the actual color temperature CCT in CIE1931 chromaticity space coordinates in the above calculation example.
According to embodiments disclosed herein, the processes described above with reference to the flowcharts may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising a computer program embodied on a computer readable medium, the computer program containing program code for performing the method illustrated in fig. 1. The computer program performs the above-described functions defined in the method of the present application when executed by a Central Processing Unit (CPU) and a Graphics Processing Unit (GPU).
It should be noted that the computer readable medium described herein can be a computer readable signal medium or a computer readable medium or any combination of the two. The computer readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor device, apparatus, or any combination of the foregoing. More specific examples of the computer readable medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the present application, a computer readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution apparatus, device, or apparatus. In this application, however, a computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution apparatus, device, or apparatus. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, fiber optic cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + +, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
With further reference to fig. 2, as an implementation of the above method, the present application provides an embodiment of an apparatus for converting color temperature by mixing cold white and warm white LEDs, which corresponds to the embodiment of the method shown in fig. 1, and which can be applied in various electronic devices.
As shown in fig. 2, the device for converting color temperature by mixing cold white and warm white LEDs of the present embodiment comprises:
the lighting module 103 comprises a warm white light module, a cold white light module and a PWM pulse module for adjusting the color temperature ratio of the warm white light and the cold white light;
the display device comprises an input module 101, wherein the input module 101 comprises a display device for inputting a target color temperature T, a color temperature control interface is arranged on the display device, and the target color temperature T can be input through the color temperature control interface.
The color temperature control module 102, the color temperature control module 102 is configured to read the target color temperature T in the input module 101, calculate and obtain target CIE1931 chromaticity values (Cx, Cy) through the calculation method in the above method embodiment, and control the PWM pulse through the target CIE1931 chromaticity values (Cx, Cy) to adjust the color temperature after mixing the warm white light and the cold white light.
Any target color temperature T can be input through the color temperature control interface, the error between the actual color temperature CCT and the target color temperature T which is calculated and output through the color temperature calculation method disclosed by the application is less than 20K, and the visual defect that the color is not smooth when the color temperature of the lighting device is continuously adjusted can be overcome.
While the principles of the present application have been described in detail above in connection with preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of exemplary implementations of the present application and are not limiting of the scope of the present application. The details of the embodiments are not to be interpreted as limiting the scope of the application, and any obvious changes, such as equivalent alterations, simple substitutions and the like, based on the technical solution of the application, can be interpreted without departing from the spirit and scope of the application.
Claims (10)
1. A method for calculating color temperature of cold white and warm white LED mixed light conversion is characterized by comprising the following steps:
s1: collecting warm white CIE1931 chromaticity values (WWx, WWy) of the warm white at different lamp panel temperatures, fitting the data into a first regression formula WW, collecting cold white CIE1931 chromaticity values (CWx, CWy) of the cold white at different lamp panel temperatures, and fitting the data into a second regression formula CW;
s2: setting a target color temperature T, calculating CIE1960 colorimetric values (Tu, Tv) of the target color temperature T through a blackbody radiation formula, and calculating a slope m1 of an isochromatic temperature line of the CIE1960 colorimetric values (Tu, Tv) of the target color temperature T;
s3: reading the current lamp plate temperature NTCTemp, substituting the current lamp plate temperature NTCTemp into the first regression formula WW to calculate a first CIE1931 colorimetric value (WWx, WWy), and substituting the current lamp plate temperature NTCTemp into the second regression formula CW to calculate a second CIE1931 colorimetric value (CWx, CWy);
s4: converting the first CIE1931 chromaticity values (WWx, WWy) into first CIE1960 chromaticity values (WWu, WWv), and converting the second CIE1931 chromaticity values (CWx, CWy) into second CIE1960 chromaticity values (CWu, CWv);
s5: calculating a linear slope m2 of a CW + WW vector of the first CIE1960 chromaticity value (WWu, WWv) and the second CIE1960 chromaticity value (CWu, CWv);
s6: calculating the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line, wherein the calculation formula is as follows:
b1＝Tv-m1×Tu；
b2＝CWv-m2×CWu；
Cu＝(b1-b2)/(m2-m1)；
Cv＝m1×Cu+b1；
s7: and converting the intersection point (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 chromaticity value (Cx, Cy) for controlling PWM pulse ratio.
2. The method as claimed in claim 1, wherein the step S7 specifically includes the following steps:
converting the intersection (Cu, Cv) of the CW + WW vector and the isochromatic temperature line into a target CIE1931 chromaticity value (Cx, Cy) for controlling PWM pulse ratio;
calculating an actual color temperature CCT of the target CIE1931 colorimetric values (Cx, Cy) through a color temperature conversion formula, and calculating an error between the actual color temperature CCT and the target color temperature T, wherein the color temperature conversion formula specifically comprises the following steps:
n＝(Cx-0.332)/(Cy-0.1858)；
CCT＝-437×n^3+3601×n^2+6861×n+5514.31。
3. the method of claim 1, wherein the method comprises: in the step S1, CIE1931 chromaticity values and luminous fluxes of the warm white light and the cold white light at different lamp panel temperatures are collected through the integrating sphere.
4. The method of claim 1, wherein the method comprises: and after the data of the warm white light and the cold white light are collected in the S1, a regression formula is established by eliminating the noise of the collected data.
5. The method as claimed in claim 1, wherein the slope m1 of the isochromatic curve for calculating the chromaticity values (Tu, Tv) of TCIE1960 of the target color temperature T in S2 is specifically: calculating adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) of a target color temperature T by a blackbody radiation formula, calculating a straight line slope m of the adjacent CIE1960 chromaticity values ((T +1) u, (T +1) v) and TCIE1960 chromaticity values (Tu, Tv) of the target color temperature T, and calculating the reciprocal of the straight line slope m to obtain the slope m1 of the isotherm.
6. The method of claim 1, wherein the method comprises: and in the step S3, reading the current lamp panel temperature NTCTemp through a temperature sensor.
7. The method of claim 1, wherein the method comprises: the formula for converting the CIE1931 chromaticity value in S4 into the CIE1960 chromaticity value is as follows:
u＝4x/(-2x+12y+3)；
v＝6y/(-2x+12y+3)。
8. the method of claim 1, wherein the method comprises: the formula of calculating the straight slope m2 of the CW + WW vector of the first CIE1960 chromaticity values (WWu, WWv) and the second CIE1960 chromaticity values (CWu, CWv) in S5 is:
m2＝(CWv-WWv)/(CWu-WWu)。
9. a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the calculation method according to any one of claims 1 to 8.
10. A device for converting color temperature by mixing cold white and warm white LEDs is characterized by comprising:
an illumination module comprising warm white light, cold white light, and a PWM pulse module for adjusting color temperatures of the warm white light and the cold white light;
an input module including a display device for inputting a target color temperature T;
a color temperature control module, configured to read the target color temperature T in the input module, calculate and obtain target CIE1931 chromaticity values (Cx, Cy) through the calculation method of any one of claims 1 to 8, and control the PWM pulse to adjust the color temperature after the warm white light and the cold white light are mixed through the target CIE1931 chromaticity values (Cx, Cy).
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