Method for calculating duty ratio of white light color temperature when RGBY four-way mixed light

Abstract

The application provides a method for calculating the duty cycle of white light color temperature when RGBY four-way mixed light is generated, which comprises the following steps: four color points of RGBY form a quadrilateral on a CIE 1931 chromaticity diagram; an intersection A1(x A1 , y A1 ) of the straight line and the straight line is obtained; two intersections of the straight line and the other two straight lines are obtained, and only one of the two intersections is located in the interior of a triangle formed by three color points of three-way light used for mixed light, and the one is selected as A2(x A2 , y A2 ); a line segment connecting A1(x A1 , y A1 ) and A2(x A2 , y A2 ) is divided into n nodes, the corresponding duty cycles are calculated by using the three color points of the three-way light used for mixed light, and the duty cycle of the remaining one-way light is calculated by using a two-way mixed light algorithm; the highest color rendering index duty cycle is selected from the obtained n groups of duty cycles; and the relationship between the duty cycle of the four-way light and the color temperature is fitted into a function. The method can effectively reduce the product cost and improve the use value of the RGB mixed light product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated LED light mixing technology, and particularly relates to a method for calculating duty cycle of white light color temperature in RGBY four-way light mixing. BACKGROUND

[0002] According to the calculation principle of the CRI index, the white light produced by mixing RGB color light with a relatively narrow half-wave width usually has a relatively low color rendering index, which has resulted in that color light lamps cannot simultaneously have the ability of high color gamut and high color rendering index for a long time.

[0003] A common method is to add 1-2 ways of white light to supplement on the basis of narrow-band RGB individual light spectrum, but this scheme also has the disadvantages of high cost, patent restrictions, etc. Another scheme is to add a way of yellow light Y to supplement the spectrum at the defect of the RG spectrum of the RGB narrow-band light spectrum, and this scheme needs four light sources to be lit at the same time to achieve the ability of high color rendering index of white light. However, when RGBY four-way light mixing is performed, there are numerous mixing ratios for the same color point, and how to conveniently and quickly achieve high light efficiency spectrum of RGBY four-way light mixing has practical application significance. SUMMARY

[0004] To achieve the above object, the present application adopts the following technical scheme:

[0005] The present application provides a method for calculating duty cycle of white light color temperature in RGBY four-way light mixing,

[0006] S1, determining an RGBY chromaticity range on a CIE1931 chromaticity diagram, defining any four color points P1, P2, P3 and P0 in the chromaticity range, obtaining a color point M(x m , y m ) formed by mixing light of the color points P1, P2 and P3, and synthesizing a white light color point T(x m , y m ) by using the color point P0 and the color point M(x t , y t );

[0007] S2, obtaining a straight line connecting the color point P0 and the color point M(x , y );

[0008]

[0009] wherein x and y are color coordinates in the CIE1931 chromaticity diagram, is a slope of the straight line , and is an intercept of the straight line corresponding to the slope m;

[0010] S3, obtain three straight lines formed by color points P1, P2 and P3, and the forms are as follows:

[0011]

[0012] wherein, is the slope corresponding to straight line P1P2, is the intercept corresponding to straight line P1P2, is the slope corresponding to straight line P2P3, is the intercept corresponding to straight line P2P3, is the slope corresponding to straight line P1P3, is the intercept corresponding to straight line P1P3; obtain the intersection points of straight lines P1P2, P2P3 and P1P3 and straight line , define the intersection point of the shortest straight line and straight line as A1(x A1 , y A1 ) and the intersection point located in the triangular region formed by color points P1, P2 and P3 as A2(x A2 , y A2 );

[0013] S4, connect A1(x A1 , y A1 ) and A2(x A2 , y A2 ), divide the line segment A1A2 into n nodes, and calculate the first duty ratio of n groups of color points P1, P2, P3 and P0 by using the light mixing algorithm;

[0014] S5, define the duty ratio of color points P1, P2, P3 and P0 with the highest color rendering index in the obtained n groups of first duty ratios as the second duty ratio, and fit the relationship between the second duty ratio and the color temperature into a function.

[0015] The technology can output a set of formulas for quickly calculating RGBY mixed high-color-rendering white light based on different RGBY spectral schemes. This technology can effectively reduce product cost and improve the use value of RGB light mixing products.

[0016] Specifically, the RGBY chromaticity range is composed of blue light, green light, red light and yellow light color points; the blue light color point is distributed as x: 0.1401±0.200, y: 0.0386±0.200, the peak wavelength is 400-470 nm, and the half wave width is 20-50 nm; the green light color point is distributed as x: 0.1213±0.200, y: 0.7453±0.200, the peak wavelength is 520±40 nm, and the half wave width is 20-70 nm; the red light color point is distributed as x: 0.6770±0.200, y: 0.3225±0.200, the peak wavelength is 590-680 nm, and the half wave width is 20-70 nm; and the yellow light color point is distributed as x: 0.3585±0.200, y: 0.6300±0.200, the peak wavelength is 570±40 nm, and the half wave width is 20-30 nm. Specifically, the blue light color point is generated by a blue light quantum dot LED chip with a peak wavelength of 400-470 nm or a blue light fluorescent powder excited by light; the green light color point is generated by a green light LED chip with a peak wavelength of 480-560 nm or a green light fluorescent powder excited by light; the red light color point is generated by a red light LED chip with a peak wavelength of 590-680 nm or a red light fluorescent powder excited by light; and the yellow light color point is generated by a yellow light LED chip with a peak wavelength of 530-610 nm or a yellow light fluorescent powder excited by light.

[0017] Specifically, the blue light, green light, red light and yellow light color points are distributed in the CIE1931 chromaticity diagram in the order of RGYB from the lower left to the lower right; and the luminous flux of the blue light, green light, red light and yellow light color points is in the order of G or Y>R>B.

[0018] The above-described spectrum includes but is not limited to the standard RGB spectrum shown above, and a spectrum scheme with a spectral root mean square error of the standard RGB spectrum within 0.3 can also be applicable to the present application. The spectral root mean square error is SRMSE, and the formula is:

[0019]

[0020] In the formula, λ is the wavelength, φ ref is the spectral energy of the standard RGB spectrum at the wavelength λ, and φ is the spectral energy of the other RGB spectrum at the wavelength λ.

[0021] Specifically, the duty cycles of the n groups of color points P1, P2, P3 and P0 are calculated according to the color points P1, P2, P3 and P0 by using the Grassmann light mixing formula, as shown below:

[0022]

[0023]

[0024]

[0025] wherein, wherein x, y, Y are target color coordinates and luminous flux respectively, and η1, η2, η3 and η0 are the first duty cycles of color points P1, P2, P3 and P0 respectively.

[0026] Specifically, S5 specifically comprises:

[0027] S501, in the selected characteristic color temperature range, the selected color temperature range is divided into N color temperature nodes, and the second duty cycle of each color temperature node under the optimal color rendering index is obtained according to the methods of S1-S4;

[0028] S502, the relationship between the second duty cycle and the color temperature is fitted as a function.

[0029] Specifically, the fitting method of fitting the relationship between the second duty cycle and the color temperature as a function in S502 comprises: adopting the least square method, Levenberg-Marquardt algorithm, in actual product use, the obtained fitting function can be written, the fitting function is used to quickly calculate the duty cycle corresponding to the white light color temperature, and the normalization calculation and the nonlinear calibration calculation need to be performed in the actual product.

[0030] Specifically, the above spectrum can form 1800K-7000K white light with a color rendering index greater than 85 after mixing light in a certain proportion.

[0031] The beneficial effects of the present application are as follows:

[0032] The technology can output a set of formulas for quickly calculating RGBY mixed high-color rendering white light based on different RGBY spectrum schemes. This technology can effectively reduce product cost and improve the use value of RGB mixed light products. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and serve the purpose of explaining principles of the present application. Other embodiments and many of the intended advantages of the embodiments will be readily appreciated as the same becomes better understood by reference to the following detailed description. Elements of the drawings are not necessarily to scale. Like reference numbers designate corresponding similar parts.

[0034] Figure 1 is a flowchart of a method for calculating the duty cycle of white light color temperature when RGBY four-way light mixing according to an embodiment of the present application;

[0035] Figure 2 is a flowchart of S5 in a method for calculating the duty cycle of white light color temperature when RGBY four-way light mixing according to an embodiment of the present application;

[0036] Figure 3 is a RGBY spectrum diagram of a method for calculating duty cycle of white light color temperature when RGBY four-way mixed light according to one embodiment of the present application;

[0037] Figure 4 is a CIE1931 color gamut diagram of a method for calculating duty cycle of white light color temperature when RGBY four-way mixed light according to one embodiment of the present application;

[0038] Figure 5 is a CIE1931 color gamut diagram of a method for calculating duty cycle of white light color temperature when RGBY four-way mixed light according to another embodiment of the present application;

[0039] Figure 6 is a red light effect diagram of obtaining relationship between RGBY and color temperature and fitting result thereof according to another embodiment of the present application;

[0040] Figure 7 is a green light effect diagram of obtaining relationship between RGBY and color temperature and fitting result thereof according to another embodiment of the present application;

[0041] Figure 8 is a blue light effect diagram of obtaining relationship between RGBY and color temperature and fitting result thereof according to another embodiment of the present application;

[0042] Figure 9 is a yellow light effect diagram of obtaining relationship between RGBY and color temperature and fitting result thereof according to another embodiment of the present application;

[0043] Figure 10 is a Duv effect diagram calculated by fitting formula of spectrum according to another embodiment of the present application. DETAILED DESCRIPTION

[0044] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration illustrative embodiments in which the application can be practiced. For purposes of explanation and illustration, directional terms are used with reference to the orientation of the described figures. However, it is to be understood that the embodiments can assume different orientations, except where otherwise specified and that the directions are, therefore, illustrative only. It is to be understood that the following detailed description is by way of illustration only, and is not intended to limit the scope of the application. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present application is defined by the appended claims.

[0045] Figure 1 is a flow chart of a method for calculating duty cycle of white light color temperature when RGBY four-way mixed light according to an embodiment of the present application, as shown in Figure 1A method for calculating the duty cycle of white light color temperature when RGBY four-way mixed light is shown,

[0046] S1, determining the RGBY chromaticity range on the CIE1931 chromaticity diagram, defining any four color points P1, P2, P3 and P0 in the chromaticity range, obtaining the color point M(x m , y m ) formed by mixing light of color points P1, P2 and P3, and synthesizing white light color point T(x m , y m ) using color point P0 and color point M(x t , y t );

[0047] S2, obtaining the straight line of P0 and M The form is as follows:

[0048]

[0049] Wherein, x, y are color coordinates in CIE1931 chromaticity diagram, is the slope of the straight line corresponding to is the intercept of the straight line corresponding to

[0050] S3, obtaining three straight lines formed by color points P1, P2 and P3, the form is as follows:

[0051]

[0052] Wherein, is the slope of the straight line P1P2 corresponding to is the intercept of the straight line P1P2 corresponding to is the slope of the straight line P2P3 corresponding to is the intercept of the straight line P2P3 corresponding to is the slope of the straight line P1P3 corresponding to is the intercept of the straight line P1P3 corresponding to Obtaining the intersection of straight lines P1P2, P2P3 and P1P3 and the straight line , defining the intersection of the shortest straight line and the straight line as A1(x A1 , y A1 ) and the intersection located in the triangular region formed by color points P1, P2 and P3 as A2(x A2 , y A2 );

[0053]

[0053] S4, connecting A1(x A1 , y A1 ) and A2(x A2 , y A2), the line segment A1A2 is divided into n nodes, and the first duty cycles of the n groups of color points P1, P2, P3 and P0 are calculated by using the light mixing algorithm;

[0054] S5, the duty cycle of the color point P1, P2, P3 and P0 with the highest color rendering index in the obtained n groups of first duty cycles is defined as a second duty cycle, and the relationship between the second duty cycle and the color temperature is fitted as a function.

[0055] The technology can output a set of formulas for quickly calculating RGBY mixed high-illuminance white light based on different RGBY spectral schemes. This technology can effectively reduce product cost and improve the use value of RGB light mixing products.

[0056] Specifically, the RGBY chromaticity range is composed of blue light, green light, red light and yellow light color points; the blue light color point is distributed as x: 0.1401±0.200, y: 0.0386±0.200, the peak wavelength is 400-470nm, and the half-wave width is 20-50nm; the green light color point is distributed as x: 0.1213±0.200, y: 0.7453±0.200, the peak wavelength is 520±40nm, and the half-wave width is 20-70nm; the red light color point is distributed as x: 0.6770±0.200, y: 0.3225±0.200, the peak wavelength is 590-680nm, and the half-wave width is 20-70nm; and the yellow light color point is distributed as x: 0.3585±0.200, y: 0.6300±0.200, the peak wavelength is 570±40nm, and the half-wave width is 20-30nm. Specifically, the blue light color point is generated by a blue light quantum dot LED chip with a peak wavelength of 400-470nm or blue light excited by a blue light fluorescent powder; the green light color point is generated by a green light LED chip with a peak wavelength of 480-560nm or green light excited by a green light fluorescent powder; the red light color point is generated by a red light LED chip with a peak wavelength of 590-680nm or red light excited by a red light fluorescent powder; and the yellow light color point is generated by a yellow light LED chip with a peak wavelength of 530-610nm or yellow light excited by a yellow light fluorescent powder.

[0057] Specifically, the blue light, green light, red light and yellow light color points are distributed in the CIE1931 chromaticity diagram in the order of RGYB from the lower left to the lower right; and the luminous flux of the blue light, green light, red light and yellow light color points is in the order of G or Y>R>B.

[0058] The above-described spectrum includes but is not limited to the standard RGB spectrum shown above, and a spectrum scheme with a spectral root mean square error of the standard RGB spectrum within 0.3 can be applied to the present application. The spectral root mean square error is SRMSE, and the formula is:

[0059]

[0060] In the formula, λ is the wavelength, and φ is the luminous flux.ref is the spectral energy of the standard RGB spectrum at the wavelength λ, and φ is the spectral energy of the other RGB spectrum at the wavelength λ.

[0061] Specifically, the duty cycles of the n groups of color points P1, P2, P3 and P0 are calculated according to the Grassmann's mixing law based on the color points P1, P2, P3 and P0, as shown below:

[0062]

[0063]

[0064]

[0065] wherein, wherein x, y and Y are the target color coordinates and luminous flux, respectively, and η1, η2, η3 and η0 are the first duty cycles of the color points P1, P2, P3 and P0, respectively.

[0066] Figure 2 is a flowchart of S5 in a method for calculating the duty cycle of white light color temperature in RGBY four-way light mixing according to an embodiment of the present application, as shown in Figure 2 S5 specifically includes:

[0067] S501, in the selected characteristic color temperature range, the selected color temperature range is divided into N color temperature nodes, and the second duty cycle optimal for the color rendering index at each color temperature node is obtained according to the methods of S1-S4;

[0068] S502, fitting the relationship between the second duty cycle and the color temperature into a function.

[0069] Specifically, the fitting method of fitting the relationship between the second duty cycle and the color temperature into a function in S502 includes: using the least square method, Levenberg-Marquardt algorithm, in actual product use, the obtained fitting function can be written, the fitting function is used to quickly calculate the duty cycle corresponding to the white light color temperature, and normalization calculation and nonlinear calibration calculation need to be performed in the actual product.

[0070] Specifically, the above spectrum can form 1800K-7000K white light with a color rendering index greater than 85 after being mixed according to a certain proportion.

[0071] Figure 3 is an RGBY spectrum diagram of a method for calculating the duty cycle of white light color temperature in RGBY four-way light mixing according to a specific embodiment of the present application, Figure 4 is a CIE1931 color gamut diagram of a method for calculating the duty cycle of white light color temperature in RGBY four-way light mixing according to a specific embodiment of the present application, Figure 3 and Figure 4To conform to this scheme, an RGBY spectrum is defined, with the following RGBY parameters:

[0072] x y Y R 0.6627 0.3291 17 G 0.1432 0.7362 26 B 0.1404 0.0505 5.5 Y 0.3828 0.6062 24

[0073] Example:

[0074] Using a color temperature of 3000K as the target point, examples of P1, P2, P3, P0, M, and T are as follows: Figure 5 As shown, after calculation according to the method of this scheme, the relationship between the four RGBY channels and the color temperature and its fitting formula are obtained.

[0075] like Figure 6 to Figure 9 As shown, the fitting formula for red light is:

[0076] y = 2E - 18x 2 +5E-14x 4 -6E-10x 3 +3E-6x 2 -0.0091x+13.837

[0077] R² = 0.9999;

[0078] The fitting formula for green light is:

[0079] y = 5E - 19x 5 -1E-14x 4 +1E-10x 3 -6E-7x 2 -0.0018x+1.8428

[0080] R² = 0.9999;

[0081] The fitting formula for blue light is:

[0082] y = -6E-19x 2 +2E-14x 4 -2E-10x 3 +8E-7x 2 -0.0011x+0.559

[0083] R2 = 1;

[0084] The fitting formula for yellow light is:

[0085] y = 2E - 19x 2 -6E-15x 4 +7E-11x 3 -4E-7x 2 -0.0011x+0.1098

[0086] R² = 0.9748;

[0087] Further, the duty cycle of the RGBY four-channel light source is calculated,

[0088]

[0089] The rendering ability of the synthesized spectrum calculated from the fitting formula is shown in Figure 10 It can be seen from Figure 10 that the color temperature points outside the range of the data source of the fitting (1700K-7000K) can also achieve good rendering ability, and the small white light error is maintained in a wide color temperature range.

[0090] It is apparent that those skilled in the art can make various modifications and changes to the embodiments of the present application without departing from the spirit and scope of the present application. In this way, if these modifications and changes are within the scope of the claims of the present application and their equivalents, the present application is also intended to cover these modifications and changes. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are recited in mutually different dependent claims does not mean that the combination of these measures cannot be used to advantage. Any reference signs in the claims should not be considered as limiting the scope.

Claims

1. A method for calculating the duty cycle of white light color temperature during RGBY four-channel light mixing, characterized in that, S1. Determine the RGBY chromaticity range on the CIE1931 chromaticity diagram, and define any four color points P1, P2, P3, and P0 within this chromaticity range. Obtain the color point M(x) formed by mixing the light from color points P1, P2, and P3. m y m ), and using color point P0 and color point M(x) m y m Synthesized white light color point T(x) t y t ); S2, Obtain the line between P0 and M. The straight line The format is as follows: Where x and y are the color coordinates within the CIE 1931 chromaticity diagram. It is a straight line Corresponding slope It is a straight line The corresponding intercept; S3. Obtain the three straight lines formed by color points P1, P2, and P3, in the following form: in, Let P1P2 be the slope of the line. The intercept of line P1P2 Let P2P3 be the slope of the line. The intercept of line P2P3 Let P1P3 be the slope of the line. Find the intercepts of lines P1P3; obtain the angles between lines P1P2, P2P3, and P1P3 and the line... The intersection of the lines is defined as the shortest line and the line. The intersection point is A1(x) A1 y A1 The intersection point of the triangle formed by color points P1, P2, and P3 is A2(x). A2 y A2 ); S4, Connect A1(x) A1 y A1 ) and A2(x A2 y A2 The line segment A1A2 is divided into n nodes, and the first duty cycle of n sets of color points P1, P2, P3 and P0 is calculated using the light mixing algorithm. S5. Define the duty cycle of the color points P1, P2, P3 and P0 with the highest color rendering index among the n groups of first duty cycles as the second duty cycle, and fit the relationship between the second duty cycle and the color temperature as a function.

2. The method for calculating the white light color temperature duty cycle during RGBY four-channel light mixing according to claim 1, characterized in that, The RGBY chromaticity range consists of blue, green, red, and yellow light points; the blue light point distribution is x: 0.1401±0.200, y: 0.0386±0.200, with a peak wavelength of 400–470 nm and a half-width of 20–50 nm; the green light point distribution is x: 0.1213±0.200, y: 0.7453±0.200, with a peak wavelength of 520±40 nm. The wavelength of the red light is 590-680 nm, and the half-width is 20-70 nm. The distribution of the yellow light is as follows: x: 0.6770±0.200, y: 0.3225±0.200, peak wavelength is 590-680 nm, half-width is 20-70 nm.

3. The method for calculating the white light color temperature duty cycle during RGBY four-way light mixing according to claim 2, characterized in that, The blue light dots are generated by blue quantum dot LED chips with a peak wavelength of 400-470nm or photoexcited blue phosphors; the green light dots are generated by green LED chips with a peak wavelength of 480-560nm or photoexcited green phosphors; the red light dots are generated by red LED chips with a peak wavelength of 590-680nm or photoexcited red phosphors; and the yellow light dots are generated by yellow LED chips with a peak wavelength of 530-610nm or photoexcited yellow phosphors.

4. The method for calculating the duty cycle of white light color temperature during RGBY four-way light mixing according to claim 2, characterized in that, The blue, green, red, and yellow light points are distributed in the CIE1931 chromaticity diagram in the order RGYB from the lower left to the lower right; the luminous flux of the blue, green, red, and yellow light points is G or Y > R > B.

5. The method for calculating the white light color temperature duty cycle during RGBY four-way light mixing according to claim 4, characterized in that, Specifically, S4 is: The duty cycles of n sets of color points P1, P2, P3, and P0 are calculated using the Grassmann mixing formula, as shown below: Among them, x, y, and Y represent the target color coordinates and luminous flux, respectively, and η1, η2, η3, and η0 represent the first duty cycles of color points P1, P2, P3, and P0, respectively.

6. The method for calculating the white light color temperature duty cycle during RGBY four-channel mixing according to claim 1, characterized in that, S5 specifically includes: S501. Within the selected characteristic color temperature range, the selected color temperature range is divided into N color temperature nodes, and the second duty cycle with the optimal color rendering index under each color temperature node is obtained according to the methods described in S1 to S4. S502. Fit the relationship between the second duty cycle and the color temperature into a function.

7. The method for calculating the white light color temperature duty cycle during RGBY four-way light mixing according to claim 6, characterized in that, The fitting methods for fitting the relationship between the second duty cycle and color temperature as a function in S502 include: using the least squares method and the Levenberg-Marquardt algorithm.

8. The method for calculating the white light color temperature duty cycle during RGBY four-way light mixing according to claim 6, characterized in that, The color temperature range is 1700K to 7000K.

9. The method for calculating the white light color temperature duty cycle during RGBY four-way light mixing according to claim 8, characterized in that, The color rendering index is greater than 85.

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