A multi-channel LED light mixing method based on a nonlinear color space and a COB light strip

Abstract

The application provides a multi-channel LED light mixing method based on a nonlinear color space, which comprises determining a target color coordinate, and acquiring color coordinates and luminous flux Y of each channel of a light source through photoelectric equipment; calculating the weight of each channel based on the relationship between the target color coordinate and the color coordinates of each channel of the light source, resetting the weight of the negative number obtained after solving to 0 and re-solving in response to the existence of the negative number of the weight obtained after solving, and determining the final weight of each channel; and acquiring the duty cycle of each channel after normalization; and the application also provides a COB lamp strip, a flexible substrate and a plurality of flip chips, the flip chips are arranged along the length direction of the flexible substrate and are directly packaged on the surface of the flexible substrate, the surface of the flip chip is covered with white packaging diffusion glue, the white packaging diffusion glue contains organic silicone glue and a diffusing agent, the plurality of flip chips form a plurality of channels, and the light is mixed by using the above method. The light mixing color of the lamp strip is integrated, the effect is realistic, and the light emission is uniform.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lamp lighting equipment, and particularly relates to a multi-channel LED light mixing method based on a nonlinear color space and a COB lamp strip. BACKGROUND

[0002] Traditional COB (Chip on Board) LED lamp strip technology is to directly install multiple LED chips on a substrate and cover them with packaging materials to achieve high-density light source arrangement. The advantages of this technology include high light efficiency, good heat dissipation performance and lower cost. However, traditional COB LED lamp strips also have some problems in practical application: uneven light emission: due to the density of chip arrangement and the unevenness of packaging materials, uneven bright and dark phenomenon is easy to occur. Poor light mixing effect: in multi-channel LED applications, the light mixing effect of traditional COB LED lamp strips is poor, and it is difficult to achieve precise color control. Light source failure: the soldering wire and support structure are easy to be damaged during use, resulting in light source failure.

[0003] In multi-channel LED applications, in order to achieve precise color control, it is usually necessary to use light mixing algorithms. Common light mixing algorithms include linear interpolation method, weighted average method and Lagrange method, etc. These algorithms adjust the duty cycle of each channel LED to achieve the mixing of different color lights. However, the existing light mixing algorithms have the following problems when applied to traditional COB LED lamp strips: insufficient algorithm accuracy: the unevenness of light emission and the poor light mixing effect of traditional COB LED lamp strips affect the accuracy of the light mixing algorithm. Difficult to achieve dynamic adjustment: in practical application, the current and voltage changes of the LED will affect the light color, and the existing algorithm is difficult to adjust and calibrate in real time. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a multi-channel LED light mixing method based on a nonlinear color space and a COB lamp strip.

[0005] According to one aspect of the present application, a multi-channel LED light mixing method based on a nonlinear color space is provided, comprising:

[0006] S1: determining a target color coordinate (x c ,y c ), and obtaining the color coordinates (x i ,y i ) and luminous flux Y of each channel of the light source through the photoelectric device;

[0007] S2: based on the relationship between the target color coordinate (x c ,y c ) and the color coordinates (x i ,y i ) of each channel of the light source: Calculate the weight p of each channel i , in response to the existence of negative numbers in the solved weight, set the weight of the negative number to 0 and re-solve, determine the final weight p of each channel i ;

[0008] S3: Obtain the duty cycle of each channel after normalization

[0009] In a specific embodiment, in response to the number of channels being 2, the relationship between the target color coordinate (x c ,y c ) and the color coordinate (x i ,y i ) of each channel of the light source is:

[0010] In a specific embodiment, in response to the number of channels being 3, the relationship between the target color coordinate (x c ,y c ) and the color coordinate (x i ,y i ) of each channel of the light source is:

[0011] In a specific embodiment, in response to the number of channels being 4 or more, the relationship between the target color coordinate (x c ,y c ) and the color coordinate (x i ,y i ) of each channel of the light source is:

[0012]

[0013] In a specific embodiment, the weight p i is obtained by solving by Lagrange method or sequential quadratic programming method.

[0014] In a specific embodiment, the calculation formula of the Lagrange method is:

[0015] According to another aspect of the present application, a COB lamp strip is provided, comprising a flexible substrate and a plurality of flip chips, the flip chips being arranged along the length direction of the flexible substrate and directly packaged on the surface of the flexible substrate, the surface of the flip chip being covered with white packaging diffusion glue, the white packaging diffusion glue containing organic silicone glue and a diffusing agent, the plurality of flip chips forming a plurality of channels, and the light being mixed by using the method as described above.

[0016] In a specific embodiment, the flip chip comprises a COB or CSP chip.

[0017] In specific embodiments, the surface of the COB chip is coated with COB fluorescent glue and then covered with white packaging diffusion glue.

[0018] In specific embodiments, the silicone glue comprises a mixture of translucent viscous liquid silicone glue and foggy liquid silicone glue, the diffusion agent is microbead with a particle size of 1-8 μm, the microstructure is spherical structure, and the adding proportion of the diffusion agent is 0.5-1%.

[0019] Compared with the prior art, the beneficial results of the present application are that:

[0020] The flip chip technology is adopted, the solder wire and the support in the traditional COB LED lamp strip are eliminated, the light blocking is reduced, and the light efficiency and the light mixing effect are improved.

[0021] The flip chip directly contacts with the substrate, the heat conduction efficiency is improved, the light attenuation and the light source failure are reduced, and the stability and the service life of the lamp strip are enhanced.

[0022] The nanoscale diffusion material is added in the white packaging diffusion glue of the flip chip COB LED lamp strip, the light is more uniformly scattered in the diffusion glue, and the light uniformity is improved.

[0023] The multi-channel LED light mixing algorithm based on the Lagrange method realizes higher precision color control by accurately calculating the duty cycle of each channel LED. Especially for the optical characteristics and electrical performance of the flip chip, optimization and calibration are carried out. BRIEF DESCRIPTION OF DRAWINGS

[0024] 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 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 when considered in connection with the accompanying drawings. Other features, objects, and advantages of the application will become apparent from the detailed description of the non-limiting embodiments made by way of illustration:

[0025] Figure 1 is a flow chart of a multi-channel LED light mixing method based on a nonlinear color space according to an embodiment of the present application;

[0026] Figure 2 is a flow chart of a multi-channel LED light mixing method based on a nonlinear color space according to a specific embodiment of the present application;

[0027] Figure 3 is an exploded view of a COB lamp strip according to an embodiment of the present application;

[0028] Figure 4is a cross-sectional view of a flip chip according to a specific embodiment of the present application;

[0029] Figures 5a-5b is a schematic diagram of light emission of a flip chip according to a specific embodiment of the present application;

[0030] Figure 6 is a schematic diagram of structure of an RGB light strip according to a specific embodiment of the present application;

[0031] Figure 7 is a schematic diagram of a flip chip covered with diffusion glue according to a specific embodiment of the present application. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and are not a limitation on the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings.

[0033] The present application proposes a multi-channel LED light mixing method based on a nonlinear color space, Figure 1 A flow chart of a multi-channel LED light mixing method based on a nonlinear color space according to an embodiment of the present application is shown, as Figure 1 The multi-channel LED light mixing method based on a nonlinear color space includes:

[0034] S1: determining a target color coordinate (x c ,y c ), and obtaining light source channel color coordinates (x i ,y i ) and luminous flux Y through a photoelectric device. Specifically, the photoelectric device can be an integrating sphere.

[0035] S2: based on the relationship between the target color coordinate (x c ,y c ) and the light source channel color coordinates (x i ,y i ): calculating the weight p i of each channel, in response to the existence of negative numbers in the solved weight, setting the negative weight after solving to 0 and re-solving, and determining the final weight p i of each channel.

[0036] In specific embodiments, x c , y c is the target color coordinate, i is the number of channels, x 1～i , y 1～i is the channel color coordinate, and p iis the weight of each channel, and When the number of channels is 2, if the target color point is within the gamut range, the equation can be simplified to the simplest form: When the number of channels is 3, the equation is in the form of: When the number of channels is 4 or more, the equation can be rewritten in the following form:

[0037] In specific embodiments, the matrix equation can be solved by the Lagrange method or the sequential quadratic programming method, etc. For example, the weight p i : where L() represents the Lagrange function, and λ represents the Lagrange multiplier.

[0038] In specific embodiments, the solved weight has a negative number, and the negative weight after solving is set to 0 and re-solved. This step can be understood as that in order to reach the target color coordinate, the complementary color of the channel corresponding to the negative solution needs to be used to participate in the light mixing.

[0039] S3: Obtain the duty cycle of each channel after normalization to obtain the parameter solution p 1～i After that, in order to compensate for different luminous flux Y of different channels, normalization is performed to obtain the duty cycle of each channel.

[0040] Figure 2 The flowchart of the multi-channel LED light mixing method based on the nonlinear color space according to one specific embodiment of the present application is shown in FIG. 2, which specifically includes the following steps: Figure 2

[0041] Obtain the basic photoelectric parameters of each channel, including CIE1931 xy chromaticity coordinates 201 and Y (luminous flux) 202;

[0042] 203: Perform nonlinear calibration with respect to temperature in combination with the basic photoelectric parameters of each channel

[0043] 204: Determine the target chromaticity coordinates (x c ,y c );

[0044] 205: Calculate the contribution rate (i.e., the weight) of each channel

[0045] 206: Judge whether all parameters f≥0, if yes, go to step 208: compensate the tristimulus value and normalize, if not, go to step 207: set f less than 0 to 0 and re-calculate, and return to step 205;

[0046] 209: Output the duty cycle of each channel;

[0047] ​210: Perform non-linear calibration with respect to current;

[0048] 211: Output to LED driver

[0049] 212: Integrating sphere measurement verification;

[0050] 213: Determine if the color difference SDCM is >= 5, if not, end, if yes, go to step 214 to perform non-linear calibration with respect to chromaticity coordinates and recalculate the duty cycle.

[0051] The input basic parameters of the light mixing method mainly include: target color coordinates, which can be calculated by RGB to xy color space conversion; lamp basic parameters: different channel LED color coordinates, luminous flux, the lamp basic parameters have a nonlinear dependence relationship with temperature; using the method of solving the minimum norm by Lagrange method to calculate the multi-channel LED color mixing duty cycle; finally, the color mixing duty cycle is calibrated for the non-linear effect of LED current.

[0052] In one specific example, taking 4-way simultaneous light mixing as an example, the basic light source parameters are as follows:

[0053]

[0054] The results calculated by the above light mixing algorithm are as follows:

[0055] Color R G B W Color tolerance 6500K 100％ 98.81％ 39.59％ 9.06％ 3.2 5700K 100％ 89.90％ 31.87％ 8.78％ 2.7 5000K 100％ 82.25％ 25.90％ 8.53％ 3.1 4500K 100％ 74.95％ 20.85％ 8.29％ 1.5 4000K 100％ 66.78％ 15.93％ 8.02％ 0.7 3500K 100％ 57.45％ 11.18％ 7.71％ 4.6 3000K 100％ 48.99％ 7.63％ 7.43％ 2.1 2700K 100％ 41.87％ 5.16％ 7.19％ 0.3 2500K 100％ 35.48％ 3.35％ 6.97％ 0.2 2200K 100％ 29.74％ 2.06％ 6.77％ 2.9

[0056] It can be seen that by the above light mixing algorithm, the target color temperature can be obtained by controlling the duty cycle of RGBW four-way, and the color difference meets the requirement of less than 5.

[0057] Another aspect of the present application proposes a COB lamp strip, Figure 3 An exploded view of the COB lamp strip according to one embodiment of the present application is shown, as Figure 3As shown, the COB lamp strip includes a flexible substrate 1, LED chips 2, COB fluorescent glue 3, white packaging diffusion glue 4, and back glue 5. The LED chips 2 of the COB lamp strip adopt COB / CSP flip-chip, the electrodes of the COB / CSP flip-chip are directly welded with the pads of the flexible substrate 1, the direct welding of the chip with the pads of the flexible substrate 1 eliminates the conventional LED light source gold wire welding and support, not only has good heat conduction performance, but also effectively avoids the light source failure problem caused by wire fracture and support damage, and improves the anti-pulling and anti-extrusion ability. The back glue 5 is arranged on the back of the flexible substrate 1. Through the actual test of the present application, the welding process of the electrodes of the COB / CSP flip-chip directly with the flexible substrate 1, under the same conditions, the temperature rise of this process will be reduced by 5-10 degrees, effectively improving the service life of the white COB lamp strip and reducing the light source failure rate. Similarly, in actual use, due to the use of the electrodes of the COB / CSP flip-chip directly with the flexible substrate process, during the installation and use of the lamp strip, the lamp strip is pulled and extruded, which is easy to cause light source failure due to gold wire fracture and support damage, especially RGB color light, the white COB of the present application can completely avoid the above situation.

[0058] In a specific embodiment, Figure 4 A cross-sectional view of a flip-chip according to a specific embodiment of the present application is shown as Figure 4 As shown, the surface of the LED chip 2 is covered with white packaging diffusion glue 4. If COB flip-chip is used, a layer of COB fluorescent glue 3 is first coated, and then a layer of white packaging diffusion glue 4 is coated. The secondary optical effect of the white packaging diffusion glue 4 not only improves the optical uniformity, but also improves the color light mixing effect in combination with the aforementioned light mixing algorithm. In addition, the white packaging diffusion glue 4 has a protective effect on the COB / CSP flip-chip after curing, improves the oxidation resistance, acid and alkalinity resistance, and extrusion resistance of the lamp strip, and protects the product quality problem caused by light source failure.

[0059] In a specific embodiment, the white packaging diffusion glue 4 comprises silicone glue and a diffusion agent, wherein the silicone glue is a flexible lamp strip special silicone glue, specifically packaged in two components A and B, component A is a translucent viscous liquid, component B is a fog-like liquid, the silicone glue has a main chain structure of silicon-oxygen (Si-O) bond, and therefore is not easy to be decomposed by ultraviolet light and ozone, and the molecular chemical bond is not easy to break under high temperature (radiation or irradiation). The glue is mixed in a proportion of A:B=10:1 by weight, and needs to be fully stirred after mixing to avoid incomplete curing. Before glue injection, the bracket is preheated at 150°C for more than 60 minutes to remove moisture, first baked at 80°C for 1 hour, basically gel, then heated to 170°C for 4 hours to achieve the best curing effect, and the segmented curing helps to improve the adhesion of the silicone glue and effectively solve the problem of air bubbles, thereby improving the yield. The diffusion agent is an organic chemical product that has been specially processed and surface treated, which is a kind of chemical product with a particle size of about 1-8 μm, a spherical microstructure, and a surface that has been treated in a certain special way. It has good flowability and good compatibility with optical resin base material, and the addition ratio is 0.5%-1%. The addition of the diffusion agent can increase the light diffusion and diffuseness, hide the point light source and become a surface light source, so that the whole light source emits more soft and beautiful, and achieves the comfortable effect of transparent and non-transparent light transmission.

[0060] In a specific embodiment, the white packaging diffusion glue 4 is applied by a glue dispenser, and the specific operation process is as follows: vacuum pumping is started at the same time as the tunnel furnace is started to heat up, the tunnel furnace parameters are 75-80-85-90-95-100-120-140-165-180-185-185-185-185-185°C, after the temperature is confirmed to be normal, the glue is discharged, and the glue is observed to be smooth, without glue breakage and air bubbles, so that the glue discharge is completed, after the glue discharge is completed, the equipment is notified to be debugged, the glue dispensing speed of the glue dispenser is fixed, the actual speed of the tunnel furnace conveying belt is 0.9 m / min, the equipment needs to be debugged according to the actual specifications, and the glue dispensing speed and the glue discharging speed need to be consistent. The running speed (X-axis running speed) of the glue dispenser corresponds to the actual glue dispensing speed of 0.87 m / min, and the running speed is fixed and cannot be changed. The conventional glue width is 3.3 mm±0.15 mm, the glue height is 1.3 mm±0.15 mm, the material is fixed on the material receiving rack after being discharged from the furnace for 14 minutes, and the glue is cooled and solidified upward. The hardness of the white packaging diffusion glue 4 after curing is 40-50 degrees, which can contain COB / CSP flip-chip, improve the flexibility of the lamp strip, and improve the anti-pulling, anti-extrusion and anti-tearing performance of the lamp strip.

[0061] Figures 5a-5b is a schematic diagram of a flip-chip light emitting according to a specific embodiment of the present application, as Figure 5a and 5bAs shown, except for the substrate connecting surface, the rest five surfaces of the flip chip can realize light emission. The packaging process adopts CSP / COB flip chip instead of traditional light source with support, the flip chip is five-surface light-emitting, after covering white packaging diffusion glue, through the light shielding and full reflection of the diffusion glue, the beam angle of the COB lamp strip is increased from the original 108 degrees to 165 degrees, and the light emission is soft and uniform.

[0062] Figure 6 is a structural schematic diagram of an RGB lamp strip according to a specific embodiment of the present application, as shown, Figure 6 for the color light RGB lamp strip, the traditional SMD light source flexible lamp strip uses a three-in-one light source, and the conventional lamp strip uses a number of light sources from 15 light sources per meter to 60 light sources per meter. Since the size of the SMD light source is relatively large, more than 72 light sources per meter cannot be arranged, after mixing light, the interval is large, it is a bright spot, the bright particle feeling is obvious, and the light mixing effect is poor. The white COB lamp strip in the present application arranges red, green and blue COB / CSP flip chips on the FPCB flexible substrate 1 in a uniform and spaced manner. Since the size is small, the number of chips per meter is 576 chips to 840 chips, and the arrangement interval is small. At the same time, the surface is covered with white packaging diffusion glue. Since the white packaging diffusion glue adds a diffusing agent, the light diffusion effect is increased, the color light sources are uniformly distributed on the lamp strip when lighting and mixing light, combined with the light mixing algorithm described above, the lamp strip mixes light into one, and achieves a realistic effect. In addition, the light emission is uniform, and the effect of mixing different colors of light is completely achieved.

[0063] Figure 7 shows a schematic diagram of a flip chip covered with diffusion glue according to a specific embodiment of the present application, as shown, Figure 7 the arc structure of the white diffusion glue is specially designed, the white packaging diffusion glue 4 is dropped by the equipment to a certain arc, the CSP or COB flip chip is located at the maximum thickness of the circular arc structure, and the overall light emission effect and hydrophobic effect are better. Specifically, the ratio of the glue coating width B and the height A is (2-4):1, and the arc of the dropped glue has better hydrophobicity under this ratio.

[0064] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and also covers other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by replacing the above features with the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A multi-channel LED light mixing method based on a non-linear color space, characterized in that, The application relates to a method for mixing light, comprising the following steps: S1: determine target color coordinates and obtain light source color coordinates of each channel by photoelectric device and luminous flux ; S2: calculating the weight of each channel based on the target color coordinate in relation to the color coordinates of each channel of the light source calculating the weight of each channel in response to the existence of negative numbers in the solved weights, setting the negative weights to 0 and re-solving, to determine the final weight of each channel ;​ S3: Obtain duty cycle of each channel after normalization .

2. A multi-channel LED light mixing method based on a non-linear color space according to claim 1, wherein, In response to the number of channels being 2, the target color coordinates and the relationship between the color coordinates of each channel of the light source is: 。 3. A multi-channel LED light mixing method based on a non-linear color space according to claim 2, wherein, In response to the number of channels being 3, the target color coordinates and the relationship between the light source channel color coordinates ​ 。 4. The multi-channel LED light mixing method based on a non-linear color space according to claim 1, wherein, In response to the number of channels being greater than or equal to 4, the target color coordinates and the relationship between the light source channel color coordinates is: .

5. The multi-channel LED light mixing method based on a non-linear color space according to claim 1, wherein, The weights Solved by Lagrangian or sequential quadratic programming methods.

6. A multi-channel LED light mixing method based on a non-linear color space according to claim 5, wherein, The calculation formula of the Lagrange method is as follows: 。 7. A COB light strip, characterized in that The application relates to a flexible substrate and a plurality of flip chips, the flip chips are arranged along the length direction of the flexible substrate and are directly packaged on the surface of the flexible substrate, the surface of the flip chips is covered with white packaging diffusion glue, the white packaging diffusion glue contains organic silicon glue and a diffusion agent, the plurality of flip chips form a plurality of channels, and the method in any one of claims 1-6 is used for mixing light.

8. The COB light strip of claim 7, wherein, The flip chip comprises a COB or CSP chip.

9. The COB light strip of claim 8, wherein, The surface of the COB chip is coated with COB fluorescent glue and then covered with the white packaging diffusion glue.

10. The COB light strip of claim 7, wherein, The organic silicon glue comprises a mixture of translucent viscous liquid silicon glue and fog-shaped liquid silicon glue, the diffusion agent is a microstructure spherical structure with a particle size of 1-8 microns, and the adding proportion of the diffusion agent is 0.5-1%.

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