Control method for linearly adjusting and maintaining color temperature and brightness of lamp in automobile

Abstract

The invention relates to a control method for linearly adjusting and maintaining color temperature and brightness of lamps in an automobile, and belongs to the technical field of automobile lamp control. The method comprises the following steps: receiving linear input of a user on color temperature and brightness through input equipment; the control unit calculates PWM duty ratio signals of the cold-color LED and the warm-color LED in real time through a conversion matrix on the basis of pre-stored LED parameters, and precise light mixing is achieved; meanwhile, the junction temperature of the LED is monitored in real time, and optical parameters are dynamically compensated according to the junction temperature, so that light attenuation and color drift caused by temperature rise are overcome. According to the invention, continuous linear adjustment of the color temperature and the brightness in a large range is realized, individual requirements of users are met, and consistency and stability of output lighting effects at different temperatures are ensured. The scheme takes a software algorithm as a core, complex hardware and a large amount of calibration are not needed, and the cost and the development period are remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of vehicle lighting control technology, and in particular to a control method for linearly adjusting and maintaining the color temperature and brightness of automotive interior lights. Background Technology

[0002] As the automotive industry continues to develop and its level of intelligence increases, cars are becoming more than just a mode of transportation; they are increasingly seen as mobile homes. The demand for personalized car cabins is growing, and cabin lighting quality has a significant impact on passengers' physical and mental health, while also being an important way to create a pleasant cabin atmosphere.

[0003] Traditional lighting can no longer meet people's needs: most car models on the market still have fixed color temperature and brightness for their interior lighting, and users cannot adjust it according to their own needs; although some models do have adjustable color temperature and brightness, they only have a few default levels, which still cannot better meet users' personalized needs. At the same time, there is no compensation mechanism for changes in color temperature and brightness of the lamps caused by temperature increases.

[0004] In summary, the existing technology has the following main drawbacks: 1. The color temperature and brightness of the lamps cannot be adjusted linearly, which fails to meet the personalized needs of users.

[0005] 2. Cockpit interior lighting typically uses multiple light sources. As the temperature rises during the lighting process, light decay occurs, causing changes in color temperature and brightness. Current technology cannot guarantee the consistency of color temperature and brightness among different light sources as temperature increases.

[0006] 3. To achieve the target color temperature and brightness, existing technologies require calibrating and setting hardware parameters. When customer needs change or the technology is applied to other projects, it is necessary to recalibrate or even redesign, resulting in a long development cycle and high costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: in order to overcome the above-mentioned technical problem, the present invention provides a control method for linear adjustment and maintenance of color temperature and brightness of automotive interior lamps.

[0008] The technical solution adopted by this invention to solve its technical problem is: a method for linearly adjusting and maintaining the color temperature and brightness of automotive interior lights, comprising the following steps: Receive the user's desired color temperature and desired brightness values ​​input through the input device; The initial optical parameters of the pre-stored cool-color LED and warm-color LED at a reference temperature are obtained. The initial optical parameters include color coordinates and luminance values. The reference temperature refers to the ambient temperature of the LED when the initial optical parameters are measured and stored. The junction temperatures of the cool-color LEDs and warm-color LEDs are collected in real time. Based on the junction temperature and the pre-stored LED light decay curve, the initial optical parameters are corrected in real time to obtain the real-time optical parameters at the current temperature. Based on the desired color temperature value, desired brightness value, and real-time optical parameters, the PWM duty cycle signal driving the cool-color LED and the warm-color LED is calculated in real time through a calculation model. The cool-color LED and warm-color LED are driven by the PWM duty cycle signal to mix light, so as to output light that meets the user's expectations and does not drift with temperature changes.

[0009] The steps for obtaining real-time optical parameters at the current temperature based on initial optical parameters include: linearizing the correspondence between the color coordinates and color temperature of the cool-color LED and the warm-color LED to establish a linear functional relationship between the color coordinates and the color temperature.

[0010] The initial optical parameters of the cool-color LED and the warm-color LED at the reference temperature are pre-stored in the control chip.

[0011] The step of calculating the PWM duty cycle signal in real time using a computational model includes: Based on the real-time optical parameters of the cool-color LED and the warm-color LED, calculate the conversion matrix M for color temperature mixing; The desired color temperature value input by the user is converted into target color coordinates, and the relative duty cycle of the mixing of the cool-color LED and the warm-color LED is calculated using the transformation matrix M. The maximum duty cycle is calculated based on the relative duty cycle and the real-time brightness parameters of the cool-color LED and the warm-color LED. Based on the user-inputted desired brightness value and the maximum duty cycle, the target PWM duty cycle signal for driving the cool-color LED and the warm-color LED is calculated.

[0012] Based on the monitored junction temperature, the real-time optical parameters are obtained using the LED's light decay curve: Cold light LED parameters: color coordinates ( , ),brightness Warm LED parameters: color coordinates ( , ),brightness ; ; The transformation matrix ; in: , , , .

[0013] The target PWM duty cycle signal is calculated as follows: Define the relative duty cycle as Its calculation formula is: ; Define the maximum duty cycle as Its calculation formula is: ; Based on the user's input of the desired brightness value Calculate the target duty cycle that meets the desired brightness value: Its calculation formula is:

[0014]

[0015] The mixing ratio of cold light LEDs and warm light LEDs is obtained through the above calculation process. The PWM duty cycle of the LED driver is controlled according to this ratio; in, , These are the maximum duty cycles for cool-color LEDs and warm-color LEDs, respectively. , The target duty cycle is the hybrid duty cycle calculated from the relative duty cycle and real-time brightness parameters. The desired brightness value input by the user; , This represents the maximum luminance value achievable under the current relative duty cycle.

[0016] The input device includes any one or more of the following: in-vehicle central control touch screen, physical rotary switch, and voice control module.

[0017] The junction temperature is acquired by a temperature sensor built into the LED driver chip or an external temperature sensor placed on the LED board, and converted into a digital signal by an ADC module.

[0018] An electronic device according to the present invention includes: a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the electronic device implements the method when executing the program.

[0019] The present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described herein.

[0020] Compared with the prior art, the linear adjustment and maintenance control method for color temperature and brightness of automotive interior lights provided by the present invention has the following main advantages: 1. Achieves true linear stepless adjustment: This invention, through software control, can receive users' linear input commands for color temperature and brightness in real time, and calculates and controls the on and off times of LEDs in real time through algorithms. Thus, it can achieve precise, continuous, and stepless adjustment within a wide range, such as color temperature from 2500K to 10000K and brightness from 0 to 1000Lm, greatly satisfying users' personalized lighting needs.

[0021] 2. Effectively ensures the consistency and stability of output: By collecting LED junction temperature in real time, and correcting and compensating the LED optical parameters in real time based on the junction temperature data and the pre-stored light decay curve, the final output color temperature and brightness can overcome the light decay phenomenon caused by temperature rise. It can maintain a high degree of consistency with the user set value at different operating temperatures, ensuring the quality and reliability of the lighting effect.

[0022] 3. Significantly reduced development costs and shortened development cycle: This invention uses software algorithms as its core, eliminating the need for complex peripheral driving circuits and reducing reliance on hardware. At the same time, this method avoids the tedious process of extensive hardware parameter calibration required in traditional technologies, enabling it to quickly adapt to changes in different projects and requirements. It has excellent flexibility and adaptability, thereby effectively reducing development costs and shortening the development cycle.

[0023] 4. High control precision and simple implementation: By establishing a precise mathematical model and calculation process for the transformation matrix, precise control of the light mixing ratio is achieved. The method has clear logic, good control effect, and is easy to integrate into existing automotive electronic control units (ECUs). Attached Figure Description

[0024] Figure 1 This is a system block diagram of the linear adjustment and maintenance control method for the color temperature and brightness of automotive interior lights according to the present invention.

[0025] Figure 2 This is a flowchart of the linear adjustment and maintenance control method for the color temperature and brightness of automotive interior lights according to the present invention. Detailed Implementation

[0026] The invention will now be described in further detail with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention.

[0027] like Figure 1 The diagram illustrates the overall control block diagram of the linear adjustment and maintenance control method for the color temperature and brightness of automotive interior lighting fixtures according to the present invention. The control algorithm comprises two parts: Part 1: The user inputs the desired color temperature and brightness via the vehicle's infotainment system or a local switch on the lighting fixture (optional examples include linear inputs such as rotary switches). The control unit receives the user-set color temperature and brightness values, retrieves stored LED parameters, and calculates and outputs a PWM drive signal to control the LEDs. This controls the mixed output of cool-colored and warm-colored LEDs to meet the user's required color temperature and brightness. During this process, the user can adjust the input in real time to achieve the desired color temperature and brightness to meet their individual needs.

[0028] Part Two: To prevent inconsistencies in color temperature and brightness due to temperature increases, it is necessary to monitor the LED junction temperature in real time and perform temperature compensation accordingly to maintain a relatively constant color temperature and brightness. Specifically, this is achieved by using the LED driver chip's built-in temperature sensor or an external temperature sensor, and employing an ADC to sample and obtain the LED's junction temperature. Based on the decay curves of junction temperature versus LED color coordinates and brightness, temperature compensation is performed to ensure that the color coordinates and brightness after light mixing remain essentially unchanged with temperature. The LED brightness decay curve, also known as the light decay curve, can be obtained by consulting the LED chip datasheet, testing the LED's optical parameters at different junction temperatures in a high and low temperature chamber, and then fitting the relationship between these parameters.

[0029] like Figure 2 The example algorithm flow for color temperature and brightness adjustment is shown in the figure.

[0030] The color coordinates and brightness of cool-color LEDs, and the color coordinates and brightness of warm-color LEDs are stored in the control chip respectively, and then linearized to establish color coordinates. and The functional relationship.

[0031] Determine the color temperature and brightness adjustment range based on the LED parameters: Parameters for cool light LEDs: , , , Warm LED parameters: , , , .

[0032] Because there is a functional relationship between chromaticity coordinates and color temperature, changing the chromaticity coordinates can change the color temperature. Linearizing this relationship, we get:

[0033] in ,

[0034] According to the above formula, color coordinates exist Variation within a range can change the color temperature. The changes between these ranges correspond to variations in brightness within a certain range. .

[0035] The user inputs their desired color temperature and brightness via the vehicle's infotainment screen or the local light switch. Based on the formula above, the input is used to obtain... Its adjustment range: exist , exist , exist .

[0036] The transformation matrix M is calculated based on the LED parameters and junction temperature. When the LED is lit, the junction temperature rises, and the LED parameters change due to light decay. Based on the monitored junction temperature, the real-time parameters are obtained using the LED's light decay curve.

[0037] Find the transformation matrix M: ; ; in: , , , .

[0038] Calculate Cx, Cy, and Lm corresponding to the target color temperature based on user input: where .

[0039] Calculate the relative duty cycle: Define the relative duty cycle as... Its calculation formula is: .

[0040] Calculate the maximum duty cycle: Define the maximum duty cycle as... Its calculation formula is:

[0041] The PWM duty cycle for calculating the target brightness is determined based on the user-input brightness value. Calculate the target duty cycle that meets the set brightness: Its calculation formula is:

[0042]

[0043] in, , These are the maximum duty cycles for cool-color LEDs and warm-color LEDs, respectively. , The target duty cycle is the hybrid duty cycle calculated from the relative duty cycle and real-time brightness parameters. The desired brightness value input by the user; , This represents the maximum luminance value achievable under the current relative duty cycle.

[0044] The mixing ratio of cold light LEDs and warm light LEDs is obtained through the above calculation process. By controlling the PWM duty cycle of the LED driver according to this ratio, the warm and cool light will be mixed to produce a light effect that meets the user's requirements for color temperature and brightness.

[0045] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A control method for linear adjustment and maintenance of color temperature and brightness of an automotive interior light, characterized in that, The method comprises the following steps: receiving a desired color temperature value and a desired brightness value input by a user through an input device; obtaining pre-stored initial optical parameters of the cool color LED and the warm color LED at a reference temperature, the initial optical parameters including color coordinates and brightness values; the reference temperature refers to the ambient temperature of the LED when the initial optical parameters are measured and stored; real-time acquisition of the junction temperature of the cool color LED and the warm color LED; real-time correction of the initial optical parameters based on the junction temperature and the pre-stored LED light decay curve to obtain real-time optical parameters at the current temperature; real-time calculation of a PWM duty cycle signal for driving the cool color LED and the warm color LED according to the desired color temperature value, the desired brightness value and the real-time optical parameters through a calculation model; light mixing of the cool color LED and the warm color LED according to the PWM duty cycle signal to output light that meets the user's expectation and does not drift with temperature changes.

2. The control method according to claim 1, characterized by: The step of obtaining real-time optical parameters at the current temperature according to the initial optical parameters comprises linearizing the correspondence between the color coordinates of the cool color LED and the warm color LED and the color temperature to establish a linear function relationship between the color coordinates and the color temperature.

3. The control method according to claim 2, characterized by: The initial optical parameters of the cool color LED and the warm color LED at the reference temperature are pre-stored in a control chip.

4. The control method of claim 1, wherein: The step of real-time calculation of the PWM duty cycle signal through the calculation model comprises: calculating a conversion matrix M for color temperature mixing according to the real-time optical parameters of the cool color LED and the warm color LED; converting the desired color temperature value input by the user into target color coordinates and calculating the relative duty cycle of light mixing of the cool color LED and the warm color LED by using the conversion matrix M; calculating the maximum duty cycle according to the relative duty cycle and the real-time brightness parameters of the cool color LED and the warm color LED; calculating the target PWM duty cycle signal for finally driving the cool color LED and the warm color LED according to the desired brightness value input by the user and the maximum duty cycle.

5. The control method according to claim 4, characterized by: The real-time optical parameters are obtained according to the monitored light decay curve of the LED: Cool light LED parameters: color coordinates (x, y) , ), luminance ; warm light LED parameters: color coordinates (x, y) , ), luminance ; ； The conversion matrix ; wherein: ， ， ， 。 6. The control method according to claim 4, characterized by: The calculation method of the target PWM duty cycle signal is: The relative duty cycle is defined as ; The calculation formula thereof is: ; The maximum duty cycle is defined as ; The calculation formula thereof is: ; According to a user inputted desired brightness value , a target duty cycle is calculated which corresponds to the desired brightness value: ; The calculation formula is: The mixing ratio of the cool light LED and the warm light LED is obtained through the above calculation process The PWM duty cycle of the LED drive is controlled according to the ratio respectively; wherein, , maximum duty cycle for cool and warm LEDs, respectively; , The mixed duty cycle calculated from the relative duty cycle and the real-time brightness parameter is the target duty cycle. a desired luminance value input by a user; , is the maximum luminance value achievable at the current relative duty cycle.

7. The control method of claim 1, wherein: The input device includes any one or more of a vehicle-mounted central control touch screen, a physical knob switch and a voice control module.

8. The control method of claim 1, wherein: The junction temperature is acquired by a temperature sensor built-in the LED driving chip or a temperature sensor externally provided on the LED lamp panel and converted into a digital signal by an ADC module.

9. An electronic device, comprising: It comprises: a memory and a processor, the memory storing a computer program executable on the processor, and the electronic device implementing the method of any one of claims 1-8 when executing the program.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method of any one of claims 1-8.

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