LED optical illumination curve calibration method, device and computer equipment

Abstract

The present invention discloses a method, device and computer equipment for calibrating an LED optical illumination curve. The method includes: obtaining the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source, and determining the first dimming grayscale level, the first dimming grayscale level being the maximum dimming grayscale level of the current climbing section; calculating the first actual output power curve of the current climbing section according to the first dimming grayscale level, calculating the second actual output power curve of the constant current section according to the average current of the constant current section, and converting the first actual output power curve and the second actual output power curve into an actual optical illumination curve output by the LED light source in proportion; adjusting the dimming current according to the actual optical illumination curve, so that the LED light source emits light accurately. The actual output power curve is calculated by segmenting the current climbing section and the constant current section to calibrate the theoretical optical illumination curve, so as to avoid color mixing and color drift of the LED light source, and make the LED light source emit light accurately.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular, to a method, device, and computer device for calibrating an LED optical illumination curve. Background Art

[0002] At present, with the popularization of the application of LED light sources, there are more and more applications pursuing high-quality optical quality, and the requirements for LED color mixing and dimming technologies are also getting higher and higher. Usually, the method for dimming and color mixing of color LEDs is as follows: first, set a linear or non-linear theoretical optical illumination curve, convert the theoretical optical illumination curve into a digital PWM (Pulse Width Modulation) signal proportional to the dimming gray level, drive a switching-type LED constant current drive circuit to make the LED light source emit light, and realize the energy conversion process in which the dimming gray level signal is proportional to the LED input current, so as to achieve the purpose of digital dimming and color mixing. This method of using a digital PWM modulation signal to achieve LED dimming and color mixing assumes that within the time range of 0-100% pulse width modulation, the average value of the current flowing through the LED is constant, that is, the PWM pulse width time is in an absolutely proportional relationship with the output power of the constant current driver.

[0003] However, in fact, when the PWM pulse width is very small, such as a pulse width below 1 / 1000, or a pulse width less than 10 μs, the switching-type constant current drive circuit is in a starting working state, and the current flowing through the LED is a pulse current generated by a switching impact response, and the maximum average value of the constant current cannot be achieved.

[0004] There will be a current rising stage. During the current rising stage, the PWM pulse width is not in a proportional relationship with the current flowing through the LED light source. This is the main reason for the color mixing color drift of the color LED light source during low-brightness dimming. Color mixing color drift is a technical problem in LED dimming applications. The fundamental reason for the low-brightness color cast is that the switching-type constant current drive circuit has a limited response speed to narrow pulse signals. Affected by the choke inductor, it outputs a non-linear current during the current rising section. This inherent characteristic cannot solve the fundamental problem by improving the circuit characteristics. The present invention provides a method for adjusting the actual output optical curve of the current rising section for the switching-type constant current drive circuit, so as to achieve a proportional relationship between the input PWM pulse width of 0-100% and the output power of the light source, thereby solving the problem of color mixing color drift existing in LED low-brightness dimming.

[0005] In the existing LED dimming method, although the excitation signal set is adjusted by subdividing the dimming gray scale set according to the theoretical optical illumination curve to achieve an ideal distortion-free optical curve effect, the current rise stage generated by the pulsed current is not considered, and the PWM pulse width is not directly proportional to the current flowing through the LED light source, resulting in color mixing and color drift easily occurring when the color LED light source is dimmed at low brightness. Summary of the Invention

[0006] The present invention provides an LED optical illumination curve calibration method, device, and computer device to solve the technical problem that in the current rise stage, the PWM pulse width is not directly proportional to the current flowing through the LED light source, and color mixing and color drift are likely to occur.

[0007] To solve the above technical problem, in the first aspect, an embodiment of the present invention provides an LED optical illumination curve calibration method, including:

[0008] According to the current waveform flowing through the LED light source, obtain the maximum current flowing through the LED light source, and determine the first dimming gray scale level, where the first dimming gray scale level is the maximum dimming gray scale level in the current rise section;

[0009] Calculate the first actual output power curve in the current rise section according to the first dimming gray scale level, calculate the second actual output power curve in the constant current section according to the average current in the constant current section, and proportionally convert the first actual output power curve and the second actual output power curve into the actual optical illumination curve output by the LED light source;

[0010] Adjust the dimming current according to the actual optical illumination curve to make the LED light source emit light precisely.

[0011] The present invention calculates the actual output power curve for the current rise section and the constant current section respectively, and converts the actual output power curve into the actual optical illumination curve through a direct proportional relationship to calibrate the theoretical optical illumination curve, so as to avoid color mixing and color drift of the LED light source caused by the non-direct proportional relationship between the PWM pulse width and the current flowing through the LED light source in the current rise section, and make the LED light source emit light precisely.

[0012] Further, the calculating the first actual output power curve in the current rise section according to the first dimming gray scale level is specifically:

[0013] Input the first gray scale level into the theoretical optical illumination curve to obtain the first theoretical optical illumination;

[0014] Obtain the maximum current in the current rise section according to the current waveform, and calculate the current change curve according to the maximum current and the first theoretical optical illumination;

[0015] Calculate the first actual output power curve of the current ramping section according to the current change curve. The first actual output power curve is a curve in which the actual output power changes with the dimming gray level when the dimming gray level is less than or equal to the first gray level.

[0016] The present invention distinguishes the current ramping section and the constant current section through the first gray level, utilizes the characteristics of the current waveform in the ramping section, calculates the current change curve of the ramping section according to the maximum current, and thus obtains the output power curve of the ramping section according to the relationship between current and power change, so as to obtain the actual output power of the LED light source in the current ramping section.

[0017] Further, calculate the second actual output power curve of the constant current section according to the average current of the constant current section, specifically:

[0018] Obtain the average current of the constant current section according to the current waveform;

[0019] Calculate the second actual output power curve of the constant current section according to the average current and the first theoretical optical illuminance. The second actual output power curve is a curve in which the actual output power changes with the dimming gray level when the dimming gray level is greater than the first gray level.

[0020] The present invention measures the average current of the constant current section through the current waveform, and calculates the output power curve of the constant current section through the current change curve of the constant current section, so as to obtain the actual output power of the LED light source changing with the current in the constant current section.

[0021] Further, convert the first actual output power curve and the second actual output power curve into the actual optical illuminance curve output by the LED light source in equal proportion, specifically:

[0022] Merge the first actual output power curve and the second actual output power curve to obtain the target actual output power curve. The target actual output power curve is a curve in which the actual output power changes with the dimming gray level within the theoretical dimming gray level;

[0023] Obtain the proportional relationship between the LED output power and the optical illuminance, and convert the target actual output power curve according to the proportional relationship to obtain the actual optical illuminance curve.

[0024] The present invention calculates the actual output power in sections, and obtains the actual optical illuminance curve according to the proportional relationship between the output power and the optical illuminance, avoiding the problems of LED light source color mixing and color drift caused by the non-proportional relationship between the PWM pulse width in the current ramping section and the current flowing through the LED light source during dimming according to the optical illuminance curve.

[0025] Further, before obtaining the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source and determining the first dimming gray level, the following steps are also included:

[0026] Obtain the theoretical optical illumination curve output by the LED light source, and obtain the theoretical optical illumination set according to the theoretical gray level and the theoretical optical illumination curve;

[0027] Input the theoretical optical illumination set into the PWM modulator to drive the switching constant current driver to output a dimming current, and obtain the waveform of the dimming current through a current oscilloscope. The dimming current is the current flowing through the LED light source.

[0028] In the present invention, the theoretical optical illumination set is used as the input value of the PWM modulator to drive the switching constant current driver to output a dimming current, so as to observe the waveform of the pulsed current and obtain the data of the current rising section and the constant current section.

[0029] Further, adjusting the dimming current according to the actual optical illumination curve to make the LED light source emit light precisely is specifically as follows:

[0030] Obtain the actual dimming gray level corresponding to the theoretical optical illumination according to the theoretical optical illumination curve and the actual optical illumination curve;

[0031] Obtain the actual optical illumination according to the actual dimming gray level, and drive the switching constant current driver to output a dimming current according to the actual optical illumination, so as to make the LED light source emit light precisely.

[0032] Further, obtaining the actual dimming gray level corresponding to the theoretical optical illumination according to the theoretical optical illumination curve and the actual optical illumination curve is specifically as follows:

[0033] Input the theoretical dimming gray level into the theoretical optical illumination curve to obtain the theoretical optical illumination set;

[0034] Input the theoretical optical illumination set into the actual optical illumination curve to obtain the actual dimming gray levels corresponding to each theoretical optical illumination in the theoretical optical illumination set.

[0035] Further, obtaining the actual optical illumination according to the actual dimming gray level and driving the switching constant current driver to output a dimming current according to the actual optical illumination to make the LED light source emit light precisely is specifically as follows:

[0036] Input the actual dimming gray levels corresponding to each theoretical optical illumination into the actual optical illumination curve to obtain the actual optical illumination corresponding to the actual dimming gray level;

[0037] Input the actual optical illuminance into a PWM modulator to drive a switched constant current driver to output an actual dimming current corresponding to the theoretical optical illuminance, so that the LED light source emits light precisely.

[0038] In the present invention, an actual optical illuminance curve is obtained by calibrating a theoretical optical illuminance curve. According to the change of the actual optical illuminance curve, a dimming current is driven and output through a PWM modulator to avoid the problems of color mixing and color drift of the LED light source easily caused by outputting current according to the theoretical optical illuminance curve.

[0039] In a second aspect, an embodiment of the present invention provides an LED optical illuminance curve calibration device, including: a current data acquisition module, an optical illuminance curve calculation module, and a driving module;

[0040] The current data acquisition module is configured to obtain the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source, and determine a first dimming gray level, where the first dimming gray level is the maximum dimming gray level in the current rising section;

[0041] The optical illuminance curve calculation module is configured to calculate a first actual output power curve in the current rising section according to the first dimming gray level, calculate a second actual output power curve in the constant current section according to the average current in the constant current section, and convert the first actual output power curve and the second actual output power curve into an actual optical illuminance curve output by the LED light source in equal proportion;

[0042] The driving module is configured to adjust the dimming current according to the actual optical illuminance curve, so that the LED light source emits light precisely.

[0043] In a third aspect, an embodiment of the present invention provides a computer device, including: a processor, a communication interface, and a memory. The processor, the communication interface, and the memory are interconnected. Among them, the memory stores executable program code, and the processor is configured to call the executable program code to execute the LED optical illuminance curve calibration method described above. Description of the Drawings

[0044] Figure 1 It is a schematic flowchart of an LED optical illuminance curve calibration method provided by Embodiment 1 of the present invention;

[0045] Figure 2 It is a schematic diagram of a current waveform of an LED optical illuminance curve calibration method provided by Embodiment 1 of the present invention;

[0046] Figure 3 It is a graph of an optical illuminance curve of step 103 provided by Embodiment 1 of the present invention;

[0047] Figure 4It is a schematic structural diagram of an LED optical illuminance curve calibration device provided in Embodiment 1 of the present invention;

[0048] Figure 5 It is a schematic flow diagram of an LED optical illuminance curve calibration method provided in Embodiment 2 of the present invention. Specific embodiments

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0050] Embodiment 1

[0051] Please refer to Figure 1 , Figure 1 It is a schematic flow diagram of an LED optical illuminance curve calibration method provided in an embodiment of the present invention, including steps 101 to 103, specifically as follows:

[0052] Step 101: According to the current waveform flowing through the LED light source, obtain the maximum current flowing through the LED light source, and determine the first dimming gray level, where the first dimming gray level is the maximum dimming gray level in the current rising section;

[0053] In this embodiment, before the step of obtaining the maximum current flowing through the LED light source and determining the first dimming gray level according to the current waveform flowing through the LED light source, it further includes:

[0054] Obtain the theoretical optical illuminance curve output by the LED light source, and according to the theoretical gray level and the theoretical optical illuminance curve, obtain the theoretical optical illuminance set;

[0055] Input the theoretical optical illuminance set into the PWM modulator to drive the switching constant current driver to output the dimming current, and obtain the waveform of the dimming current through the current oscilloscope, where the dimming current is the current flowing through the LED light source.

[0056] In this embodiment, input the theoretical gray level into the theoretical optical illuminance curve to obtain the theoretical optical illuminance.

[0057] In this embodiment, a theoretical optical illuminance mapping curve equation Y(x) is preset for the LED light source output, and it is expected that the output illuminance of the LED light source changes with the curve equation Y(x). Y(x) can be of the linear or non-linear curve type. The value of Y(x) represents the proportional relationship with the actual illuminance L(x). Assuming L(x) is the actual optical illuminance equation, L(x) = Y(x) * η, where η is the proportionality constant. The value range of the curve equation Y(x) is Y(x) ∈ (0, Ymax), and the maximum value Ymax = 65535. Among them, the variable x is the input dimming gray level, x ∈ (0, Gmax), and the maximum gray level Gmax = 255. Y(x), x, and the relevant constants jointly generate the optical illuminance curve equation Y(x); the input variable x value is 0 - 255, and the data set Y[x] is generated by the curve equation Y(x). For the convenience of calculation, the corresponding value of Y(x) is obtained by looking up the table Y(x) = Y[x], and the Y[x] is the theoretical optical illuminance set.

[0058] In this embodiment, the MCU controller sets the input variable of the PWM pulse width modulator as pwm, and the pulse width modulation range is pwm ∈ (0, Ymax), which is the same as the value range of the curve equation Y(x).

[0059] In this embodiment, by means of looking up the table, according to the dimming gray level x, the theoretical optical illuminance set Y[x] is queried, and the corresponding illuminance value Y[x] is obtained. The value of Y[x] is used as the dimming fine grading level to assign to the PWM pulse width modulator, generating a PWM pulse width modulation signal to drive the switching constant current drive circuit, and the switching constant current drive circuit outputs a dimming current proportional to the PWM pulse width modulation signal.

[0060] Please refer to Figure 2 , Figure 2 which is a schematic diagram of a current waveform of a method for calibrating an LED optical illuminance curve provided by an embodiment of the present invention.

[0061] In this embodiment, use a current oscilloscope to measure and record that the dimming gray level x = N required for the current rising section. Then N is the first dimming gray level. The dimming gray level less than N is the current rising section, and greater than N is the constant current drive section; the corresponding illuminance curve set Y[x] value Y[N] is obtained by looking up N, and Y[N] is the PWM pulse width modulation input value when the current climbs to the maximum value Imax.

[0062] In this embodiment, the specific theoretical power equation output by the LED driver is as follows:

[0063] P(x) = Uf * Imax * Pwm(x) (1)

[0064] Where Pwm(x) is the pulse width modulation function, Pwm(x) = Y(x) / Ymax, Uf is the voltage drop of the LED light source, Imax is the average current of the drive output, x is the dimming gray scale variable, Y(x) is the input variable value of the PWM modulator, and Ymax is the maximum amplitude of the PWM modulation.

[0065] Then the LED driver output power equation can be combined as:

[0066] P(x) = (Uf * Imax * / Ymax) * Y(x) (2)

[0067] P(x) = μ * Y(x) (3)

[0068] Where μ = Uf * Imax / Ymax, and the value of μ is a constant.

[0069] In this embodiment, the LED driver output power P(x) changes in a proportional relationship with the curve equation Y(x). Then the power equation can be transformed into:

[0070] P(x) = (Uf / Ymax) * S (4)

[0071] Where S = Imax * Y(x), S is the rectangular area formed by the average current Imax and the pulse width modulation input variable Y(x), and the area S reflects the process of the output power accumulating with the change of the pulse width modulation input variable Y(x).

[0072] Step 102: Calculate the first actual output power curve of the current rising section according to the first dimming gray scale level, calculate the second actual output power curve of the constant current section according to the average current of the constant current section, and convert the first actual output power curve and the second actual output power curve into the actual optical illumination curve output by the LED light source in equal proportion;

[0073] In this embodiment, it is necessary to generate the actual optical illumination mapping curve equation YA(x) of the LED light source output. Calculate the actual output power curve equations P(x) of the current rising section and the constant current section respectively, and convert the power curve equation P(x) into the actual optical illumination mapping curve equation YA(x) of the LED light source output in equal proportion.

[0074] In this embodiment, the calculating the first actual output power curve of the current rising section according to the first dimming gray scale level is specifically:

[0075] Input the first gray scale level into the theoretical optical illumination curve to obtain the first theoretical optical illumination;

[0076] Obtain the maximum current of the current rising section according to the current waveform, and calculate the current change curve according to the maximum current and the first theoretical optical illumination;

[0077] Calculate the first actual output power curve of the current rising section according to the described current change curve. The first actual output power curve is a curve in which the actual output power changes with the dimming gray level when the dimming gray level is less than or equal to the first gray level.

[0078] In this embodiment, in the current rising section, before the current rises to the maximum value Imax, the current waveform is approximately a perfect triangular waveform, so the current curve is the hypotenuse of a right triangle. Measuring the maximum average current Imax, then the output current I(x) of the constant current driver in the current rising section changes with the PWM modulation variable Y(x), and the specific formula of I(x) is:

[0079] I(x) = (Imax / Y(N)) * Y(x), x <= N (5)

[0080] Since the driving output current I(x) is variable at this time and is no longer the constant Imax. From formula 4, we can get:

[0081] P1(x) = (Uf / Ymax) * S1 (6)

[0082] S1 = I(x) * Y(x) / 2; x <= N (7)

[0083] Where S1 is the triangular area formed by the variable current I(x) and the pulse width modulation input variable Y(x).

[0084] That is, the specific formula of the first actual output power curve is:

[0085] P1(x) = (Uf / Ymax) * Imax * Y(x) * Y(x) / Y(N) / 2; x <= N (8)

[0086] P1(x) = μ * (Y(x) * Y(x) / Y(N) / 2); x <= N (9)

[0087] In this embodiment, since the current in the constant current section is constant at Imax, from formula 4, the power equation in the constant current section can be obtained, and the specific formula is:

[0088] P2(x) = (Uf / Ymax) * S2 (10)

[0089] S2 = Imax * (Y(x) - Y(N)), x > N (11)

[0090] That is, the specific formula of the second actual output power curve is:

[0091] P2(x) = (Uf / Ymax) * Imax * (Y(x) - Y(N)); x > N (12)

[0092] P2(x) = μ * (Y(x) - Y(N)); x > N (13)

[0093] In this embodiment, the method of equally scaling the first actual output power curve and the second actual output power curve into the actual optical illumination curve output by the LED light source is specifically as follows:

[0094] Merge the first actual output power curve and the second actual output power curve to obtain a target actual output power curve, where the target actual output power curve is a curve in which the actual output power changes with the dimming gray level within the theoretical dimming gray level range;

[0095] Obtain the proportional relationship between the LED output power and the optical illumination, and convert the target actual output power curve according to the proportional relationship to obtain the actual optical illumination curve.

[0096] In this embodiment, calculate the actual optical illumination mapping curve YA(x) output by the LED light source.

[0097] Merging the first actual output power curve and the second actual output power curve gives:

[0098]

[0099] According to formula 3: P(x) = μ * Y(x), it can be seen that since μ = Uf * Imax / Ymax, when the circuit parameters are determined, the values of Uf, Imax, and Ymax are all determined constants, so the value of μ is also a determined constant. For the convenience of calculation, assume that the value of μ is 1. Then the actual optical illumination mapping curve YA(x) output by the actual LED light source is specifically:

[0100] Power equation (6):

[0101]

[0102] Input the variable x value from 0 to 255, and the actual illumination set YA[x] can be generated from the curve equation YA(x);

[0103] Step 103: Adjust the dimming current according to the actual optical illumination curve to make the LED light source emit light precisely.

[0104] In this embodiment, the method of adjusting the dimming current according to the actual optical illumination curve to make the LED light source emit light precisely is specifically as follows:

[0105] Obtain the actual dimming gray level corresponding to the theoretical optical illumination according to the theoretical optical illumination curve and the actual optical illumination curve;

[0106] Obtain the actual optical illuminance according to the actual dimming gray level, and drive a switching constant current driver to output a dimming current according to the actual optical illuminance, so that the LED light source emits light precisely.

[0107] In this embodiment, obtaining the actual dimming gray level corresponding to the theoretical optical illuminance according to the theoretical optical illuminance curve and the actual optical illuminance curve specifically includes:

[0108] Input the theoretical dimming gray level into the theoretical optical illuminance curve to obtain a set of theoretical optical illuminances;

[0109] Input the set of theoretical optical illuminances into the actual optical illuminance curve to obtain the actual dimming gray levels corresponding to the respective theoretical optical illuminances in the set of theoretical optical illuminances.

[0110] In this embodiment, obtaining the actual optical illuminance according to the actual dimming gray level, and driving a switching constant current driver to output a dimming current according to the actual optical illuminance, so that the LED light source emits light precisely, specifically includes:

[0111] Input the actual dimming gray levels corresponding to the respective theoretical optical illuminances into the actual optical illuminance curve to obtain the actual optical illuminance corresponding to the actual dimming gray level;

[0112] Input the actual optical illuminance into a PWM modulator to drive a switching constant current driver to output the actual dimming current corresponding to the theoretical optical illuminance, so that the LED light source emits light precisely.

[0113] As a specific example of an embodiment of the present invention, please refer to Figure 3 , Figure 3 which is an optical illuminance curve diagram of step 103 provided by an embodiment of the present invention.

[0114] In this embodiment, from the set of theoretical optical illuminances Y[x1], the set of values of the actual optical illuminance curve YA[x] is inversely looked up to obtain the accurate dimming gray value x2.

[0115] In this embodiment, first input the theoretical dimming gray level into the theoretical optical illuminance curve to obtain the set of theoretical optical illuminances Y[x], then input the dimming gray level x = x1 into the set of theoretical optical illuminances Y[x] to look up the mapped illuminance value Y[x1]; input the mapped illuminance value Y[x1] into the set of actual optical illuminance curve data YA[x] to inversely look up the dimming gray level x = x2 corresponding to the mapped illuminance value Y[x1] on the mapped curve data set YA[x]; input x = x2 into the set of actual mapped curve data YA[x] to obtain the actual mapped illuminance value YA[x2], and input YA[x2] into a PWM pulse width modulator, so as to obtain the accurate illuminance in the actual full power range, thereby solving the problem of color drift in low-brightness color mixing.

[0116] In this embodiment, by calculating the actual output power curve in segments for the current ramp-up section and the constant current section, and converting the actual output power curve into the actual optical illumination curve through a proportional relationship to calibrate the theoretical optical illumination curve, it is possible to avoid color mixing and color drift of the LED light source caused by the non-proportional relationship between the PWM pulse width in the current ramp-up section and the current flowing through the LED light source, enabling the LED light source to emit light precisely.

[0117] Please refer to Figure 4 , Figure 4 FIG. is a schematic structural diagram of an LED optical illumination curve calibration device provided by an embodiment of the present invention, which mainly includes a current data acquisition module 401, an optical illumination curve calculation module 402, and a driving module 403;

[0118] The current data acquisition module 401 is configured to obtain the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source, and determine the first dimming gray level, where the first dimming gray level is the maximum dimming gray level in the current ramp-up section;

[0119] The optical illumination curve calculation module 402 is configured to calculate the first actual output power curve of the current ramp-up section according to the first dimming gray level, calculate the second actual output power curve of the constant current section according to the average current of the constant current section, and convert the first actual output power curve and the second actual output power curve into the actual optical illumination curve output by the LED light source in equal proportion;

[0120] The driving module 403 is configured to adjust the dimming current according to the actual optical illumination curve, so that the LED light source emits light precisely.

[0121] An embodiment of the present invention also provides a computer device, including: a processor, a communication interface, and a memory. The processor, the communication interface, and the memory are interconnected. Among them, the memory stores executable program code, and the processor is configured to call the executable program code to execute the LED optical illumination curve calibration method described above.

[0122] Embodiment 2

[0123] As a specific example of an embodiment of the present invention, please refer to Figure 5 , Figure 5 FIG. is a schematic flow diagram of an LED optical illumination curve calibration method provided by an embodiment of the present invention, which mainly includes step 501 to step 502, specifically as follows:

[0124] Step 501: Preset the theoretical optical illumination mapping equation Y(x):

[0125] Y(x) = a * x * x; (16)

[0126] Among them, the coefficient a = 1.007843, x ∈ (0, 255).

[0127] In this embodiment, the theoretical optical illumination mapping equation data set (taking integers) Y[x] = {1, 4, 9, 16, 25, 36, 49, 65, 82, 101, 122, 145, 170, 198…, 65535} is generated from the equation Y(x).

[0128] Step 502: Drive the switch-mode constant current driver to output a dimming current. Input the dimming gray level x into the data set Y[x]. The gray level variable x changes from 0 to 255. The corresponding value of Y[x] is obtained, and Y[x] is input into the PWM modulator to drive the switch-mode constant current driver to output a dimming current.

[0129] Step 503: Use an oscilloscope to obtain the current waveform flowing through the LED light source, and record the dimming gray level x = N value required for the current to climb to the maximum value. Assume N = 30. Then, the dimming gray level value less than 30 is the current climbing section, and the dimming gray level value greater than 30 is the constant current section. Check the data set Y[x], Y

[30] = 907.

[0130] Step 504: Calculate the actual output optical illumination mapping equation data set. According to the actual optical illumination mapping curve equation YA(x):

[0131]

[0132] In this embodiment, calculate the actual output optical illumination mapping equation data set. The optical illumination mapping equation data set is specifically:

[0133] YA[x] = {0.0006, 0.01, 0.05, 0.14, 0.35, 0.73, 1.34, 2.29, 3.67, 5.60, 8.20, 11.61,…, 65535}

[0134] Since when x = Gmax (the maximum gray level), the value of YA[Gmax] does not reach the maximum value of 65535, but when the PWM pulse width reaches 100%, the driving output current waveform is a straight line without a falling edge, so x = Gmax, and YA[Gmax] is forcibly assigned 65535.

[0135] Step 505: Drive the LED light source to emit light according to the actual optical illuminance. First, input the dimming gray level x1 = 40 into the set of theoretical optical illuminance mapping curves Y[x], and obtain Y

[40] = 1613. Then input it into the set YA[x] = 1613, and inversely look up the gray value x2 corresponding to the actual illuminance mapping curve set YA[x]. YA

[45] = 1588, YA

[46] = 1680. It is found that the gray value x2 is between 45 and 46. The gray value x2 can be further subdivided into a 16-bit gray value, and represented by a two-byte two-dimensional array for gray: D[x, ux]; where x2 is the low-order integer part, corresponding to the point on the set YA[x], x = 45, and ux is the proportional value after 255 equal divisions between the set YA[x] and YA[x + 1]. The specific formula for the ux value is as follows:

[0136] ux = (Y[x1] - YA[x2]) * 255 / (YA[x + 1] - YA[x]); ux ∈ (0, 255) (18)

[0137] ux = (Y

[40] - YA

[45] ) * 255 / (YA

[46] - YA

[45] ) = 69 (19)

[0138] Therefore, the dimming gray level x2 can be represented by the two-dimensional array D[x, ux] as D[45, 69]; so the dimming process is to convert the input dimming gray level x1 into another gray value x2, x2 is represented by the two-dimensional array D[x, ux], and then input the gray value D[x, ux] into the data set YA[x], and obtain the corresponding YA[x2] value. The YA[x2] value is input into the PWM pulse width modulator to perform dimming output on the switched constant current drive circuit. The specific formula for inputting the gray value D[x, ux] into the data set YA[x] is:

[0139] YA[x2] = (YA[x + 1] - YA[x]) * ux / 255 (20)

[0140] In this embodiment, input D[45, 69] into the set of actual illuminance curves YA[x], and calculate YA[x2] = 1613; input the value YA[x2] into the PWM pulse width modulator to drive the LED light source to emit light, and the LED light source can output a mapped illuminance value of 1613, which is the same as the value of the theoretical optical illuminance curve Y(x).

[0141] In this embodiment, input the gray value x1 = 40. After looking up the table and calculation and conversion, the corresponding input gray level x2 = D[45, 69] is obtained. The YA[x2] value is obtained by looking up the set of actual illuminance curves YA[x] from the gray level x2. Input the value YA[x2] into the PWM pulse width modulator to generate a PWM pulse width modulation signal to drive the switched constant current circuit, and output a dimming current to excite the LED light source to emit light.

[0142] In this embodiment, within one PWM cycle, the output current of the constant current driver is calculated in two stages: the current ramping stage and the constant current stage. Different power calculation equations are used for the current ramping stage and the constant current stage, and finally a power calculation equation for the output of the constant current driver that conforms to the actual situation within one PWM cycle is synthesized. Since the output optical illuminance of the LED light source is proportional to the input power, the LED input power equation is the equation of the LED output optical illuminance curve. Then, according to the required optical illuminance, the actual output optical illuminance curve table is inversely looked up to obtain the actual required PWM pulse width modulation gray level, thereby achieving precise dimming.

[0143] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calibrating an LED optical illumination curve, characterized in that: include: According to the current waveform flowing through the LED light source, a maximum current flowing through the LED light source is obtained, and a first dimming grayscale level is determined, where the first dimming grayscale level is a maximum dimming grayscale level in the current climbing section; The first actual output power curve of the current climbing section is calculated according to the first dimming grayscale level, the second actual output power curve of the constant current section is calculated according to the average current of the constant current section, and the first actual output power curve and the second actual output power curve are proportionally converted into an actual optical illumination curve output by the LED light source; the first actual output power curve of the current climbing section is calculated according to the first dimming grayscale level, specifically: the first grayscale level is input into the theoretical optical illumination curve to obtain the first theoretical optical illumination; Obtaining the maximum current of the current climbing section according to the current waveform, and calculating the current change curve according to the maximum current and the first theoretical optical illumination; calculating the first actual output power curve of the current climbing section according to the current change curve, wherein the first actual output power curve is a curve in which the actual output power changes with the dimming gray level when the dimming gray level is less than or equal to the first gray level; The dimming current is adjusted according to the actual optical illumination curve to enable the LED light source to emit light accurately.

2. The LED optical illumination curve calibration method according to claim 1, characterized in that: The second actual output power curve of the constant current section is calculated according to the average current of the constant current section, specifically: Obtain the average current of the constant current section according to the current waveform; A second actual output power curve of the constant current section is calculated according to the average current and the first theoretical optical illumination, wherein the second actual output power curve is a curve in which the actual output power changes with the dimming grayscale when the dimming grayscale is greater than the first grayscale.

3. The LED optical illumination curve calibration method according to claim 2, characterized in that: The first actual output power curve and the second actual output power curve are converted into an actual optical illumination curve output by the LED light source in equal proportion as follows: The first actual output power curve and the second actual output power curve are combined to obtain a target actual output power curve, wherein the target actual output power curve is a curve showing that the actual output power changes with the dimming gray level within the theoretical dimming gray level; The proportional relationship between the LED output power and the optical illumination is obtained, and the target actual output power curve is converted according to the proportional relationship to obtain the actual optical illumination curve.

4. The LED optical illumination curve calibration method according to claim 1, characterized in that: Before obtaining the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source and determining the first dimming grayscale level, the method further includes: Obtain a theoretical optical illumination curve output by the LED light source, and obtain a theoretical optical illumination set according to the theoretical grayscale level and the theoretical optical illumination curve; The theoretical optical illumination set is input into a PWM modulator to drive a switch-type constant current driver to output a dimming current, and a waveform of the dimming current is obtained through a current oscilloscope. The dimming current is the current flowing through the LED light source.

5. The LED optical illumination curve calibration method according to claim 1, characterized in that: The dimming current is adjusted according to the actual optical illumination curve to make the LED light source emit light accurately, specifically: According to the theoretical optical illumination curve and the actual optical illumination curve, obtaining an actual dimming grayscale level corresponding to the theoretical optical illumination; The actual optical illumination is obtained according to the actual dimming grayscale level, and the switch-type constant current driver is driven to output a dimming current according to the actual optical illumination, so that the LED light source can emit light accurately.

6. The LED optical illumination curve calibration method according to claim 5, characterized in that: The actual dimming grayscale level corresponding to the theoretical optical illumination is obtained according to the theoretical optical illumination curve and the actual optical illumination curve, specifically: Inputting the theoretical dimming grayscale level into the theoretical optical illumination curve to obtain a theoretical optical illumination set; The theoretical optical illumination set is input into the actual optical illumination curve to obtain the actual dimming grayscale level corresponding to each theoretical optical illumination in the theoretical optical illumination set.

7. The LED optical illumination curve calibration method according to claim 6, characterized in that: The actual optical illumination is obtained according to the actual dimming grayscale level, and the switch-type constant current driver is driven to output the dimming current according to the actual optical illumination, so that the LED light source emits light accurately, specifically: Inputting the actual dimming grayscale level corresponding to each theoretical optical illumination into the actual optical illumination curve to obtain the actual optical illumination corresponding to the actual dimming grayscale level; The actual optical illumination is input into the PWM modulator to drive the switch-type constant current driver to output the actual dimming current corresponding to the theoretical optical illumination, so that the LED light source can emit light accurately.

8. An LED optical illumination curve calibration device, characterized in that: include: Current data acquisition module, optical illumination curve calculation module and driving module; The current data acquisition module is used to obtain the maximum current flowing through the LED light source according to the current waveform flowing through the LED light source, and determine a first dimming grayscale level, where the first dimming grayscale level is the maximum dimming grayscale level in the current climbing section; The optical illumination curve calculation module is used to calculate the first actual output power curve of the current climbing section according to the first dimming grayscale level, calculate the second actual output power curve of the constant current section according to the average current of the constant current section, and convert the first actual output power curve and the second actual output power curve into an actual optical illumination curve output by the LED light source in proportion; the calculation of the first actual output power curve of the current climbing section according to the first dimming grayscale level is specifically: inputting the first grayscale level into the theoretical optical illumination curve to obtain the first theoretical optical illumination; Obtaining the maximum current of the current climbing section according to the current waveform, and calculating the current change curve according to the maximum current and the first theoretical optical illumination; calculating the first actual output power curve of the current climbing section according to the current change curve, wherein the first actual output power curve is a curve in which the actual output power changes with the dimming gray level when the dimming gray level is less than or equal to the first gray level; The driving module is used to adjust the dimming current according to the actual optical illumination curve so as to make the LED light source emit light accurately.

9. A computer device, characterized in that: include: A processor, a communication interface and a memory, wherein the processor, the communication interface and the memory are interconnected, wherein the memory stores an executable program code, and the processor is used to call the executable program code to execute the LED optical illumination curve calibration method as described in any one of claims 1-7.

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