CN111182679A

CN111182679A - LED color temperature compensation method, circuit, color modulation chip and LED system

Info

Publication number: CN111182679A
Application number: CN201911398453.3A
Authority: CN
Inventors: 黄河; 孙顺根
Original assignee: Shanghai Bright Power Semiconductor Co Ltd
Current assignee: Shanghai Bright Power Semiconductor Co Ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-05-19
Anticipated expiration: 2039-12-30
Also published as: CN111182679B

Abstract

The invention provides an LED color temperature compensation method, a circuit, a color mixing chip and an LED system, which can adjust the conducting duty ratio of each path of LED in the LED system through the input of one path of original dimming signal, namely, each path of LED can adjust the color temperature under the control of the compensated dimming signal to reach the required target color temperature of the LED system, namely, the color temperature actually reached by the LED system is the required target color temperature, thereby solving the problem that the inherent color temperature is imbalanced between the color temperature actually reached by the LED system and the target color temperature. And the upper computer is not required to modify the original dimming signal, so that the software of the upper computer for generating the original dimming signal can be kept uniform, and the problem that the software of the upper computer is not modified without permission or a plurality of software versions are required in the upper computer after the software of the upper computer is modified is solved.

Description

LED color temperature compensation method, circuit, color modulation chip and LED system

Technical Field

The invention relates to the technical field of LED lighting, in particular to an LED color temperature compensation method, a circuit, a color mixing chip and an LED system.

Background

With the development of intelligent illumination of the LED, the brightness, the color temperature, the color and the like of the LED can be controlled in various wireless or wired modes, and the control becomes increasingly simple and convenient. At present, dimming and color mixing of an LED are generally realized by adopting a PWM (pulse width modulation) mode, namely, the adjustment of brightness and color temperature is realized by adjusting the duty ratio of a PWM signal. Specifically, referring to fig. 1, IN the application of the two-path complementary LED color modulation system commonly used at present, an upper computer is used to provide a PWM signal (denoted as PWM _ IN) with a higher frequency (e.g., 2KHz) to control the LED1 and the LED2 to emit light alternately, for example, IN a PWM period of the PWM _ IN signal, the LED1 is on and the LED2 is off at a high level, and the LED1 is off and the LED2 is on at a low level. Assuming that the color temperature of the LED1 is 5000K and the color temperature of the LED2 is 3000K, the color temperature between 3000K and 5000K can be achieved by adjusting the duty ratio of the two LED channels (i.e., adjusting the duty ratio of the input PWM signal PWM _ IN, i.e., adjusting the ratio between the high level duration and the low level duration of the PWM signal PWM _ IN). Assuming that a target color temperature of 4000K is needed, the upper computer calculates that the duty ratio of the conduction of the LED1 is 50% and the duty ratio of the conduction of the LED2 is 50% by theory, and the duty ratio of the PWM signal PWM _ IN output by the upper computer is 50% at the moment. However, due to non-ideal factors, when two LEDs need to be turned on complementarily at a ratio of 50%, the actual color temperature is not 4000K, and there is an inherent deviation, that is, a problem of inherent color temperature imbalance (also called primary color temperature failure) occurs.

At present, when the actual color temperature does not reach the target color temperature, a person with the authority of modifying the upper computer is usually required to modify the duty ratio of the output PWM signal PWM _ IN at the upper computer, so that the LED system finally reaches the target color temperature. Obviously, when the color temperature of the LED system needs to be adjusted each time, the upper computer needs to modify the PWM signal output by the upper computer, which may cause a problem that there are multiple software versions in the upper computer at the same time, and a problem that the LED system cannot reach the target color temperature without permission to modify the software of the upper computer.

Disclosure of Invention

The invention aims to provide an LED color temperature compensation method, a circuit, a color mixing chip and an LED system, which can perform color temperature compensation in the process of controlling each path of LED in the LED system to adjust the color temperature by using one path of original dimming signal input so as to eliminate the inherent color temperature imbalance between the color temperature actually achieved by the LED system and the target color temperature required to be achieved.

In order to solve the above technical problem, the present invention provides a method for compensating a color temperature of an LED, including:

acquiring an original dimming signal for controlling the color temperature of the LED system;

compensating the original dimming signal according to the target color temperature required by the LED system to output a compensated dimming signal;

and adjusting the conducting ratio of each path of LED in the LED system by using the compensated dimming signal so as to enable the LED system to reach the target color temperature.

Optionally, the original dimming signal is a PWM signal or an analog signal; when the original dimming signal is a PWM signal, performing a compensation method on the original dimming signal according to a target color temperature required by the LED system, including at least one of compensating a high level duration of the PWM signal, converting the PWM signal into an analog signal to compensate a dc voltage corresponding to the converted analog signal, and performing a digital circuit compensation on the PWM signal; when the original dimming signal is an analog signal, the compensation of the original dimming signal according to the target color temperature required by the LED system includes at least one of compensating a dc voltage corresponding to the analog signal, converting the analog signal into a PWM signal to perform high level duration compensation, and converting the analog signal into a digital signal to perform digital circuit compensation.

Optionally, when the original dimming signal is a PWM signal, the step of performing high-level duration compensation on the original dimming signal according to a target color temperature required by the LED system includes:

calculating the original duration time of the PWM high level corresponding to the original dimming signal;

calculating the actual duration time of the PWM high level corresponding to the actual PWM signal duty ratio required for reaching the target color temperature, and calculating the time difference between the original duration time of the PWM high level and the actual duration time of the PWM high level, wherein the time difference is the compensation time of the PWM high level;

delaying the rising edge and/or the falling edge of the original dimming signal by the PWM high-level compensation time to perform high-level duration compensation on the original dimming signal, and further obtaining a compensated dimming signal as the compensated dimming signal.

Optionally, the step of performing dc voltage compensation on the original dimming signal according to the target color temperature required by the LED system includes:

converting the original dimming signal into a corresponding original direct current voltage signal;

calculating an actual direct current voltage signal required for reaching the target color temperature, and calculating a voltage difference value between the original direct current voltage signal and the actual direct current voltage signal, wherein the voltage difference value is the direct current compensation voltage;

and compensating the converted original direct-current voltage signal by the direct-current compensation voltage, outputting the compensated direct-current voltage signal, and further converting the compensated direct-current voltage signal into the compensated dimming signal.

Based on the same inventive concept, the invention also provides an LED color temperature compensation circuit, comprising:

the LED system comprises a color temperature compensation module, a light source module and a light source module, wherein the color temperature compensation module is used for acquiring an original dimming signal for controlling the color temperature of the LED system and compensating the original dimming signal according to a target color temperature required by the LED system so as to output a compensated dimming signal;

and the LED driving module is used for adjusting the conducting ratio of each path of LED in the LED system by using the compensated dimming signal so as to enable the LED system to reach the target color temperature.

Optionally, the color temperature compensation module comprises:

the delay setting submodule is used for configuring a delay parameter according to a target color temperature and accessing a reference voltage so as to generate a delay signal according to the configured delay parameter and the reference voltage;

the delay compensation submodule is used for acquiring an original dimming signal for controlling the color temperature of the LED system, obtaining corresponding compensation time according to the delay signal and the original dimming signal, and further compensating the original dimming signal according to the compensation time to output a compensated dimming signal, wherein the compensated dimming signal can adjust the on-state duty ratio of each path of LED in the LED system so that the LED system reaches the target color temperature.

Optionally, the delay setting submodule includes an operational amplifier, a configuration unit, a first switch unit, and a proportional current mirror; one input end of the operational amplifier is connected to the reference voltage, the other input end of the operational amplifier is connected to one end of the configuration unit and one end of a switch path of the first switch unit, an output end of the operational amplifier is connected to a control end of the first switch unit, the other end of the configuration unit is grounded, the other end of the switch path of the first switch unit is connected to an input end of the proportional current mirror, and an output end of the proportional current mirror is used as an output end of the delay setting submodule and used for outputting a delay signal related to the configuration parameters of the configuration unit to an input end of the delay compensation submodule.

Optionally, the configuration unit comprises a ground resistance and/or a ground capacitance; and/or the proportional current mirror comprises two transistors, the grids of the two transistors and the source electrode of one transistor are mutually connected and used as the input end of the proportional current mirror, the drain electrodes of the two transistors are connected, and the source electrode of the other transistor is used as the output end of the proportional current mirror.

Optionally, the configuration unit is a parameter-adjustable built-in unit, and is integrated with other units in the delay setting sub-module and the delay compensation sub-module in the same chip; or, the configuration unit is a replaceable external unit, the other units in the delay setting sub-module and the delay compensation sub-module are integrated in the same chip, and an external interface is arranged at one end of the other input end of the operational amplifier connected with one end of the switch path of the first switch unit to access and replace the configuration unit.

Optionally, the delay compensation submodule includes an oscillator, a counter, an inverter, and a flip-flop; the input end of the oscillator is connected with the output end of the delay setting submodule and is used for outputting a periodic clock signal according to the delay signal; the input end of the counter is connected with the output end of the oscillator, the enable end of the counter is connected with the original dimming signal, the output end of the counter is connected with one input end of the trigger, and the counter is used for outputting a delayed dimming signal which is delayed by the compensation time relative to the rising edge and/or the falling edge of the original dimming signal under the control of the periodic clock signal; the input end of the inverter is connected with the original dimming signal, the output end of the inverter is connected with the other input end of the trigger, and the inverter is used for providing an inverse signal of the original dimming signal for the trigger; the trigger is used for outputting the compensated dimming signal according to the delayed dimming signal and the inverse signal of the original dimming signal.

Optionally, the delay compensation submodule includes an inverter, a second switching unit, a third switching unit, a charging capacitor, and a schmitt trigger; the input end of the inverter is connected to the original dimming signal, the output end of the inverter is respectively connected to the control end of the second switching unit and the control end of the third switching unit, and the inverter is used for outputting a reverse signal of the original dimming signal to control the on or off of the switching paths of the second switching unit and the third switching unit; one end of a switch path of the second switch unit is connected with the output end of the delay setting submodule, the other end of the switch path of the second switch unit is connected with one end of a switch path of the third switch unit, one end of the charging capacitor and the input end of the Schmitt trigger, and the other end of the switch path of the third switch unit and the other end of the charging capacitor are both grounded; the second switching unit and the third switching unit are used for charging the charging capacitor through the delay signal under the control of an inverse signal of the original dimming signal, and the schmitt trigger is used for outputting the compensated dimming signal and turning over the compensated dimming signal after the voltage at one end of the charging capacitor rises to a corresponding turning point threshold.

Optionally, the color temperature compensation module comprises:

the original direct-current voltage conversion submodule is used for acquiring an original dimming signal for controlling the color temperature of the LED system and converting the original dimming signal into a corresponding original direct-current voltage signal;

the voltage compensation submodule is used for carrying out direct-current voltage compensation on the original direct-current voltage signal according to the target color temperature required by the LED system so as to output a compensated direct-current voltage signal;

and the signal conversion submodule is used for converting the compensated direct-current voltage signal into a compensated dimming signal and outputting the compensated dimming signal, and the compensated dimming signal can adjust the conducting ratio of each path of LED in the LED system so as to enable the LED system to reach the target color temperature.

Optionally, the original dc voltage conversion sub-module includes a level shifter and a low-pass filter, an input end of the level shifter is connected to the original dimming signal, an output end of the level shifter is connected to an input end of the low-pass filter, and the level shifter is configured to convert the original dimming signal into a high-low level signal set inside the LED system; the low-pass filter is used for converting the high-low level signal into the original direct-current voltage signal.

Optionally, the original dc voltage conversion sub-module further includes a buffer, an input end of the buffer is connected to an output end of the low-pass filter, and the buffer is configured to further process the original dc voltage signal output by the low-pass filter, so as to enhance the driving capability of the compensated dimming signal.

Optionally, the voltage compensation submodule includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to the output end of the original dc voltage conversion submodule, the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor and the input end of the signal conversion submodule, and the other end of the second voltage-dividing resistor is grounded.

Optionally, the voltage compensation submodule is a built-in unit with an adjustable voltage division ratio, and is integrated with the original dc voltage conversion submodule and the signal conversion submodule in the same chip; or, the voltage compensation submodule is a replaceable external unit, the original direct-current voltage conversion submodule and the signal conversion submodule are integrated in the same chip, and an external interface is arranged between the output end of the original direct-current voltage conversion submodule and the input end of the signal conversion submodule so as to access and replace the voltage compensation submodule.

Based on the same inventive concept, the invention also provides an LED color-adjusting chip which comprises the LED color temperature compensation circuit.

Based on the same inventive concept, the invention also provides an LED system, which comprises the LED color-mixing chip, at least two LEDs connected with the LED color-mixing chip and an upper computer connected with the input end of the LED color temperature compensation circuit of the LED color-mixing chip; the upper computer is used for providing original dimming signals for controlling the LEDs to adjust the color temperature and input the original dimming signals to the LED color temperature compensation circuit

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. in the process of controlling each path of LEDs in the LED system to adjust the color temperature by using one path of original dimming signal input, the original dimming signal can be compensated according to the target color temperature required by the LED system to output a compensated dimming signal, so that the duty ratio of the conduction of each path of LEDs in the LED system can be adjusted by using one path of the compensated dimming signal to achieve the target color temperature required by the LED system, namely the color temperature actually achieved by the LED system is the required target color temperature, and the inherent color temperature imbalance between the color temperature actually achieved by the LED system and the target color temperature required to be achieved can be eliminated.

2. Because the original dimming signal is not required to be modified at the upper computer, the software of the upper computer for generating the original dimming signal can be kept uniform, and the problem that the software of the upper computer is modified without permission or a plurality of software versions exist after modification is avoided.

3. The LED color temperature compensation circuit of the invention is provided with a circuit part integrated in a color mixing chip and a replaceable configuration unit or a replaceable voltage compensation submodule which is arranged outside the color mixing chip, so that the compensation degree of an original dimming signal can be changed through corresponding arrangement on the periphery of the color mixing chip, the conducting proportion of each path of LED in an LED system is adjusted to carry out color temperature control, the original color temperature is compensated to be invalid, and therefore, after the problem of inherent color temperature offset occurs, the input of the original dimming signal can be compensated through the replaceable configuration unit or the replaceable voltage compensation submodule which is arranged outside the color mixing chip, so that the problem of inherent color temperature offset is eliminated.

Drawings

FIG. 1 is a schematic circuit diagram of a two-way complementary LED color matching system;

FIG. 2A is a schematic diagram of a method for compensating a color temperature of an LED according to a first embodiment of the present invention;

FIG. 2B is a flowchart illustrating a method for compensating a color temperature of an LED according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram of an exemplary structure of an LED color temperature compensation circuit according to a first embodiment of the invention;

FIG. 4 is a timing diagram of the LED color temperature compensation circuit shown in FIG. 3 for delaying the original dimming signal;

FIG. 5 is a schematic diagram of another exemplary structure of an LED color temperature compensation circuit according to a first embodiment of the invention;

FIG. 6 is a timing diagram of the LED color temperature compensation circuit shown in FIG. 6 for delaying the original dimming signal;

fig. 7 is a schematic structural diagram of an LED system according to a first embodiment of the present invention;

FIG. 8 is a timing diagram of an LED system according to a first embodiment of the present invention;

FIG. 9A is a schematic diagram of a second embodiment of the LED color temperature compensation method according to the present invention;

FIG. 9B is a flowchart of a LED color temperature compensation method according to a second embodiment of the present invention;

FIG. 10 is a schematic diagram of an exemplary structure of a second embodiment of the LED color temperature compensation circuit according to the present invention;

fig. 11 is a timing diagram of an LED color temperature compensation circuit according to a second embodiment of the invention.

Detailed Description

As described in the background art, when the color temperature of the LED system is adjusted by adjusting the duty ratio of the two LED circuits using one PWM signal, there is an inherent deviation between the target color temperature and the actually achieved color temperature, i.e., a problem of inherent color temperature imbalance (also referred to as primary color temperature failure) is generated.

The core idea of the technical scheme of the invention is that on the premise that an upper computer is not needed to modify an original dimming signal for LED color modulation, and before the proportion of the conduction of each path of LED (at least two paths) of the LED system is adjusted by using one path of the original dimming signal, the original dimming signal is correspondingly compensated to output a compensated dimming signal, so that the proportion of the conduction of each path of LED is adjusted by the compensated dimming signal to achieve the required target color temperature when the color temperature of the LED system is adjusted. Therefore, the problem of inherent color temperature maladjustment can be prevented, and the input of the original dimming signal can be timely compensated after the problem of inherent color temperature maladjustment is caused, so that the problem of inherent color temperature maladjustment is eliminated, namely, the problem of inherent color temperature maladjustment generated when the color temperature of the LED system is adjusted is solved.

The technical solution proposed by the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Example one

The present embodiment provides an LED color temperature compensation method, where an original dimming signal obtained for controlling a color temperature of an LED system is a PWM signal, and IN the present embodiment, the original dimming signal is defined as an original PWM signal PWM _ IN, and a compensated dimming signal is defined as a compensated PWM signal PWM _ OUT, and an operating principle of the LED color temperature compensation method of the present embodiment for performing color temperature compensation is as shown IN fig. 2A, where it is assumed that a period T0 of the original PWM signal PWM _ IN input before color temperature detuning is 1ms, and a duty ratio D0 is 50%, and a high level duration TH0 of the original PWM signal PWM _ IN input before color temperature detuning is 0.5 ms; when the color temperature is found to be offset, if the upper computer modifies the duty ratio of the original PWM signal PWM _ IN to generate the original PWM signal (i.e., the original PWM signal input after the color temperature is offset) PWM _ IN input into the color adjusting chip after the color temperature is offset, so as to finally make the actual output color temperature of the LED system normal (i.e., the actual color temperature reaches the target color temperature), at this time, the duty ratio D1 of the corresponding original PWM signal PWM _ IN input after the color temperature is offset is 40%, and the high level duration TH1 is 0.4 ms. Therefore, the duty ratio of the original PWM signal PWM _ IN input to the color-toning chip before and after the color temperature is off-regulated has an inherent off-regulation Dd (D0-D1) of 10%, and the corresponding high-level failure time Td (D0-D1) T0 of 0.1 ms. IN this case, please refer to fig. 2A to fig. 5, the LED color temperature compensation method provided IN this embodiment can perform high level duration compensation on the original PWM signal PWM _ IN received by the color chip from the upper computer, so that the high level duration of the compensated PWM _ OUT signal is smaller than the original PWM signal PWM _ IN by Td time, and when the compensated PWM _ OUT signal is used to control each LED IN the LED system to perform color temperature adjustment, a desired target color temperature can be obtained. It should be appreciated that when the inherent offset Dd corresponding to the duty ratio of the input PWM signal before and after the color temperature offset is a negative value, the high level duration of the compensated PWM _ OUT signal can be increased by Td time from the original PWM signal PWM _ IN.

Based on the above working principle, the LED color temperature compensation method of this embodiment can be used for performing color temperature compensation in the process of controlling each path of LEDs (for example, two or three paths of LEDs) in the LED system to perform color temperature adjustment by using one path of original PWM signal, please refer to fig. 2B, and the LED color temperature compensation method includes the following steps:

s11, acquiring an original PWM signal for controlling the color temperature of the LED system;

s12, performing high-level duration compensation on the original PWM signal according to the target color temperature required by the LED system to output a compensated PWM signal, wherein the duty ratio of the compensated PWM signal is increased or decreased relative to the duty ratio of the original PWM signal;

and S13, adjusting the conducting ratio of each path of LED in the LED system by using the compensated PWM signal so as to control the LED system to reach the target color temperature.

Referring to fig. 2A to 4, the original PWM signal obtained IN step S11 is denoted as PWM _ IN, and the compensated PWM signal (i.e., the compensated dimming signal) output IN step S12 is denoted as PWM _ OUT. Wherein, IN step S12, the step of performing high level duration compensation on the original PWM signal PWM _ IN according to the target color temperature required by the LED system includes: firstly, calculating the original duration TH0 of the PWM high level corresponding to the original PWM signal PWM _ IN; then, calculating a PWM high level actual duration TH1 corresponding to an actual PWM signal duty cycle required to reach the target color temperature, and calculating a time difference Td between the PWM high level original duration TH0 and the PWM high level actual duration TH0, where the time difference Td is the PWM high level compensation time; next, delaying the rising edge and/or the falling edge of the original PWM signal by the PWM high-level compensation time Td to perform high-level duration compensation on the original PWM signal PWM _ IN, so as to obtain the compensated PWM signal PWM _ OUT, wherein the compensated PWM signal PWM _ OUT increases or decreases the high-level duration within one PWM period relative to the original PWM signal PWM _ IN, so as to increase or decrease the corresponding duty ratio relative to the original PWM signal PWM _ IN, and further IN step S13, after adjusting the duty ratio of each LED on IN the LED system by the compensated PWM signal PWM _ OUT, the LED system can reach the target color temperature.

Referring to fig. 3, IN order to implement the LED color temperature compensation method of the present embodiment, the present embodiment further designs an LED color temperature compensation circuit, which includes a color temperature compensation module 10 and an LED driving module 20, wherein the color temperature compensation module 10 is configured to obtain an original dimming signal PWM _ IN for controlling a color temperature of an LED system, and perform high-level time compensation on the original dimming signal PWM _ IN according to a target color temperature required by the LED system to output a compensated dimming signal PWM _ OUT; the LED driving module 20 is configured to adjust a ratio of LED conduction in each path of the LED system by using the compensated dimming signal PWM _ OUT, so that the LED system reaches the target color temperature.

Specifically, the color temperature compensation module 10 includes a delay setting submodule 11 and a delay compensation submodule 12, wherein the delay setting submodule 11 is configured to configure a delay parameter Rdelay according to a target color temperature and access a reference voltage Vref, so as to generate a delay current Idelay (i.e., a delay signal) according to the configured delay parameter Rdelay and the reference voltage Vref. The delay compensation submodule 12 is configured to obtain an original PWM signal PWM _ IN for controlling a color temperature of an LED system, obtain a corresponding PWM high-level compensation time Td (i.e., a compensation time) according to the delay current Idelay and the original PWM signal PWM _ IN, and further compensate the original PWM signal PWM _ IN according to the PWM high-level compensation time Td to output a compensated PWM signal PWM _ OUT, where a duty ratio of the compensated PWM signal PWM _ OUT is increased or decreased relative to a duty ratio of the original PWM signal PWM _ IN, and the compensated PWM signal PWM _ OUT can adjust a duty ratio of each path of LED conduction IN the LED system, so that the LED system reaches the target color temperature.

Referring to fig. 3, as an example, the delay setting submodule 11 includes an operational amplifier OP, a configuration unit 111, a first switch unit 112, and a proportional current mirror 113. Wherein the configuration unit 111 includes a ground resistance Rdelay, the first switching unit 112 includes an NMOS transistor Q1, and the proportional current mirror 113 includes a PMOS transistor Q2 and a PMOS transistor Q3. An input terminal (e.g., non-inverting input terminal +) of the operational amplifier OP is connected to the reference voltage Vref, another input terminal (e.g., inverting input terminal-) of the operational amplifier OP is connected to one terminal of the ground resistor Rdelay (i.e., one terminal of the configuration unit 111) and a source terminal of the NMOS transistor Q1 (i.e., one terminal of the switching path of the first switching unit 112), an output terminal of the operational amplifier OP is connected to a gate terminal of the NMOS transistor Q1 (i.e., the control terminal of the first switching unit 112), another terminal of the ground resistor Rdelay is grounded (i.e., another terminal of the configuration unit 111 is grounded), a drain terminal of the NMOS transistor Q1 (i.e., another terminal of the switching path of the first switching unit 112) is connected to a gate terminal and a drain terminal of the PMOS transistor Q2 and a gate terminal of the PMOS transistor Q3, a gate and a drain terminal of the PMOS transistor Q2, the sources of PMOS transistors Q2 and Q3 are connected to each other and coupled to the system voltage VDD (which is the system operating voltage of the color-tuning chip). The drain of the PMOS transistor Q3 is connected to the input of the delay compensation submodule 12 as the output of the proportional current mirror 113, i.e. the output of the delay setting submodule 11. The proportional current mirror 113 in the present embodiment can make the ratio between the input current and the output current be N:1, and the output delay current Idelay thereof is Vref/(N × rredelay), that is, the proportional current mirror 113 can output the delay current Idelay inversely proportional to the configuration parameter Rdelay of the configuration unit to the input terminal of the delay compensation submodule 12.

Continuing to refer to fig. 3, as an example, the delay compensation sub-module 12 is mainly composed of an oscillator 121, a counter 122, an inverter 123 and an RS flip-flop 124. Wherein, the input end of the oscillator 121 is connected to the output end of the delay setting submodule 11, and is configured to output a periodic clock signal clk according to the delay current Idelay; the input terminal CLK of the counter 122 is connected to the output terminal OUT of the oscillator 121, the enable terminal EN of the counter 122 is connected to the original PWM signal PWM _ IN, the output terminal OUT of the counter 122 is connected to one input terminal S of the RS flip-flop 124, the counter 122 is configured to input a delayed PWM signal S (i.e. a delayed dimming signal) delayed by M clock cycles with respect to the rising edge and/or the falling edge of the original PWM signal PWM _ IN under the control of the periodic clock signal CLK, and referring to fig. 4, the M clock cycles correspond to the exactly required PWM high-level compensation time Td; the input end of the inverter 123 is connected to the original PWM signal PWM _ IN, the output end of the inverter 123 is connected to another input end R of the RS flip-flop 124, and the inverter 123 is configured to provide an inverse signal R of the original PWM signal PWM _ IN to the RS flip-flop 124; the RS flip-flop 124 is configured to output the compensated PWM signal PWM _ OUT according to the delayed PWM signal s and the inverse signal r of the original PWM signal PWM _ IN. In this embodiment, the period (frequency) of the periodic clock signal clk is determined by the magnitude of Idelay, Tclk — K/Idelay, K is a coefficient, and Idelay — Vref/(N × rrelay).

Fig. 4 is a timing diagram of signals in the delay compensation submodule 12 shown in fig. 3 (when the intrinsic mismatch Dd corresponding to the duty ratio in fig. 2A is a positive value). Referring to fig. 4, after the delay compensated periodic clock signal clk is inputted to the counter 122, the counter 122 can output a delayed PWM signal s delayed by M clock cycles with respect to the original PWM signal PWM _ IN, where the delayed PWM signal s has the same period as the original PWM signal PWM _ IN, but the rising edge is delayed by Td, and the duration of the high level is shortened by Td. The RS flip-flop 123 outputs the compensated PWM signal PWM _ OUT according to the inverse signal r of PWM _ IN and the delayed PWM signal s. As can be seen from fig. 4, the high level duration of the compensated PWM signal PWM _ OUT is shortened by Td with respect to the original PWM signal PWM _ IN, and the rising edge of PWM _ OUT is delayed by Td with respect to PWM _ IN, and the periods of PWM _ OUT and PWM _ IN are the same, whereby the duty ratio of PWM _ OUT is reduced with respect to PWM _ IN. Where Td is tmdelay, M × Tclk, M × K × N × rtdelay/Vref, and M, K, N, Vref are all constants. Obviously, by configuring different values of the Rdelay resistance, different Td values can be achieved, i.e. different requirements for detuning of the inherent color temperature can be met. Thus, optionally, in some embodiments of the present invention, the configuration unit 111 may be a parameter-adjustable built-in unit, which is integrated in the same chip with other units in the delay setting sub-module 11 and each unit in the delay compensation sub-module 12; or, the configuration unit 111 is a replaceable external unit, other units in the delay setting submodule 11 and the delay compensation submodule 12 are integrated in the same chip, and an external interface Pin _ R is arranged at a position where the configuration unit 111 is connected to the other input end of the operational amplifier OP and the source of the transistor Q1, so as to access and replace the configuration unit 111. The parameters of the configuration unit 111 are variable, so that in the process of controlling each path of LEDs in the LED system to adjust the color temperature by using one path of original PWM signal input, the problem of inherent color temperature imbalance can be prevented by configuring the parameters in the configuration unit in advance, and after the problem of inherent color temperature imbalance occurs, the parameters of the configuration unit can be changed in time to compensate the original PWM signal input, so as to eliminate the problem of inherent color temperature imbalance.

The LED color temperature compensation circuit of the present embodiment is not limited to the circuit example shown in fig. 3, specifically, the configuration unit 111 may not be limited to be designed by the ground resistor Rdelay, but may also be designed by a capacitor, a transistor, an RC delay circuit, or the like, and the delay compensation submodule 12 is not limited to be formed by the oscillator 121, the counter 122, the inverter 123, and the RS flip-flop 124, and may also be formed by components such as a transistor, a charging capacitor, an inverter, and other flip-flops.

Referring to fig. 5, as another example of the LED color temperature compensation circuit of the present embodiment, the component composition and the connection relationship of the delay setting submodule 11 are not changed, but the delay compensation submodule 12 is replaced by a module mainly composed of an inverter 125, a second switching unit Q4, a third switching unit Q5, a charging capacitor C1, and a schmitt trigger 126. The second switching unit Q4 is a PMOS transistor, and the third switching unit Q5 is an NMOS transistor. The input end of the inverter 125 is connected to the original PWM signal PWM _ IN, the output end of the inverter 125 is simultaneously connected to the gate of the second switching unit Q4 (i.e., the control end of Q4) and the gate of the third switching unit Q5 (i.e., the control end of Q5), and the inverter 125 is configured to output the inverse signal a of the original PWM signal PWM _ IN, so as to control the switching paths (i.e., the paths between the source and the drain) of the second switching unit Q4 and the third switching unit Q5 to be turned on or off; a source of the second switching unit Q4 (i.e., one end of the switching path of Q4) is connected to the output terminal of the delay setting submodule 11 to switch in the delay current Idelay ═ Vref/(N × rredelay), a drain of the second switching unit Q4 (i.e., the other end of the switching path of Q4) is connected to the drain of the third switching unit Q5 (i.e., one end of the switching path), one end of the charging capacitor C1, and the input terminal of the schmitt trigger 126, thereby forming a node b, and a source of the third switching unit Q5 (i.e., the other end of the switching path of Q5) and the other end of the charging capacitor C1 are both grounded; the second switching unit Q4 and the third switching unit Q5 are configured to charge the charging capacitor C1 by the delay current Idelay under the control of an inverse signal a of the original PWM signal PWM _ IN, and the schmitt trigger 126 is configured to output the compensated PWM signal PWM _ OUT and to flip the compensated PWM signal PWM _ OUT after the voltage at one end of the charging capacitor C1 rises to a corresponding flip-point threshold.

Fig. 6 is a timing diagram of signals in the delay compensation submodule 12 shown in fig. 5 (when the intrinsic mismatch Dd corresponding to the duty ratio in fig. 2A is a positive value). Referring to fig. 6, IN a signal period of PWM _ IN and during the high duration Td of PWM _ IN, Idelay charges the charging capacitor C1, the voltage at the node b gradually increases along with the charging process, the rising slope of the voltage at the node b is Δ V/Δ t ═ Idelay/C, PWM _ OUT is low, when the voltage at the node b rises to the upper transition point Vth of the schmitt trigger 126, PWM _ OUT is inverted to high, and when PWM _ IN changes from high to low, PWM _ OUT is inverted to low again. Therefore, IN one period of PWM _ IN, the delay time Td (C1 Vth)/Idelay (C1 Vth N Rdelay)/Vref, during which the rising edge of PWM _ OUT is delayed with respect to the rising edge of PWM _ IN. And the periods of PWM _ OUT and PWM _ IN are the same, and the high level duration of PWM _ OUT is shortened by Td with respect to PWM _ IN, whereby the duty ratio of PWM _ OUT is reduced with respect to PWM _ IN.

It should be noted that, although fig. 4 and 5 illustrate performing the high-level duration compensation on the rising edge of the original PWM signal PWM _ IN, the technical solution of the present invention is not limited thereto, and IN other embodiments of the present invention, the high-level duration compensation may be performed on the falling edge of the original PWM signal PWM _ IN, or the high-level duration compensation may be performed on both the rising edge and the falling edge of the original PWM signal PWM _ IN, so that the periods of the finally obtained compensated PWM _ OUT and PWM _ IN are the same, but the high-level duration of the PWM _ OUT is shortened or increased relative to the PWM _ IN, and thus the duty ratio of the PWM _ OUT is decreased or increased relative to the PWM _ IN.

Based on the same inventive concept, the present embodiment further provides an LED color-adjusting chip 2, please refer to fig. 7, which includes the LED color temperature compensation circuit described in the present embodiment, and the LED driving module 20 can be implemented by specifically adopting the circuit design shown in fig. 3 or fig. 5. The LED driving module 20 is connected to the color temperature compensation module 10 and each LED in the LED system, and the LED driving module 20 is configured to enable a corresponding LED in the LED system to be turned on and adjust a duty ratio of the LED in the LED system to be turned on under the control of the compensated PWM signal PWM _ OUT output by the color temperature compensation module 10, so as to achieve a target color temperature required by the LED system. The LED driving module 20 is provided with LED driving units corresponding to the LEDs, for example, when the LED system is a two-color temperature LED system, the LED driving module 20 has two LEDs 1 and an LED2, the LED driving module 20 has a first LED driving unit for driving the LED1 to be turned on or off according to the compensated PWM signal PWM _ OUT, and a second LED driving unit for driving the LED2 to be turned on or off according to the compensated PWM signal PWM _ OUT.

With reference to fig. 7, the present embodiment further provides an LED system, which includes the LED color-adjusting chip 2, at least two LEDs connected to the LED color-adjusting chip 2, and an upper computer 1 connected to an input end of the color temperature compensation module 10 of the LED color-adjusting chip 2. The upper computer 1 is used for providing original PWM signals PWM _ IN for controlling the LEDs to adjust the color temperature for the color temperature compensation module 10, the color temperature compensation module 10 of the LED color matching chip 2 is used for compensating the original PWM signals PWM _ IN for high-level duration time so as to output compensated PWM signals PWM _ OUT, and the duty ratio of the compensated PWM signals PWM _ OUT is increased or decreased relative to the original PWM signals PWM _ IN. The LED driving module 20 of the LED color matching chip 2 is provided with LED driving units corresponding to the LEDs of each channel one by one, and the LED driving module 20 is configured to enable the corresponding LED to be turned on and adjust the duty ratio of the LED to be turned on in the LED system under the control of the compensated PWM signal PWM _ OUT output by the color temperature compensation module 10, so as to achieve the target color temperature required by the LED system.

Referring to fig. 8, fig. 8 shows a timing sequence example of the LED system of the present embodiment, and it can be seen from fig. 8 that the compensated PWM signal PWM _ OUT has the same period as the original PWM signal PWM _ IN, but the rising edge is delayed by Td with respect to the original PWM signal PWM _ IN, and the high-level duration is shortened by Td with respect to the original PWM signal PWM _ IN, so that the duty ratio is reduced with respect to the original PWM signal PWM _ IN. The color temperatures of the LED1 and the LED2 are different, and when the compensated PWM signal PWM _ OUT is adopted, the LED1 and the LED2 can be controlled to alternately emit light at the same time, for example, in a PWM period of the PWM _ OUT signal, the LED1 is on and the LED2 is off at a high level, and the LED1 is off and the LED2 is on at a low level, so that the duty ratio of the conduction of the two LEDs 1 and the LED2 can be adjusted by the compensated PWM signal PWM _ OUT, and the color temperature of each LED can be adjusted, thereby realizing the target color temperature of the LED system.

In summary, in the technical solution of the present embodiment, on the premise that the upper computer is not required to modify the original PWM signal, in the process of controlling each path of LEDs in the LED system to adjust the color temperature by using one path of original PWM signal input, high level duration compensation of the original PWM signal according to a target color temperature required by the LED system, to output a compensated PWM signal having a duty cycle that is increased or decreased relative to a duty cycle of the original PWM signal, therefore, the conducting ratio of each path of LED in the LED system can be adjusted by utilizing one path of the compensated PWM signal so as to control the LED system to reach the required target color temperature, namely, the color temperature actually achieved by the LED system is the required target color temperature, so that the inherent color temperature imbalance between the color temperature actually achieved by the LED system and the required target color temperature can be eliminated. In addition, because the upper computer is not required to modify the original PWM signal, the software of the upper computer for generating the original PWM signal can be kept uniform, and the problem that the software of the upper computer is modified without permission or a plurality of software versions exist simultaneously after modification is avoided. In addition, the LED color temperature compensation circuit of this embodiment may further have a circuit portion integrated in the color-mixing chip and a replaceable configuration unit externally disposed outside the color-mixing chip, so that after the duty ratio of the original PWM signal is increased or decreased by corresponding settings on the periphery of the color-mixing chip, the color temperature control is performed by adjusting the duty ratio of the turn-on of each LED in the LED system, thereby compensating for the failure of the original color temperature.

It should be noted that, although the above-mentioned embodiment performs high-level duration compensation on the original PWM signal based on the principle of converting the duty ratio of the PWM signal into the high-level duration to obtain the compensated PWM signal with the increased or decreased duty ratio, the technical solution of the present invention is not limited thereto, and in other embodiments of the present invention, the original PWM signal may be subjected to dc voltage compensation based on the principle of converting the duty ratio of the original PWM signal into the dc voltage to obtain the compensated PWM signal (i.e., the compensated dimming signal) with the increased or decreased duty ratio. The voltage compensation scheme is described in detail below with reference to the second embodiment and the corresponding drawings.

Example two

The present embodiment provides an LED color temperature compensation method, wherein an original dimming signal for controlling a color temperature of an LED system is obtained as a PWM signal, the original dimming signal is defined as an original PWM signal PWM _ IN, and a compensated dimming signal is defined as a compensated PWM signal PWM _ OUT, the LED color temperature compensation method of the present embodiment performs color temperature compensation according to the working principle as shown IN fig. 9A, assuming that the input original PWM signal PWM _ IN, Vref corresponding to 100% duty ratio, and 0.5 × Vref corresponding to 50% duty ratio, and the duty ratio D0 of the input original PWM signal PWM _ IN before the color temperature imbalance is equal to 50%, when the color temperature imbalance is found, if the original PWM signal PWM _ IN is generated by modifying the duty ratio of the original PWM signal PWM _ IN by an upper computer after the color temperature imbalance is generated (i.e. the input PWM signal after the color temperature imbalance is obtained) PWM _ IN, finally, the actual output color temperature of the LED system is normal (that is, the actual color temperature reached is the target color temperature), and the duty ratio D1 of the input original PWM signal PWM _ IN after the corresponding color temperature is detuned is 40%. Therefore, the duty ratio of the original PWM signal PWM _ IN input to the color-toning chip before and after the color temperature is detuned has inherent detuning Dd (D0-D1) of 10%, and the corresponding voltage Vd (D0-D1) of 0.1 Vref. IN this case, please refer to fig. 9A to 11, the LED color temperature compensation method provided IN this embodiment can convert the original PWM signal PWM _ IN received by the color-adjusting chip from the upper computer into an analog signal, then perform dc voltage compensation on the converted analog signal, so that the dc voltage value corresponding to the compensated analog signal is reduced relative to the voltage value corresponding to the analog signal converted from the original PWM signal PWM _ IN, and then convert the compensated analog signal into a compensated PWM _ OUT signal, at this time, the duty ratio of the compensated PWM _ OUT signal is reduced relative to the original PWM signal PWM _ IN, and when the compensated PWM _ OUT signal is used to control each path of LEDs IN the LED system to perform color temperature adjustment, the LED system can reach the desired target color temperature. It should be appreciated that, when the inherent offset Dd corresponding to the duty ratio of the input original PWM signal PWM _ IN before and after the color temperature offset is a negative value, the dc voltage value corresponding to the compensated analog signal is increased relative to the voltage value corresponding to the analog signal converted from the original PWM signal PWM _ IN, so that the duty ratio of the compensated PWM _ OUT signal converted from the compensated analog signal is increased relative to the original PWM signal PWM _ IN.

Based on the above working principle, the LED color temperature compensation method of this embodiment can be used for performing color temperature compensation in the process of controlling each path of LEDs (for example, two or three paths of LEDs) of the LED system to perform color temperature adjustment by using one path of original PWM signal, please refer to fig. 9B, and the LED color temperature compensation method includes the following steps:

s21, acquiring an original PWM signal for controlling the color temperature of the LED system;

s22, converting the original PWM signal into an original DC voltage signal, and performing DC voltage compensation on the original DC voltage signal according to the target color temperature required by the LED system to output a compensated PWM signal, wherein the duty ratio of the compensated PWM signal is increased or decreased relative to the duty ratio of the original PWM signal;

and S23, adjusting the conducting duty ratio of each path of LED in the LED system by using the compensated PWM signal so as to control the LED system to reach the target color temperature.

Referring to fig. 9A to 11, the original PWM signal obtained IN step S21 is denoted as PWM _ IN, and the compensated PWM signal output IN step S22 is denoted as PWM _ OUT. IN step S22, the step of performing dc voltage compensation on the original PWM signal PWM _ IN according to the target color temperature required by the LED system includes: firstly, converting the original PWM signal PWM _ IN into an original dc voltage signal Vc IN proportion to the duty ratio of the original PWM signal PWM _ IN (i.e. PWM _ IN is converted into an analog signal, and the dc voltage value corresponding to the analog signal is Vc); then, calculating an actual direct-current voltage signal Vc2 corresponding to an actual PWM signal duty ratio required for reaching the target color temperature, and calculating a voltage difference value between the original direct-current voltage signal Vc and the actual direct-current voltage signal Vc2, wherein the voltage difference value is the direct-current compensation voltage Vd; then, the converted original dc voltage signal Vc is compensated with the dc compensation voltage Vd and then output as a compensated dc voltage signal Vc2 (i.e., a compensated analog signal, the corresponding dc voltage value is Vc2), and the compensated dc voltage signal Vc2 is further converted into a compensated PWM signal PWM _ OUT, the duty ratio of the compensated PWM signal PWM _ OUT is increased or decreased relative to the original PWM signal PWM _ IN, and then IN step S3, after the duty ratio of each LED IN the LED system is adjusted by the compensated PWM signal PWM _ OUT, the target color temperature required by the LED system can be achieved.

Referring to fig. 10, in order to implement the LED color temperature compensation method of the present embodiment, the present embodiment further designs an LED color temperature compensation circuit, which also includes a color temperature compensation module 10 and an LED driving module 20, and the function and design of the LED driving module 20 may be completely the same as those of the first embodiment. The LED color temperature compensation circuit of the present embodiment is different from the first embodiment IN that the color temperature compensation module 10 has different functions and circuit designs, so that the color temperature compensation module 10 has different compensation ways for obtaining the original dimming signal PWM _ IN. The color temperature compensation module 10 of this embodiment can convert the original dimming signal PWM _ IN into the corresponding original dc voltage signal Vc, then perform dc voltage compensation on the original dc voltage signal Vc according to the target color temperature required by the LED system, and convert the compensated dc voltage signal into the compensated dimming signal PWM _ OUT.

Specifically, the color temperature compensation module 10 of the present embodiment includes an original dc voltage conversion submodule 31, a voltage compensation submodule 33, and a signal conversion submodule 34. The original dc voltage conversion submodule 31 is configured to obtain an original PWM signal PWM _ IN for controlling a color temperature of the LED system, and convert the original PWM signal PWM _ IN into an original dc voltage signal Vc IN proportion to a duty ratio of the original PWM signal PWM _ IN, that is, the original dc voltage conversion submodule 31 is configured to convert the original PWM signal PWM _ IN into an analog signal, where a dc voltage value corresponding to the analog signal is Vc. The voltage compensation submodule 33 is configured to perform dc voltage compensation on the original dc voltage signal Vc according to a target color temperature required by the LED system to output a compensated dc voltage signal Vc2, that is, the voltage compensation submodule 33 is configured to compensate the dc voltage of the analog signal converted from the original PWM signal PWM _ IN to output a compensated analog signal, a dc voltage value corresponding to the compensated analog signal is Vc2, and Vc2 is increased or decreased relative to Vc. The signal conversion sub-module 34 is configured to convert the compensated dc voltage signal Vc2 into a compensated PWM signal PWM _ OUT and output the compensated PWM signal PWM _ OUT, where a duty ratio of the compensated PWM signal PWM _ OUT is increased or decreased relative to a duty ratio of the original PWM signal PWM _ IN, and the compensated PWM signal PWM _ OUT can adjust a duty ratio of each LED IN the LED system to enable the LED system to reach the target color temperature.

As an example, the original dc voltage conversion sub-module 31 includes a level shifter 311 and a low pass filter 312, an input terminal of the level shifter 311 is connected to the original PWM signal PWM _ IN, an output terminal of the level shifter 312 is connected to an input terminal of the low pass filter 312, and an input terminal of a buffer 313 is connected to an output terminal of the low pass filter 312. The level shifter 311 is used for converting the high-low level of the original PWM signal PWM _ IN into a high-low level signal a set inside the LED system; the low pass filter 312 is used to convert the high-low level signal a into an original dc voltage signal b proportional to the duty ratio of the original PWM signal PWM _ IN; the buffer 313 is configured to further process the original dc voltage signal b output by the low-pass filter 312 into an original dc voltage signal Vc with relatively enhanced driving capability, where the voltage value of the original dc voltage signal Vc is unchanged relative to the original dc voltage signal b, but the driving capability is enhanced, so as to enhance the driving capability of the compensated PWM signal.

As an example, the voltage compensation submodule 32 includes a first voltage-dividing resistor R1 and a second voltage-dividing resistor R2, one end of the first voltage-dividing resistor R1 is connected to the output terminal of the buffer 313 (i.e., the output terminal of the original dc voltage conversion submodule 31), the other end of the first voltage-dividing resistor R1 is connected to one end of the second voltage-dividing resistor R2 and the input terminal of the signal conversion submodule 33, the other end of the second voltage-dividing resistor R2 is grounded, and a node where the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 are connected is used for outputting the compensated dc voltage signal Vc 2.

The signal conversion sub-module 33 can convert the compensated dc voltage signal Vc2 output by the voltage compensation sub-module 32 into a PWM signal output, i.e., output the compensated PWM signal PWM _ OUT.

Fig. 11 is a timing chart of signals in the LED color temperature compensation circuit shown in fig. 10 (when the inherent offset Dd corresponding to the duty ratio in fig. 9A is a positive value). Referring to fig. 11, when the duty ratio of the original PWM signal PWM _ IN is 50%, the highest value of the corresponding high-low level signal a is Vref, the voltage values of the corresponding original dc voltage signal b and Vc are both Vref/2, the voltage value of the compensated dc voltage signal Vc2 obtained by voltage compensating Vc is both 0.4 × Vref, and then the duty ratio of the compensated PWM signal PWM _ OUT is 40%.

In addition, it should be noted that in the voltage compensation submodule 32, R1 and R2 form a voltage dividing network, and different compensated dc voltage signals Vc2 can be obtained by adjusting the proportions of R1 and R2, so that the voltage compensation submodule 32 may be a built-in unit with an adjustable voltage dividing proportion, which is integrated with the original dc voltage conversion submodule 31 and the signal conversion submodule 33 in the same chip; or, the voltage compensation submodule 32 is a replaceable external unit, the original dc voltage conversion submodule 31 and the signal conversion submodule 33 are integrated in the same chip, and an external interface 321 is arranged between the output end of the original dc voltage conversion submodule 31 and the input end of the signal conversion submodule 33 to access and replace the voltage compensation submodule 32, so as to meet the requirement of different color temperatures of the LED system. Namely, the voltage division ratio of the voltage compensation submodule 32 is variable, so that in the process of controlling each path of LED in the LED system to adjust the color temperature by using one path of original PWM signal input, the problem of inherent color temperature imbalance can be prevented by configuring the voltage division ratio of the voltage compensation submodule 32 in advance, and after the problem of inherent color temperature imbalance occurs, the voltage division ratio of the voltage compensation submodule 32 can be changed in time to compensate the original PWM signal input, so as to eliminate the problem of inherent color temperature imbalance.

Referring to fig. 7, based on the same inventive concept, the present embodiment further provides an LED color-adjusting chip 2, which includes a color temperature compensation module 10 and an LED driving module 20, wherein the color temperature compensation module 10 can be implemented by using the circuit design shown in fig. 10. The LED driving module 20 is connected to the color temperature compensation module 10 and each LED in the LED system, and the LED driving module 20 is configured to enable a corresponding LED in the LED system to be turned on and adjust a duty ratio of the LED in the LED system to be turned on under the control of the compensated PWM signal PWM _ OUT output by the color temperature compensation module 10, so as to achieve a target color temperature required by the LED system. The LED driving module 20 is provided with LED driving units corresponding to the LEDs, for example, when the LED system is a two-color temperature LED system, the LED driving module 20 has two LEDs 1 and an LED2, the LED driving module 20 has a first LED driving unit for driving the LED1 to be turned on or off according to the compensated PWM signal PWM _ OUT, and a second LED driving unit for driving the LED2 to be turned on or off according to the compensated PWM signal PWM _ OUT.

With reference to fig. 7, the present embodiment further provides an LED system, which includes the LED color-adjusting chip 2, at least two LEDs connected to the LED color-adjusting chip 2, and an upper computer 1 connected to an input end of the color temperature compensation module 10 of the LED color-adjusting chip 2. The upper computer 1 is configured to provide an original PWM signal PWM _ IN for controlling each path of the LEDs to perform color temperature adjustment and input to the color temperature compensation module 10, and the color temperature compensation module 10 of the LED color adjusting chip 2 is configured to perform dc voltage compensation on the original PWM signal PWM _ IN to output a compensated PWM signal PWM _ OUT, where a duty ratio of the compensated PWM signal PWM _ OUT is increased or decreased relative to the original PWM signal PWM _ IN. The LED driving module 20 of the LED color matching chip 2 is provided with LED driving units corresponding to the LEDs of each channel one by one, and the LED driving module 20 is configured to enable the corresponding LED to be turned on and adjust the duty ratio of the LED to be turned on in the LED system under the control of the compensated PWM signal PWM _ OUT output by the color temperature compensation module 10, so as to achieve the target color temperature required by the LED system.

In summary, in the technical solution of the present embodiment, on the premise that the upper computer is not required to modify the original PWM signal, in the process of controlling each path of LEDs in the LED system to adjust the color temperature by using one path of original PWM signal input, performing DC voltage compensation on the original PWM signal according to a target color temperature required by the LED system to output a compensated PWM signal, the duty ratio of the compensated PWM signal is increased or decreased relative to the original PWM signal, so that the conducting duty ratio of the two LEDs is adjusted through the compensated PWM signal, namely, each path of LED can adjust the color temperature under the control of the compensated PWM signal to reach the target color temperature needed when adjusting the color temperature of the LED system, namely, the color temperature actually achieved by the LED system is the required target color temperature, so that the inherent color temperature imbalance between the color temperature actually achieved by the LED system and the required target color temperature can be eliminated. In addition, because the upper computer is not required to modify the original PWM signal, the software of the upper computer for generating the original PWM signal can be kept uniform, and the problem that the software of the upper computer is modified without permission or a plurality of software versions exist simultaneously after modification is avoided. In addition, the LED color temperature compensation circuit of this embodiment may further have a circuit portion integrated in the color-mixing chip and a replaceable configuration unit externally disposed outside the color-mixing chip, so that after the duty ratio of the original PWM signal is increased or decreased by corresponding settings on the periphery of the color-mixing chip, the color temperature control is performed by adjusting the duty ratio of the turn-on of each LED in the LED system, thereby compensating for the failure of the original color temperature.

In the first and second embodiments, although the embodiments respectively illustrate the method of performing the high level duration compensation on the original dimming signal according to the target color temperature required by the LED system and the method of performing the compensation on the dc voltage corresponding to the PWM signal when the original dimming signal is the PWM signal, the technical solution of the present invention is not limited thereto, and in other embodiments of the present invention, the dimming signal may be compensated in the digital circuit manner according to the target color temperature required by the LED system when the original dimming signal is the PWM signal. In addition, in another embodiment of the present invention, the original dimming signal may also be an analog signal, and the compensating of the original dimming signal according to the target color temperature required by the LED system may include compensating a dc voltage corresponding to the analog signal, or converting the analog signal into a PWM signal for high level duration compensation, or converting the analog signal into a digital signal for digital circuit compensation. That is, as long as the LED color temperature compensation circuit (i.e., the circuit of the color temperature compensation module 10) can be designed reasonably according to the form of the original dimming signal and the compensation mode to be used without modifying the original dimming signal by the upper computer, the original dimming signal can be converted correspondingly in the process of controlling each path of LED in the LED system to adjust the color temperature by using one path of original dimming signal input, and the compensated dimming signal can be obtained by compensating the converted signal by using the compensation mode, and the duty ratio of each path of LED conduction of the LED system can be adjusted by the compensated dimming signal, so that the LED system can reach the required target color temperature, and the obtained technical solutions all belong to the technical solution scope of the present invention.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. An LED color temperature compensation method, characterized in that the color temperature compensation method comprises:

2. The color temperature compensation method of claim 1, wherein the original dimming signal is a PWM signal or an analog signal; when the original dimming signal is a PWM signal, performing a compensation method on the original dimming signal according to a target color temperature required by the LED system, including at least one of compensating a high level duration of the PWM signal, converting the PWM signal into an analog signal to compensate a dc voltage corresponding to the converted analog signal, and performing a digital circuit compensation on the PWM signal; when the original dimming signal is an analog signal, the compensation of the original dimming signal according to the target color temperature required by the LED system includes at least one of compensating a dc voltage corresponding to the analog signal, converting the analog signal into a PWM signal to perform high level duration compensation, and converting the analog signal into a digital signal to perform digital circuit compensation.

3. The color temperature compensation method of claim 2, wherein when the original dimming signal is a PWM signal, the step of performing high-level duration compensation on the original dimming signal according to a target color temperature required by the LED system comprises:

4. The color temperature compensation method of claim 2, wherein the step of performing dc voltage compensation on the original dimming signal according to the target color temperature required by the LED system comprises:

5. An LED color temperature compensation circuit, comprising:

the color temperature compensation module is used for acquiring an original dimming signal for controlling the color temperature of the LED system, and compensating the original dimming signal according to the target color temperature required by the LED system so as to output the compensated dimming signal;

6. The LED color temperature compensation circuit of claim 5, wherein the color temperature compensation module comprises: the delay setting submodule is used for configuring a delay parameter according to a target color temperature and accessing a reference voltage so as to generate a delay signal according to the configured delay parameter and the reference voltage;

7. The LED color temperature compensation circuit of claim 6, wherein the delay setting submodule comprises an operational amplifier, a configuration unit, a first switching unit and a proportional current mirror; one input end of the operational amplifier is connected to the reference voltage, the other input end of the operational amplifier is connected to one end of the configuration unit and one end of a switch path of the first switch unit, an output end of the operational amplifier is connected to a control end of the first switch unit, the other end of the configuration unit is grounded, the other end of the switch path of the first switch unit is connected to an input end of the proportional current mirror, and an output end of the proportional current mirror is used as an output end of the delay setting submodule and used for outputting a delay signal related to the configuration parameters of the configuration unit to an input end of the delay compensation submodule.

8. The LED color temperature compensation circuit of claim 7, wherein the configuration unit comprises a resistance to ground and/or a capacitance to ground; and/or the proportional current mirror comprises two transistors, the grids of the two transistors and the source electrode of one transistor are mutually connected and used as the input end of the proportional current mirror, the drain electrodes of the two transistors are connected, and the source electrode of the other transistor is used as the output end of the proportional current mirror.

9. The LED color temperature compensation circuit of claim 7, wherein the configuration unit is a parameter-adjustable built-in unit integrated with other units in the delay setting submodule and the delay compensation submodule in a same chip; or, the configuration unit is a replaceable external unit, the other units in the delay setting sub-module and the delay compensation sub-module are integrated in the same chip, and an external interface is arranged at one end of the other input end of the operational amplifier connected with one end of the switch path of the first switch unit to access and replace the configuration unit.

10. The LED color temperature compensation circuit of claim 6, wherein the delay compensation submodule comprises an oscillator, a counter, an inverter and a flip-flop; the input end of the oscillator is connected with the output end of the delay setting submodule and is used for outputting a periodic clock signal according to the delay signal; the input end of the counter is connected with the output end of the oscillator, the enable end of the counter is connected with the original dimming signal, the output end of the counter is connected with one input end of the trigger, and the counter is used for outputting a delayed dimming signal which is delayed by the compensation time relative to the rising edge and/or the falling edge of the original dimming signal under the control of the periodic clock signal; the input end of the inverter is connected with the original dimming signal, the output end of the inverter is connected with the other input end of the trigger, and the inverter is used for providing an inverse signal of the original dimming signal for the trigger; the trigger is used for outputting the compensated dimming signal according to the delayed dimming signal and the inverse signal of the original dimming signal.

11. The LED color temperature compensation circuit of claim 6, wherein the delay compensation submodule comprises an inverter, a second switching unit, a third switching unit, a charging capacitor, and a Schmitt trigger; the input end of the inverter is connected to the original dimming signal, the output end of the inverter is respectively connected to the control end of the second switching unit and the control end of the third switching unit, and the inverter is used for outputting a reverse signal of the original dimming signal to control the on or off of the switching paths of the second switching unit and the third switching unit; one end of a switch path of the second switch unit is connected with the output end of the delay setting submodule, the other end of the switch path of the second switch unit is connected with one end of a switch path of the third switch unit, one end of the charging capacitor and the input end of the Schmitt trigger, and the other end of the switch path of the third switch unit and the other end of the charging capacitor are both grounded; the second switching unit and the third switching unit are used for charging the charging capacitor through the delay signal under the control of an inverse signal of the original dimming signal, and the schmitt trigger is used for outputting the compensated dimming signal and turning over the compensated dimming signal after the voltage at one end of the charging capacitor rises to a corresponding turning point threshold.

12. The LED color temperature compensation circuit of claim 5, wherein the color temperature compensation module comprises:

13. The LED color temperature compensation circuit of claim 12, wherein the original dc voltage conversion submodule comprises a level shifter and a low pass filter, an input terminal of the level shifter is connected to the original dimming signal, an output terminal of the level shifter is connected to an input terminal of the low pass filter, and the level shifter is configured to convert the original dimming signal into a high-low level signal set inside the LED system; the low-pass filter is used for converting the high-low level signal into the original direct-current voltage signal.

14. The LED color temperature compensation circuit of claim 13, wherein the original dc voltage conversion sub-module further comprises a buffer, an input terminal of the buffer is connected to an output terminal of the low pass filter, and the buffer is configured to further process the original dc voltage signal output by the low pass filter to enhance the driving capability of the compensated dimming signal.

15. The LED color temperature compensation circuit of claim 12, wherein the voltage compensation sub-module comprises a first voltage dividing resistor and a second voltage dividing resistor, one end of the first voltage dividing resistor is connected to the output terminal of the original dc voltage conversion sub-module, the other end of the first voltage dividing resistor is connected to one end of the second voltage dividing resistor and the input terminal of the signal conversion sub-module, and the other end of the second voltage dividing resistor is grounded.

16. The LED color temperature compensation circuit of claim 15, wherein the voltage compensation submodule is a built-in unit with adjustable voltage division ratio, which is integrated with the original dc voltage conversion submodule and the signal conversion submodule in the same chip; or, the voltage compensation submodule is a replaceable external unit, the original direct-current voltage conversion submodule and the signal conversion submodule are integrated in the same chip, and an external interface is arranged between the output end of the original direct-current voltage conversion submodule and the input end of the signal conversion submodule so as to access and replace the voltage compensation submodule.

17. An LED color-modulation chip, characterized by comprising the LED color temperature compensation circuit of any one of claims 5 to 16.

18. An LED system, comprising the LED color tuning chip of claim 17, at least two LEDs connected to the LED color tuning chip, and an upper computer connected to an input terminal of an LED color temperature compensation circuit of the LED color tuning chip; the upper computer is used for providing original dimming signals for controlling the LEDs to adjust the color temperature and input the original dimming signals for the LED color temperature compensation circuit.