Light emitting diode (LED) controller having function of flicker removal, LED flicker removal circuit and related method
An LED controller and controller technology, which is applied in the direction of electric lamp circuit layout, electric light source, lighting device, etc., can solve the problems of unstable dimming signal, flickering and distortion of LED circuit 4, etc.
Inactive Publication Date: 2012-02-01
RICHTEK TECH
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Problems solved by technology
However, if figure 2 As shown, the actual PWM signal 2 is skewed during the turn-on and turn-off process, and the clock signal CLK 3 also has jitter
The distortion of the PWM signal 2 and the sharp jump of the clock signal CLK 3 will lead to errors in the calculation of the duty ratio
For example, the same PWM signal 2 may calculate a different duty ratio, and the dimming signal will be unstable due to the calculation error, which will cause the LED circuit 4 to flicker
Method used
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[0070] The main technical idea of the invention is to use hysteresis judgment to eliminate the flickering problem of the LED circuit.
[0071] see image 3 , shows an embodiment of the LED controller with flicker removal function of the present invention. As shown in the figure, the PWM signal 2 is input to the duty ratio calculation circuit 110 in the LED controller 10, and the duty ratio calculation circuit 110 operates as follows figure 2 The shown clock signal CLK 3 (which can be internally generated or externally input) is used to calculate the duty ratio of the PWM signal 2, and express the duty ratio in n-digit form, which is the duty input signal Duty-IN. For example, assuming that the working time of PWM signal 2 is t and the period is T, then
[0072] Working input signal Duty-IN=(t / T)×2 n
[0073] The duty input signal Duty-IN is input to the LED flicker removal circuit 120 . The LED flicker removal circuit 120 outputs the duty output signal Duty-OUT accordi...
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The invention provides a light emitting diode (LED) controller having a function of flicker removal, an LED flicker removal circuit and a related method. The LED controller having the function of the flicker removal comprises a duty ratio counting circuit, the LED flicker removal circuit and a dimming circuit, wherein the duty ratio counting circuit is used for receiving a pulse width modulation (PWM) signal and generating an operating input signal to represent the duty ratio of the PWM signal; the LED flicker removal circuit is used for receiving the operating input signal and generating an operating output signal to filter noise of the operating input signal; and the dimming circuit is used for receiving the operating output signal and generating a dimming signal to control an LED circuit, wherein the operating output signal retains a previous operating output signal and is unchanged when the change value of the operating input signal is not greater than a hysteresis critical value, and the operating output signal follows the current operating input signal when the change value of the operation input signal is greater than the hysteresis critical value.
Description
technical field [0001] The invention relates to a light-emitting diode (LED) controller with the function of removing flicker, in particular to an LED controller using hysteresis effect to remove flicker. The present invention also relates to an LED circuit for removing flicker and a method for removing flicker for the LED circuit. Background technique [0002] figure 1 Showing a prior art circuit, the LED controller 1 controls the LED circuit 4 . The brightness of the LED can be adjusted according to the duty ratio of the pulse width modulation (PWM) signal 2, the higher the duty ratio, the brighter the LED. exist figure 1 In the circuit, the calculation of the duty ratio is to use the clock signal CLK 3 with a higher frequency in the duty ratio calculation circuit 110 to count the pulse width and period of the PWM signal 2, thereby calculating the duty ratio (in the n-bit digital signal indicates), the dimming circuit 11 generates a dimming signal according to the n-bi...
Claims
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Inventor 杨世杰林水木萧全佑杨奂箴
Owner RICHTEK TECH