Light modulation control drive control device, system and method

Abstract

The invention provides a drive control device for controlling light modulation, and a light modulation system containing the drive control device, comprising an enabling and light modulation signal generation unit and a reference voltage converting unit, wherein the enabling and light modulation signal generation unit carries out the operation of asymmetric delay treatment on an external first light modulation and enable signal so as to generate an enable signal, and the reference voltage converting unit generates a variable control signal of which the level amplitude is in positive relationship with the duty ratio of the first light modulation and enable signal. The invention also provides a light modulation method using the light modulation system, including the step of carrying out theoperation of asymmetric delay treatment on the external first light modulation and enable signal so as to generate the enable signal, and the step of generating the variable control signal of which the level amplitude is in positive relationship with the duty ratio of the first light modulation and enable signal.

Description

technical field [0001] The invention relates to a drive control device, system and method for dimming control. Background technique [0002] At present, hand-held devices such as mobile phones and MP3 basically use color LCD screens. Among them, white light emitting diodes (Light Emitting Diode, LED) have become a common backlight source. Depending on the size of the screen, it generally takes 3 -6 white LEDs as backlight. Usually handheld devices use a lithium-ion battery to power the entire system, and the voltage of the lithium-ion battery is generally between 3.6V-4.2V. [0003] There are two ways to drive and control white LEDs: one is the series drive mode, all LEDs are connected in series, and the inductive DC / DC boost conversion principle is used to generate a higher voltage for driving. The other is the parallel drive mode, all LEDs are connected in parallel, and the principle of step-up charge pump is used to generate a voltage adaptively determined according to ...

AI Technical Summary

Problems solved by technology

Periodic current spikes on the boost inductor L11 can also cause electromagnetic interference to other systems other than the dimming system

Secondly, the periodic turn-on / off of the light-emitting diode group 300 will generate a voltage ripple at the voltage output terminal OUT with the same frequency as the enabling and dimming signal V102. If the frequency of the enabling and dimming signal V102 is in the audio frequency range, then An audible sharp noise is generated on the output capacitor C12

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