Display Backlight Control via Hybrid PWM and Analog Dimming
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Solution Overview
Problem
Existing display technologies face challenges in efficiently controlling backlight brightness and power consumption, with PWM dimming being quick but inefficient, and analog dimming offering better efficiency but slow response and requiring additional circuits.
Innovation Solution
A display apparatus that employs a combination of PWM and analog dimming methods by using a multiplexer and constant current controller to adjust the current level per screen mode, allowing for real-time control of backlight brightness without the need for separate analog circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PWM dimming method is used to control backlight brightness, then response speed is improved and brightness can be changed per frame, but light-emitting efficiency decreases and power consumption increases
Solution Approach 1:
The patent dynamically switches between PWM dimming and analog dimming methods based on the required response speed and brightness level. When fast response is needed, PWM is used; when power efficiency is priority, analog dimming is applied. This dynamic selection resolves the contradiction by adapting the dimming method to real-time requirements.
Solution Approach 2:
The patent changes the operating parameters of the backlight driver, specifically switching between different dimming control modes (PWM duty cycle control vs. analog current control) and adjusting the reference current level. By changing these parameters dynamically, the system achieves both fast response when needed and power efficiency when possible.
2Use of energy by moving object
If analog dimming method is used to control backlight brightness, then power consumption is reduced and light-emitting efficiency is improved, but response speed decreases and brightness cannot be changed per frame
Solution Approach 1:
The system dynamically adjusts the reference current level in analog dimming mode based on the displayed image content and brightness requirements. When the image requires rapid brightness changes, the system can switch to PWM mode. This dynamic adaptation allows analog dimming to maintain power efficiency while being able to respond to brightness changes when necessary.
Solution Approach 2:
The patent pre-sets multiple reference current levels that correspond to different brightness requirements. By having these reference levels prepared in advance, the analog dimming system can quickly switch between brightness states without requiring complex real-time calculations, thereby improving response speed while maintaining power efficiency.
3Use of energy by moving object
If analog dimming is implemented, then power consumption is reduced, but additional circuits such as D/A converter are required increasing device complexity
Solution Approach 1:
The patent merges the analog dimming functionality with the existing digital backlight driver by using a digital-to-analog conversion mechanism that is already present in the driver circuitry. The reference current generation is integrated into the existing driver architecture, eliminating the need for separate external D/A converters and reducing overall device complexity.
Solution Approach 2:
The backlight driver is designed to perform multiple functions: it can operate in both PWM dimming mode and analog dimming mode, and it can generate reference currents for analog control. This multi-functionality allows the single driver circuit to replace what would otherwise require separate dedicated circuits for different dimming methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves light-emitting efficiency and reduces power consumption by allowing precise control of backlight brightness per frame, balancing the advantages of both PWM and analog dimming methods.
Implementation Method 1
a current flowing in a light emitting diode (LED) and backlight, i.e., a light source 13
Data Source
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AI summary
Disclosed are a display apparatus, a light source driving apparatus and a driving method thereof, the display apparatus including: an image processor which is configured to process an image; and a controller which is configured to set a plurality of current levels corresponding to a plurality of screen modes for a display and control the display to perform a dimming by receiving a current level of a current which corresponds to a screen mode of the display.