LED Array Brightness Control via Dual-Dimension Segmentation
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Solution Overview
Problem
Existing display apparatuses using LED arrays face challenges in achieving precise brightness control, particularly at lower brightness levels, due to limitations in pulse width modulation (PWM) dimming methods, which can result in color shift and inadequate brightness representation.
Innovation Solution
The proposed display apparatus incorporates a LED array, a power source, a controller, a PWM switch, and a current source module. The controller generates control signals to manage the PWM switch and current source module, allowing for precise control of both the lit time and current level of the LEDs, thereby enabling more accurate brightness control across a wider range of values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM dimming method is used to control LED brightness by adjusting lit time, then brightness control is achieved, but at lower brightness levels the lit time becomes shorter than LED response time causing color shift and inaccurate brightness representation
Solution Approach 1:
The patent segments the brightness control into two independent dimensions: temporal control (lit time via PWM switch) and amplitude control (current level via current source module). This segmentation allows each dimension to operate independently, ensuring that even at low brightness levels where lit time is short, the current level can be adjusted to maintain accurate brightness representation and prevent color shift.
Solution Approach 2:
The patent adds a new dimension to brightness control by introducing current level adjustment as a separate control parameter alongside lit time. Instead of controlling brightness solely through temporal dimension (lit time), the system now operates in a two-dimensional space of (lit time, current level), enabling precise brightness control across the entire range without the limitations of traditional PWM dimming.
2Adaptability or versatility
If lit time is shortened to achieve lower brightness levels, then brightness range is expanded, but the LED cannot be driven appropriately due to response time limitations
Solution Approach 1:
The patent segments brightness control into temporal (lit time) and amplitude (current level) components. By independently controlling current level through the current source module, the system can maintain accurate brightness representation even when lit time is shortened to expand the brightness range, resolving the contradiction between versatility and precision.
Solution Approach 2:
The patent changes the control parameters from single-dimensional (lit time only) to two-dimensional (lit time and current level). This parameter change enables the system to achieve both extended brightness range and maintained representation accuracy by adjusting current level as a compensating parameter when lit time is reduced.
3Device complexity
If traditional PWM dimming is used, then device complexity is low, but brightness control precision deteriorates at lower brightness levels
Solution Approach 1:
The patent segments the control system into distinct functional modules: PWM switch for temporal control and current source module for amplitude control. This segmentation, while increasing complexity, enables precise brightness control at all levels by distributing control functions across specialized components that can operate independently and optimally.
Solution Approach 2:
The patent introduces a new control dimension (current level) to the traditional PWM dimming approach. This dimensional expansion provides an additional degree of freedom for brightness control, allowing precise regulation at low brightness levels where traditional single-dimensional PWM control fails, despite the increased device complexity.
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 solution effectively addresses the limitations of traditional PWM dimming by allowing for higher precision in brightness control, reducing the likelihood of color shift, and ensuring that the expected brightness levels are achieved, even at lower settings.
Implementation Method 1
Some display apparatuses may be implemented by a LED array
Implementation Method 2
The brightness of each LED in the array may be controlled by the length of the lit time of each LED
Data Source
AI summary
The present disclosure provides a display apparatus including an LED array. The display apparatus comprises a light emitting diode (LED) array, a power source, a controller, a PWM switch, and a current source module. The controller is configured to generate a control signal for controlling a first LED column during a scan period. The PWM switch is electrically connected between the first LED column and a second power level. The current source module is electrically connected between the first LED column and the second power level. The current source module is configured to provide a current flow with multiple levels. The PWM switch is controlled based on a first portion of the control signal, and the amount of the current flow provided by the current source module in the scan period depends on a second portion of the control signal.