Programmable Gamma Circuit for EMI-Resistant LCD Displays
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Solution Overview
Problem
Portable computers are susceptible to electromagnetic interference (EMI) which causes water ripple phenomenon and V-band effect, affecting gray scale display and color white balance on LCD panels.
Innovation Solution
A display system with a programmable gamma circuit, timing controller, and source driver that dynamically adjusts gamma voltage and provides an offset voltage level to mitigate EMI effects, using a notification signal to program the gamma circuit for a predetermined time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a portable computer uses an LCD panel with gamma voltage control, then display quality (gray scale and color white balance) is improved, but the system becomes susceptible to EMI causing water ripple phenomenon and V-band effect
Solution Approach 1:
The gamma circuit is made programmable and dynamic, allowing it to adjust its transfer function in real-time based on EMI detection. The system transitions from a static gamma voltage generator to a dynamic one that can modify its characteristics to counteract EMI effects, resolving the contradiction between maintaining display quality and resisting EMI susceptibility.
Solution Approach 2:
The system changes the parameters of the gamma circuit by programming different transfer functions and applying offset voltages to binding points. By dynamically adjusting these parameters in response to detected EMI, the system maintains display quality while mitigating EMI-induced artifacts like water ripple and V-band effects.
2Reliability
If the gamma circuit is made programmable to resist EMI, then EMI resistance is improved, but device complexity increases
Solution Approach 1:
The timing controller is given multiple functions: it controls the source driver, monitors for EMI conditions, and programs the gamma circuit when EMI is detected. By consolidating these functions in a single component, the system achieves improved EMI resistance without proportionally increasing overall device complexity.
Solution Approach 2:
The system implements self-diagnosis and self-correction by having the source driver detect EMI conditions and automatically trigger the timing controller to program the gamma circuit with appropriate transfer functions. This self-service capability improves EMI resistance while minimizing the need for additional external control systems.
3Object-affected harmful factors
If offset voltage is applied to binding points for a predetermined time period, then water ripple phenomenon and V-band effect are mitigated, but energy consumption increases
Solution Approach 1:
The system applies offset voltage periodically rather than continuously - specifically for predetermined time periods when EMI is detected. This periodic action mitigates EMI effects (water ripple and V-band phenomena) while minimizing energy consumption by activating the correction only when necessary, rather than maintaining constant offset voltage.
Data Source
AI summary
A display system with electromagnetic susceptibility includes a programmable gamma circuit capable of being adjusted dynamically to supply a programmable gamma voltage curve that provides gamma voltage; a timing controller that receives image data and converts format of the received image data, thereby generating data signal; and a source driver that receives the data signal from the timing controller and the gamma voltage from the programmable gamma circuit. The source driver sends a notification signal to the timing controller indicating that the data signal is not properly received, and the timing controller then programs the programmable gamma circuit to provide an offset voltage level to binding points of the programmable gamma circuit for a predetermined time period.