LCD Backlight Inverter Current Control for Human Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display devices lack the ability to automatically adjust and reduce the driving current of the light source when its phase is inverted or reversed by a human body, posing a risk of damage to users.
Innovation Solution
A driving apparatus comprising a driving controller, master inverter, slave inverter, and current limiting circuit that adjusts the duty ratio of the driving current using pulse width modulation signals and feedback currents to reduce or restore the driving current levels, and applies an enable signal based on the phase of feedback currents to prevent user harm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the driving current of the backlight assembly is maintained at a high level to ensure sufficient illumination, then the illumination intensity is improved, but the safety is worsened when a human body contacts the inverter outputs
Solution Approach 1:
The patent implements a feedback mechanism where the inverter outputs are connected to detection circuits that monitor the electrical state. When a human body contacts the inverter outputs, the feedback signal changes, triggering the control circuit to reduce the driving current. This closed-loop feedback system automatically responds to safety conditions while maintaining normal operation when no contact occurs.
Solution Approach 2:
The patent makes the driving current dynamic rather than static. The control circuit adjusts the driving current level based on real-time detection of human contact conditions. The system transitions between high current (normal operation) and reduced current (safety mode), allowing the system to adapt its behavior according to operational context and safety requirements.
2Object-affected harmful factors
If the driving current is reduced when human contact is detected to ensure safety, then the safety is improved, but the illumination intensity is worsened
Solution Approach 1:
The patent employs periodic scanning or continuous monitoring of the inverter output states to detect human contact. The system periodically checks the electrical conditions and adjusts the driving current accordingly. This periodic detection mechanism ensures safety is maintained while allowing rapid restoration of full illumination when the contact condition resolves.
Solution Approach 2:
The patent changes the electrical parameter (driving current level) in response to detected safety conditions. The control circuit modifies the current parameter from high to reduced levels based on the presence or absence of human contact, thereby dynamically balancing safety requirements with illumination quality without requiring physical shielding or structural modifications.
3Object-affected harmful factors
If a detection circuit is added to monitor inverter output phases for safety, then the safety is improved, but the device complexity is worsened
Solution Approach 1:
The patent designs the detection circuit to serve multiple functions: it monitors the phase of inverter outputs, detects human contact conditions, and provides feedback to the control circuit. By making the detection circuit multi-functional, the patent reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while maintaining comprehensive safety monitoring.
Solution Approach 2:
The patent merges the detection function with the existing inverter output structure by directly monitoring the inverter outputs themselves rather than requiring separate sensor systems. The detection circuit is integrated into the existing signal path, combining safety monitoring with the normal operation circuitry, which minimizes additional complexity compared to separate sensor-based systems.
Data Source
AI summary
A driving apparatus of a liquid crystal display device for reducing or automatically restoring a driving current of a light source by being inversed or re-inversed a phase of a driving current with which a light source of a liquid crystal display device is supplied by the human body is disclosed.In the driving apparatus of the liquid crystal display device, a driving controller reduces or restores a duty ratio of a driving control signal which controls a generation of a driving current of a backlight assembly in accordance with whether a predetermined enable signal is applied or not. A master inverter reduces or restores a level of a driving current of the backlight assembly in accordance with a duty ratio of a driving control signal from the driving controller. A slave inverter reduces or restores a level of a driving current of the backlight assembly in accordance with a duty ratio of the driving control signal. And a current limiting circuit applies the predetermined enable signal to a ground or the driving controller in accordance with a phase of feedback currents of the master inverter and the slave inverter.