Backlight Driving Circuit Short-Circuit Sensing via Ground-Referenced Resistor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing backlight driving circuits for LCDs require additional high voltage amplifiers and components to sense short-circuits, increasing costs and complexity due to the high voltage levels involved in the high side current sensing method.
Innovation Solution
A backlight driving circuit design that includes a short-circuit sensor with a feedback resistor and a short-circuit sensing resistor connected between the power supply unit's ground and the feedback resistor's ground, allowing the sensor to determine short-circuits without the need for an additional high voltage amplifier by comparing voltage values with reference voltages and generating a short-circuit sensing signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high side current sensing method is used to sense short-circuits in the backlight driving circuit, then the short-circuit detection capability is improved, but additional high voltage amplifiers and components are required, increasing device complexity and cost
Solution Approach 1:
The patent extracts the short-circuit sensing function from the high voltage domain by using a separate low-voltage sensing resistor connected to ground. This allows the sensing operation to be performed at low voltage levels, eliminating the need for high voltage amplifiers while maintaining detection capability. The sensing resistor is taken out from the main high voltage current path and placed in a separate low-voltage sensing path.
Solution Approach 2:
The patent introduces a ground-referenced sensing resistor as an intermediary element that mediates between the high voltage backlight driving circuit and the low voltage sensing circuitry. This intermediary resistor allows voltage proportional to the current to be sensed at ground potential, enabling simple voltage measurement without requiring high voltage handling components.
2Measurement precision
If additional high voltage amplifiers are added to the backlight driving circuit for short-circuit sensing, then the short-circuit detection precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive high voltage amplifiers with a simple, low-cost sensing resistor and low-voltage measurement circuitry. The sensing resistor is a basic passive component that is inexpensive to manufacture, and the associated low-voltage sensing circuit requires simpler, cheaper components compared to high voltage amplification equipment.
Solution Approach 2:
The patent extracts the sensing function from the expensive high voltage domain and relocates it to the inexpensive low voltage domain. By measuring the voltage across the sensing resistor at ground potential, the system achieves accurate current sensing without requiring costly high voltage amplifiers, thereby reducing manufacturing costs while maintaining detection precision.
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 design effectively senses short-circuits in the backlight driving circuit without the need for additional high voltage amplifiers, reducing costs and complexity while protecting the circuit from damage.
Implementation Method 1
a feedback resistor connected to an output terminal of the switch, the feedback resistor being configured to sense a voltage of a current flowing in the light-emitting module
Implementation Method 2
a short-circuit sensing resistor connected between a ground of the power supply unit and a ground of the feedback resistor, and a short-circuit sensor configured to sense a voltage value of a current applied to the feedback resistor or the short-circuit sensing resistor
Data Source
AI summary
A backlight driving circuit that provides backlight to a display panel of a display apparatus includes a power supply unit configured to supply power, a converter configured to convert and output a voltage of the supplied power, a light-emitting module supplied with the outputted voltage from the converter and providing the backlight, a switch connected to an output terminal of the light-emitting module and controlling an operation of the light-emitting module, a feedback resistor connected to an output terminal of the switch and sensing a voltage of a current flowing in the light-emitting module, a short-circuit sensing resistor connected between a ground of the power supply unit and a ground of the feedback resistor, and a short-circuit sensor configured to sense a voltage value of a current applied to the feedback resistor or the short-circuit sensing resistor according to whether the switch is switched on or off.