DC Voltage Conversion Circuit with Short-Circuit Protection for LCD
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Solution Overview
Problem
Liquid crystal display (LCD) devices face issues with short-circuiting between the VGH line and either the VGL or VCOM line due to conductive particles, leading to increased current flow and potential damage to the device's layout and components.
Innovation Solution
A DC voltage conversion circuit comprising a booster circuit and a protection circuit, which includes detection, current-voltage conversion, comparison, and control units to detect excessive current and turn off the booster circuit when a short circuit is detected, preventing damage by selecting appropriate reference voltages and using thin-film transistors and resistors to manage current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the booster circuit continuously provides high voltage to the VGH line, then the LCD device can operate normally, but the risk of short-circuit damage increases
Solution Approach 1:
The protection circuit performs preliminary detection of current before the short-circuit damage can occur. The detection unit continuously monitors the current on the VGH line, and when abnormal current is detected, the control unit immediately turns off the booster circuit, preventing the harmful effect from materializing.
Solution Approach 2:
The protection circuit establishes a feedback mechanism where the detection unit monitors the current status and feeds this information to the control unit, which then adjusts the booster circuit operation accordingly. This closed-loop control ensures the system responds dynamically to changing conditions and prevents damage.
2Reliability
If the detection circuit continuously monitors current, then short-circuit protection is improved, but power consumption increases
Solution Approach 1:
The protection circuit performs current detection periodically rather than continuously. The detection unit monitors current at specific intervals or under specific conditions (such as during voltage switching phases), which reduces power consumption while still providing effective protection against short-circuits.
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
Effectively prevents component burnout in LCD devices by automatically turning off the booster circuit when short circuits between the VGH and VGL or VGH and VCOM lines are detected, thereby safeguarding the device's layout and components.
Implementation Method 1
The detection current is converted into a detection voltage by the current-voltage conversion unit
Implementation Method 2
the source of the first TFT whose gate receives a first gate signal and whose drain is electrically connected to the VGH line
Data Source
AI summary
The DC voltage conversion circuit includes a booster circuit and a protection circuit. The booster circuit receives a first voltage, converts the first voltage into a second voltage, and provides the second voltage to a VGH line of a LCD device. The protection circuit includes a detection unit, a current-voltage conversion unit, a comparison unit, and a control unit. The detection unit detects a current flowing between the VGH line and a transmission line and obtains a detection current. The detection current is converted into a detection voltage by the current-voltage conversion unit. The comparison unit compares the detection voltage against a reference voltage. When the detection voltage is greater, the control unit issues a control signal to turn off the booster circuit. The transmission line is one of a VGL line and a VCOM line of the LCD device.