LCD Polarity Switching Circuit for Lower Bias Current
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Solution Overview
Problem
Existing liquid crystal display apparatuses face high power consumption when switching between positive and negative polarity video signals multiple times within the vertical scanning period.
Innovation Solution
The liquid crystal display apparatus employs a configuration with dual data wirings, selection switches, and a polarity switching control circuit that intermittently conducts switches and buffer circuits to synchronize bias current with the vertical scanning period, reducing bias current during non-essential periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the liquid crystal display apparatus switches between positive polarity video signal and negative polarity video signal multiple times within the vertical scanning period, then burn-in is prevented and display quality is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by switching between positive and negative polarity video signals at specific intervals during the vertical scanning period. The polarity switching control circuit controls the selection switches to alternate polarity application to pixel electrodes at predetermined periods, which prevents burn-in while managing power consumption through timed, periodic operations rather than continuous switching.
2Reliability
If the selection switches and buffer circuits are continuously conducted to maintain drive voltage, then display quality is maintained, but current consumption increases
Solution Approach 1:
The patent implements periodic action by controlling the selection switches and buffer circuits to conduct intermittently at predetermined periods rather than continuously. The polarity switching control circuit manages the conduction timing to coincide with necessary display refresh intervals, reducing current consumption during non-essential periods while maintaining display quality through periodic updates.
Solution Approach 2:
The patent applies dynamics by making the conduction state of selection switches and buffer circuits variable rather than fixed. The system dynamically adjusts conduction timing and duration based on the vertical scanning period and horizontal scanning period, allowing the circuit to be conductive only when necessary for display refresh and inactive during other periods, thereby optimizing current consumption.
Data Source
AI summary
The polarity switching control circuit causes the first switch to conduct intermittently at each predetermined unit period, in a first period in the vertical scanning period, causes the second switch to conduct intermittently at each unit period, in a second period following the first period, and intermittently induces a bias current in the first buffer circuit and the second buffer circuit in synchronization with conduction of the first switch or the second switch. In each of the first period and the second period, the polarity switching control circuit causes the bias current to be equal to a reference value in some of a plurality of unit periods and decreases the bias current from the reference value in the remaining unit periods.