Display Panel Driver Circuit Symmetric Output Pulse Control
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Solution Overview
Problem
Large-sized liquid crystal display panels face increased power consumption and heat issues due to high loads on data lines, leading to inefficient operational amplifiers in LCD drivers, which affect the symmetry of output characteristics and charge/discharge capabilities.
Innovation Solution
The operational amplifier circuit incorporates a first input differential stage, a first and second output stage, and a switch circuit to equalize the rise and fall times of output signals, ensuring symmetric pulse formation and reduced power consumption by operating within specific voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of outputs from one LCD driver chip is increased to reduce the number of drivers, then the power consumption of the chip increases, but the power consumption of the entire LCD driver system increases and chip temperature becomes abnormally high
Solution Approach 1:
The patent applies periodic action by switching between two operational patterns (Pattern 1 and Pattern 2) in alternating frames. In odd frames, Pattern 1 is used where specific amplifiers drive specific data lines, and in even frames, Pattern 2 is used with different amplifier assignments. This periodic switching distributes the power consumption load over time, preventing any single amplifier from continuously operating at high power levels, thereby reducing overall chip temperature while maintaining high output capacity.
Solution Approach 2:
The patent implements dynamics by making the amplifier-to-data-line assignment flexible and switchable rather than fixed. The switch circuit dynamically reconfigures which amplifiers are connected to which data lines based on the frame number (odd or even). This dynamic reconfiguration allows the system to adapt power distribution in real-time, optimizing thermal management while maintaining the ability to drive multiple outputs simultaneously.
2Productivity
If amplifiers operate over the full voltage range from VSS to VDD, then the output swing is maximized, but the rise time and fall time become asymmetric and power consumption increases
Solution Approach 1:
The patent applies segmentation by dividing the voltage range into two separate segments: a first voltage range from VSS to an intermediate voltage VMH, and a second voltage range from VM L to VDD. Different amplifiers are assigned to operate in different voltage segments. This segmentation allows each amplifier to operate within an optimized voltage range that reduces power consumption while maintaining sufficient output swing for driving data lines, eliminating the need for any single amplifier to traverse the full VSS to VDD range.
3Productivity
If different input differential stage circuits are used for positive and negative outputs, then the output characteristics can be optimized for each polarity, but the symmetry of rise and fall times deteriorates
Solution Approach 1:
The patent applies universality by using the same input differential stage circuit (first input differential stage circuit 14) for both positive and negative output operations. Rather than having separate dedicated circuits for each polarity, this single differential stage serves multiple functions by working in conjunction with different output stage circuits (first output stage 13 and second output stage 23) and being switched to different data lines through the switch circuit. This universal approach maintains symmetry in the pulse formation while still allowing optimization of output characteristics through the combination of components.
Data Source
AI summary
Provided is a display panel driver with an improved driving characteristic by use of an amplifier output having excellent symmetry of an output characteristic. The display panel driver according to the present invention includes a first input differential stage circuit, a first output stage circuit, a second output stage circuit, and a first switch circuit. The first input differential stage circuit outputs two first input stage output signals according to one of a positive voltage and a negative voltage. The first switch circuit selects one of the first and second output stage circuits, and connects the selected circuit to the first input differential stage circuit. The output stage circuit connected to the first input differential stage circuit outputs a single-ended signal based on the two first input stage output signals from the first input differential stage circuit.