Liquid Crystal Display Driving IC Output Circuit Voltage Management
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Solution Overview
Problem
The existing liquid crystal display driving ICs face challenges in reducing manufacturing costs and improving operation rate while minimizing power consumption, particularly when outputting high voltage difference signals, due to the need for high voltage resistance processes which complicate manufacturing and increase costs.
Innovation Solution
The output circuit is designed with a series connection of transistors and a switch element to manage voltage, allowing the use of lower voltage resistance transistors, which reduces manufacturing complexity and cost, and improves operation rate by minimizing power consumption and output impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage resistance elements are used for outputting high potential difference signals, then voltage resistance is improved, but operation rate decreases and power consumption increases
Solution Approach 1:
The output circuit is divided into multiple stages: a first output circuit stage using high voltage resistance elements for signal output, and a second output circuit stage using low voltage resistance elements for driving. This segmentation allows each stage to use elements optimized for its specific function, resolving the contradiction between voltage resistance and operation rate.
Solution Approach 2:
Different parts of the output circuit are assigned different element characteristics: the first stage near the output terminal uses high voltage resistance elements to handle high potential difference signals, while the second stage uses low voltage resistance elements for efficient driving. This local differentiation optimizes both voltage resistance and operation rate in their respective locations.
2Reliability
If high voltage resistance processes are employed in manufacturing, then voltage resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
High voltage resistance processes are applied only to the first output circuit stage that requires high voltage resistance, while the second stage uses standard low voltage resistance processes. This localized application reduces overall manufacturing complexity and cost while maintaining necessary voltage resistance characteristics.
Solution Approach 2:
The manufacturing process is segmented into two parts: a first process for creating high voltage resistance elements in the first stage, and a second process for creating low voltage resistance elements in the second stage. This segmentation allows optimization of each process independently, reducing overall complexity.
3Reliability
If high voltage resistance elements are used, then voltage resistance is improved, but power consumption increases
Solution Approach 1:
The output circuit is segmented into two stages with different element characteristics. The first stage uses high voltage resistance elements only where necessary for signal output, while the second stage uses low voltage resistance elements for efficient power consumption during driving operations.
Solution Approach 2:
High voltage resistance elements are placed only in the first output circuit stage where they are locally needed for handling high potential difference signals. The second stage uses low voltage resistance elements to minimize power consumption, achieving optimal energy efficiency.
4Reliability
If high voltage resistance elements are used, then voltage resistance is improved, but manufacturing cost increases
Solution Approach 1:
The output circuit is divided into two stages, with high voltage resistance elements used only in the first stage where they are necessary. This segmentation reduces the total quantity of expensive high voltage resistance elements required, thereby lowering manufacturing cost while maintaining necessary reliability.
Solution Approach 2:
High voltage resistance characteristics are applied only in the first output circuit stage where they are locally required. The second stage uses standard low voltage resistance elements, reducing overall manufacturing cost while maintaining necessary voltage resistance for high potential difference signal output.
Data Source
AI summary
A voltage impressed across the drain and source is reduced by further connecting in series one or two or more transistors between a couple of transistors in an output circuit including an output stage formed by connecting in series a couple of output transistors between a couple of power source voltage terminals and outputting the signal supplied to a gate signal generating circuit of a liquid crystal panel. Simultaneously, potential setting switch elements are also provided to prepare an intermediate potential of a couple of power source voltages and impress the intermediate potential to a base material of output transistors of the OFF state while the output transistors are turned OFF. Thereby, a liquid crystal display driving semiconductor integrated circuit may be realized. Accordingly, low manufacturing cost can also be realized without use of the high voltage resistance process by constituting a circuit for outputting the signal supplied to a gate signal generating circuit of a liquid crystal panel with an element having low resistance voltage. Moreover, operation rate of the output circuit can be improved and power consumption thereof can also be reduced.