Liquid Crystal Display Gate Drive Circuit Integration
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Solution Overview
Problem
The manufacturing cost of active matrix liquid crystal displays is high due to the use of expensive integrated circuits (ICs), and the size of the printed circuit board (PCB) is increased by the large number of ICs required, leading to defective liquid crystal orientation during the chip-on-glass (COG) process due to thermal expansion coefficient differences.
Innovation Solution
A liquid crystal display design that reduces the number of source driver ICs by using chip-on-films (COFs) connected to data lines and directly mounts the gate drive circuit on the lower glass substrate, eliminating the need for tape carrier packages and reducing the PCB size, while preventing defective liquid crystal orientation by avoiding the COG process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of source driver ICs is reduced by using COFs, then the PCB size is reduced, but the manufacturing complexity increases due to direct mounting requirements
Solution Approach 1:
The gate drive circuit is segmented from the traditional PCB and directly mounted onto the lower glass substrate, separating the driving function from the interconnection medium. This reduces PCB area while the direct mounting process, though more complex, eliminates the need for extensive PCB routing and IC mounting operations.
Solution Approach 2:
COFs (chip-on-films) serve as an intermediary between the source driver ICs and the data lines, enabling electrical connection without requiring the ICs to be mounted on the PCB. This intermediary approach reduces PCB complexity and area while providing a flexible connection path.
2Ease of manufacture
If COG technology is used to bond ICs on glass substrate, then the liquid crystal display can be manufactured with standard processes, but defective liquid crystal orientation is generated due to thermal expansion coefficient differences
Solution Approach 1:
The gate drive circuit is extracted from the COG process and directly mounted onto the lower glass substrate. This eliminates the high-temperature laminating process that causes thermal expansion issues and liquid crystal orientation defects, while still achieving manufacturability through direct bonding techniques.
Solution Approach 2:
The mounting process parameter changes from high-temperature COG lamination to lower-temperature direct mounting, reducing thermal stress on the liquid crystals and preventing orientation defects while maintaining manufacturing feasibility.
3Adaptability or versatility
If a large number of ICs are used to drive the liquid crystal display, then the display functionality is complete, but the PCB size increases
Solution Approach 1:
The gate drive circuit is merged directly with the lower glass substrate, eliminating the need for separate PCB mounting. This combining of functions reduces the overall PCB area while maintaining complete display functionality through the integrated approach.
Solution Approach 2:
The gate drive circuit is moved from the planar PCB dimension to the vertical dimension by direct mounting on the glass substrate. This dimensional transition reduces PCB area while preserving all necessary display functions.
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 reduces the size of the PCB, decreases the number of ICs required, and prevents defective liquid crystal orientation, resulting in a thinner and more compact liquid crystal display with improved manufacturing efficiency.
Implementation Method 1
a liquid crystal layer between the upper substrate and the lower substrate, and m×n liquid crystal cells (where m and n are a positive integer) arranged in a matrix format
Data Source
AI summary
A liquid crystal display is disclosed. The liquid crystal display includes a liquid crystal display panel including an upper substrate, a lower substrate, a liquid crystal layer between the upper substrate and the lower substrate, and m×n liquid crystal cells (where m and n are a positive integer) arranged in a matrix format according to a crossing structure of m/2 data lines and 2n gate lines, a plurality of chip on films (COFs) on which source driver integrated circuits (ICs) supplying a data voltage to the data lines are mounted, a printed circuit board (PCB) connected to input terminals of the COFs, and a gate drive circuit directly mounted onto the lower substrate, the gate drive circuit supplying a gate pulse to the gate lines.