Chip on Glass LCD Driving Circuit Voltage Attenuation
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Solution Overview
Problem
In conventional chip-on-glass (COG) type liquid crystal displays, the series connection of driving circuits results in voltage signal attenuation due to screen wire resistance, leading to inadequate driving of source and gate driving circuits.
Innovation Solution
Incorporating a constant current source connected to each of the source and gate driving circuits, with converter circuits in each to convert the constant current signals into voltage signals, ensuring equal current values are transmitted and eliminating the impact of screen wire resistance on voltage attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If driving circuits are connected in series through screen wires, then the structure is simple and manufacturing is easy, but voltage signals attenuate due to screen wire resistance causing driving failure
Solution Approach 1:
The patent divides the series connection into multiple parallel segments. Instead of connecting all driving circuits in a single series chain through screen wires, the circuit is segmented into multiple parallel paths. Each segment connects driving circuits with shorter screen wires, reducing resistance and voltage attenuation while maintaining the overall series functionality.
Solution Approach 2:
The patent transitions from a one-dimensional series connection to a two-dimensional arrangement by introducing parallel connection paths. This dimensional change allows current to flow through multiple simultaneous paths rather than a single sequential path, reducing the effective resistance and preventing voltage signal attenuation.
2Area of stationary object
If screen wire size is reduced to minimize area, then the display area increases, but voltage attenuation increases due to higher resistance
Solution Approach 1:
By segmenting the connection into parallel paths, each individual screen wire can be thinner and occupy less area, while the combined parallel structure maintains low enough resistance to prevent voltage attenuation. This allows maximization of display area while ensuring reliable driving.
Solution Approach 2:
The patent changes the electrical parameters of the connection system by introducing parallel paths, which fundamentally alters the effective resistance. This parameter change allows the use of thinner screen wires (smaller cross-sectional area) while maintaining acceptable voltage levels at the driving circuits.
3Reliability
If thicker screen wires are used to reduce resistance, then voltage attenuation is reduced, but the occupied area increases reducing display area
Solution Approach 1:
The patent segments the current path into multiple parallel channels, allowing the use of thinner individual wires that occupy less area. The combined effect of multiple parallel thin wires achieves the same low-resistance performance as a single thick wire, thereby maximizing display area while maintaining reliability.
4Device complexity
If multiple driving circuits are connected in series, then the device complexity is reduced, but power loss increases due to cumulative resistance
Solution Approach 1:
The patent segments the series connection into parallel sub-paths, reducing the cumulative resistance that current experiences. This segmentation reduces I²R power losses while maintaining the simplified series control architecture, thereby reducing energy loss without significantly increasing device complexity.
Solution Approach 2:
The parallel connection structure acts as an intermediary that reduces the effective resistance between the power source and the driving circuits. This intermediary structure minimizes energy loss during signal transmission while preserving the overall system simplicity.
Data Source
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AI summary
A chip on glass (COG) type liquid crystal display comprises: a glass substrate (3); two or more than two driving circuits, which are provided on the glass substrate (3) and are connected one another in series; a constant current source (9), which is separately connected to at least one of the two or more than two driving circuits to supply a constant current signal to each driving circuit; and converting circuits (8), which are provided in each driving circuit to convert the constant current signal received to a voltage signal.