Shift Register Circuit for LCD Pre-Charging Pulse Generation
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Solution Overview
Problem
In liquid crystal display (LCD) manufacturing, the increasing pixel density leads to pixel charge coupling effects, resulting in abnormal display images like low brightness uniformity, which is exacerbated by the half source driving structure in gate drive circuits.
Innovation Solution
A shift register circuit comprising two interconnected shift register strings, where the first string receives a start signal to output a control signal, and the second string receives this control signal and a second start signal to generate scan signals with different pulse widths, allowing for pre-charging of pixels to reduce voltage coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the half source driving (HSD) structure is employed to reduce driver IC cost and increase scan lines, then the number of scan lines is doubled and driver cost is reduced, but pixel charge coupling effects are exacerbated and display uniformity deteriorates
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charging pulse before the main scanning pulse. This pre-charging pulse (first pulse) is generated by the shift register circuit to partially charge the pixel electrodes in advance, thereby reducing the potential difference that would otherwise cause charge coupling effects during the main scanning operation. This resolves the contradiction by maintaining the HSD structure's cost benefits while eliminating its harmful charge coupling effects through the preliminary pre-charging action.
2Manufacturing precision
If pixel density is increased to improve display resolution, then display quality is improved, but pixel charge coupling effects become more serious and lead to abnormal display images
Solution Approach 1:
The pre-charging pulse generated by the shift register circuit performs preliminary charging of pixel electrodes before the main scanning operation. This preliminary action reduces the potential difference between pixels, thereby preventing charge coupling effects that would otherwise be exacerbated by high pixel density. This allows the patent to maintain high display resolution while eliminating the harmful charge coupling effects.
3Area of stationary object
If the number of scan lines is increased to improve display coverage, then display area is improved, but charge coupling effects worsen and cause brightness uniformity issues
Solution Approach 1:
The shift register circuit generates a pre-charging pulse that performs preliminary charging of pixel electrodes before the main scanning operation. This preliminary action reduces the potential difference that causes charge coupling effects, thereby allowing the patent to increase the number of scan lines and display area without suffering from the harmful charge coupling effects that would otherwise cause brightness uniformity issues.
Data Source
AI summary
A shift register circuit includes a first shift register string and a second shift register string. The first shift register string is configured to receive a first start signal and output a first-stage control signal. The second shift register string, electrically connected to the first shift register string, is configured to receive the first-stage control signal and a second start signal and output the first pulse of a first-stage scan signal according to the first-stage control signal and the second start signal and consequently output the second pulse of the first-stage scan signal according to the second start signal; wherein the first and second pulses are configured to have different pulse widths. A driving method of a shift register circuit is also provided.