Liquid Crystal Pixel Inspection via Separate Read Paths
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Solution Overview
Problem
Existing liquid crystal display apparatuses face challenges in quickly inspecting pixels due to the large wiring capacity added to the propagation path of video signals, leading to prolonged inspection times and increased costs.
Innovation Solution
A liquid crystal display apparatus with separate paths for writing and reading video signals, utilizing switch elements and sense amplifiers to quickly read out pixel drive voltages and detect potential differences, allowing for rapid inspection of pixels without excessive loading on the data lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the video signal is read out using the normal writing path, then the pixel can be inspected, but the inspection time is prolonged due to large wiring capacity on the propagation path
Solution Approach 1:
The patent divides the data line into two separate paths: a first data line for writing video signals and a second data line for reading out pixel drive voltages. This segmentation allows the reading operation to occur on a dedicated path without the large wiring capacity burden of the writing path, thereby reducing inspection time while maintaining inspection accuracy.
Solution Approach 2:
The patent introduces a sense amplifier as an intermediary device that connects to the second data line. The sense amplifier quickly amplifies the read-out pixel drive voltages, enabling rapid inspection without being constrained by the wiring capacity of the original data line used for writing.
2Speed
If separate paths for writing and reading are implemented, then reading speed is improved, but device complexity increases
Solution Approach 1:
The first and second sample-and-hold circuits are designed to serve dual purposes: they function during normal display operation to hold video signals for writing, and during inspection mode to hold pixel drive voltages for rapid reading. This multi-functionality reduces the need for completely separate dedicated circuits, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the writing and reading operations into a unified pixel structure where the same pixel components (sample-and-hold circuits, switch transistors) are used for both functions. The polarity changeover switch and switch transistors are configured to alternate between writing mode and reading mode, combining multiple functions into shared hardware to minimize complexity.
Data Source
AI summary
A liquid crystal display apparatus includes a plurality of sense amplifiers configured to amplify respective potential differences between a plurality of positive-polarity pixel drive voltages read out from a plurality of pixels of a row to be inspected to a plurality of positive-polarity data lines and a plurality of negative-polarity pixel drive voltages read out from a plurality of pixels of a row to be inspected to a plurality of negative-polarity data lines, in which each of the pixels includes a first switch transistor configured to switch whether or not to output a positive-polarity pixel drive voltage before it is applied to a pixel drive electrode to a corresponding positive-polarity data line and a second switch transistor configured to switch whether or not to supply a negative-polarity pixel drive voltage before it is applied to the pixel drive electrode to a corresponding negative-polarity data line.