Display Device Inspection Switching Element Voltage Control
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Solution Overview
Problem
In liquid crystal display devices, the prolonged application of a constant voltage to inspection switching elements can lead to a change in their threshold value, causing unexpected ON states and resulting in video quality degradation due to unnecessary currents flowing to display switching elements.
Innovation Solution
A display device configuration where a second switching element is used to inspect the state of a first switching element, applying specific voltage levels during display and non-display periods to prevent prolonged same-level voltage application, including applying an OFF voltage during display periods and a voltage between OFF and ON levels during non-display periods to the third electrode of the second switching element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant voltage is continuously applied to inspection switching elements, then the inspection function is maintained, but the threshold value of the inspection switching elements changes and unnecessary currents flow to display switching elements
Solution Approach 1:
The patent applies periodic voltage changes to the inspection switching elements by switching between display period voltage (first voltage level) and non-display period voltage (second voltage level different from first). This periodic voltage application prevents threshold value drift while maintaining inspection capability, as the voltage is not held constant but periodically varied according to display timing.
Solution Approach 2:
The patent dynamically adjusts the voltage level applied to inspection switching elements based on the display timing. During display periods, a first voltage is applied; during non-display periods, a second voltage (different from first) is applied. This dynamic voltage adjustment prevents the harmful effects of constant voltage while ensuring inspection function reliability.
2Ease of operation
If the inspection switching elements are kept in ON state for inspection, then inspection can be performed, but leak currents flow to display switching elements and video quality degrades
Solution Approach 1:
The patent uses periodic voltage application synchronized with display timing. During display periods, voltage is applied to maintain inspection capability; during non-display periods, voltage level changes to prevent leak currents. This periodic action ensures inspection can be performed when needed while preventing harmful currents during display.
Solution Approach 2:
The patent applies a preventive voltage change during non-display periods to counteract potential threshold value changes and prevent leak currents before they can affect display quality. By proactively changing the voltage level when display is not active, the system prevents harmful effects rather than reacting to them.
Data Source
AI summary
In a display period, a display device applies a voltage of a level for turning a state of an inspection switching element to an OFF state to a gate electrode of the inspection switching element. Moreover, in a vertical blanking period while a state of a switching element is the OFF state, the display device performs voltage application processing for applying a voltage, which indicates an ON level, or a voltage, which indicates a level between the ON level and an OFF level, to the gate electrode of the switching element.