Display Device Sink Driver False Lighting Suppression
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Solution Overview
Problem
In narrow-pitch dot matrix LED display devices, false lighting occurs due to increased parasitic capacitance and micro currents, making it difficult to suppress unwanted illumination of unlit LEDs, especially as LED packages are downscaled and dot pitches become narrower.
Innovation Solution
The display device employs a configuration with multiple common lines and drive lines, where a sink driver is connected to both anodes via the drive line, allowing for a selected and unselected state, and by setting the forward voltage of unselected light-emitting elements higher than the selected ones, the device controls current flow to minimize false lighting. This involves a specific sequencing of voltage application to common lines and drive lines to manage parasitic capacitance and micro currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LED packages are downscaled and dot pitches become narrower, then display resolution is improved, but false lighting occurs more easily due to increased parasitic capacitance
Solution Approach 1:
The patent applies preliminary action by pre-charging the common line connected to unselected light-emitting elements before selecting them. This ensures that when a light-emitting element is selected, the common line is already at the appropriate voltage level, preventing false lighting caused by voltage transients during switching. The method charges the common line in advance during the unselected state, so when selection occurs, no sudden current surge activates unselected elements.
2Object-generated harmful factors
If multiple common lines are used with sequential voltage supply, then false lighting is suppressed, but device complexity increases
Solution Approach 1:
The patent segments the common lines into multiple separate lines, each dedicated to specific light-emitting elements. By dividing the common line network into multiple segments that are controlled independently with sequential voltage supply, the system can suppress false lighting by ensuring only the intended common line is active at any given time. This segmentation allows precise control of voltage application to different groups of light-emitting elements.
Solution Approach 2:
The patent implements periodic action through sequential voltage supply to multiple common lines in a time-multiplexed manner. Each common line receives voltage in a specific sequence, with timing coordinated so that only one common line is actively charged at a time. This periodic, sequential activation pattern prevents simultaneous voltage transients that would cause false lighting, while maintaining simple driver circuitry.
3Object-generated harmful factors
If sink driver operates in unselected state, then current flow through unselected LEDs is reduced, but forward voltage of unselected LEDs must be higher than selected LEDs
Solution Approach 1:
The patent applies local quality by creating different electrical conditions for selected and unselected light-emitting elements. Unselected light-emitting elements are connected to common lines that are pre-charged to a higher voltage level, while selected elements connect to common lines at a lower voltage level. This local differentiation in voltage levels ensures that unselected elements experience higher forward voltage and remain off, while selected elements operate at appropriate voltage for light emission.
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 configuration effectively suppresses false lighting by ensuring that unlit LEDs remain dark even with micro currents, improving the overall brightness control and reducing visually noticeable brightness of unlit LEDs, thereby enhancing the display performance.
Implementation Method 1
A second forward voltage of the second light-emitting element when voltage is supplied to the second common line and when the sink driver is in the unselected state is larger than a first forward voltage of the first light-emitting element when voltage is supplied to the first common line and when the sink driver is in the unselected state
Data Source
AI summary
A display device includes a first light-emitting element connected to the first drive line and the first common line, a second light-emitting element connected to the first drive line and the second common line, and a sink driver connected to the first and second light-emitting elements via the first drive line. The sink driver is configured to alternatively take a selected state in which the sink driver pulls a current and an unselected state in which the sink driver does not pull a current. A second forward voltage of the second light-emitting element when voltage is supplied to the second common line and when the sink driver is in the unselected state is larger than a first forward voltage of the first light-emitting element when voltage is supplied to the first common line and when the sink driver is in the unselected state.