Display Scan-Line Control to Prevent PM Display Acoustic Noise
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Solution Overview
Problem
Passive matrix (PM) driven display devices generate acoustic noise due to increased current levels when multiple pixels are operated simultaneously, leading to discomfort for users, especially in quiet environments.
Innovation Solution
Implement a control method that alternately applies scan signals to pixel lines with different luminance levels using an interlaced scanning method, adjusting the number and separation of scan lines to reduce current amplitude and frequency below audible thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If progressive scanning method is used to drive the display, then image refresh rate is improved, but acoustic noise is generated due to current waveform patterns
Solution Approach 1:
The patent applies interlaced scanning method which divides the scanning process into two fields (odd and even lines), alternating between them to refresh the display. This periodic action with doubled field frequency transforms the current waveform pattern from progressive scanning into a pattern that exceeds audible frequency thresholds, thereby eliminating acoustic noise while maintaining effective refresh rate
Solution Approach 2:
The patent changes the scanning parameter from progressive to interlaced mode based on detected image content characteristics. When high-luminance and low-luminance pixel lines are detected to form a pattern that could generate audible noise, the system dynamically switches to interlaced scanning, altering the temporal distribution of current consumption to push noise frequency beyond human hearing range
2Object-generated harmful factors
If interlaced scanning method is used to reduce acoustic noise, then acoustic noise is prevented, but image quality may be degraded
Solution Approach 1:
The patent implements dynamic scanning method selection that adapts to real-time image content characteristics. The system continuously monitors pixel luminance patterns and dynamically switches between progressive and interlaced scanning modes, applying interlaced scanning only when necessary to prevent acoustic noise, thereby preserving image quality when progressive scanning is used
Solution Approach 2:
The patent segments the scanning process into field-based operations (odd and even lines) when interlaced mode is activated. This segmentation allows the system to process and display image data in alternating passes, maintaining visual coherence while transforming the current consumption pattern to eliminate acoustic noise generation
3Area of stationary object
If multiple pixels in same scan line are operated simultaneously, then display coverage is improved, but current level increases causing acoustic noise
Solution Approach 1:
The patent uses interlaced scanning to divide simultaneous pixel operation across two alternating fields. Odd lines are activated in one field while even lines are activated in the next field, spreading out the current consumption over time. This periodic activation pattern prevents the formation of constant frequency waveforms that cause acoustic noise, while still achieving full display coverage across both fields
Data Source
AI summary
An electronic apparatus is disclosed. The electronic apparatus includes a display including a plurality of scan lines arranged in one direction, a plurality of data lines arranged in a direction perpendicular to the plurality of scan lines, a pixel generated in an intersection area of the scan lines and the data lines, and one or more processors configured to provide the scan signal to the plurality of scan lines in an interlaced scanning method based on the image frame being an image in which a first pixel line having high-luminance greater than or equal to a threshold luminance and a second pixel line having low-luminance less than the threshold luminance are alternately arranged.