Sensor Control Board Phase Inversion for Display Noise Reduction
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Solution Overview
Problem
Existing display apparatuses suffer from noise inclusion in images due to potential variations in transmission signals affecting the common potential of image elements, as described in Japanese Patent No. 4972782, which can lead to noise in the displayed image.
Innovation Solution
A sensor control board is introduced with a clock generation circuit and phase adjustment circuit to generate and adjust clock signals, inverting phases at predetermined timings, and a timing adjustment circuit to synchronize horizontal synchronization signals, reducing noise by stabilizing the common potential variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position detector sends a transmission signal to the position pointer, then the position detection function is achieved, but noise is included in the displayed image due to potential variations affecting the common potential
Solution Approach 1:
The patent applies preliminary anti-action by inverting the phase of the transmission signal at predetermined timing before the potential variation can affect the common potential. The phase inversion creates an opposing signal that cancels out the harmful potential variation, preventing noise from being introduced to the image elements during position detection operations.
Solution Approach 2:
The patent implements periodic action by inverting the phase of the transmission signal at regular predetermined intervals. This periodic phase inversion synchronizes with the display refresh cycle, allowing the transmission signal to be sent during periods when it will not interfere with the common potential, thus enabling continuous position detection without introducing noise.
2Productivity
If the transmission signal is sent continuously for position detection, then real-time detection is achieved, but potential variations continuously affect the common potential causing image noise
Solution Approach 1:
The patent uses periodic action to enable real-time detection while avoiding continuous interference. By periodically inverting the phase of the transmission signal synchronized with the display refresh rate, the system maintains continuous position detection capability while ensuring that transmission signals are sent only during safe periods that do not interfere with the common potential.
Solution Approach 2:
The system performs preliminary action by predicting safe transmission windows based on the display refresh cycle. The phase inversion timing is predetermined to occur before potential variations can affect the common potential, allowing the system to proactively prevent noise interference while maintaining continuous detection operations.
Data Source
AI summary
A sensor control board in a display apparatus includes a display device and a position detector, the display device including a plurality of image elements each having a first end that receives input of a common potential and a second end that receives input of an individual potential, the image elements being arrayed in a grid pattern, the position detector located either above or below the display device, the position detector detecting a pointed position on the display device, the sensor control board outputting a transmission signal to the position detector. The sensor control board includes a clock generation circuit which, in operation, generates a clock signal, and a phase adjustment circuit which, in operation, adjusts a phase of the clock signal such that the phase is inverted at each predetermined timing and output an adjusted clock signal as the transmission signal to the position detector.