Display Sensor Precharge Circuit for Noise Reduction
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Solution Overview
Problem
The integration of position sensing devices into display monitors for higher picture quality and definition leads to noise coupling and increased power dissipation, affecting the accuracy and efficiency of sensor detection, particularly when multiple sensors are used.
Innovation Solution
A display apparatus with a switch integrated inside the display block, utilizing precharge potentials to stabilize sensor detection while minimizing power dissipation, by giving precharge potentials to electrodes before detection and using detection potentials to set desired signal potentials, thereby reducing noise and detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If sensors are integrated inside the display block, then picture quality is maintained without reduction, but noise coupling occurs between sensing elements and display drive elements
Solution Approach 1:
The patent applies preliminary action by precharging the sensing electrode to a specific potential before detection occurs. This precharge step prepares the sensing element in advance, establishing a known initial state that prevents noise coupling during the detection phase. The precharge potential is set to a value that minimizes interference with display drive signals while maintaining sensing accuracy.
2Measurement precision
If the number of sensors is increased to increase resolution, then detection precision is improved, but power dissipation increases
Solution Approach 1:
The patent implements periodic action by detecting sensors in sequential groups rather than simultaneously. The sensor detection is divided into multiple detection periods within each frame cycle, where different groups of sensors are activated and detected at different time intervals. This time-division multiplexing approach allows high-resolution sensing with many sensors while maintaining low power consumption, as only a subset of sensors is active at any given moment.
3Reliability
If precharge potential is given to sensing electrode before detection, then detection stability is improved, but additional driving periods are required
Solution Approach 1:
The patent merges the precharge function with the display drive signal timing. The precharge potential is applied to the sensing electrode during the same horizontal or vertical drive period when display signals are being written to picture elements. By combining the sensing precharge operation with the existing display drive timeline, the patent achieves stable sensor detection without adding separate dedicated precharge time periods, thus avoiding increase in overall driving time.
Data Source
AI summary
Disclosed herein is a display apparatus including: a display block configured to have a plurality of picture elements; a switch arranged inside the display block and configured to be closed by an external pressure; a detection block configured to detect whether the switch is closed based on a comparison between a signal supplied from the switch and a reference signal; a precharge block configured to give a precharge potential to a wire conducting with one of electrodes of the switch before detection is executed in the detection block; and a detection block potential supply block configured to give a predetermined potential to a wire conducting with the other electrode of the switch before detection is executed in the detection block.