Smoothing Capacitor Noise Suppression in Display Devices

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Solution Overview

Problem

Display devices experience audible noise due to periodic voltage changes in smoothing capacitors, which are used to stabilize power supply, especially during alternating display and touch detection operations.

Innovation Solution

Incorporating a power consumption unit that adjusts its power consumption to match the display operation period, either by using a source selector as a power consumption unit, a test switching element, or a capacitor to perform charge and discharge operations during touch detection periods, thereby stabilizing the voltage applied to smoothing capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a smoothing capacitor is incorporated into the power supply to stabilize power, then power supply stability is improved, but audible noise occurs due to periodic voltage changes during display and touch detection operations

Engineering Contradiction:

Improvepower supply stabilityVSAvoidaudible noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies the principle of converting harm into benefit by utilizing the smoothing capacitor's inherent charging and discharging characteristics. During the touch detection period, the smoothing capacitor discharges to supply power to the display section, which converts the previously harmful periodic voltage change into a beneficial effect. This discharge operation equalizes the power consumption between display and touch detection periods, eliminating the voltage fluctuation that caused audible noise while maintaining power supply stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Use of energy by moving object

If power consumption is reduced during touch detection period to save energy, then energy efficiency is improved, but voltage fluctuation increases causing audible noise

Engineering Contradiction:

Improvepower consumptionVSAvoidaudible noise

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies periodic action by introducing a power consumption unit that operates periodically during the touch detection period. This unit activates in sync with the display refresh rate, creating a periodic power consumption pattern that matches the display section's power consumption cycle. This synchronization ensures that the total power consumption remains relatively constant across both display and touch detection periods, preventing voltage fluctuations in the smoothing capacitor while maintaining energy efficiency.

Inventive Principle:

Principle #19Periodic action

3Reliability

If display section operates continuously to maintain image display, then display quality is improved, but power consumption variation during touch detection causes voltage instability

Engineering Contradiction:

Improvedisplay qualityVSAvoidvoltage stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a power consumption unit as an intermediary element between the power supply and the display section. This intermediary unit specifically operates during the touch detection period to bridge the power consumption gap. By activating the power consumption unit during touch detection, the system maintains stable voltage levels in the smoothing capacitor while allowing the display section to continue operating continuously, thus preserving display quality without compromising voltage stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach reduces periodic changes in voltage applied to smoothing capacitors, thereby suppressing or eliminating audible noise and ensuring stable power supply during both display and touch detection operations.

Implementation Method 1

a smoothing capacitor that stabilizes power supplied to the display section

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a power consumption unit that consumes the supplied power in the second period

Methodology Applied

Scientific EffectElectrical energy consumption:

Data Source

PatentUS9791954B2Display device and electronic apparatus

Publication Date: 2017.10.17 MAGNOLIA WHITE CORP

AI summary

According to an aspect, a display device includes: a display section that has a first period to consume predetermined power and a second period to consume less power than in the first period, and power consumption of which periodically changes by repeating the first period and the second period; a smoothing capacitor that stabilizes power supplied to the display section; and a power consumption unit that consumes the supplied power in the second period.