Display Backlight PWM Control for Privacy Filter Brightness Consistency

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Solution Overview

Problem

Electronically-activated privacy filters in information handling systems cause abrupt changes in display panel brightness when switching between private and non-private viewing modes, disrupting the user experience due to changes in the number of active backlights.

Innovation Solution

Implementing a firmware and/or software-based control mechanism that automatically varies the brightness intensity of the display panel backlights using Pulse Width Modulation (PWM) control signals to maintain consistent brightness levels across viewing modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the number of active backlights is reduced to narrow the viewing cone for private viewing mode, then privacy protection is improved, but display panel brightness decreases

Engineering Contradiction:

Improveprivacy protectionVSAvoiddisplay panel brightness

Core Design Contradiction:

Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The patent changes the brightness parameter of the active backlight to compensate for the reduction in the number of active backlights. By increasing the brightness intensity of the single active backlight in private viewing mode, the system maintains consistent display panel brightness while achieving privacy protection through the narrowed viewing cone.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the number of active backlights is changed when switching between viewing modes, then viewing angle control is improved, but brightness consistency deteriorates

Engineering Contradiction:

Improveviewing angle controlVSAvoidbrightness consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent dynamically changes the brightness parameter of the backlight in response to mode switching. When transitioning from normal viewing mode to private viewing mode, the system increases the brightness of the active backlight to compensate for the reduced number of active backlights, thereby maintaining brightness consistency while achieving viewing angle control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the system detects the current viewing mode and automatically adjusts the backlight brightness parameter accordingly. The embedded controller receives mode information and generates appropriate PWM signals to maintain consistent display brightness regardless of the number of active backlights.

Inventive Principle:

Principle #23Feedback

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

Ensures consistent display panel brightness by automatically adjusting backlight intensity when switching between private and non-private viewing modes, enhancing the user experience by minimizing noticeable brightness changes.

Implementation Method 1

The privacy filter film redirects light from a first side of the film onto the display panel in one or more directions that are dictated by the direction or directions of light as they are shined at any given time onto a second side of the privacy filter film from one or more of the backlights.

Methodology Applied

Scientific EffectLight redirection: Reflection

Implementation Method 2

The privacy filter film is in turn configured to redirect this single-direction light received from the designated single backlight to only the center of the LCD display panel so as to produce a narrowed viewing cone angle for images displayed to the system user.

Methodology Applied

Scientific EffectLight redirection: Reflection

Implementation Method 3

Methodology Applied

Scientific EffectPulse Width Modulation:

Data Source

PatentUS11428966B2Systems and methods for adapting display brightness to match privacy filter usage

Publication Date: 2022.08.30 DELL PROD LP

AI summary

Systems and methods are provided that may be implemented to increase display panel brightness consistency when using an electronically-activated privacy filter of an information handling system to switch back and forth between a private viewing mode and a non-private viewing mode. The provided systems and methods may automatically vary the brightness intensity of currently-active display panel backlight/s without user control so as to compensate for changes in the display panel brightness that would otherwise occur due to changes in the number of active backlights caused by switching between private viewing mode and non-private viewing mode.