Backlight Control for Head Mount Display Afterimage Suppression

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Solution Overview

Problem

Liquid crystal display devices used in head mount displays face issues with differing display qualities between left and right eye images due to varying turn-on times of the backlight, leading to afterimages and increased circuit complexity with higher backlight division numbers.

Innovation Solution

A display device configuration with a liquid crystal panel divided into two areas, where the backlight is driven with distinct turn-on periods for each area within a frame period, ensuring the pixel circuit response is complete before backlight activation, and using edge or direct type backlight configurations with separate light-emitting sections to minimize circuit complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the backlight is divided into a larger number of portions for scan drive, then the afterimage is reduced, but the circuit amount of backlight drive circuit and number of wirings increase

Engineering Contradiction:

ImproveafterimageVSAvoidcircuit amount of backlight drive circuit

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The backlight is divided into two portions (first and second portions) corresponding to first and second areas of the display panel, allowing independent control of each portion to reduce afterimage while maintaining manageable circuit complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The backlight portions are controlled to turn on at different timings within the frame period, with the first portion turning on during the first period and the second portion turning on during the second period, creating a periodic scanning effect that reduces afterimage

Inventive Principle:

Principle #19Periodic action

2Reliability

If the backlight turn-on time is not synchronized with pixel circuit response, then the display quality difference between left and right eye images increases

Engineering Contradiction:

Improvedisplay quality consistencyVSAvoidbacklight turn-on timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The pixel circuits in the first area complete their response before the first backlight portion turns on, and pixel circuits in the second area complete their response before the second backlight portion turns on, ensuring proper image display quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Different backlight portions are dynamically controlled to turn on at different timings based on the scanning period, with the first backlight portion turning on after the first scanning period and the second backlight portion turning on after the second scanning period

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10923048B2Display device having backlight and control method thereof

Publication Date: 2021.02.16 SHARP KK

AI summary

In a display device including a display panel having two areas and a backlight having two light-emitting sections, a first scanning period, a first blanking period, a second scanning period, and a second blanking period are set sequentially in one frame period, scanning lines in a first area are selected sequentially in the first scanning period, the scanning lines in a second area are selected sequentially in the second scanning period, a second light-emitting section is made to turn on in a first turn-on period set in the first blanking period, and a first light-emitting section is made to turn on in a second turn-on period set in the second blanking period.