Backlight Module Switching Viewing Angles via Dual Light Sources

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Solution Overview

Problem

Conventional liquid crystal display apparatuses cannot be switched between narrow and wide viewing angle modes, making them inconvenient for users with varying display needs.

Innovation Solution

A backlight module comprising a first and second surface light source assembly, a first optical film with prisms, and a light filter element, allowing the module to be driven to provide either a wide or narrow viewing angle surface light source by controlling the emission of light from the light emitting units, with the light filter element determining the incident angle range for light passage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional liquid crystal display apparatus uses a single backlight module, then the structure is simple, but the viewing angle cannot be switched between narrow and wide modes

Engineering Contradiction:

Improveviewing angle switching capabilityVSAvoidbacklight module structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The backlight module is divided into two independent surface light source assemblies: a first surface light source assembly for narrow viewing angle mode and a second surface light source assembly for wide viewing angle mode. Each assembly includes its own light emitting unit and light guide plate, allowing independent operation to achieve viewing angle switching capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The backlight module is designed to perform multiple functions by incorporating both narrow and wide viewing angle light source assemblies. The same backlight module structure can switch between different viewing angle modes based on user needs, making it adaptable to various display scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the first surface light source assembly is used for narrow viewing angle mode, then the viewing angle control is achieved, but the light utilization efficiency decreases due to the light filter element

Engineering Contradiction:

Improveviewing angle controlVSAvoidlight utilization efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

A light filter element is introduced as an intermediary component between the first surface light source assembly and the display panel. This filter element selectively transmits light within a predetermined incident angle range, enabling viewing angle control for narrow viewing angle mode while maintaining reasonable light utilization efficiency.

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

Enables the backlight module and associated display apparatus to be switched between wide and narrow viewing angle modes, optimizing light distribution and utilization according to user needs, thereby enhancing user convenience and display performance.

Implementation Method 1

the first prism sheet disposed on a light-lead-outside of the first light guide plate so that the side facing the first light guide plate forms a triangular prism string... the light emitted from the second light source is controlled to have directivity in the normal direction of an outgoing surface of the first prism sheet by narrowing the angle distribution of the light from the second light source by the view angle adjusting film

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The light filter element is disposed between the first surface light source assembly and the second surface light source assembly. The light filter element is configured to allow an incident light ray within a predetermined range of incident angle to pass through the light filter element

Methodology Applied

Scientific EffectAngular filtering: Filter (optical)

Data Source

PatentEP3173859B1Backlight module, driving method thereof, and display apparatus using the backlight module

Publication Date: 2019.12.25 CORETRONIC CORPORATION

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AI summary

A backlight module includes a first surface light source assembly, a second surface light source assembly disposed above the first surface light source assembly, a first optical film disposed above the second surface light source assembly and including a plurality of prisms arranged along a first direction, and a light filter element disposed between the first and second surface light source assemblies. Both of the first surface light source assembly and the second surface light source assembly include a light emitting unit and a light guide plate. Each prism has a tip end facing the second surface light source assembly. The light filter element is configured to allow an incident light ray within a predetermined range of incident angle to pass therethrough. The backlight module can be switched between a narrow viewing angle mode and a wide viewing angle mode. Related driving method and display apparatus are also provided.