Hybrid Display Assembly with Solar Cell for Energy-Efficient Readability

Solution Overview

Problem

Existing display devices face challenges in maintaining readability and energy efficiency across varying ambient light conditions, with transflective liquid crystal displays losing light in absorption and emissive OLEDs consuming excessive power, making them unsuitable for portable devices with limited energy reserves.

Innovation Solution

A hybrid display assembly combining a reflective liquid crystal display and an emissive organic light-emitting diode (OLED) display, with a solar cell integrated underneath, allowing the assembly to switch between reflective and emissive modes based on lighting conditions, optimizing energy use and readability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a transflective liquid crystal display cell is optimized to reflect sunlight for daytime readability, then readability in bright light is improved, but transmission efficiency is greatly limited causing light loss in absorption phenomena and mediocre energy efficiency

Engineering Contradiction:

Improvereadability in bright lightVSAvoidenergy efficiency

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The display system is segmented into two independent display devices: a first display device optimized for reflective mode (daytime) and a second display device optimized for emissive mode (nighttime/dim light). Each device is independently controlled based on ambient light conditions, allowing optimal performance in各自的 working conditions without compromising energy efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between reflective and emissive display modes based on ambient light detection. The control unit adjusts which display device is active according to lighting conditions, enabling the system to adapt its energy consumption profile to match environmental conditions and maintain optimal energy efficiency.

Inventive Principle:

Principle #15Dynamics

2Illumination intensity

If an emissive display device increases current supply to increase LED brilliance for outdoor readability, then readability in bright light is improved, but power consumption increases making it difficult to operate permanently in portable devices

Engineering Contradiction:

Improvereadability in bright lightVSAvoidpower consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by stationary object

Solution Approach 1:

The display system is segmented into two independent display devices: a first display device optimized for reflective mode (daytime) and a second display device optimized for emissive mode (nighttime/dim light). Each device is independently controlled based on ambient light conditions, allowing optimal performance in各自的 working conditions without compromising energy efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a reflective display device that copies the functionality of high-brilliance emissive displays during daytime by reflecting ambient light, thereby achieving comparable readability without the high power consumption of emissive technology. This allows portable devices to maintain permanent operation with limited battery reserves.

Inventive Principle:

Principle #26Copying

3Illumination intensity

If a transflective liquid crystal display cell activates backlighting to improve nighttime readability, then readability in dark environment is improved, but a major part of light emitted by backlighting is lost in absorption phenomena reducing energy efficiency

Engineering Contradiction:

Improvereadability in dark environmentVSAvoidlight absorption loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The display system is segmented into two independent display devices: a first display device optimized for reflective mode (daytime) and a second display device optimized for emissive mode (nighttime/dim light). Each device is independently controlled based on ambient light conditions, allowing optimal performance in各自的 working conditions without compromising energy efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention extracts the backlighting function from the reflective display device and assigns it to a dedicated emissive display device. This separation allows the reflective device to operate without backlighting losses during daytime, while the emissive device provides efficient nighttime illumination without the absorption losses inherent in transflective designs.

Inventive Principle:

Principle #2Taking out (Extraction)

4Illumination intensity

If liquid crystal display cells are optimized for reflective mode to improve daytime readability, then readability in bright light is improved, but optical qualities become highly dependent on viewing angle

Engineering Contradiction:

Improvereadability in bright lightVSAvoidviewing angle independence

Core Design Contradiction:

Illumination intensityVSEase of operation

Solution Approach 1:

The display system is segmented into two independent display devices: a first display device optimized for reflective mode (daytime) and a second display device optimized for emissive mode (nighttime/dim light). Each device is independently controlled based on ambient light conditions, allowing optimal performance in各自的 working conditions without compromising energy efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention employs an emissive display device with uniform light emission characteristics that provides consistent optical qualities across different viewing angles. This homogeneity in light emission from the OLED device compensates for the viewing angle dependence of reflective liquid crystal displays, ensuring reliable readability from various perspectives during nighttime operation.

Inventive Principle:

Principle #33Homogeneity

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

The hybrid display assembly ensures optimal readability and energy efficiency in both bright and dark environments, with the solar cell providing sufficient power to operate the displays without depleting the portable device's energy reserves.

Implementation Method 1

the quantity of light reaching the solar cell through the set of two superposed display devices was sufficient to supply, by photoelectric conversion phenomenon, the quantity of electrical energy necessary for the operation of the two superimposed display devices

Methodology Applied

Scientific EffectPhotoelectric conversion: Photovoltaic Effect

Implementation Method 2

this reflective display device, taking advantage of a phenomenon of reflection of sunlight to display information, is energy efficient

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentEP3007015B1Hybrid display assembly including a solar cell

Publication Date: 2018.01.31 THE SWATCH GRP RES & DEVELONMENT LTD

Figure 1~2
Figure 3A~3D
Figure 4~5D

AI summary

Display assembly for a portable object, this display assembly (1) comprising a first emissive display device (2) at least partially transparent located on the side of an observer (4), a second reflective display device (6) and a solar cell (10) being arranged in that order under the first emissive display device (2), the second reflective display device (6) being capable of switching between a transparent state in which it displays no information and a reflective state when it is activated.