Transparent Window Diffractive Layer OLED Display
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Solution Overview
Problem
Electronic devices with full-face OLED displays face challenges in sensor performance due to low light transmission through the display stack, as most of the visible and infrared light is lost, making it difficult for sensors like cameras and ambient light sensors to function effectively.
Innovation Solution
The implementation of non-pixel regions, or 'transparent windows,' beneath the display where thin-film transistors and other display components are absent, along with a light spreading layer using diffractive elements and a lens layer, to increase light transmittance and maintain display resolution by spreading light from pixels to non-emitting areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display stack is made opaque to block light for display pixels, then display visibility is improved, but light transmission to underlying sensors deteriorates
Solution Approach 1:
The display stack is segmented into pixel regions and non-pixel regions (transparent windows). The non-pixel regions are devoid of light-emitting components, creating localized transparent areas that allow light to pass through to the sensor while pixel regions maintain display functionality. This segmentation resolves the contradiction by spatially separating the light-blocking function (in pixel regions) from the light-transmission function (in non-pixel regions).
Solution Approach 2:
Different regions of the display stack are given different optical properties: pixel regions are designed to be opaque for display visibility, while non-pixel regions are designed to be transparent for sensor light transmission. This local differentiation of quality allows both contradictory requirements to be satisfied in their respective locations.
2Loss of energy
If transparent windows are created by removing pixels, then light transmission to sensor is improved, but display resolution deteriorates
Solution Approach 1:
The diffractive layer creates optical copies (virtual images) of the pixel array that appear at the outer surface of the display. These copied images fill in the gaps where transparent windows are located, making the display resolution appear uniform across the entire surface including areas with no physical pixels. This copying mechanism resolves the resolution deterioration caused by removing pixels for transparent windows.
Solution Approach 2:
The diffractive layer acts as an intermediary between the physical pixel array and the viewer's perception of the display. It mediates the optical path to create virtual pixel images that compensate for the missing physical pixels in transparent window regions, thereby maintaining apparent resolution without requiring physical pixels in every location.
3Manufacturing precision
If a light spreading layer with diffractive elements is added, then apparent display resolution is improved, but device complexity increases
Solution Approach 1:
The diffractive layer utilizes changes in the refractive index parameter of materials to create the light spreading effect. By selecting materials with appropriate refractive index differences at visible wavelengths, the layer can diffract light to create virtual pixel images without requiring complex mechanical or optical mechanisms. This parameter-based approach resolves the contradiction by achieving resolution enhancement through material property optimization rather than structural complexity.
4Loss of energy
If lens layer is added to focus light onto transparent windows, then light transmission to sensor is improved, but device complexity increases
Solution Approach 1:
The lens layer employs curved (spheroidal) optical surfaces to focus ambient light onto the transparent windows. This geometric curvature approach is a well-established optical principle that achieves light concentration without requiring complex active control mechanisms. The curved lens surfaces naturally guide and focus light paths to the sensor through transparent windows, resolving the contradiction by using simple geometric optics rather than complex systems.
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 solution enhances light transmission to underlying sensors while maintaining the display's resolution at the outer surface, allowing for improved sensor performance without compromising the visual quality of the OLED display.
Implementation Method 1
a light spreading layer that includes a plurality of diffractive elements. The light spreading layer may spread visible light from the array of pixels
Implementation Method 2
The lens layer may be formed from first and second layers that have a refractive index difference at infrared wavelengths
Implementation Method 3
each pixel includes a light-emitting diode and thin-film transistors for controlling application of a signal to the light-emitting diode to produce light
Data Source
AI summary
An electronic device may include a display and an optical sensor formed underneath the display. The electronic device may include a plurality of transparent windows that overlap the sensor. The resolution of the display panel may be reduced in some areas due to the presence of the transparent windows. To increase the apparent resolution of the display in portions of the display panel with the transparent windows, the display may include a light spreading layer that includes a plurality of diffractive elements. The light spreading layer may spread visible light from the array of pixels such that the display resolution at the outer surface of the display is greater than at the display panel. The light spreading layer may selectively spread visible light but not infrared light. The display may also include a lens layer that focuses light onto the transparent windows.