Under-Display Proximity Sensing With Diffused IR Light
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Solution Overview
Problem
The integration of optical proximity sensors under OLED displays in smartphones causes screen distortion due to IR or NIR light energy, which is visible as bright spots on the screen, especially when displaying black images.
Innovation Solution
Implementing a microlens array or optical diffuser to spread the light beam emitted by the proximity sensor, reducing its maximum energy density on the OLED screen, and using multiple emitters to distribute the light energy evenly across the screen to prevent concentration and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the proximity sensor is moved under the OLED display to maximize screen area, then the screen area is increased and the sensor can be integrated, but screen distortion occurs due to light energy concentration
Solution Approach 1:
The patent introduces a light diffuser as an intermediary component between the proximity sensor and the OLED display. This diffuser scatters the concentrated light energy from the IR/NIR emitter, preventing direct illumination of the OLED while still allowing the sensor to function. The diffuser acts as a mediator that transforms the harmful concentrated light into beneficial distributed light.
Solution Approach 2:
The patent applies local quality modification by creating a light diffuser with specific optical properties at the location between the sensor and display. The diffuser has varying optical characteristics that selectively scatter light in different directions, maintaining sensor functionality while protecting the display area from distortion. This localized optical treatment addresses the problem without affecting the entire system.
2Object-affected harmful factors
If multiple light emitters are used to distribute light energy evenly, then screen distortion is reduced, but device complexity increases
Solution Approach 1:
The patent segments the light emission function by using multiple separate light emitters instead of a single emitter. Each emitter contributes to the overall light distribution, and when combined with the diffuser, creates a more uniform light pattern across the display. This segmentation approach distributes the light energy more evenly, reducing hot spots and screen distortion.
Solution Approach 2:
The patent combines multiple light emitters with the light diffuser in a unified sensor module design. The emitters and diffuser work together as an integrated system, where the diffuser compensates for the increased complexity by providing a simple optical element that achieves the desired light distribution. This merging approach balances the added emitter complexity with the simplicity of the diffuser solution.
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
Reduces or eliminates screen distortion by minimizing the maximum energy density and uniformity of light on the OLED screen, ensuring optimal display performance without visible bright spots.
Implementation Method 1
Implementing a microlens array or optical diffuser to spread the light beam emitted by the proximity sensor, reducing its maximum energy density on the OLED screen
Implementation Method 2
The adoption of organic light emitting displays (OLEDs)... the proximity sensor is buried behind the OLED, which allows some light, including IR and NIR radiation, to pass through
Implementation Method 3
Optical proximity sensing typically relies on emitting infra-red (IR) or near infra-red (NIR) light and measuring the light energy reflected back from the object to be detected
Data Source
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AI summary
An apparatus includes a display screen, and an optical proximity sensor module disposed behind the display screen. The optical proximity sensor module includes a light emitter operable to produce light having a wavelength for transmission through the display screen toward a target object, and a light sensor operable to sense light reflected by the target object and having the wavelength. The optical proximity sensor module can includes means for reducing a maximum energy density of a light beam produced by the light emitter. The means for reducing the maximum energy density of the light beam is disposed between the light emitter and the display screen so as to intersect the light beam produced by the light emitter. In some cases, there are multiple light emitters collectively operable to provide sufficient optical energy for proximity sensing without producing a visible spot on the display screen. These and other techniques can help reduce or eliminate display screen distortion caused by energy from the light emitters.