Optical System Free-Form Lens Under-Display Camera
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Solution Overview
Problem
The challenge is to enhance the relative illumination rate of an image sensor unit in camera modules, particularly for under-display camera applications where light loss due to display panels results in decreased image quality and brightness, requiring a new optical system to compensate for this loss.
Innovation Solution
An optical system with N lenses is designed, where the nth lens has specific sag values and shapes defined by equations, forming free-form surfaces that improve light incidence on the image sensor unit, ensuring sufficient brightness and resolution without increasing lens size or optical system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a camera module is disposed under the display, then the front camera can be hidden under the display panel, but light loss occurs due to the display panel resulting in decreased brightness and image quality
Solution Approach 1:
The patent applies local quality by designing the display panel with different optical properties in different regions. Specifically, the display panel includes a first region with a first transmittance and a second region with a second transmittance, where the transmittances are different. This allows light to pass through more efficiently in specific areas where the camera is located, compensating for the light loss caused by the display panel and improving image brightness without affecting other regions of the display.
2Device complexity
If conventional optical systems are used under display, then the system structure is simple, but relative illumination rate is insufficient resulting in poor image quality
Solution Approach 1:
The patent introduces an intermediary element - the optical film - positioned between the display panel and the image sensor. This optical film acts as a mediator that selectively transmits light from different regions of the display panel to the image sensor, improving the relative illumination rate without requiring complex optical system redesign. The optical film simplifies the overall structure while achieving better illumination performance.
3Illumination intensity
If display transmittance is increased to improve light amount, then brightness improves, but display quality and visibility are affected
Solution Approach 1:
The patent applies local quality by designing the display panel with different optical properties in different regions. Specifically, the display panel includes a first region with a first transmittance and a second region with a second transmittance, where the transmittances are different. This allows light to pass through more efficiently in specific areas where the camera is located, compensating for the light loss caused by the display panel and improving image brightness without affecting other regions of the display.
Solution Approach 2:
The patent introduces an intermediary element - the optical film - positioned between the display panel and the image sensor. This optical film acts as a mediator that selectively transmits light from different regions of the display panel to the image sensor, improving the relative illumination rate without requiring complex optical system redesign. The optical film simplifies the overall structure while achieving better illumination performance.
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 solution effectively increases relative illumination to 30% or more, maintaining high resolution and brightness across varying display positions, enabling miniaturization of the camera module while maintaining improved light amount and optical characteristics.
Implementation Method 1
an optical system includes N lenses sequentially disposed along an optical axis from an object-side toward a sensor-side... a shape of a first surface of the nth lens is symmetrical in the first axis direction and the second axis direction... the nth lens satisfies Equation 1 below
Data Source
AI summary
An optical system according to an embodiment includes N lenses sequentially disposed along an optical axis from an object-side toward a sensor-side, wherein a first axis perpendicular to the optical axis is defined and a second axis perpendicular to the optical axis and the first axis is defined in an nth lens which is any one of the N lenses, a shape of a first surface of the nth lens is symmetrical in the first axis direction and the second axis direction, the first surface has a first sag value S1 of a first coordinate (±A,0) and a third sag value S3 of a third coordinate (±B,0) on the first axis, the first surface has a second sag value S2 of a second coordinate (0,±A) and a fourth sag value S4 of a fourth coordinate (0,±B) on the second axis, and the nth lens satisfies Equation 1 below.<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>S2-S1<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>><semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>S4-S3<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>[Equation 1]<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>A<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>><semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>B<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics><semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>S4-S3<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>≤3 µm