Optical Fingerprint Module Without Light Focusing Lens
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Solution Overview
Problem
Existing optical fingerprint modules are large in size, have poor mechanical reliability due to external vibrations, and require complex manufacturing processes, which affect the quality of captured fingerprint images.
Innovation Solution
The optical fingerprint module design places the optical fingerprint sensor and backlight source under the protective layer, eliminating the need for a light focusing lens and allowing the backlight source to be disposed at a side of the sensor, thereby reducing module size, simplifying manufacturing, and enhancing mechanical reliability while increasing light utilization for improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light focusing lens is used in the optical fingerprint module, then the imaging quality is improved, but the device size increases and mechanical reliability deteriorates due to external vibrations
Solution Approach 1:
The patent removes the light focusing lens from the optical fingerprint module structure. By extracting this component, the device eliminates the mechanical reliability issues associated with lens alignment and vibration sensitivity, while maintaining imaging quality through alternative optical design approaches using only the protective layer and sensor.
2Illumination intensity
If a light focusing lens is included in the module structure, then light focusing capability is improved, but the module size increases
Solution Approach 1:
The patent extracts the light focusing lens from the module structure, eliminating the need for additional optical components. The protective layer itself serves as the optical interface, and the sensor is positioned directly beneath it, creating a compact module design without compromising light collection efficiency.
Solution Approach 2:
The patent merges the functions of the protective layer and the optical interface by eliminating the separate light focusing lens. The protective layer directly interfaces with the sensor, combining structural protection and optical function into a single integrated design that reduces overall module size.
3Illumination intensity
If the optical fingerprint sensor is positioned far from the protective layer, then light reflection is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the sensor position directly beneath the protective layer, eliminating intermediate optical components like light focusing lenses. This direct stacking arrangement simplifies the structural design while maintaining effective light reflection and detection through the contact interface between finger and protective layer.
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 design reduces the size and cost of the module, improves mechanical reliability, and enhances the quality of captured fingerprint images by ensuring more light is reflected and utilized from the interface between the finger and the protective layer.
Implementation Method 1
a backlight source, where the optical fingerprint sensor is directly stacked below the protective layer or directly adhered to a bottom of the protective layer, and the backlight source is disposed at a side of the optical fingerprint sensor
Implementation Method 2
output light 11 of the backlight source 1 irradiates to the protective layer 3, passes through the protective layer 3, and is partially reflected and transmitted at a contact interface between the finger 2 and the protective layer 3. The reflected light 12 is focused by the light focusing lens 4 and irradiates onto the optical fingerprint sensor 5
Implementation Method 3
The optical fingerprint sensor 5 performs photoelectric conversion and signal processing to realize fingerprint image capturing
Data Source
AI summary
An optical fingerprint module, comprising: a protective layer; an optical fingerprint sensor; a backlight source, said backlight source being located below the protective layer; the optical fingerprint sensor is stacked directly below the protective layer, or directly adhered to the bottom of the protective layer; the backlight source is located at a side of the optical fingerprint sensor. The present optical fingerprint module has a smaller size and better mechanical reliability.