Wafer-Scale Optical Navigation Sensor With Integrated Illumination
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Solution Overview
Problem
Miniaturization of optical navigation sensors leads to reduced resolution and efficiency due to short focal lengths, inhomogeneous illumination, and increased scattering, resulting in poor image contrast and signal-to-noise ratio, especially with the separation of illumination and imaging optics.
Innovation Solution
Integration of micro-optical illumination and imaging optics on a common carrier structure, using a microlens array and beam-shaping optics with an aperture diaphragm layer to ensure homogeneous illumination and efficient imaging, with the radiation source and image sensor array on the same support structure, allowing for a thin and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical structure is miniaturized to reduce overall length, then the device size is reduced, but the resolution is greatly reduced due to very large angles relative to the optical axis and off-axis aberrations
Solution Approach 1:
The imaging optics are divided into multiple independent channels, each with its own optical axis perpendicular to the tracking surface. This segmentation allows each channel to image a specific region without suffering from off-axis aberrations, maintaining resolution while enabling compact integration of multiple imaging paths
Solution Approach 2:
The patent transitions from a single optical axis to multiple optical axes arranged in a dimensional array. By stacking multiple imaging channels in different spatial dimensions, the system achieves both miniaturization and maintained resolution through parallel imaging paths rather than extending a single path
2Volume of moving object
If the overall structure is shortened to achieve miniaturization, then the device becomes more compact, but brightness is greatly reduced due to natural vignetting at the edges of the image
Solution Approach 1:
The illumination is divided into multiple independent channels, each providing dedicated lighting for its corresponding imaging channel. This ensures that each imaging path receives sufficient illumination without suffering from vignetting effects that plague single-channel systems with large field angles
Solution Approach 2:
Each imaging channel is provided with localized illumination optimized for its specific field of view. The illumination quality is tailored locally to each channel's requirements, ensuring uniform brightness across all image regions without compromising overall device length
3Volume of moving object
If the object distance is reduced to achieve miniaturization, then the device becomes more compact, but the illumination radiation hits the tracking surface at a very flat angle, leading to inhomogeneous illumination and reduced efficiency
Solution Approach 1:
The illumination system is segmented into multiple independent illumination paths, each with its own radiation source and beam shaping optics. This allows each illumination path to be optimized independently for the specific object distance and angle requirements of its corresponding imaging channel
Solution Approach 2:
Each illumination channel provides localized lighting with optimized incidence angles for its specific region. The beam shaping optics in each channel are tailored to achieve the desired illumination angle and distribution pattern, ensuring high illumination efficiency and homogeneous lighting across the entire tracking surface despite miniaturized object distances
4Volume of moving object
If the object distance is reduced to achieve miniaturization, then the device becomes more compact, but a large number of reflections are necessary, leading to increased scattering and false light and thus reduced image contrast
Solution Approach 1:
The optical path is segmented into separate illumination and imaging channels with minimal cross-interference. Each channel is designed to reduce the number of reflections required, and the separation between channels prevents scattered light from one channel from affecting others, reducing false light and maintaining image contrast
Solution Approach 2:
The harmful reflections and scattered light are extracted and blocked using aperture diaphragms and beam shaping optics that selectively allow only the desired light paths to proceed. This removes the harmful components from the optical system while maintaining the miniaturized object distance
5Manufacturing precision
If the illumination and imaging optics are separated to achieve independent optimization, then each optics can be optimized independently, but further miniaturization is limited
Solution Approach 1:
The illumination optics and imaging optics are merged into an integrated multi-channel system where both functions coexist in a unified compact structure. The shared substrate and coordinated channel arrangement enable both independent optimization of each optics type and significant miniaturization of the overall device
Solution Approach 2:
The multi-channel system serves dual functions: it provides independent illumination optimization for each region while simultaneously achieving compact integration. The same structural framework supports both illumination and imaging functions, making the system universally applicable to both requirements without compromise
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 approach achieves a highly miniaturized optical navigation sensor with improved resolution, higher lighting efficiency, and reduced power consumption, enabling effective use in portable devices while maintaining image quality.
Implementation Method 1
at least one microlens array assigned to the image sensor array and arranged between an object to be imaged and the image sensor array
Implementation Method 2
at least one associated beam shaping optics
Implementation Method 3
at least one aperture diaphragm layer, which consists of an absorbent material or a material that is at least reflective on one side
Implementation Method 4
a material that is at least reflective on one side
Data Source
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AI summary
The invention relates to an optical navigation device based on production on wafer scale, in which both the illumination path and the imaging lens system are integrated on a common carrier structure. The optical navigation devices according to the invention are used for controlling a cursor on an image output device or in the field of finger navigation.