Optoelectronic Sensor Depth of Field Adjustment
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Solution Overview
Problem
Conventional barcode scanners and laser scanners face limitations in depth of field, particularly in close-up ranges, due to the fixed nature of their transmission optics, which restricts their ability to read barcodes and other codes effectively, and require complex and costly mechanical adjustments for focus tracking.
Innovation Solution
The use of transmission optics with multiple partial areas having different beam-shaping properties, such as varying focal lengths or aberrations, allows for non-mechanical adjustment of the depth of field by selectively activating light sources or shading areas, thereby expanding the depth of field beyond traditional limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fixed transmission optics are used in conventional barcode scanners, then the device structure is simple and manufacturing cost is low, but the depth of field is limited and cannot be adjusted
Solution Approach 1:
The transmission optics are divided into multiple partial optics areas (first, second, and third partial optics areas) with different focal lengths. Each partial optics area corresponds to a specific object distance range, allowing the system to segment the depth of field into multiple zones that can be selectively activated based on the object distance.
Solution Approach 2:
The patent introduces dynamic switching capability between different partial optics areas through control units that can activate specific light generation areas or shade others. This allows the optical system to dynamically adjust its effective focal length based on the detected object distance, transforming a static optical system into a dynamic one without mechanical moving parts.
2Manufacturing precision
If mechanical tracking of focus position is implemented to exceed the theoretical depth of field limit, then the depth of field can be extended, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
Instead of using a single complex mechanical tracking system, the patent segments the optical system into multiple static partial optics areas with different focal lengths. This segmentation allows the system to achieve extended depth of field by selecting among pre-configured optical paths rather than mechanically adjusting a single optical path.
Solution Approach 2:
The patent replaces mechanical focus adjustment mechanisms with an optical/electrical switching system. Control units activate or shade specific light generation areas corresponding to different partial optics areas, eliminating the need for mechanical moving parts while achieving the same functional result of focus adjustment.
3Manufacturing precision
If mechanical focus adjustment mechanisms are added to extend depth of field, then the depth of field can be increased, but the reliability decreases due to moving parts susceptible to maintenance
Solution Approach 1:
The patent completely eliminates mechanical moving parts from the focus adjustment mechanism by using optical switching between static partial optics areas. Control units electronically activate or shade specific light generation areas, replacing mechanical focus tracking with an electrical/optical control system that has no moving parts to wear or fail.
Solution Approach 2:
The system achieves dynamic focus adjustment capability through electrical control of light generation area activation rather than mechanical movement. This dynamic switching between pre-configured optical paths maintains reliability while providing the flexibility of adjustable focus.
4Manufacturing precision
If multi-zone lenses are used on the transmission side, then the depth of field can be expanded, but the beam caustic broadens and resolution deteriorates
Solution Approach 1:
The patent segments the transmission optics into distinct partial optics areas, each with its own optimized beam-shaping properties and focal length. This segmentation allows each zone to maintain tight beam focus for its specific focal range, avoiding the beam broadening that occurs when multiple zones with different focal lengths are simultaneously active in a multi-zone lens.
Solution Approach 2:
Each partial optics area is designed with specific local optical properties (different focal lengths and beam-shaping characteristics) optimized for particular object distance ranges. This local optimization ensures that when a specific partial optics area is activated, the beam maintains high quality and tight focus appropriate for that distance range, rather than suffering from the compromised performance of a general-purpose multi-zone lens.
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 enables a cost-effective expansion of the depth of field, eliminating the need for expensive mechanical focus adjustments and allowing for higher object resolution, especially in close-up ranges, by dynamically adjusting the beam caustic to match varying object distances.
Implementation Method 1
a transmitting optics (14) which shapes an emitted light beam (102) in such a way that a beam cross-section diameter of the emitted light beam is limited to a predetermined diameter within a depth of field
Implementation Method 2
a light transmitter (12) which generates a transmitted light beam
Data Source
Figure 1~2
Figure 3~4b
AI summary
An optoelectronic sensor (100) for acquiring object information from a monitoring area (108) is described, wherein the sensor (100) comprises a light transmitter (12) with an associated transmitting optic (14) for shaping the beam of an emitted light beam (102, 20, 24) and limiting its beam cross-section to a predetermined diameter within a depth of field, a light receiver (116) for generating a received signal from the reflected light beam (112), and a control and evaluation unit (118) for obtaining object information from the received signal. The transmitting optic (14) has at least two partial optic areas (18a-b) with different beam-shaping properties, and the partial optic area (18a-b) that shapes the emitted light beam (20, 24) is adjustable to change the depth of field.