Low Resolution Image Sensor Optical Geometry for Extended Symbol Reading
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Solution Overview
Problem
Conventional imaging readers require high-resolution linear image sensors to maintain adequate working distance range for decoding one-dimensional symbols, leading to high costs and limited functionality due to the need for sufficient light sensitivity and resolution, which is not efficiently addressed by lower resolution sensors.
Innovation Solution
Configuring a low-resolution image sensor with fewer than 2000 pixels, positioning the imaging lens deeper in the housing to reduce the scan angle, and enhancing the illuminating light assembly for increased intensity, allowing for effective symbol decoding at extended working distances while maintaining cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution linear image sensors are used to maintain adequate working distance range for decoding one-dimensional symbols, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent changes the optical parameters by using a reduced scan angle (less than 40 degrees) and positioning the imaging lens deeper in the housing (at least one inch from the front). This parameter change allows low-resolution sensors to achieve the same effective measurement precision at extended working distances, resolving the contradiction between measurement precision and device cost.
2Measurement precision
If high-resolution image sensors are used to extend working distance range, then measurement precision is improved, but light sensitivity requirements increase
Solution Approach 1:
The patent modifies the optical geometry by reducing the scan angle and increasing the lens-to-front distance, which concentrates the light collection more effectively. This allows low-resolution sensors with better per-pixel light sensitivity to achieve adequate signal levels at extended working distances, resolving the contradiction between measurement precision and light sensitivity requirements.
3Device complexity
If imaging lens is positioned closer to the front for compact design, then device complexity is reduced, but working distance range is limited
Solution Approach 1:
The patent moves the imaging lens deeper into the housing along the optical axis (increased spacing of at least one inch), utilizing the depth dimension rather than increasing lateral dimensions. This dimensional change enables extended working distance range while maintaining a compact handheld form factor, resolving the contradiction between device complexity and adaptability.
4Measurement precision
If reduced scan angle is used with low-resolution sensor, then measurement precision is maintained, but illumination intensity requirements increase
Solution Approach 1:
The patent optimizes the illumination system parameters by increasing illumination light intensity to compensate for the reduced scan angle. The enhanced illumination ensures adequate light return to the low-resolution sensor, maintaining measurement precision while enabling the use of fewer pixels. This resolves the contradiction between measurement precision and illumination intensity requirements.
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
Enables the use of lower-cost, lower-resolution sensors to read symbols at distances up to 24 inches with improved resolution and reduced accidental imaging of neighboring symbols, while maintaining adequate signal quality and intensity for reliable decoding.
Implementation Method 1
a solid-state image sensor having a linear array of pixels arranged in the housing along a scan direction for sensing return light returning along an optical path
Implementation Method 2
The imaging reader preferably includes an illuminating light assembly for illuminating the target with illumination light from an illumination light source, e.g., one or more light emitting diodes (LEDs)
Implementation Method 3
an imaging lens in the housing for capturing the return light over a scan angle and for projecting the captured light onto the sensor
Data Source
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AI summary
A reader for and method of electro-optically reading symbols aim a front of a handheld housing at a symbol during reading. A solid-state, low resolution image sensor having a linear array of pixels is arranged in the housing and has less than 2000 pixels in number. The pixels sense return light returning along an optical path away from the symbol that is located in an extended range of working distances relative to the front of the housing. An imaging lens is positioned deep in the housing at an increased spacing of at least one inch as measured along the optical path away from the front of the housing, for capturing the return light over a reduced scan angle that is less than 40 degrees, and for projecting the captured light onto the sensor. A controller processes the return light sensed by the imager into data relating to the symbol.