Optoelectronic Sensor Focus Module With Parallel-Guided Receiver Motion

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Solution Overview

Problem

Existing focus adjustment mechanisms for optoelectronic sensors, particularly in camera-based code readers, face challenges with mechanical wear and limited compatibility with various lens weights and types, leading to reduced service life and increased development and manufacturing costs.

Innovation Solution

The focus adjustment mechanism involves moving the light receiver along the optical axis using a parallel guide with flexible holding elements, maintaining a constant orientation and minimizing wear, allowing the use of a wide range of lenses without redesigning the focus adjustment unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a motor-driven cam and parallel guidance mechanism is used for focus adjustment, then the focus position can be adjusted, but mechanical wear increases with lens weight, limiting the choice to smaller lenses

Engineering Contradiction:

Improvelens compatibilityVSAvoidservice life

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of moving the lens along the optical axis as in conventional systems, the invention inverts the approach by moving the light receiver (image sensor) towards or away from the lens. This allows the lens to remain stationary while achieving focus adjustment, thereby eliminating mechanical wear on the lens mounting structure and enabling compatibility with lenses of various sizes and weights without compromising service life.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention replaces the mechanical cam-driven lens movement system with a system that moves the light receiver using a plunger coil (electromagnetic actuator). This substitution eliminates the need for mechanical transmission elements like cams and reduces mechanical wear, thereby improving reliability and extending service life while maintaining focus adjustment capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a voice coil actuator is used to reduce mechanical wear, then service life is extended, but the circular motion of the swivel arm causes offset between the lens and light transmitter, leading to optical degradation

Engineering Contradiction:

Improveservice lifeVSAvoidoptical alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention inverts the conventional approach by keeping the lens stationary and moving the light receiver instead. This eliminates the need for circular swivel arm motion and prevents offset between the lens and light transmitter, thereby maintaining optimal optical alignment while still achieving focus adjustment. The plunger coil moves the light receiver in a linear fashion along the optical axis, ensuring precise alignment is maintained throughout the focus range.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If the lens position is changed to achieve refocus, then focus adjustment is achieved, but the receiving optics must be moved, increasing device complexity

Engineering Contradiction:

Improvefocus adjustmentVSAvoidmechanical structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention inverts the conventional focus adjustment approach by moving the light receiver instead of the lens. This allows focus adjustment to be achieved while keeping the lens and receiving optics stationary relative to each other, thereby simplifying the mechanical structure. The plunger coil actuator provides straightforward linear motion of the light receiver along the optical axis, reducing the complexity of mechanical guidance and mounting structures required.

Inventive Principle:

Principle #13The other way round (Inversion)

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 extends the service life of the sensor, reduces mechanical wear, and enables the use of various lenses, enhancing the versatility and cost-effectiveness of the focus module while avoiding the limitations of liquid lenses.

Implementation Method 1

a plunger coil is provided as the actuator

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

parallel guide with flexible holding elements

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP4296771B1Opto-electronic sensor and focus displacement method

Publication Date: 2024.05.29 SICK AG

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Figure 6~8b

AI summary

An optoelectronic sensor (10) is described, comprising a light receiver (16), a receiving optic (14) arranged upstream of the light receiver (16), and a focus adjustment unit (18) with an actuator (38) designed to move the light receiver (16). The focus adjustment unit (18) has a parallel guide with at least one flexible retaining element (28, 30) that moves the light receiver (16) in a constant orientation on the optical axis of the receiving optic (14).