Eccentric Field Imaging Lens Tilted Surfaces Keystone Distortion

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Solution Overview

Problem

Conventional optical mice suffer from distortion and depth of field issues due to lens tilting or large, fast lenses that exclude specular beams, leading to costly implementations and inefficient use of the wide field angle lens, resulting in keystone distortion and suboptimal image quality.

Innovation Solution

An optical navigation device with an eccentric field imaging lens system, featuring multiple lens surfaces tilted at different oblique angles relative to the navigation surface, an aperture stop with a perpendicular optical axis, and an image sensor oriented parallel to the surface, which directs scattered light to minimize keystone distortion and enhance image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the lens is tilted relative to the navigation surface to receive direct specular reflection light, then the lens can receive more light, but distortion and depth of field issues affect image accuracy

Engineering Contradiction:

Improvelight receptionVSAvoidimage accuracy

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent segments the lens into multiple independent lens elements (first lens element, second lens element, third lens element) with different functions. The first lens element captures specular reflection light, while subsequent elements correct distortion and focus light, resolving the contradiction between light reception and image accuracy

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an aperture stop as an intermediary element positioned between the lens elements. This aperture stop filters and controls the light paths, allowing specular reflection light to be captured while preventing distortion from affecting the final image quality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the image sensor is at an oblique angle to exclude the specular reflected beam, then only scattered light is accepted, but the lens system becomes large and costly

Engineering Contradiction:

Improveimage qualityVSAvoidlens system size

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of excluding specular reflection light by positioning the sensor at an oblique angle, the patent inverts the approach by using a tilted lens system that actively captures specular reflection light and redirects it through multiple lens elements to form a focused image, thereby reducing lens system size while maintaining image quality

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the orientation parameters of the lens elements relative to the navigation surface. The first lens element is tilted at a first angle to the normal, and subsequent elements are tilted at different angles, allowing the system to capture and focus specular reflection light without requiring a large lens aperture

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If a wide field angle lens is used to provide a good image field of view, then the field of view is improved, but most of the useful field of view is not utilized

Engineering Contradiction:

Improvefield of viewVSAvoidlens utilization efficiency

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

The patent applies local quality by assigning different functions to different parts of the lens system. The first lens element is optimized for capturing specular reflection light at specific angles, while subsequent elements are optimized for correcting distortion and focusing. This localized optimization ensures that each part of the lens system contributes effectively to the overall imaging function, maximizing the utilization of the wide field angle lens

Inventive Principle:

Principle #3Local quality

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

The solution provides sharp, bright images of the eccentric field with a center point off the optical axis, optimizing image quality and reducing costs by utilizing a more efficient lens configuration that effectively captures scattered light without the need for large, fast lenses.

Implementation Method 1

The eccentric field imaging lens includes multiple lens surfaces which are tilted at different oblique angles relative to the navigation surface to direct the light scattered off of the navigation surface toward the image sensor

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS8188419B2Eccentric field imaging lens with titlted and decentered surfaces

Publication Date: 2012.05.29 PIXART IMAGING INC

AI summary

An optical navigation device determines relative movement between the optical navigation device and a navigation surface. The optical navigation device includes a light source, an image sensor, and an eccentric field imaging lens. The light source illuminates a navigation surface. The image sensor generates a navigation image of light scattered off of the navigation surface. The eccentric field imaging lens is disposed between the navigation surface and the image sensor. The eccentric field imaging lens includes multiple lens surfaces which are tilted at different oblique angles relative to the navigation surface to direct the light scattered off of the navigation surface toward the image sensor.