Portable Camera Lighting Unit Positioning to Eliminate Sensor Glare
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Solution Overview
Problem
Compact magnifying cameras face challenges with glare and uneven lighting due to the proximity of lighting units, leading to issues like light spots and overexposure on reflective surfaces, which complicates image processing, especially in high contrast images.
Innovation Solution
The camera positions the lighting unit outside the viewing field of the sensor using a mirror or lens for specular reflection or transmission, ensuring direct light transmission without diffusion, and incorporates a light mirror to fold the light path, maintaining a compact design while enhancing light distribution and reducing glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffuser is added between the object and lighting unit to minimize shadow and light spots, then lighting uniformity is improved, but light efficiency is reduced due to light blocking
Solution Approach 1:
A reflective surface (mirror or white surface) is introduced as an intermediary between the lighting unit and the object. The lighting unit illuminates this reflective surface, which then reflects light onto the object. This mediator approach achieves uniform lighting distribution through diffuse reflection while maintaining high light efficiency, as the reflective surface redirects rather than blocks light.
2Volume of moving object
If the lighting unit is positioned close to the object for compact design, then device size is reduced, but glare and light spots occur due to direct reflection into the sensor
Solution Approach 1:
The lighting unit is positioned in a location that is optically separated from the sensor's viewing angle by utilizing the third dimension (depth/distance). Specifically, the lighting unit is placed above or to the side of the optical axis, at a distance greater than the focal length from the sensor. This spatial arrangement in another dimension allows compact device design while preventing direct reflection of the lighting unit into the sensor, thereby eliminating glare and light spots.
3Object-affected harmful factors
If a larger diffuser is used to prevent overexposure on reflective surfaces, then glare is reduced, but the device becomes too big for portable use
Solution Approach 1:
The critical parameter changed is the distance between the lighting unit and the sensor, set to be greater than the focal length. This parameter change fundamentally alters the optical geometry, creating a situation where the lighting unit falls outside the sensor's field of view even without a large diffuser. This allows glare reduction while maintaining a compact portable device size.
4Illumination intensity
If indirect or concealed lighting is used to solve glare, then lighting uniformity is improved, but light efficiency is reduced due to multiple reflections and diffusion
Solution Approach 1:
A reflective surface serves as an intermediary that enables indirect lighting while preserving light efficiency. Unlike diffuse transmitters that block and scatter light, the reflective surface bounces light directionally, achieving uniform illumination through controlled reflection. This intermediary approach provides the benefits of concealed lighting without the severe light losses associated with diffuse transmission methods.
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 solution effectively eliminates glare and achieves even lighting, improving image quality by preventing light source reflection and allowing for more precise control of light intensity, especially on reflective surfaces, thus enhancing the portrayal of black and white tones and reducing overexposure issues.
Implementation Method 1
light rays of the at least one lighting unit which are, in use, submitted to the object via a mirror and/or a lens, wherein the camera is arranged such that light rays of the at least one lighting unit which are, in use, submitted to the object are not diffused, and are submitted to the object via at least one light mirror of the camera by means of specular reflection only
Implementation Method 2
submitted to the object via at least one light mirror of the camera by means of specular reflection only and/or via at least one lens by means of specular transmission
Data Source
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AI summary
A portable camera for recording and displaying an image of an object such as printed paper wherein the camera is arranged to be positioned on an object to be recorded wherein the cameras is provided with an outer lower surface which is arranged to be in contact with the object if the camera is positioned on the object, a light sensitive sensor for obtaining an image of at least a portion of the object, a display and processing means for processing the image obtained by means of the sensor and for displaying at least a portion of the recorded image on the display in a possible magnified form, wherein the camera is provided with at least one lighting unit for lighting the object to be recorded when the camera is positioned on the object, wherein the camera is arranged such that light rays of the at least one lighting unit which are, in use, submitted to the object are directly submitted to the object, possibly via a mirror and/or a lens wherein the lighting unit is arranged within the camera such that if the object which is recorded would be a flat mirror whereon the camera is positioned for recording the flat mirror, the lighting unit is located outside a viewing field of the sensor which viewing field is formed in combination with the flat mirror.