Sensor Head Ring Member Shields Ambient Light
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Solution Overview
Problem
Existing color proofing systems face challenges in achieving reproducible and reliable color measurements due to ambient light interference and variable substrate backgrounds, which affect the accuracy of color assessments before a print run.
Innovation Solution
A sensor head with a ring member that acts as a light shield to isolate the measurement spot from ambient light and maintains a consistent distance for precise illumination, combined with a background member to ensure a constant color background, using an array of low-index optical waveguides for collimated light and pneumatic actuators for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the measurement spot is exposed to ambient light, then the sensor head can operate with a simpler structure, but the color measurement accuracy deteriorates due to light interference
Solution Approach 1:
A light-tight ring member is introduced as an intermediary component between the ambient environment and the measurement spot. This ring member acts as a physical barrier that blocks ambient light from reaching the measurement area, thereby protecting the color measurement accuracy without requiring complex active shielding systems
Solution Approach 2:
The ring member is positioned and configured in advance to preemptively block ambient light before it can interfere with the measurement. By establishing the light barrier prior to measurement, the system ensures accurate color readings without needing complex real-time adjustment mechanisms
2Ease of operation
If the distance between substrate and light capturing element varies, then the sensor head has easier operation, but the measurement precision deteriorates
Solution Approach 1:
Mechanical adjustment mechanisms are replaced by a standardized ring member with a fixed, pre-determined geometry. The ring member's inherent dimensions automatically establish the correct focal distance when engaged with the substrate, eliminating the need for complex mechanical positioning systems while ensuring consistent measurement accuracy
Solution Approach 2:
The focal distance parameter is fixed by the geometric parameters of the ring member rather than being continuously adjustable. This parameter fixation through standardized geometry ensures consistent measurement conditions while simplifying operation, as the ring member's engagement automatically sets the optimal distance
3Adaptability or versatility
If the substrate background varies, then the sensor head can accommodate different substrates, but the measurement precision deteriorates due to background interference
Solution Approach 1:
The variable substrate background is effectively extracted or removed from the measurement equation by the light-tight ring member. By blocking ambient light that would otherwise illuminate and reveal substrate background variations, the ring member isolates the measurement to only the light reflected from the printed spot, thereby eliminating background interference while maintaining substrate versatility
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
Ensures reliable and reproducible color measurements by shielding the measurement spot from ambient light and maintaining a consistent substrate position, reducing errors caused by background variations and ensuring accurate color assessments.
Implementation Method 1
The light source comprises a circular array of optical waveguides and condensor lenses which focus the light emitted from the waveguides onto the desired spot on the proof
Implementation Method 2
condensor lenses which focus the light emitted from the waveguides onto the desired spot on the proof
Implementation Method 3
The light capturing element is formed by another optical waveguide having an end aligned on the axis of the circular light source array and extending normal to the plane of the substrate for capturing the light reflected from the substrate
Implementation Method 4
The sensor head may include one or more pneumatic actuators for projecting and retracting the ring member
Data Source
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AI summary
A sensor head (10) for a colour proofing apparatus, comprising a light source (24) for illuminating a measurement location (38) on a surface of a proof substrate (14), and a light capturing element (22) arranged to capture light that is reflected from said measurement location (38), characterized in that the sensor head (10) has a ring member (48) that surrounds the light source (24) and the light capturing element (22) and is slidably guided in the sensor head and adapted to be projected towards the substrate (14) into a position where it engages a stop (52) that is fixed relative to the light source (24) and the light capturing element (22).