Tile Surface Scanning Using Filterless Photodetector Matrix
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Solution Overview
Problem
Existing scanning devices for colored surfaces suffer from artifact formation due to the distance between photodetector rows, which is influenced by the size of color filters, and struggle to identify defective ink release units when using tri-linear cameras with multiple ink colors.
Innovation Solution
The use of multiple lamps emitting specific color spectra, allowing photodetectors to be placed close together without color filters, and a 2D CMOS area camera to acquire images, enabling precise scanning and identification of ink release unit errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If colour filters are positioned in front of photodetector rows to enable color separation, then color information can be acquired, but the distance between photodetector rows must be increased by a multiple of pixel width, leading to artifact formation in image reconstruction
Solution Approach 1:
The patent removes the color filters from the photodetector rows entirely. Instead of filtering light at the detector level, the system extracts color information by selectively illuminating the scanned surface with monochromatic light of specific wavelengths (red, green, blue) using separate light sources. This extraction approach eliminates the need for physical filters and the associated spacing requirements, thereby preventing artifact formation during image reconstruction.
Solution Approach 2:
The system employs periodic illumination with monochromatic light sources that cycle through different colors (red, green, blue) in synchrony with the photodetector readout. Each light source is activated in sequence during specific time intervals, allowing the same photodetector array to capture color information without requiring physical separation or filters. This temporal multiplexing resolves the contradiction by achieving color separation through time rather than space.
2Manufacturing precision
If the distance between adjacent photodetector rows is reduced to minimize artifacts, then image reconstruction quality improves, but color filter miniaturization becomes increasingly difficult and costly
Solution Approach 1:
The patent eliminates the color filter component entirely from the system architecture. By removing filters completely rather than merely miniaturizing them, the design avoids all associated manufacturing complexities and costs. The color separation function is transferred to the illumination system, which uses independently controllable monochromatic light sources to provide the necessary spectral information to the unfiltered photodetectors.
3Reliability
If a tri-linear camera with three fixed color filters is used, then the system can identify defects for three specific ink colors, but it cannot detect erroneous ink release when different colors or more than three colors are used
Solution Approach 1:
The system achieves universality by using multiple independent monochromatic light sources that can be selectively activated. Each light source corresponds to a specific wavelength, and by controlling which light sources are active, the system can be adapted to detect any combination of ink colors. This multi-functional illumination approach allows the same photodetector array to reliably identify defects across diverse color configurations without requiring physical reconfiguration or filter changes.
Solution Approach 2:
The system employs dynamic control of light source activation rather than fixed filter configurations. The illumination wavelengths are made variable and adaptable through electronic control, allowing the system to dynamically adjust to different ink color requirements. This dynamic approach enables reliable defect detection across multiple color scenarios by matching the illumination spectrum to the specific ink colors being monitored.
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 reduces artifact formation and allows for flexible adaptation to different scanning requirements, including the ability to identify defective ink release units, by eliminating the need for color filters and enabling the use of any number of lamps with different colors.
Implementation Method 1
a plurality of lamps (7) which emit a light with a determined light emitting spectrum
Implementation Method 2
a matrix of photodetectors (4) comprising a plurality of rows of photodetectors (5)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for scanning a coloured surface (2) of a tile and a device which actuates the method. The device (1 ) for scanning a coloured surface (2) of a tile (3) comprises a matrix of photodetectors (4) comprising a plurality of rows of photodetectors (5) which are parallel and placed side by side, the matrix of photodetectors (4) does not comprise any colour filter above the photodetectors (4) and the rows of photodetectors (5) are near each other and spaced by a distance equal to at least one pixel; the matrix of photodetectors (4) is arranged such as to acquire, in synchrony with a temporal scanning interval, an image of a surface band (6) of a coloured surface (2) to be scanned of a tile (3). The device also comprises: a plurality of lamps (7) each having a light emission spectrum different from a light emission spectrum of another lamp of the plurality of lamps (7); the lamps of the plurality of lamps (7) being arranged such as to illuminate the surface band (6) of the coloured surface (2) to be scanned of the tile (3); the lamps of the plurality of lamps (7) being commandable to switch on at least one at a time at each temporal scanning interval; conveyor means (8) provided for restingly receive and transport the tile (3) to be scanned and for determining a relative movement between the tile (3), on a side, and the matrix of photodetectors (4) and the plurality of lamps (7), on the other side, in a movement direction which is perpendicular to the plurality of rows of photodetectors (5) such that for each surface band (6) of the coloured surface (2) to be scanned of the tile (3) a predetermined number of images is acquired.