WO1998010241A1 - Color printer scanner - Google Patents

Color printer scanner

Info

Publication number
WO1998010241A1
WO1998010241A1 PCT/IB1997/001222 IB9701222W WO9810241A1 WO 1998010241 A1 WO1998010241 A1 WO 1998010241A1 IB 9701222 W IB9701222 W IB 9701222W WO 9810241 A1 WO9810241 A1 WO 9810241A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
label
diffuser
color
image
color printer
Prior art date
Application number
PCT/IB1997/001222
Other languages
French (fr)
Inventor
John M. Suhan
Original Assignee
Wea Manufacturing, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/95Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/9506Optical discs

Abstract

A polychromatic print scanner and more specifically a print scanner for determining defects in the printing of a compact disc (3) label has color discernment features and fast electronic components.

Description

COLOR PRINTER SCANNER

Field Of The Invention

This invention relates to a print scanner and more specifically to a print scanner for determining defects in the printing of a compact disc label.

Background Of The Invention Various arrangements are known in the prior art for scanning printing such as that contained on a label. Some of these devices take their reference and sample signals from a video camera. The images are stored in a computer's random access memory wherein comparisons are made between the reference and sample images by template matching tailored to the nature of the inspection being performed. While most of these systems are satisfactory for the purposes for which they are designed, in general they are not suitable for the inspection of compact disc labels, owing to the nature of the labels and their reflective diffraction grating substrates. In most instances, moreover, they are not as sensitive as is desired. Most of them inspect for missing ink but fail to make any provision for inspection with reference to added or superfluous ink.

A print scanner for detecting defects in the label of a compact disc supported on a carrier moved through a label printing station into a substantially light tight housing in which the disc is illuminated with diffuse light through a mask so that a video cameras in the housing sees only the label area is disclosed in patent 5,181,081. A reference image derived from a multiplicity of video frames and a sample image derived from a plurality of video frames are subtracted each from the other, two histograms are computed from the subtraction results and respective figures of merit for missing ink and added ink are calculated from the histograms.

Brief Description Of The Invention This invention allows for detecting defects in the label of a compact disc sporting multicolored labels. The color print scanner resolves a given color into its component colors. A unique light diffuser comprising woven fiber optic strands is employed. With this technique even the most subtle defects in a complicated color shading are effectively detected.

Brief Description Of The Drawings Figure 1 is a drawing of the print scanner of the present invention. Detailed Description Of A Preferred Embodiment

The printed artwork for optical storage discs has become quite advanced. Multicolored labels now require that print scanning devices detect fine shades of color from dot to dot. Additionally, these dots are now of much smaller dimensions. Cycle times of the latest optical disc printers are also much faster than those of the above discussed prior art. The Color Print Scanner of the present invention accommodates the new demanding requirements of optical disc printing quality control.

The components of the system are an improvement upon those of the print scanner disclosed in U.S. patent 5,181,081, whose disclosure is incorporated herein by reference. The addition of color video capabilities employing a faster microprocessor for the CPU highlighting, and an improved light diffuser are the main improvements. The present invention is concerned with an in-line capacity on the conveyor of an optical disc printer. An RGB color video camera 1. is used to capture the image of a reference label _3 on a compact disc. The disc is illuminated by a light source 5 housed within a print scanner housing 1_ that receives the disc _3 on an assembly line (not shown) . The light from the light source 5 passes through a diffuser 9 before reaching the disc. The video camera passes its image to a computer 11. A color f amegrabber, residing within the computer, converts the analog digital video signal into a digital format, and stores the image for later processing. Preferably, this particular framegrabber, the Data

Translation DT-2871, converts the RGB video signal into a format of HSI (hue, saturation, intensity) . The advantage of using the HSI color space in place of the RGB color space lies in the fact that with HSI, usually only one of the three components needs to be analyzed to process images. The RGB color space requires that all three components be analyzed without exception for image processing to take place. An auxiliary frame processor board quickens the execution of math operations of the framegrabber.

In capturing the images, it is essential to devise an illumination system which permits a glare-free viewing of the label area. .An improvement upon the original illumination enclosure is made through the use of woven fiber optic strands in the form of a diffuser layer 9^. A much more uniform light distribution is achieved with such a diffuser. This is important since the subtle color changes from dot to dot must be detectable. The diffuser resides directly above the label surface in a parallel fashion. The camera lens protrudes through a circular hole in the surface of the diffuser.

Once a reference image is captured, it is held within the memory of the framegrabber board. Each subsequent test label that passes through the view of the camera is compared to the reference label via a subtraction algorithm, where a pixel-for-pixel video frame subtraction occurs. Normally, this would be done using the hue component, where a zero remainder indicates good quality and a nonzero remainder indicates lesser quality.

The complexity of the label design determines whether or not the saturation and intensity components also need to be used. The same subtraction logic would be used for those components, as well. The use of these two components must take place in between cycles of the printer, since the additional operations add time to the inspection. Noisy video signals will be corrected, if detected, through the use of a frame averaging routing. Histogram processes also enhance the detection of defects through noisy signals. Once a defective label has been detected, an output signal is sent to an in-line robot for the removal of the disc containing the defective label. The said action is repeated over a course lasting as long as the production run containing the respective label. A new reference label must be acquired with each new production order. Failing to do so results in false rejects. While there have been shown and described and pointed out the fundamental novel features of the invention as applied to preferred embodiments thereof, it will be -understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention as exemplified in the following claims:

Claims

1. A color printer scanner for compact discs comprising a housing for receiving compact discs from an assembly line, a light source within said housing for illuminating a label area on said disc, an RGB color video camera for capturing the image of the on the compact disc, a light diffuser located between said label and said light source, a computer for receiving an image from said video camera, said computer comprising a color framegrabber for converting an analog digital video signal into a digital format, and storing the image for later processing, said framegrabber comprising means to convert the RGB video signal into a format of HSI (hue, saturation, intensity) .
2. The color printer scanner for compact discs of claim 1, wherein said diffuser comprises woven fiber optic strands in the form of a diffuser layer, said diffuser located directly above and parallel to the label surface in a parallel fashion.
3. The color printer scanner for compact discs of claim 2, wherein said camera comprises a lens protruding the surface of said diffuser.
PCT/IB1997/001222 1996-09-05 1997-09-05 Color printer scanner WO1998010241A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US70845596 true 1996-09-05 1996-09-05
US08/708,455 1996-09-05

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU4316197A AU4316197A (en) 1996-09-05 1997-09-05 Color printer scanner

Publications (1)

Publication Number Publication Date
WO1998010241A1 true true WO1998010241A1 (en) 1998-03-12

Family

ID=24845854

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB1997/001222 WO1998010241A1 (en) 1996-09-05 1997-09-05 Color printer scanner

Country Status (1)

Country Link
WO (1) WO1998010241A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004021279A1 (en) * 2002-08-30 2004-03-11 Hewlett-Packard Development Company, L.P. Method and apparatus for automatic removal of optical artifacts in scanning

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5040878A (en) * 1990-01-26 1991-08-20 Dimension Technologies, Inc. Illumination for transmissive displays
US5181081A (en) * 1990-09-06 1993-01-19 Wea Manufacturing, Inc. Print scanner
US5483603A (en) * 1992-10-22 1996-01-09 Advanced Interconnection Technology System and method for automatic optical inspection

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5040878A (en) * 1990-01-26 1991-08-20 Dimension Technologies, Inc. Illumination for transmissive displays
US5181081A (en) * 1990-09-06 1993-01-19 Wea Manufacturing, Inc. Print scanner
US5483603A (en) * 1992-10-22 1996-01-09 Advanced Interconnection Technology System and method for automatic optical inspection

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SPIE, Vol. 2247, Sensors and Control for Automation, (1994), HAYES B., "Fully Automatic Color Print Inspection by Digital Image Processing Systems", pages 235-244. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004021279A1 (en) * 2002-08-30 2004-03-11 Hewlett-Packard Development Company, L.P. Method and apparatus for automatic removal of optical artifacts in scanning
US7397939B2 (en) 2002-08-30 2008-07-08 Hewlett-Packard Development Company, L.P. Method and apparatus for automatic removal of optical artifacts in scanning

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