Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1998-06-18
2001-04-10
Mancuso, Joseph (Department: 2723)
Image analysis
Applications
Manufacturing or product inspection
C348S092000
Reexamination Certificate
active
06215895
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to display panel inspection.
BACKGROUND OF THE INVENTION
Conventional systems for inspecting display panels include the system described in Cummins, R. et al, “Evaluating image quality and defect characterization in flat panel display”, Photon Dynamics, Inc., 1504 McCarthy Blvd., Milpitas, Calif., USA.
In conventional display panel inspection, an image of a display panel, including a multiplicity of pixels, is imaged by a sensor which is also pixelated, the pixels of the sensor normally not being contiguous (i.e., having a fill factor of less than 100%) and normally not being equally sized nor perfectly aligned relative to the pixels of the display panel image.
FIG. BA-
1
is a diagram of a display panel image including, for simplicity, four display panel pixels
10
which are imaged by a sensor including, for simplicity, six sensing elements
20
. The sensor is ideal, i.e. theoretical, in the sense that the sensor elements thereof are contiguous. Typically, nonuniform display panel intensity shows up as a local variation in the video signal of the sensors. The numbers within the display panel pixels
10
indicate the proportion of the total area of the display panel pixel that is sensed by the respective camera pixel, in arbitrary units.
FIG. BA-
2
is a diagram of a display panel image which is not ideal in that the sensor elements
20
are not contiguous. In FIG. BA-
2
, for simplicity, three display panel pixels
30
,
40
and
50
are shown. The portion of display panel pixel
40
which is not sensed, as indicated by cross-hatching
70
is smaller than the portions of display panels
30
and
50
, as indicated by diagonal lines
80
. This results in inaccuracies in measuring the intensities of the display panel pixels. Specifically, local variation in the video signal of the sensors does not necessarily indicate nonuniform display panel intensity.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved system for display panel inspection.
There is thus provided in accordance with a preferred embodiment of the present invention a system for inspecting a display panel including a plurality of pixels, the system including a selective pixel actuator which causes only some of the plurality of pixels to be actuated, a sensor for acquiring an image of a pattern which is generated on the panel, and an image processor operative to identify nonuniformities in the intensities of pixels of the panel.
Further in accordance with a preferred embodiment of the present invention the display panel includes an LCD (liquid crystal display) panel, and the system also includes an illuminator operative to provide illumination to a panel to be inspected.
Still further in accordance with a preferred embodiment of the present invention the illumination of the panel to be inspected includes back illumination and actuation of pixels includes changing the local transmittance thereof.
Additionally in accordance with a preferred embodiment of the present invention the selective pixel actuator is operative to sequentially actuate a sequence of pixel subsets, and each pixel subset includes only a single pixel within each of a plurality of pixel vicinities of predetermined size within the display panel.
There is further provided in accordance with a preferred embodiment of the present invention a system for inspecting a display panel including a plurality of pixels, the system including a sensor for simultaneously acquiring an image of substantially the entirety of a pattern which is generated on the panel, and an image processor operative to identify nonuniformities in the intensities of pixels of the panel.
There is additionally provided in accordance with a preferred embodiment of the present invention a method for inspecting a display panel including a plurality of pixels, the method including actuating only some of the plurality of pixels, acquiring an image of a pattern which is generated on the panel, and identifying nonuniformities in the intensities of pixels of the panel.
There is further provided in accordance with a preferred embodiment of the present invention a system for inspecting a display panel including a plurality of pixels, the system including a sensor for acquiring an image of a pattern which is generated on the panel at a resolution which does not substantially exceed that of a standard TV camera, and an image processor operative to identify nonuniformities in the intensities of pixels of the panel.
Further in accordance with a preferred embodiment of the present invention the sensor includes less than 1300×1000 sensing elements.
Still further in accordance with a preferred embodiment of the present invention the sensor includes no more than 800×500 sensing elements.
There is additionally provided in accordance with a preferred embodiment of the present invention a system for inspecting a display panel including a plurality of pixels, the system including a sensor for acquiring an image of a pattern which is generated on the panel, and an image processor operative to identify the intensity of each pixel of the panel.
Further in accordance with a preferred embodiment of the present invention the display panel includes a liquid crystal display (LCD) panel.
Still further in accordance with a preferred embodiment of the present invention the display panel includes an LCD cell without illumination, driver or polarizer.
Additionally in accordance with a preferred embodiment of the present invention the system also includes a fixture for holding the panel to be inspected.
There is also provided in accordance with a preferred embodiment of the present invention a method for inspecting a display panel including a plurality of pixels, the method including simultaneously acquiring an image of substantially the entirety of a pattern which is generated on the panel, and identifying nonuniformities in the intensities of pixels of the panel.
There is further provided in accordance with a preferred embodiment of the present invention a method for inspecting a display panel including a plurality of pixels, the method including acquiring an image of a pattern which is generated on the panel at a resolution which does not substantially exceed that of a standard TV camera, and identifying nonuniformities in the intensities of pixels of the panel.
Still further provided in accordance with a preferred embodiment of the present invention is a method for inspecting a display panel including a plurality of pixels, the method including acquiring an image of a pattern which is generated on the panel, and identifying the intensity of each pixel of the panel.
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Dotan Noam
Gross Abraham
Katzir Yigal
Sali Erez
Ladas & Parry
Mancuso Joseph
Orbotech Ltd.
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