Television – Monitoring – testing – or measuring – Testing of image reproducer
Reexamination Certificate
1998-01-13
2001-01-23
Kostak, Victor R. (Department: 2611)
Television
Monitoring, testing, or measuring
Testing of image reproducer
C348S142000, C345S904000, C324S701000, C382S141000
Reexamination Certificate
active
06177955
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to test systems for measuring the performance of visual displays and, particularly, to a system having dual stages for providing five-axis motion for use in testing a visual display.
Present systems for testing visual displays, particularly flat panel displays, provide measurements concerning contrast ratio, luminance uniformity, chromaticity uniformity, viewing angle dependence, luminous efficiency and other such display characteristics. These measurements may be used, for example, by display manufacturers and researchers for gathering performance data, comparing the performance of materials, for new product evaluation and for quality control purposes. The Video Electronics Standards Association (VESA) publication “Flat Panel Display Measurements Standard (Proposal),” Doc. #136, Nov. 10, 1997, provides standard measurement procedures to quantify flat panel display characteristics.
Standard test procedures require the measurement of the display's light output at various locations and from various angles relative to the display surface. Positioning apparatus is available for moving a light measuring device, such as a photometer or colorimeter, relative to a stationary display under test or for moving the display relative to a stationary light measuring device. However, conventional positioning apparatus are not well suited for concurrently controlling both motions which results measurement inaccuracies. One disadvantage with conventional systems is that when examining a particular spot on the display, turning and tipping the display or the light measuring device moves the location of the spot within the light measuring device's field of view. Further, conventional display testing systems are not adaptable for use with a number of different light measuring devices nor do they provide automated testing to obtain a full range of normal and off-normal electro-optical performance measurements.
SUMMARY OF THE INVENTION
The invention meets the above needs and overcomes the deficiencies of the prior art by providing an accurate, reliable and adaptable system for measuring the optical performance of a visual display under test. This is accomplished by an improved five-axis motion stage which controls relative movement between a light measuring device and the display. Such a motion stage moves the light measuring device in three orthogonal directions and moves the display in two rotational directions to provide complementary movements with respect to five axes. Thus, the light measuring device of the system can inspect the display's light output from a number of different viewing angles and at a number of different positions. By concurrently controlling three-axis and two-axis motion, the system can automatically track a region of interest on the display and maintain a substantially uniform distance between the light measuring device and the spot which results in maintaining focus and approximate spot size. In this manner, the system may be used to verify several aspects of display performance including contrast ratio, luminance uniformity, chromaticity uniformity, viewing angle dependence and luminous efficiency. In addition, the system is easily implemented, economically feasible and commercially practical.
Briefly described, a visual display inspection system embodying aspects of the invention includes an optical instrument for measuring an electro-optical characteristic within a defined region of interest on a display under test. The optical instrument is mounted on a translational stage which moves it relative to the display in at least one of three generally orthogonal directions. The display is mounted on a rotational stage which rotates it about at least one of two generally orthogonal axes. The system also includes a controller for controlling the translational and rotational stages to position the optical instrument at a desired position relative to the display and to position the display at a desired viewing angle relative to the optical instrument.
Another embodiment of the invention is directed to a method of inspecting a visual display under test with an optical instrument positioned apart from the display and having a field of view which defines an optical axis. The method includes the steps of mounting the display on a rotational stage for rotating the display about at least one of two generally orthogonal axes and rotating the display with the rotational stage to position the display at a desired viewing angle relative to the optical axis. The method also includes defining a region of interest on the display and adjusting the position of the optical instrument relative to the display in at least one of three generally orthogonal directions to maintain the optical axis approximately centered within the defined region of interest on the display when the display is rotated. The method further includes the step of measuring an electro-optical characteristic within the defined region of interest on the display with the optical instrument.
Alternatively, the invention may comprise various other systems and methods.
Other objects and features will be in part apparent and in part pointed out hereinafter.
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Aoun Michael C.
Downen Phillip A.
Kostak Victor R.
Senniger Powers Leavitt & Roedel
Westar Corporation
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