Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Reexamination Certificate
2000-06-30
2003-07-08
Mathews, Alan A. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
C356S326000
Reexamination Certificate
active
06590648
ABSTRACT:
This application claims priority under 35 U.S.C. §§119 and/or 365 to 99 113 557.5 filed in Europe on Jul. 6, 1999; the entire content of which is hereby incorporated by reference.
FIELD OF THE INVENTION
The invention relates to an apparatus for measuring light that is emitted, remitted, or transmitted from a measuring object.
BACKGROUND OF THE INVENTION
The so-called color management, i.e. the mutual tuning of all color capable computer peripheral devices (monitor, scanner, printer etc.) as well as the communication of reliable color values gains an increasingly great importance in the course of the continuous further distribution of color capable computer peripherals.
The creation of manufacturer specific device profiles or the creation of device profiles that correspond to a standard (e.g. ICC) is a central point of the color management. These device profiles allow for the conversion of device specific color values to device independent color values and hence into generally valid color values. The creation of device profiles is based on the characterization of the colorimetric properties of the input and output devices, such as color printer and scanner. This requires the colorimetric evaluation of color test cards (so-called test charts), such as described in the ISO standard IT8. One such test chart is composed of several hundreds of test fields. With the available portable measuring devices, the manual measuring of all test fields of a test chart requires a lot of work and time. This is due to the required precise manual positioning of the measuring device on the measuring field and the measurement time per color field which can last from one to several seconds. Even though the measuring of a test chart can be automated using a computer controlled XY-shifting table, it can be accelerated only insignificantly. Furthermore, such a XY-shifting table is very expensive.
The characterization and calibration of monitors is carried out by means of a direct measurement of the light emitted from the monitor. In doing so, the measuring device is commonly fastened to the screen of the monitor by means of a suction cup, for example.
The following basic requirements on a measuring device for color management can be derived from the steps described: the measuring device must have a flexible measuring geometry for the characterization of the different input and output devices (emission and remission) as well as a simple and efficient capacity for reading in one-dimensional and two-dimensional color test cards.
Existing color management solutions require several different measuring devices and apparatuses and are usually relatively expensive. The high purchase price of the measuring devices in comparison to peripheral devices restricts the use of color management to high end applications. Existing low cost color measuring devices require too much work for the creation of device profiles and thus have only a limited suitability for this application.
A characteristic feature of existing portable color measuring devices is a classical serial interface through which the device-internal and computer-based controller can communicate with a connected external computer. Communication means amongst other things, that measuring processes can be initiated and controlled by the external computer on one hand, and on the other hand the thus obtained measurement data transferred to the external computer, for example for further processing. The communication is controlled by corresponding software which is permanently stored in the color measuring device and loaded into the external computer when needed. Furthermore, data (e.g. measurement parameters) and if necessary specific software can be loaded from the external computer into the internal computer of the measuring device. Finally it is possible to manually trigger measuring processes at the measuring device itself.
Typical representatives of existing measuring devices that are designed to be portable are the “Colortron” (U.S. Pat. No. 5,684,582), the disclosure of which is hereby incorporated by reference in its entirety, the “Digital Swatchbook” of the X-Rite company, and the “Spectrolino” of the applicant. As a low cost device, the “Colormouse too” of the ColorSavvy company is mentioned.
The mentioned devices are different from each other by the type of their spectral analyzers. The “Swatchbook” is based on a greater number of narrow-band interference filters which are installed on a rotatable disk that is arranged in the path of the beam. This concept is not suitable for the measurement of narrow emission lines of CRT monitors because of the coarse wavelength resolution.
The “Colortron” is based on a classical lattice monochromator combined with a receiver diode. This architecture evaluates the different wavelengths in a chronologically sequential manner. This leads to long measuring times during remission measurements. When performing emission measurements on the monitor, the measurement times are impractically long.
The spectral separation in the “Colormouse too” device is achieved through illumination by using different light emitting diodes (LED). The low illumination power of the LED combined with sequential measurements at different wavelengths leads to long measuring times. This measurement principle can inherently not be used for wavelength selective emission measurements.
The “Spectrolino” of the applicant is based on a conventional diode array spectrometer which allows for short measuring times based on the simultaneous measurement of all wavelengths and can be used for emission measurements as well as remission measurements. Presently commonly used manufacturing technologies for diode array spectral modules cause relatively high costs and hence are unsuitable for a low cost device.
Today, the measurement off a complete test chart is carried out using time intensive manual performances of individual measurements which are carried out line-by-line using a device exclusively specialized for this application (e.g. DTP 41 by X-Rite) or fully automatic using a measuring device that is mounted on a computer controlled XY-table (e.g. Spectrolino-Spectroscan by the applicant). “Scanning” color measuring devices that are mounted on a computer controlled measuring table are already mostly known in the printing industry and are described, for example, in EP-A 0064024, the disclosure of which is hereby incorporated by reference in its entirety.
A manually moved “scanning” portable measuring device is the subject of DE-A 197 16 066, the disclosure of which is hereby incorporated by reference in its entirety. The device described therein is moved parallel to its longitudinal edge during use, which is not optimal from an ergonomic point of view. It evaluates the received data for the measuring field recognition using the computer available in the detector. This requires the use of an extremely efficient small computer in the measuring device because of the high measuring speed. This concept can not be used in a low cost device.
It is an object of the present invention to improve a measuring apparatus of this type such that the constructive and conceptional prerequisites are created for a portable measuring device which is extremely affordable to produce and with which all necessary measurements for a complete color management process can be carried out in an efficient and precise manner. The measuring apparatus can perform approximately 100 measurements per second in a continuous measuring mode which allows for the automatic recording of several color fields through a manual pass across the color fields using the detector of the apparatus. In addition to its capability of being produced in an affordable manner, the measuring apparatus can be designed in a small and manageable manner, can be user friendly and not require maintenance, and thus can be generally available to a wide range of users.
SUMMARY OF THE INVENTION
In accordance with an embodiment of the invention the bidirectional interface is designed as a USB interface or fire wire interface wh
Ehbets Peter
von Orelli Adrian
Cummings & Lockwood
Gretag-Macbeth AG
Mathews Alan A.
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