Optics: measuring and testing – By shade or color
Reexamination Certificate
2000-05-15
2001-07-17
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By shade or color
C356S406000, C356S407000, C235S462450
Reexamination Certificate
active
06262804
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to color measurement instruments, and more particularly to handheld color measurement instruments.
II. Description of the Art
Color measurement instruments are capable of reading colors for the subsequent conversion of the colors to a mathematical representation. That representation can be processed using techniques known to those skilled in the art to perform color functions. Color measurement instruments include, by way of illustration and not limitation, spectrophotometers, calorimeters, densitometers, and spectroradiometers.
A handheld color measurement instrument is disclosed in U.S. Pat. No. 5,986,769 issued Nov. 16, 1999 to Krzyminski and entitled “Hand-Held Instrument for Reflection Measuring on Printed Sheets and Test Charts.” This instrument is used in reading “color bars” on printed sheets. While providing a certain level of convenience and accuracy, this scanner is not without its drawbacks. First, the instrument requires a handheld rule to guide the instrument along a linear path. Second, the instrument appears to include a single photodetector. Third, the space required by the encoder wheel limits the positioning of the support wheels.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome in the present invention wherein a handheld color measurement instrument is provided with improved functionality and ease of use. In all aspects of the invention, the instrument includes support rollers that guide movement of the instrument on a surface in a linear direction. The instrument includes a color measurement engine having an aperture opening through the bottom of the instrument. Consequently, the aperture scans along a line as the instrument is rolled over a surface such as a printed sheet.
In a first aspect of the invention, the instrument housing includes line-defining elements for defining a visual line that is parallel to the linear direction of travel and that is aligned with the scanning aperture. The elements can be one or more of wings on the housing, notches in the housing, or lights supported by the housing. The line-defining elements assist in aligning the instrument with a target for accurate scanning.
In a second aspect of the invention, the instrument is a densitometer including a blunt nose, and the scanning aperture is located proximate the nose. A plurality of photodetectors are arranged in an arcuate configuration about the scanning aperture. No photodetector is closer to the blunt nose than the scanning aperture. Consequently, the photodetectors do not interfere with placement of the aperture closely proximate the blunt nose of the instrument.
In a third aspect of the invention, rolling support elements and an encoder wheel are mounted in the bottom of the instrument. The support wheels are proximate the perimeter of the bottom of the instrument. By separating the rolling support elements from one another as much as possible (i.e. positioning them proximate the perimeter of the bottom), the tracking of the instrument is improved. The encoder wheel is positioned interiorly of the support elements, where room is available for the entire encoder assembly.
In a fourth aspect of the invention, the single color measurement engine within the instrument is capable of reading both bar codes and color bars or other targets. Consequently, the instrument can be used to read barcode information, for example, to configure the instrument. The instrument does not require a separate optical mechanism for reading the bar codes.
These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
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X-Rite DTP Series, Auto Scan Densitometer & Colorimeter RCI Manual, 1996.
Baker Douglas V.
Friend Timothy R.
Peterson Steven H.
Evans F. L.
Warner Norcross & Judd
X-Rite Incorporated
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