Image analysis – Image sensing
Reexamination Certificate
1998-07-22
2002-04-16
Couso, Jose L. (Department: 2621)
Image analysis
Image sensing
C250S226000
Reexamination Certificate
active
06373999
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to photoelectric imaging devices and, more particularly, to a photoelectric imaging device adapted to use an external light source to illuminate the object being imaged.
BACKGROUND OF THE INVENTION
Photoelectric imaging devices are well known in the art and produce machine-readable data representative of an object which is imaged, e.g., a page of printed text. One type of photoelectric imaging device is an optical scanning device. In an optical scanning device, an object is moved relative to the optical scanning device or visa versa as the optical scanning device generates data representative of the object. The data generated may be in the form of binary numbers and stored in a data storage device for processing. The following patents which describe optical scanners are hereby incorporated by reference for all that is disclosed therein: U.S. Pat. No. 5,552,597 of McConica for HAND-HELD SCANNER HAVING ADJUSTABLE LIGHT PATH; U.S. Pat. No. 5,646,394 of Steinle for IMAGING DEVICE WITH BEAM STEERING CAPABILITY; and U.S. Pat. No. 5,680,375 of Cristie et al. for ULTRAPORTABLE SCANNER.
Some photoelectric imaging devices employ line-focus systems, which image an object by sequentially focusing narrow “scan line” portions of the object onto a linear photosensor array. Examples of photoelectric imaging devices that use line-focus systems include optical scanning devices and facsimile machines. Scanning is performed by illuminating the object and focusing a line portion of the light reflected from the object onto the photosensor array. The narrow strip or line portion of the object which is imaged on the linear photosensor array is usually called a “scan line.” As the object is moved relative to the photoelectric imaging device, a plurality of scan line images are formed, which taken collectively, represent the object.
A photosensor array generally consists of a linear array of photodetector elements (or simply photodetectors), which correspond to small area locations on the scan line. These small area locations on the scan line are commonly referred to as “picture elements” or “pixels.” The corresponding photodetectors themselves are also sometimes referred to as pixels. In response to light from its corresponding pixel location on the scan line, each photodetector in the photosensor array produces a data signal which is representative of the light it experiences during an interval of time known as a sampling interval. The data signals from the photodetectors may be received and processed by an appropriate data processing system.
Monochrome optical scanners generate machine-readable data corresponding to a single monochrome image of the object being scanned. A monochrome scanner may, for example, generate a “black and white” image of a scanned object regardless of the actual colors contained in the object. In a color, or polychrome, optical scanner, machine-readable data is generated corresponding to a plurality of monochrome components (typically, red, green and blue) appearing in the object. Generally, the monochrome components are combined to arrive at a polychrome (color) image of the object.
Several methods for accomplishing color optical scanning are known in the art. One such method, known as a “multi-pass” scanning method, involves scanning the object several times. On the first “scanning pass”, monochrome scan line images of the object corresponding to a single color (e.g., red) are impinged onto a single linear photosensor array. On the second scanning pass, monochrome scan line images are acquired which correspond to a second color (e.g., blue). The process is then repeated until the desired number of monochrome images of the object has been acquired. Thereafter, a computer processor may be used to combine the individual monochrome images into a polychrome image of the object. In some multi-pass scanning devices, the light source may be manipulated to provide the desired color of monochrome light during each scanning pass in order to select the color of the monochrome image which is acquired during each pass. In other multi-pass scanning devices, a plurality of filters may be selectively placed between the object and the photosensor array in order to select the color during each pass.
Another method for accomplishing color optical scanning is known as a “single pass” scanning method. In single pass color scanning, a plurality of linear photosensor arrays (e.g., three) may be used. Each of the photosensor arrays receives light of a different color (e.g., red, green and blue). In this manner, all of the desired monochrome images of the object may be acquired in a single scanning pass. Each of the linear photosensor arrays may be provided with a filter to cause the desired color of light to be impinged on the array. Alternatively, an optical beam splitting device may be used to separate light from the object being scanned into a plurality of monochrome components. Examples of optical scanning devices using such beam splitting devices are disclosed in the following U.S. Pat. No. 5,410,347 of Steinle et al. for COLOR OPTICAL SCANNER WITH IMAGE REGISTRATION HOLING ASSEMBLY; U.S. Pat. No. 4,870,268 of Vincent et al. for COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS; U.S. Pat. No. 4,926,041 of Body for OPTICAL SCANNER (and corresponding EPO patent application no. 90306876.5 filed Jun. 22, 1990) U.S. Pat. No. 5,032,004 of Steinle for BEAM Splitter APPARATUS WITH ADJUSTABLE IMAGE FOCUS AND REGISTRATION (and corresponding EPO patent application no. 91304185.1 filed May 9, 1991); U.S. Pat. No. 5,044,727 of Steinle for BEAM Splitter/COMBINER APPARATUS (and corresponding EPO patent application no. 91303860.3 filed Apr. 29. 1991); U.S. Pat. No. 5,040,872 of Steinle for BEAM Splitter/COMBINER WITH PATH LENGTH COMPENSATOR (and corresponding EPO patent application no. 90124279.2 filed 12/14/90 which has been abandoned); and 5,227,620 of Elder, Jr. et al. for APPARATUS FOR ASSEMBLING COMPONENTS OF COLOR OPTICAL SCANNERS (and corresponding EPO patent application no. 91304403.8 filed May 16, 1991), which are all hereby incorporated by reference for all that is disclosed therein.
There are many types of photosensor devices known in the art. Two types of photosensor devices, however, are commonly used in optical scanning devices. These are the charged coupled device and the contact image sensor. A charged coupled device-type photosensor device is typically a single semiconductor chip with at least one linear array of photodetectors mounted to it. The semiconductor chip is typically much smaller than a desired scan line, so the image of the object must be focused onto the charged coupled device. For this reason, optical scanners using charged coupled devices typically require an extended focal length between the object being imaged and the charged coupled device.
A contact image sensor-type photosensor device is typically a linear arrangement of linear optical arrays. Each linear optical array has at least one linear array of photodetectors mounted to it. One example of a commercially available linear optical array used in a contact image sensor-type photosensor device is available from Texas Instruments, Inc. of Austin, Tex. and sold as model number TSL2301. The linear optical arrays are in close proximity to a lens, which in turn is in close proximity to the object being scanned. The lens typically has a reduction ratio of 1:1. An example of such a lens is the SELFOC lens manufactured by Mirco Optics Company, Limited, a subsidiary of the Nippon Sheet Glass, Limited. SELFOC is a registered trademark of Nippon Sheet Glass, Limited.
The lens receives light reflected from the object and focuses a scan line of the object onto the array of photodetectors. The photodetectors, in turn, output electrical data corresponding to the light they receive. The data from the photodetectors may be processed by a computer as is known in the art. Due to the 1:1 lens ratio, the length of a contact image sensor array of photodetectors may be substantiall
Couso Jose L.
Dang Duy M.
Hewlett--Packard Company
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