Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1998-09-11
2001-07-31
Lee, Michael G. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C348S314000
Reexamination Certificate
active
06267294
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to copending U.S. patent application Ser. No. (Symbology Imager System) and United States Application No. (Bar Code Illumination System) the entire disclosures of which are incorporated herein by reference. Further, International Application Serial No. WO 97/42756 filed on May 6, 1996, for a Smart Progressive-Scan Charge Coupled Device Camera, and which was filed by CIMatrix, one of the co-applicant's of the present application is also incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of operating a charge coupled device in an accelerated mode. More particularly, the present invention relates to a method of operating a charge coupled device in accelerated mode in conjunction with an optical symbology imager, as set forth in copending application Ser. No. 09/151,766 filed simultaneously with the present application, and incorporated herein by reference.
The charge coupled device is employed in an optical symbology imager for reading optical symbologies such as linear codes including traditional bar codes and 2D symbologies, such as Dot Matrix codes.
2. Description of the Prior Art
The use of bar codes has proliferated to the point where they are used in almost every industry to provide machine readable information about an item or product and to help track such items. Numerous different symbologies have been developed, such as one dimensional linear codes and 2D codes, such as Data Matrix. Typical linear codes comprise a series of parallel lines of varying thickness and spacing which are arranged in a linear configuration to represent a digital code containing information relating to the object. The use of bar codes has expanded due to the fact that the imaging and tracking process eliminates human error and can be performed quickly.
The amount of information a bar code can contain is dependent upon the size of the markings employed in the bar code, which determines the density of the code. Linear bar codes such as UPC codes, are only recorded in one dimension. On the other hand, 2D symbologies are encoded in two dimensions to contain greater information density.
In a typical reading process, a spot of light from a laser is projected and swept across the code, and the reflected light is sensed by a photosensitive element. In conventional imagers, lasers are used as the source illumination. Scanners may be either installed in a fixed location or portable hand-held units.
Hand-held scanners must be designed to operate in situations where the number of varying factors is greater than for fixed scanners. For instance, the distance between the scanner and the bar code, the amount of illumination, the focusing of the scanner, the orientation of the scanner relative to the bar code, and the angle of the scanner relative to the bar code are all factors which must be considered for the scanner to operate correctly. For instance, U.S. Pat. No. 5,296,690 to Chandler et al. discloses a system for locating and determining the orientation of bar codes in a two-dimensional image. The Chandler et al. patent is primarily concerned with making sure that the scan of the bar code is performed correctly with regard to the orientation of the scanner and the bar code.
Some hand-held scanning devices have a wand-like configuration where the device is intended to make contact with the code as it is swept across the code. Such a wand eliminates the variation in the distance between the scanner and the code and therefore requires no focusing.
Two-dimensional arrays such as CCD arrays have been used to create the image of the bar code as it is scanned, but traditionally a laser and a single photodiode are used for scanning a linear bar code. A CCD having dimensions of 640 by 480 pixels provides sufficient resolution for use with VGA monitors, and is widely accepted. The video image is sensed in the CCD, which generates an analog signal representing the variation in intensity of the image, and an analog to digital converter puts the image signal into digital form for subsequent decoding. Two dimensional sensors are used with spatially oriented 2D codes.
For a non-contact hand-held scanner, it is necessary to be able to read the bar code over a reasonable distance, to provide sufficient illumination, to focus the scanner onto the bar code, and perform the entire operation in a reasonable amount of time. While it may be possible to create an imager which can perform all of the desired functions, if the imager does not operate in a manner the user finds comfortable and sufficient, then the imager will not be accepted by end users and will not be commercially viable. For example, if the imager cannot perform the focusing quickly enough, then variations in the position of the scanner, due to the inability of the user to hold the imager steady, will create problems which cannot be easily overcome.
By way of example, if a scanner takes too long to perform a focusing function from the moment the user depresses a trigger, then the position of the scanner relative to the bar code may vary during the focusing operation thereby requiring yet another focusing operation. Similarly, such movement in the position of the scanner relative to the bar code will change the parameters for achieving the desired illumination.
Scanners which have been designed to read linear, or one dimensional, codes are, for the most part, incapable of scanning 2D symbologies. Linear and 2D symbologies may be provided on items by attaching a label to the item, putting the item in a container having a preprinted code, or by directly marking the product, such as by etching. Most conventional scanners may find it difficult to read symbologies which have been etched directly onto a product.
SUMMARY OF THE INVENTION
These and other deficiencies of the prior art are addressed by the present invention which is directed to a method of operating a CCD in an accelerated mode, and in particular in connection with an optical symbology imager, so as to minimize variations in the position of the imager relative to the code.
The CCD has two horizontal shift registers, each receiving every other scan line. The CCD is maintained in a reset mode when not imaging. The method of the present invention uses a total time to shift 500 vertical scan lines in a normal mode of 31.84 milliseconds, and a total time for fast mode of 5.5 milliseconds.
The method skips through multiple lines of image data, then provides a black reference signal, then shifts a series of lines at a slower speed, these lines being the liens of interest for focusing and illumination operations in the optical symbology imager. Finally, the remaining lines are passed through quickly.
The imager goes back into reset mode after either normal or fast mode operation, and is thereby immediately ready to perform another scan. The fast mode operation enables the imager to obtain the approximately ten lines of image data of concern in only 5.5 milliseconds, a significant time savings. This operation can be performed for some or all of the multiple optical positions.
It is an object of the present invention to provide a method of operating a charge coupled device in an accelerated mode.
Another object of the present invention is to provide a method of operating a charge coupled device in an accelerated mode for use in an optical symbology imager.
Yet another object of the present invention is to provide a method of operating a charge coupled device in an accelerated mode to facilitate focusing and illumination adjustment.
Still another object of the present invention is to provide a method of operating a charge coupled device in an accelerated mode to facilitate focusing and illumination adjustment, where only a few scan lines are provided at a normal speed, and the preceding and following data is passed through in an accelerated manner.
REFERENCES:
patent: 5157775 (1992-10-01), Sanger
patent: 5196939 (1993-03-01), Clabd et al.
patent: 5296690 (1994-03-01
Dowling John H.
Stern Howard
Hoffman Wasson & Gitler
Lee Diane I.
Lee Michael G.
Pollack Morris I.
Robotic Vision Systems Inc.
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