Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1998-06-12
2002-01-22
Frech, Karl D. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462010
Reexamination Certificate
active
06340114
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to imaging, aiming and target illumination in optical code reading devices. Aspects of the invention are particularly useful in solid state, area image sensor based, handheld code readers which are positioned at variable orientations and distances with respect to a target code.
BACKGROUND OF THE INVENTION AND OBJECTS
Optical codes are patterns made up of image areas having different light reflective or light emissive properties, which are typically assembled in accordance with a priori rules. The term “barcode” is sometimes used to describe certain kinds of optical codes. The optical properties and patterns of optical codes are selected to distinguish them in appearance from the background environments in which they are used. Devices for identifying or extracting data from optical codes are sometimes referred to as “optical code readers” of which barcode scanners are one type. Optical code readers are used in both fixed or portable installations in many diverse environments such as in stores for check-out services, in manufacturing locations for work flow and inventory control and in transport vehicles for tracking package handling. The optical code can be used as a rapid, generalized means of data entry, for example, by reading a target barcode from a printed listing of many barcodes. In some uses, the optical code reader is connected to a portable data processing device or a data collection and transmission device. Frequently, the optical code reader includes a handheld sensor which is manually directed at a target code.
Most conventional optical scanning systems are designed to read one-dimensional barcode symbols. The barcode is a pattern of variable-width rectangular bars separated by fixed or variable width spaces. The bars and spaces have different light reflecting characteristics. One example of a one dimensional barcode is the UPC/EAN code used to identify, for example, product inventory. An example of a two-dimensional or stacked barcode is the PDF417 barcode. A description of PDF417 barcode and techniques for decoding it are disclosed in U.S. Pat. No. 5,635,697 to Shellhammer et al., and assigned to Symbol Technologies, Inc., which is incorporated herein by reference. Another conventional optical code is known as “MaxiCode”. It consists of a central finder pattern or bull's eye center and a grid of hexagons surrounding the central finder. It should be noted that the aspects of the inventions disclosed in this patent application are applicable to optical code readers, in general, without regard to the particular type of optical codes which they are adapted to read. The invention described may also be applicable to some associated image recognition or analysis.
Most conventional scanning systems generate one or more beams of laser light which reflects off a barcode symbol and back to the scanning system. The system obtains a continuous analog waveform corresponding to the light reflected by the code along one or more scan lines of the system. The system then decodes the waveform to extract information from the barcode. A system of this general type is disclosed, for example, in U.S. Pat. No. 4,251,798, assigned to Symbol Technologies, Inc. A beam scanning system for detecting and decoding one and two dimensional barcodes is disclosed in U.S. Pat. No. 5,561,283, also assigned to Symbol Technologies, Inc.
Barcodes can also be read employing imaging devices. For example an image sensor may be employed which has a two dimensional array of cells or photo sensors which correspond to image elements or pixels in a field of view of the device. Such an image sensor may be a two dimensional or area charge coupled device (CCD) and associated circuits for producing electronic signals corresponding to a two-dimensional array of pixel information for a field of view.
Many scanners in use today employ a scanning laser beam. Some such systems are deployed in handheld units which may be manually pointed at the target. Often an individual scanner is a component of a much larger system including other scanners, computers, cabling, data terminals, etc. Such systems are frequently designed and constructed on the basis of mechanical and optical specifications for the scanning engine, sometimes called “form factors”. One such form factor is the SE 1200 form factor employed by Symbol Technologies, Inc.
It is an object of the present invention to provide a compact imaging engine which can be substituted for conventional laser line scanning engines in currently designed and currently deployed optical code reader systems.
It is another object of the present invention to provide an imaging engine which can be substituted for SE1200 form factor scanning engines in currently designed and currently deployed optical code reading systems to increase the reliability, versatility and target working range of such systems.
It is known in the art to use a CCD photo detector and objective lens assembly in an optical code reader. In the past, such systems have employed complex objective lenses assemblies originally designed for use in relatively expensive video imaging systems. Such lens assemblies typically employ multiple, large diameter, aspheric lens elements. Use of aspheric lens elements and a CCD photo detector in a code reader is illustrated in U.S. Pat. No. 5,703,349. Aspheric lens systems are relatively costly and difficult to build. They also have a single sharp focus and a limited depth of field, which along with conventional aiming, illumination and signal processing and decoding algorithms, limits the versatility and working range of the system.
Applicants assignee, Symbol Technologies, Inc. has developed bi-stable high speed zone collection systems for barcode scanners. Systems which employed lens structures moveable into the input optical path of the scanner (drop-in optics) are disclosed in U.S. patent application Ser. Nos. 08/627,167 and 08/627,168 filed Apr. 3, 1996 to Li et al.
It is an object of the present invention to provide an easily constructed and inexpensive objective lens assembly for an imaging optical code reader.
It is another object of the present invention to provide an optical code reader which can be used to read codes at a wide range of distances.
It is another object of the present invention to provide an imaging optical code reader with selectable fields of view and working depths of view appropriate to the signal processing and decoding capabilities of the reader.
Various approaches have been proposed for aiming optical code readers. The simplest approach is to use the familiar red projected laser lines from a laser line scanner as an indication of the aim of the device. In passive, imaging systems, it has been proposed to project beams toward the target for aiming purposes. The device shown in U.S. Pat. No. 5,703,349 projects laser light from two targeting lens elements to form so called “hot spots” in the target area at an angle corresponding to the horizontal field of view of the system. An improved aiming system is disclosed in U.S. patent application Ser. No. 08/444,387 assigned to Symbol Technologies, Inc., the contents of which is incorporated herein by reference. This system employs a single laser diode and a diffractive optic element to produce multiple spots or beamlets for identifying corners or edges of a target area. This system uses different wavelength light for illumination and aiming, and appropriate optical filtering to eliminate the aiming pattern from the detected image.
It is an object of the present invention to provide an improved aiming system for an optical code reader.
It is another object of the present invention to provide a simply and inexpensively fabricated aiming system for an optical code imaging engine.
It is another object of the present invention to project an aiming pattern useable by the operator to aim the device and to provide data useful to the overall system.
It is another object of the present invention to provide an optical code reader which can use an aiming system to measur
Correa Mark
Gelles Rubin
He Duanfeng
Joseph Eugene
Li Yajun
Frech Karl D.
Symbol Technologies Inc.
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