Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1999-04-13
2002-10-01
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S472010
Reexamination Certificate
active
06457645
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to optical assemblies and, more particularly, to an optical assembly having an optical device and a lens wherein the optical device is spaced a distance from the optical axis of the lens.
BACKGROUND OF THE INVENTION
An optical assembly uses a lens to focus light associated with an optical device. The optical device may, as examples, be a light source or a photosensor. When the optical device is a light source, the optical assembly may serve as an illuminator in which the lens focuses light emitted by the light source onto an object. When the optical device is a photosensor, the optical assembly may serve is an imaging device in which the lens focuses light reflected from the object onto the photosensor to generate an image of an object. Optical assemblies may be used in a variety of applications, such as electronic scanners and bar code readers, to illuminate objects and to generate images of objects.
Bar codes are used in numerous applications to identify objects to which the bar codes are affixed. Examples of bar codes include the uniform price code used to identify retail goods and various forms of shipping labels used to track parcels. A bar code is an optical symbol containing coded information, in which the symbol is able to be imaged by an imaging device. The imaging device generates an image of the bar code and converts the image to machine-readable image data, referred to herein simply as “image data.” The image data is output to a processor, which deciphers the image data representing the bar code to “read” the bar code. Reading the bar code is the operation of deciphering the bar code to obtain the information encoded in the bar code. The information encoded in the bar code may, as an example, identify the object to which the bar code is affixed.
A bar code may, as an example, be a representation of a character set, e.g., ASCII characters represented by binary numbers. One type of bar code format that represents a binary number consists of an array of alternating reflective and nonreflective surfaces in which the transition from one surface to an adjacent surface represents the transition from one bit to another bit of a binary number. The alternating reflective and nonreflective surfaces may, for example, be alternating reflective and nonreflective stripes. The reflective stripes are sometimes referred to herein as spaces and the nonreflective stripes are sometimes referred to herein as bars. The bars may, as an example, be dark-colored stripes and the spaces may, as an example, be light-colored stripes. Each stripe, thus, represents one bit of the binary number. The stripes may, as an example, be either wide or narrow. A wide stripe may represent a one and a narrow stripe may represent a zero. The binary number represented by the bar code is, thus, defined by the widths of the alternating bars and spaces.
The array of alternating bars and spaces in the bar code format described above has numerous different specifications that may apply to the format. The specifications define the numbers of, and widths of, the bars and spaces used to represent the characters used in the format. These specifications also define the reflectivity of the bars and spaces for the various formats. Other bar code formats, may, as examples, comprise two-dimensional arrays of reflective and nonreflective areas or concentric reflective and nonreflective circles. All the bar codes, however, have reflective and nonreflective surfaces.
A bar code reader is a photoelectric device that is used to “read” bar codes. Reading a bar code is the process of analyzing the areas of high and low reflectivity to decipher the information encoded in the bar code. The bar code reader typically comprises an illuminator, an imaging device, and a processor. The illuminator serves to illuminate the bar code via an illumination beam of light. The illuminator may, for example, be a laser or an array of light-emitting diodes. An image beam of light constituting an image of the bar code reflects from the bar code. The imaging device receives the image beam and converts the image of the bar code to image data. The processor analyzes the image data to distinguish the image data representing the reflective spaces from the image data representing the nonreflective bars. Based on the analysis of the image data, the processor is able to decipher the information encoded in the bar code.
The imaging device uses a photosensor, such as a charge-coupled device, often referred to herein simply as a CCD, to convert the image beam to image data. A CCD typically consists of at least one linear array of photodetector elements, referred to herein simply as photodetectors, mounted to a substrate, or etched into a wafer, e.g., a silicon wafer used in semiconductor fabrication. A CCD may, as an example, comprise approximately 2,700 photodetectors in the array wherein the individual photodetectors have a width of approximately 11 microns, thus, making the array approximately three centimeters long and 11 microns wide. The high concentration of photodetectors in the array typically allows a single CCD to image a bar code as described above with enough precision to determine the widths of the reflective and nonreflective surfaces. The CCD typically images a very narrow “scan line” portion of the bar code wherein the scan line transverses the stripes comprising the bar code. The scan line is generally as narrow as the array of photodetectors, e.g., 11 microns.
The illuminator should uniformly illuminate the bar code; otherwise, the processor may be unable to distinguish the reflective areas from the nonreflective areas. For example, if one end of the bar code is more intensely illuminated than the other end of the bar code, the nonreflective areas in the intensely illuminated end may reflect more light than the reflective areas in the less intensely illuminated end of the bar code. The processor will likely be unable to read the bar code because it will not be able to distinguish the non reflective surfaces from the reflective surfaces.
Bar codes, as described above, are sometimes used in autochangers. An autochanger is a device that stores media pieces in a library and moves selected media pieces from the library to a media player when a user requests information stored on the selected media pieces. Likewise, when the user no longer requires the information on a selected media piece, the autochanger moves the media piece from the media player to a specific location in the library. The autochanger uses a media handling device, sometimes referred to herein as a picker, to move selected media pieces between the library and the media players. Bar codes may be affixed to the media pieces and may serve to identify contents of the media pieces. A bar code reader, as described above, may be affixed to the picker and may serve to read the bar codes affixed to the media pieces.
Two objectives in the design of an autochanger are to minimize human involvement required in the operation of the autochanger and to maximize the space available in the autochanger for media storage. Minimizing human involvement required in the operation of the autochanger may, in part, be achieved by the use of bar codes affixed to the media pieces as described above. The autochanger, rather than a human user, may read the bar codes to determine the contents of the media pieces and the locations of the media pieces within the autochanger. The user, thus, only needs to place the media pieces into the library. This minimizes human involvement in the operation of the autochanger and reduces the probability of errors in identifying the contents and locations of the media pieces.
Maximizing the space available for media storage within an autochanger may be achieved, in part, by reducing the amount movement required by the picker, minimizing the size of the components comprising the autochanger, and integrating the components comprising the autochanger into single packages. Reducing the picker movement increases the sp
Hewlett--Packard Company
Le Thien M.
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