Patent Publication Number: US-8967474-B2

Title: Tunnel or portal scanner and method of scanning for automated checkout

Description:
RELATED APPLICATION DATA 
     This application is a continuation of U.S. application Ser. No. 13/357,356 filed Jan. 24, 2012, U.S. Pat. No. 8,716,561 which claims priority to U.S. provisional application No. 61/435,777 filed Jan. 24, 2011, hereby incorporated by reference. 
    
    
     BACKGROUND 
     The field of the present disclosure relates to systems and methods for item checkout and in certain aspects to retail checkstands or other checkout stands (e.g., a parcel distribution station) that incorporate data readers and other electronic devices. The field of the present disclosure further relates generally to data reading devices, and more particularly to automated devices by which items are conveyed, typically on a conveyor, through a read zone of the data reader by which the items are identified such as, for example, by reading optical codes or RFID (radio frequency identification) tags on the items. 
     Data reading devices are used to obtain data from optical codes or electronic tags (e.g., RFID tags), or use image recognition to identify an item. One common data reader device is an RFID reader. Another common data reader device is an optical code reader. Optical codes typically comprise a pattern of dark elements and light spaces. There are various types of optical codes, including linear or 1-D (one-dimensional) codes such as UPC and EAN/JAN barcodes, 2-D (two-dimensional codes) such as MaxiCode codes, or stacked codes such as PDF 417 codes. For convenience, some embodiments may be described herein with reference to capture of 1-D barcodes, but the embodiments may also be useful for other optical codes and symbols or objects. 
     Various types of optical code readers, also known as scanners, such as manual readers, semi-automatic readers and automated readers, are available to acquire and decode the information encoded in optical codes. In a manual reader (e.g., a hand-held type reader, a fixed-position reader), a human operator positions an object relative to the reader to read the optical code associated with the object. In a semi-automatic reader, either checker-assisted or self-checkout, objects are moved usually one at a time by the user into or through the read zone of the reader and the reader then reads the optical code on the object. In an automated reader (e.g., a portal or tunnel scanner), an object is automatically positioned transported through the read zone via a conveyor) relative to the reader, with the reader automatically reading the optical code on the object. 
     One type of data reader is referred to as a flying spot scanner wherein an illumination beam is moved (i.e., scanned) across the barcode while a photodetector monitors the reflected or backscattered light. For example, the photodetector may generate a high voltage when a large amount of light scattered from the barcode impinges on the detector, as from a light space, and likewise may produce a low voltage when a small amount of light scattered from the barcode impinges on the photodetector, as from a dark bar. The illumination source in flying spot scanners is typically a coherent light source, such as a laser or laser diode, but may comprise a non-coherent light source such as a light emitting diode. A laser illumination source may offer advantages of higher intensity illumination which may allow barcodes to be read over a larger range of distances from the barcode scanner (large depth of field) and under a wider range of background illumination conditions. 
     Another type of data reader is an imaging reader that employs an imaging device or sensor array, such as a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) device. Imaging readers can be configured to read both 1-D and 2-D optical codes, as well as other types of optical codes or symbols and images of other items. When an imaging reader is used to read an optical code, an image of the optical code or portion thereof is focused onto a detector array. Though some imaging readers are capable of using ambient light illumination, an imaging reader typically utilizes a light source to illuminate the item being read to provide the required signal response in the imaging device. A camera is typically a combination of a lens and an imaging device/sensor array, but the terms imager and camera will be used somewhat interchangeably herein. 
     An imager-based reader utilizes a camera or imager to generate electronic image data, typically in digital form, of an optical code. The image data is then processed to find and decode the optical code. For example, virtual scan line techniques are known techniques for digitally processing an image containing an optical code by looking across an image along a plurality of lines, typically spaced apart and at various angles, somewhat similar to the scan pattern of a laser beam in a laser-based scanner. 
     Imager-based readers often can only form images from one perspective—usually that of a normal vector out of the face of the imager. Such imager-based readers therefore provide only a single point of view, which may limit the ability of the reader to recognize an optical code in certain circumstances. For example, because the scan or view volume of an imager in an imager-based reader is typically conical in shape, attempting to read a barcode or other image in close proximity to the scanning window (reading “on the window”) may be less effective than with a basket-type laser scanner. Also, when labels are oriented such that the illumination source is reflected directly into the imager, the imager may fail to read properly due to uniform reflection washing out the desired image entirely, or the imager may fail to read properly due to reflection from a textured specular surface washing out one or more elements. This effect may cause reading of shiny labels to be problematic at particular reflective angles. In addition, labels oriented at extreme acute angles relative to the imager may not be readable. Lastly, the label may be oriented on the opposite side of the package with respect to the camera view, causing the package to obstruct the camera from viewing the barcode. 
     Thus, better performance could result from taking images from multiple perspectives. A few imager-based readers that generate multiple perspectives are known. One such reader is disclosed in U.S. Pat. No. 7,398,927 which discloses an embodiment having two cameras to collect two images from two different perspectives for the purpose of mitigating specular reflection. U.S. Pat. No. 6,899,272 discloses one embodiment that utilizes two independent sensor arrays pointed in different orthogonal directions to collect image data from different sides of a package. Multiple-camera imager-based readers that employ spatially separated cameras require multiple circuit boards and/or mounting hardware and space for associated optical components which can increase the expense of the reader, complicate the physical design, and increase the size of the reader. Improved multi-camera systems are disclosed in U.S. Published Application Nos. US-2010-0163626, US US-2010-0163627, and US-2010-0163628. 
     The present inventors have, therefore, determined that it would be desirable to provide an improved imager-based reader and an improved tunnel or portal scanner system for automated checkout. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Understanding that drawings depict only certain preferred embodiments and are not therefore to be considered to be limiting in nature, the preferred embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is a front top isometric view of a checkout system including a tunnel or portal scanner according to a preferred embodiment, installed on a checkstand, as viewed from the upstream side of the conveyor. 
         FIG. 2  is a rear top isometric view of the tunnel scanner of  FIG. 1 . 
         FIG. 3  is a partially exploded isometric view of the scanner of  FIGS. 1-2 . 
         FIG. 4  is a front side isometric view of the scanner of  FIG. 1  showing image views from the right side legs. 
         FIG. 5  is a front side isometric view of the scanner of  FIG. 1  showing image views from the left side legs. 
         FIG. 6  is a top plan view of the scanner of  FIG. 1  showing image views from the left and right side legs. 
         FIG. 7  is a front side isometric view of the scanner of  FIG. 1  showing image views of the rear left side leg. 
         FIG. 8  front side elevation view of the scanner of  FIG. 1  showing image views of the rear left side leg. 
         FIG. 9  is a top plan view of the scanner of  FIG. 1  showing image views of the rear left side leg. 
         FIG. 10  is a diagrammatic front side isometric view of the optics set for forming the image views of the rear left side leg of  FIGS. 7-9 . 
         FIG. 11  is a detail of the optic set of  FIG. 10  illustrating the lower image view. 
         FIG. 12  is a detail of the optic set of  FIG. 10  illustrating the upper image view. 
         FIG. 13  is a right side elevation view of the optic set of  FIG. 11  illustrating the lower image view. 
         FIG. 14  is a right side elevation view of the optic set of  FIG. 12  illustrating the upper image view. 
         FIG. 15  is a top view of the optic set of  FIG. 11  illustrating the lower image view. 
         FIG. 16  is a top view of the optic set of  FIG. 12  illustrating the upper image view. 
         FIG. 17  is a front side isometric view of the scanner of  FIG. 1  showing image views from the rear arch top section. 
         FIG. 18  is a front side isometric view of the scanner of  FIG. 1  showing image views from the front arch top section. 
         FIG. 19  is a rear isometric view of the scanner of  FIG. 1  (with side legs and rear arch removed) showing image views from the front arch top section. 
         FIG. 20  is a front side elevation view showing the image views of the front arch top section of  FIG. 19 . 
         FIG. 21  is a left side diagrammatic view showing the optic set and image views of the front arch top section of  FIG. 19 . 
         FIG. 22  is a detailed view of the optic set of the front arch top section of  FIG. 21 . 
         FIG. 23  is a rear side isometric view of the scanner of  FIG. 1  showing image views from the bottom reader through the conveyor gap. 
         FIG. 24  is a diagrammatic isometric view of bottom reader of  FIG. 23  with the arch sections of the tunnel scanner removed. 
         FIG. 25  is a diagrammatic side view of the optic set of the bottom reader of  24 . 
         FIG. 26  is a detailed view of a portion of  FIG. 25 . 
         FIG. 27  is a diagrammatic front side isometric view of part of an optic set of the bottom reader. 
         FIG. 28  is a side view of the optic set of  FIG. 24 . 
         FIG. 29  is a rear side elevation view of part of the optic set of  FIG. 24 . 
         FIG. 30  is a top plan view of part of the optic set of  FIG. 24 . 
         FIG. 31  is a diagram of the imagers for the optic sets of the bottom reader. 
         FIG. 32  is an isometric view of an alternate tunnel or portal scanner. 
         FIG. 33  is a rear side elevation view of the rear arch section of the scanner of  FIG. 1  showing illumination sets in the left side leg and top section. 
         FIG. 34  is a right side elevation view of the scanner of  FIG. 1  showing illumination sets in the rear arch left side leg and rear arch top section. 
         FIG. 35  is a partial view, on an enlarged scale, of the top section of the rear arch section of  FIG. 33  showing details of top section illumination optics. 
         FIG. 36  is a right side view detail of  FIG. 35  illustrating details of the illumination set for the scanner of  FIG. 1  according to a preferred embodiment. 
         FIG. 37  is a rear side elevation view of the rear arch section of the scanner of  FIG. 1  illustrating a first group of illumination sets in the left side leg of the rear arch. 
         FIG. 38  is a right side elevation view of the first group of illumination sets in the rear arch left side leg of the scanner of  FIG. 1 . 
         FIG. 39  is a top plan view of the first group of illumination sets in the left side leg of the rear arch section. 
         FIG. 40  is a rear side elevation view of the rear arch section illustrating a second group of illumination sets in the left side leg of the rear arch section. 
         FIG. 41  is a right side elevation view of the second group of illumination sets in the rear arch left side leg. 
         FIG. 42  is a top plan view of the second group of illumination sets in the rear arch left side leg. 
         FIG. 43  is a diagram of the bottom reader illumination of the scanner of  FIG. 1  according to a preferred embodiment. 
         FIG. 44  is a schematic of an example processing system architecture for the scanner of  FIG. 1 . 
         FIG. 45  is a flow chart of a side scanner and top scanner decode processor algorithm according to an embodiment. 
         FIG. 46  is a flow chart of a bottom scanner decode processor algorithm according to an embodiment. 
         FIG. 47  is a flow chart of a light curtain processor algorithm according to an embodiment. 
         FIG. 48  is a flow chart of an interconnect processor algorithm according to an embodiment. 
         FIG. 49  is a flow chart of a correlation processor algorithm according to an embodiment. 
         FIG. 50  is an isometric view of a tunnel or portal scanner showing a vertical object sensor system of an object measurement system according to one embodiment. 
         FIG. 51  is a side elevation cross-sectional view of the vertical object sensor system of  FIG. 50 . 
         FIG. 52  is a vertical object sensor system of the object measurement system according to another embodiment. 
         FIG. 53  is an isometric view of a lateral object sensor system of the object measurement system according to one embodiment. 
         FIG. 54  is an isometric view of the lateral object sensor system according to or one embodiment. 
         FIG. 55  is a side elevation view of the lateral object sensor system of  FIG. 54 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     With reference to the above-listed drawings, this section describes particular embodiments and their detailed construction and operation. The embodiments described herein are set forth by way of illustration only and not limitation. It should be recognized in light of the teachings herein that there is a range of equivalents to the example embodiments described herein. Most notably, other embodiments are possible, variations can be made to the embodiments described herein, and there may be equivalents to the components, parts, or steps that make up the described embodiments. 
     For the sake of clarity and conciseness, certain aspects of components or steps of certain embodiments are presented without undue detail where such detail would be apparent to those skilled in the art in light of the teachings herein and/or where such detail would obfuscate an understanding of more pertinent aspects of the embodiments. 
     In some embodiments, an image field of an imager may be partitioned into two or more regions, each of which may be used to capture a separate view of the view volume. In addition to providing more views than imagers, such embodiments may enhance the effective view volume beyond the vim volume available to a single imager having a single point of view. 
       FIGS. 1-3  illustrate a scanner  100  installed at a checkstand  5  such as may be used at a high-volume retail establishment such as a grocery store or big-box store. The checkstand  5  includes a base or stand  7  with a conveyor configuration with a front end section  11  and a rear end section  12 . The conveyor section front end  11  has a feed-in or shelf portion  13  on which items may be laid prior to and in preparation for placing on the front conveyor section  15 . The items are transported to the scanner  100  and through the read volume or read region generally defined by the confines of the front and rear scanner arches  110 ,  120  and the surfaces of the conveyor sections  15 ,  16 . It is noted that there is a gap between the input or entry conveyor  15  and the exit conveyor  16  as will be described in more detail below. The input conveyor  15  may be described as on the upstream side of the scanner  100  and the exit conveyor  16  may be described as being on the downstream side of the scanner  100 . After passing through the scanner  100 , items are deposited by the exit conveyor  16  onto an optional roller or bagging area  17  where they are boxed, bagged or loaded onto a cart for removal by the customer. The lower section of the stand  7  is shown with a bottom of basket (BOB) detector  9  that detects items on the bottom shelf of a grocery basket. Such detection may be used to alert the customer and/or store personnel or to otherwise process items that are either large or bulky or potentially forgotten and left on the bottom shelf of the grocery basket/cart. 
     For general purposes of discussion, an item  20  (typically bearing a barcode to be scanned) is represented by a rectangular shaped six-sided polyhedron, such as a cereal box (hereinafter referred to as a box-shaped item or object) that may be passed through a read region of a data reader, such as for example the data reader  100  installed in a checkout stand  5  at a retail store (e.g., a supermarket). As to the description of the following embodiments, it should be understood that certain capabilities of the data reader  100  will be described with respect to reading sides of the box-shaped object  20  and that a checkout stand and conveyor described is an example transport structure for the checkstand discussed herein and should not be considered as limiting. The transport systems are generally described with respect to belt-type conveyor, but other conveyor/transport systems may be employed such as: inclined slides, vibratory conveyors, roller conveyors, turntables, blower systems (the items driven along a surface via a blower), combinations thereof, or other suitable transport systems. 
     For convenience of description, referring to  FIG. 1 , this box-shaped object  20  may be described with respect to its direction of travel  22  relative to the ability of the data reader  100  to read certain of the sides of the box-shaped object  20  being passed (as moved by the conveyors  15 ,  16 ) through the read volume defined by the front and rear scanner arches  110 ,  120  and the surfaces of the conveyors  15 ,  16 . Referring to the orientation as illustrated, the box-shaped object  20  may be described as having a top side  26 , a bottom side  28 , and four lateral sides  30 ,  32 ,  34 , and  36 . The lateral sides may be referred to as the leading (or front lateral) side  30  (the side leading the object as it is passed through the read region), the trailing (or rear lateral) side  32  (the trailing side of the object as it is passed through the read region), the checker (or left lateral) side  34  (due to its proximity to a checkout clerk  38 ), and the customer (or right lateral) side  36  (due to its proximity to a customer  40 ). Since a use of this tunnel or portal scanner, in a preferred application, is to enable self-checkout, no checkout clerk may be required and the customer or user/operator may operate the scanner  100  from either side. The arbitrary side definitions are merely given to provide a frame of reference to facilitate written description. For example, the right and left sides shall be used with reference to the box  20 . The customer side  36  or right lateral side may alternatively be described as a side oriented generally vertically facing the customer  40 . The checker side  34  or left lateral side may alternatively be described as the side facing opposite the customer side  36 . The front and rear lateral sides may be described as being disposed to one side of the arch legs in a direction perpendicular to the item direction  22 . 
     The scanner  100  includes a front arch section  110  and a rear arch section  120 . Though there may be some differences in the internal optical components housed within the arch sections, the external arch sections are preferably identical configurations. As shown in  FIG. 3 , the arch sections  110  and  120  are preferably attached to an understructure  135  for mounting to the counter section  10 . Further as shown in  FIG. 3 , the under conveyor optics, as will be described in more detail below, are housed in a sliding drawer section  130  that slides out from the checkstand base  7  and is slidably mounted to the chassis section  135  on rails  137 . Thus, all the optics, namely the optics in front arch section  110 , rear arch section  120 , and drawer section  130  are mounted and thus aligned on a common chassis  135 . Front arch section  110  includes the right leg or post section  112  and the left leg or post section  114  such that when installed/assembled on the chassis  135  extend upward and diagonally forward or upstream relative to the conveyor with a front arch top section or cross arm  116  spanning between the arch leg sections  112 ,  114 , thus forming an inverted U-shaped structure. The front arch top section  116  includes an enlarged or extension portion  118  to provide for enlarged interior space accommodating internal optics within the enlarged volume. The front arch sections  112 ,  114 ,  116  are essentially hollow for accommodating optics and other components. Similarly, the rear arch section  120  comprises an inverted U-shaped housing structure including a rear arch first leg section  122 , a rear arch second leg section  124  and a rear arch top section or cross arm  126  spanning therebetween. The front arch section  110  and the rear arch section  120  are positioned back-to-back with the front arch section  110  being slanted forward and the rear arch section  120  being slanted rearward. 
     Advantageously over prior designs of a large rectangular enclosed box-shaped tunnel, the arch sections  110 ,  120  may be disassembled and stacked in a more compact package thus saying on shipping, staging and storage costs. 
     When assembled, the arch sections  110 ,  120  together form somewhat of a V or Y shape as shown in  FIGS. 1-2  when viewed from the lateral side (e.g., from the vantage of the customer  40  or the checkout clerk  38 ) and thus produces an open and airy architecture that is more inviting and much less bulky than a large enclosed tunnel structure. The open architecture structure or configuration also provides sight lines for the customer to see customer&#39;s items passing through the read region. Nonetheless, access to items passing through the read region is still inhibited by the general structure thereby enhancing security. This V or Y-shaped structure with the dual arches produces this open architecture tunnel scanner, and at most may be described as semi-enclosed in contrast to an enclosed structure more akin to the airport carry-on luggage security checkpoint scanners. 
     Although the arch sections  110 ,  120  are illustrated as including an open space between them, the arch sections  110 ,  120  may be embodied in an elongated tunnel formed over or around the conveyors  15 / 16 . The portal data reader  100  may thus be partially open and partially enclosed, such as the example illustrated in  FIG. 1 , or fully enclosed such as via a tunnel enclosure. The configuration of the dual arches  110 ,  120  creates an open architecture that provides some barrier/inhibition from a customer reaching into the read zone and yet provides sight lines for allowing the customer to generally continuously observe items passing through the arches. A suitable portal scanner may be constructed with more or less openness than the one illustrated. Additionally, a suitable portal scanner may be constructed, for example, with a single arch that has similar functionality to the dual arch design described herein. 
     Though in the present descriptions the tunnel or portal scanner  100  may be described in greater detail as an optical code reader, the scanner  100  may alternately comprise an RFID reader, an image recognition reader, an optical code reader, or combinations thereof. 
     Internal read optics will now be described in more detail. As previously mentioned, internal read optics are disposed within (1) the arch leg sections  112 ,  114 ,  122 ,  124 , (2) the upper arch sections  116 ,  126 , and (3) the drawer section  130  forming in combination an open dual-arch structure which will nonetheless be referred to as a tunnel scanner. Though the detailed example configuration of the tunnel/portal scanner will be described as an imaging system comprised of fourteen cameras with each camera having multiple views, other reading system combinations may be employed including other imaging configurations, laser reading systems, combinations thereof, or even including RFID readers. 
     The reading function from the arch leg sections will be described first with respect to  FIGS. 4-12 . Turning to  FIG. 4 , an optic set  150 , including a camera and mirrors, is disposed within the first leg section  112  of the front arch  110 , producing an upper view segment or image path  152  and a lower view segment or image path  154  into the read region. The view segments  152 ,  154  are aimed or directed inwardly, upwardly and rearwardly into the read region for obtaining two-dimensional images of view of customer side  36  and trailing side  32  of the item passing through the read region. Similarly, an optic set  160 , including a camera, is disposed in the second leg section  124  in the rear arch  120 , the camera and mirror set producing two fields of view into the read region, namely an upper view segment or image path  162  and a lower view section or image path  164 . The view segments  162 ,  164  are aimed or directed inwardly, upwardly and forwardly into the read region for obtaining two-dimensional images of view of customer side  36  and leading side  30  of the item passing through the read region. 
       FIG. 5  illustrates similar configurations for the camera optics in the second leg  114  of the front arch  110  and the first leg section  122  of the rear arch  120 . An optic set  170 , including a camera and mirrors, is disposed within the second leg section  114  of the front arch  110 , producing an upper view segment or image path  172  and a lower view segment or image path  174  into the read region. The view segments  172 ,  174  are aimed or directed inwardly, upwardly and rearwardly into the read region for obtaining two-dimensional images of view of checker side  34  and trailing side  32  of the item passing through the read region. Similarly, an optic set  180 , including a camera and mirrors, is disposed in the first leg section  122  in the rear arch  120 , the camera and mirror set producing two fields of view into the read region, namely an upper view segment or image path  182  and a lower view section or image path  184 . The view segments  182 ,  184  are aimed or directed inwardly, upwardly and forwardly into the read region for obtaining two-dimensional images of view of checker side  34  and leading side  30  of the item passing through the read region. 
       FIG. 6  is a diagram of a top view regarding the camera sections illustrated in  FIGS. 4 and 5  and their crossing nature through the read region. Specifically, optic set  150  within the first leg section  112  of the front arch  110 ; the optic set  170  in the second leg  114  of the front arch  110 ; the optic set  160  in the second leg section of the rear arch  120 ; and the optic set  180  in the first leg section of the rear arch  120 . 
     Details of the optic set and image view sections for the side leg sections will now be described with reference to optic set  180  in the first leg section  122  of the rear arch  120  and with respect to  FIGS. 7-16 . It should be understood that the description would be equally applicable to the other optic sets  150 ,  160 ,  170  adapted as needed to create image paths  152 ,  154 ,  162 ,  164 ,  172  and  174 . 
       FIG. 7  is essentially a simplified version of  FIG. 5  but showing only the optic set  180  in the first leg section of the rear arch  120 ,  FIG. 8  is a front side view of the optic set  180 , and  FIG. 9  is a top view of the optic set  180 . The optic set  180  (including a camera and mirror set) is disposed in the first leg section  122  in the rear arch  120 , the camera and mirror set producing two fields of view into the read region, an upper view segment or image path  182  and a lower view section or image path  184 . The view segments  182 ,  184  are aimed or directed inwardly, upwardly and forwardly into the read region for obtaining two-dimensional images of view of checker side  34  and leading side  30  of the item  20  passing through the read region. 
       FIG. 10  illustrates both the upper view segment  182  and the lower view segment  184  produced from the optics set  180 .  FIG. 11  illustrates details of the optic set  180  that produces the lower view segment  184 . Optic set  180  includes the camera along with the mirror sets. The camera comprises an imager  192  mounted on an image board (PCB)  190  and the focusing lens  194  for focusing the incoming image onto the imager  192 . 
     Both the upper and lower image segments  182 ,  184  are imaged by the same camera onto a common imager. In a preferred embodiment, the image segments  182 ,  184  are focused onto different regions of the image array. For purposes of description, each individual mirror component will be identified with a unique identifying numeral (e.g., mirror  208 ) however in parentheses after certain of these numerals a mirror designation will be at times provided in the form of M 1 , M 2 , M 3 , etc. to describe the mirror reflection order for that optical set. For a particular image acquisition sequence, the designation M 1  would be the first mirror closest to the imager reflecting the image directly to the imager or imaging lens, M 2  would be the second mirror which would direct the image to M 1 , third mirror M 3  would be the mirror which directs the image to second mirror M 2 , etc. Thus for an example five mirror system (M 1 -M 5 ), the image from the read region would be reflected first by the fifth mirror M 5 , which in turn reflects the image to fourth mirror M 4 , which in turn reflects the image to third mirror M 3 , which in turn reflects the image to second mirror M 2 , which in turn reflects the image to first mirror M 1 , which in turn reflects the image onto the imager. 
     Turning to  FIG. 11  (and using this M 1 , M 2 , M 3 , etc. naming convention), the image view segment  181  comprises the first view  181   a  which is reflected by mirror  208  (M 5 ) with image segment  184   b  then being reflected by mirror  206  (M 4 ) with image segment  184   c  then being reflected by mirror  204  (M 3 ) as image segment  184   d  which is in turn reflected by mirror  202  (M 2 ) from which view segment  184   e  is then reflected by mirror  200  (M 1 ) with image segment  184   f  then being focused by lens set  194  onto the imager  192 . The lens set  194  may include an aperture and one or more lens elements. 
     In similar fashion with respect to  FIG. 12 , the view segment  182  has a first image view segment  182   a  which reflects off mirror  208  (M 4 ). It is noted that mirror  208  producing the upper image view  182  is designated as M 4  whereas in  FIG. 11  for the lower view segment  184  mirror  208  is designated as mirror M 5  according to the convention. The image then reflects off of mirror  208  (M 4 ) with segment  182   b  then reflecting off of mirror  206  (M 3 ) with image segment  182   c  then being reflected off of mirror  210  (M 2 ) with image segment  182   d  then reflecting off of mirror  200  (M 1 ) which then reflects image segment  182   e  back to imaging lens  194  and onto (a region of) the imager  192 . 
       FIGS. 13 and 14  are respective side views of the side leg imagers of optic set  180  with  FIG. 13  illustrating the view path for image segment  184  and  FIG. 14  illustrating the view path for image segment  182 . The elements are the same as described in relation to  FIGS. 11-12 .  FIGS. 13-14  well illustrate the orientation of the first mirror  200 . It is noted here that the mirror  200  is a common mirror for both image views  182  and  184  with one side of the mirror  200  reflecting the image view  182  and the other side of the mirror  200  reflecting image view  184 . 
       FIGS. 15 and 16  are respective top views of the side leg optic set  180  with  FIG. 15  illustrating the lower view segment  184  and  FIG. 16  illustrating the upper view segment  182 . As shown in  FIGS. 15 and 13 , the image view segment  184  comprises the first image segment  184   a  which is reflected by mirror  208  (M 5 ) with image segment  184   b  then being reflected by mirror  206  (M 4 ) with image segment  184   c  then being reflected by mirror  204  (M 3 ) as image segment  184   d  which is in turn reflected by mirror  202 , (M 2 ) from which view segment  184   e  is then reflected by mirror  200  (M 1 ) with image segment  184   f  then being focused by lens  194  onto the imager  192  on image board  190 . As shown in  FIGS. 16 and 14 , the view segment  182  has a first image view segment  182   a  which reflects off mirror  208  (M 4 ) (it is noted that mirror  208  producing the upper image view  182  is designated as M 4  whereas in  FIG. 11  for the lower view segment  184  mirror  208  is designated as mirror M 5 ). The image then reflects off of mirror  208  (M 4 ), then with image segment  182   b  reflecting off of mirror  206  (M 3 ), then with image segment  182   c  being reflected off of mirror  210  (M 2 ), then with image segment  182   d  reflecting off of mirror  200  (M 1 ), which then reflects image segment  182   e  back to imaging lens and onto (another region of) the imager on image board  190 . It is noted in a preferred construction that the upper view segment  182  is focused onto a first region of the imager  192  and the lower view segment  184  is focused onto a second (different) region of the imager  192 . 
       FIGS. 17-22  illustrate optic sets and read regions for the top down reading sections out of the front arch top section  116  and the rear arch top section  126 . Specifically in  FIG. 17  the rear arch top section  126  includes optic sets  250 ,  260 ,  270 ,  280 . Each of these optic sets includes a camera and respective reflecting mirrors for producing an upper view segment or image path and a lower view segment or image path. Specifically optic set  250  produces an upper view segment  252  and a lower view segment  254  that project onto regions of a common imager of the camera. The views of the upper and lower view segments  252 ,  254  are directed downward from the rear arch  120  and forwardly for reading optical codes on the leading side  30  and top side  26  of the item  20  passing through the read region. Similarly, optic set  260  produces an upper view segment  262  and lower view segment  264 ; optic set  270  produces an upper view segment  272  and a lower view segment  274 ; and optic set  280  produces an upper view segment  282  and a lower view segment  284 . It is noted that these view segments, for example, view segments  252 ,  262 ,  272 ,  282  are arranged side by side and overlapping to (collectively) provide a continuous image view width-wise across the read region. It is noted that the upper view segments  252 ,  262 ,  272 ,  282  are at a more forwardly facing angle than the lower view segments  254 ,  264 ,  274 ,  284 . 
     In similar fashion, as shown in  FIGS. 18-20 , a set of four optic sets  300 ,  310 ,  320 ,  330  are disposed in the top arch section  116  of the front arch  110 . Specifically, the front arch top section  116  includes optic sets  300 ,  310 ,  320 ,  330 . Each of these optic sets includes a camera and respective reflecting mirrors for producing an upper view segment or image path and a lower view segment or image path. Specifically optic set  300  produces an upper view segment  302  and a lower view segment  304  that project onto regions of a common imager of the camera. The views of the upper and lower view segments  302 ,  304  are directed downward from the front arch  110  and rearwardly for reading optical codes on the trailing side  32  and top side  26  of the item  20  passing through the read region. Similarly, optic set  310  produces an upper view segment  312  and lower view segment  314 ; optic set  320  produces an upper view segment  322  and a lower view segment  324 ; and optic set  330  produces an upper view segment  332  and a lower view segment  334 . It is noted that these view segments, for example, view segments  302 ,  312 ,  322 ,  332  are arranged side by side and overlapping to (collectively) provide a continuous image view width-wise across the read region. It is noted that the upper view segments  302 ,  312 ,  322 ,  332  are at a more rearwardly facing angle than the lower view segments  304 ,  314 ,  324 ,  334 . 
     Details of the optic set and image view sections for each of the top arch sections  116 ,  126  will now be described with respect to optic set  330 , and with reference to  FIGS. 21-22 . It should be understood that the description would be equally applicable to the other optic sets  300 ,  310 ,  320  in the top section  116  of the front arch  110  as well as the optic sets  250 ,  260 ,  270 ,  280  in the rear arch top section  126 . 
       FIG. 21  is a diagrammatic view primarily for showing the general direction of the upper view segment  332  relative to the lower view segment  334 .  FIG. 22  is a diagrammatic view of the optic set  330  as shown in  FIG. 21  but on an enlarged scale with greater detail. Optic set  330  includes a camera comprised of au imager  342  mounted on an imager board  340  and a lens set  343  including an aperture for focusing an incoming image onto the imager  342 . The lower image view  334  includes the first image segment  334   a  which is reflected by a first mirror  344  (M 1 ) downwardly to the lens set  343  where the image is captured on a region of the imager  342 . Thus the image view  334  is produced by a single reflection. As visible in the diagrams of  FIGS. 21-22 , the image section  334   a  is on one side (the left side) of the mirror  344 . 
     The upper image view  332  is produced by a four mirror reflection sequence. The upper image view  332  includes a first image view segment  332   a  which is reflected by a first mirror  348  (M 4 ), with second view segment  332   b  then being reflected by second mirror  346  (M 3 ), with image segment  332   c  then reflected by third mirror  345  (M 2 ), with image view segment  332   d  then reflected by mirror  344  (M 1 ), with image segment  332   e  then focused by lens set  343  onto a region of imager  342 . The mirror  344  is a reflection mirror common to both the upper image view  332  and the lower image view  334 . The reflection portions of the mirror  344  for each of the respective image views may be separate, but alternately may be overlapping. It is noted in a preferred construction that the upper image view  332  is focused onto a first region of the imager  342  and the lower image view  334  is focused onto a second (different) region of the imager  342 . Alternately, the mirror  344  may be divided into separate mirrors, each of those separate mirrors providing the M 1  mirror function. A window  117  is optionally provided in the lower surface of the arch section  116  for permitting passage of the image views  332   a ,  334   a  into the interior of the arch section  116 . 
     The previously-described sets of cameras in the arch sections  110 ,  120  may be effective for collectively reading bar codes appearing on any of the upper five sides of the item  20  not obscured by the conveyor belt  15  (namely the top side  26 , leading side  30 , customer side  36 , trailing side  32  and checker side  34 . In order to provide the capability of reading bar codes on the bottom side  28 , a bottom scanner function is provided as will be illustrated with reference to  FIGS. 23-31 . Visible on several of the figures, a gap  50  is provided between adjacent ends of conveyor belts  15 ,  16 . The gap  50  permits an opening through which the bottom scanner  400  may scan to read the bottom side  28  of the item  20  as the item is passed over the gap  50 . In a preferred configuration, the bottom scanner  400  includes two cameras  410 ,  420 , situated side-by-side, each camera providing for half the length of the gap  50  between the side leg sections  112 ,  114 . As will be described, each camera  410 ,  420  is divided into four separate linear scan views for its imager to provide coverage over the entire length of the gap  50 . The length of the gap  50  corresponds to the width of the conveyor belts  15 ,  16  between the side leg sections  112 ,  114 . As shown in  FIGS. 25-26 , the gap  50  formed between the first conveyor  15  and second conveyor  16  may include a slide plate (or slide plates) helping to the bridge the transition over the gap  50 .  FIGS. 25-26  show a pair of slide plates  52   a ,  52   b  with a small opening  51  therebetween through which the various views from the cameras disposed below may pass.  FIG. 26  shows a gap  15   a  between slide plate  52  and conveyor belt  15  and gap  16   a  between slide plate  52   b  and conveyor belt  16 . Alternately the slide plates  52   a / 52   b  may comprise a single transparent plate, or a single plate with a central transparent region for permitting passage of the images from the scanner  400  below. The surface of conveyor  15  is at a height h 1  higher than the surface of the downstream conveyor  16 . This height or step may provide for more smooth movement of items across the gap  50 , particularly larger items that would pass over the gap  50  without touching the plates  52   a / 52   b . Details of the gap  50  and related components are further described in U.S. Application No. 61/435,744, filed on Jan. 24, 2011, hereby incorporated by reference. 
     As viewed in  FIG. 24 , the camera  410  includes an optic set which divides the view on its imager into four view sections namely two upwardly and rearwardly angled view sections  402 ,  404  passing through the left side of the gap  50  and upwardly and forwardly slanted view sections  406 ,  408  also spanning the left portion of the gap  50 . Similarly, the camera  420  has its view divided into four image segments with upwardly and forwardly directed views  412 ,  414  and upwardly and rearwardly directed views  416 ,  418 . 
     These view segments may alternately contain (a) a larger plurality of imager rows (e.g., up to 200 rows or some other suitable number depending on optics and imager size) to create a relatively narrow view, (b) a few imager rows (e.g., 2 to 10 rows), or (c) a single imager row to create a linear view. In a preferred configuration, each of the view segments is a relatively narrow, or nearly linear, scan through the gap  50 . Instead of generating what would be more of a two-dimensional view, a more linear read view plane may be generated through the gap  50  aimed such that the item being passed over the gap  50  is moved by the conveyors  15 ,  16  through the read plane. Considering an item  20  with a barcode on the bottom side  28 , the camera takes a first linear image. Then the object/item is moved a certain distance and the process is repeated (i.e., another linear image is acquired) generating a multitude of linear images combined together resulting in a 2-D raster image. At a given item velocity (as determined by the conveyor speed) and image view repetition rate, a given linear image spacing results, defining the resolution in this axis (along with the projected imager pixel size and the imaging lens blur spot size). At a given scan rate, the faster the item moves, the lower the resolution and the slower the item moves, the higher the resolution (until limited by the resolution due to the pixel size and the imaging lens blur function). Such a read mechanism is described in U.S. Published Application No. US-2006-0278708 hereby incorporated by reference. 
     Details of the optic set for camera  420  will now be described with particular reference to  FIGS. 25-31 . It should be understood that the description would be equally applicable in the optic set for camera  410 . Camera  420  includes an imager  424  mounted on an imager board  422  with a lens system  426  for focusing the image onto the imager  424 . The imager  424  comprises a two dimensional image array and accommodates multiple image fields in the single array as shown in  FIG. 31 . Specifically, the imager  424  has four image regions or zones  424   a ,  424   b ,  424   c , and  424   d . The image zones  424   a - 424   d  are separated by suitable gaps on the two dimensional image array  424 . The imager  411  of camera  410  is of similar configuration. 
       FIG. 27  illustrates one side of the bottom reader generating the image view  402  using the previously-described mirror order convention, the image view  412  includes a first view segment  412   a  which is reflected by first mirror  430  (M 4 ) directing second view segment  412   b  onto second mirror  432  (M 3 ), which directs third image segment  412   e  onto third mirror  434  (M 2 ), which then directs fourth view segment  412   d  onto fourth mirror  436  (M 1a ), which then reflects fifth view segment  412   e  to the camera  420  and imager  424  as focused by lens set  426 . The image view segment  412   e  as laid out on the image array would for example correspond to the imager zone section  424   b  of  FIG. 31 . 
       FIG. 28  is a side view of the optic set of  FIG. 24  also illustrating, the right side of the bottom reader generating the image view  413  using the previously-described mirror order convention in like mirror configuration as the image view  412  illustrated in  FIG. 27 . The image view  413  includes a first view segment  413   a  which is reflected by first mirror  440  directing second view segment  413   b  onto second mirror  442 , which directs third image segment  413   c  onto a third mirror, which then directs fourth view segment onto fourth mirror  446 , which then reflects fifth view segment  413   e  to the camera and imager  424  as focused by lens set  426 . The image view segment  413   e  as laid out on the image array would for example correspond to the imager zone section  424   b  of  FIG. 31 . 
       FIG. 32  illustrates an alternate tunnel scanner  1000 . The tunnel scanner arches  1010 ,  1020  of  FIG. 32 , spanning over the conveyor  1005  of the counter section  1007 , are shown with a greater angle and a larger opening in the central V shape structure. Such a design may provide for greater openness to the structure, particularly to the center of this alternate scanner  1000 . 
     The configurations for the arch sections  110 ,  120 , as described above, may provide sufficient height below the top cross-sections  116 ,  126  to accommodate items of varying height as well as sufficient width between the side leg sections  112 ,  114  to provide sufficient area to accommodate items of expected width and height. The leg sections  112 ,  114  of the housing for the tunnel scanner  100  may have curved or straight sections, or alternately angled as desired.  FIG. 32  illustrates an alternate tunnel scanner  500 . The tunnel scanner arches of  FIG. 32  are shown with a greater angle and a larger opening in the central V shape structure. Such a design may provide for greater openness to the structure, particularly to the center of this alternate scanner  500 . 
     As described above, the tunnel scanner  100  provides an arrangement of 14 cameras (six cameras in each arch section  110 ,  120  and two cameras in the bottom reader) with 32 unique images arranged out of the arches  110 ,  120  and up through the gap  50 . The relatively open architecture as formed by the back-to-back combination of separate arch sections  110 ,  120  permits ambient light to reach into the inner read region. Since these arch sections  110 ,  120  provide a relatively open and non-enclosed structure, this ambient light may be sufficient for illuminating the various other sides of the item  20  (other than potentially for the bottom side  28 ). Nonetheless, each image or view must have sufficient light to illuminate the barcode and allow imaging and decoding. Therefore it may be preferable to provide separate illumination. Such illumination should not have any direct internal reflections and should minimize specular reflections from products being scanned. Additionally, minimizing direct view of the lights by the user or customer is desirable. 
     The illumination is organized into three separate regions, namely, top arch regions, side regions, and below the conveyor bottom region that scans up through the gap  50 . These illumination regions will be separately described in following. 
       FIGS. 33-42  illustrate the various illumination sets disposed about the tunnel scanner housing.  FIG. 33  is a rear side elevation view and  FIG. 34  is a diagrammatic cross-sectional side view of  FIG. 33 , these two figures illustrating illumination sets in the rear arch top section  126  and the rear arch first (left) leg section  122 . Though only the illumination sets in the rear arch top section  126  and the rear arch first leg section  122  are described, the illumination sets from the opposing leg sections and from the front arch top section  116  are of like configuration and thus their descriptions are omitted for brevity. There are five illumination sets or modules  500 ,  510 ,  520 ,  530 ,  540  arranged across the rear arch top section  126  (as shown in  FIGS. 33-36 ). Each of the illumination modules includes three light emitting diodes (LEDs). As shown in the cross-sectional views of  FIGS. 34 and 36 , as an example, illumination module  540  includes three LEDs  542 ,  544 ,  546 , which in combination provide an overlapping illumination in a forwardly (upstream) and downwardly direction. The illumination set  540  is adjacent to the optic set  280  and provides in combination with the illumination set  530  on the opposite side of the optic set  280  a relatively diffuse and complete illumination for the image views  282 ,  284  from optic set  280 . 
     Similarly, illumination sets  530  and  520  are disposed on opposite sides of optic set  270  for providing illumination for image views  272 ,  274 ; illumination sets  520 ,  510  on opposite sides of optic set  260  provide illumination for image views  262 ,  264 ; and illumination sets  510 ,  500  on opposite sides of optic set  250  provide illumination for image views  252 ,  254 . It is noted that for simplicity that optics sets  250 ,  260 ,  270  are not shown in  FIG. 33  and imaging optic sets  250  and  260  are not shown in  FIG. 35 , but the positioning of these optics sets would be understood with reference to prior figures (e.g.,  FIG. 17 ). As previously mentioned, the optic modules  500 ,  510 ,  520 ,  530 ,  540  provide primary illumination for the top side  26  as well as some illumination for the leading side  30  of the item  20 . 
       FIG. 36  is a diagrammatic cross-section (on an enlarged scale) of the rear arch top section  126  with the illumination set  540  comprised of the LEDs  542 ,  544 ,  546 . LED  542  generates an illumination region or cone  543 ; LED  544  produces an illumination region or cone  545 ; and LED  546  produces an illumination region or cone  547 .  FIG. 36  also illustrates the position of the illumination regions relative to the image views of the optic set  280 .  FIGS. 33-34  also illustrate the illumination from the side leg section  122 . The upper illumination portion of the side leg section  122  includes illumination sets  550 ,  560 ,  570 ,  580  which as shown in  FIGS. 33-34  and  37 - 42  project downwardly and laterally across the opening underneath the arch  126 ; and as best shown in  FIG. 38  the illumination is directed forwardly from the rear arch  120 . Such inward and forward illumination direction is effective for illuminating the customer side  36  and the leading side  30  and to some degree the top side  26  of the item  20  passing through the read region depending upon the item&#39;s particular location and dimensions. 
       FIGS. 37-39  illustrate a first group of illumination sets and relative directional angles of the illumination cones with illumination set  550  having illumination cone  552 ; illumination set  560  having illumination cone  562 ; illumination set  570  having illumination cone  572 ; and illumination set  580  having illumination cone  582 . It would be noted that these cones are merely representations of illumination light direction as produced by the dual LED source of any particular illumination set. Each illumination set may be provided with a diffuser or focusing optics in order to diffuse or otherwise focus light generated as desired. These cones in the drawings are merely representations of light emitted from the respective LED sets and are not intended to be precise representations of light beams but are provided to illustrate general light aiming direction and alignment relative to the view images from the cameras as previously described. 
       FIGS. 40-42  show the second group of illumination sets  600 ,  610 ,  620 ,  630  disposed in the side leg  122 . The direction of the light from the second group of LED sets  600 ,  610 ,  620 ,  630  is directed at a steeper downward angle than that of the first group of illumination sets  550 ,  560 ,  570 ,  580 . In similar fashion, as previously described, illumination set  600  includes two LEDs producing the downwardly directed illumination cone  602 ; illumination set  610  produces downward illumination cone  612 ; illumination set  620  produces downward illumination cone  622 ; and illumination set  630  produces downward illumination cone  632 . As shown in  FIGS. 41-42 , the illumination regions are formed in a somewhat adjacent and overlapping arrangement so as to provide a desired broad illumination pattern within the region. These illumination patterns  602 ,  612 ,  622 ,  632  are effective for illuminating a top side  26 , leading side  30  and customer side  36  of an item  20  being passed through the read region. 
     This combination of illumination sources provides a full illumination across the entirety of the width of the conveyor  15 / 16 . Illumination from the top arch sections  116 ,  126  is angled downwardly to concentrate at a far end of the field of view. As for the side illumination, all of the LEDs and lenses are placed outside the view of any direct window reflection. Having the illumination direction of the LEDs generally downward also helps avoid a specular reflection off shiny surfaces (such as a soft drink can) and makes the direction of illumination lower than a typical adult eye level of a person standing to the side of the tunnel scanner  100  at the customer side, thus the likelihood of direct viewing of illumination by the customer is minimized. Furthermore, the illumination is generally aimed to the opposite side arm, thus blocking direct view of the illumination from a human viewer. 
     The illumination LEDs are preferably pulsed and synchronized to a common timing signal. Such synchronization minimizes motion blur and flicker. The illumination frequency is preferably greater than 60 Hz (or more preferably on the order of 90 Hz) to avoid human flicker perception. The LEDs in the arch sections  110 ,  120  are preferably full spectrum or white light LEDs configured to illuminate the scan volume with multiple wavelengths of light within a wavelength band of approximately (for example) 380 nm to approximately 750 nm. Using white light allows the scanner illumination to also provide light for exception and security cameras, if provided, and may provide a more pleasing natural looking illumination, which may in turn improve device aesthetics. 
     Bottom illumination is provided from a set of two LEDs and an array of cylinder lenses.  FIG. 43  illustrates an example bottom illumination for one of the image planes  402  produced for each image plane by mirrors  430 ,  432 ,  434 ,  436  focused by lens  426  into imager  424  (see further details of the imager in  FIG. 27 ). Two illumination planes  704 ,  710  are produced on opposite sides of the image plane  402  to provide illumination generally coextensive with the image plane  402   b . A first set or row of LEDs  700  generates a diffuse plane of light that is focused by cylinder lens  702  to form illumination plane  704  and a second row of LEDs  706  generates a diffuse plane of light that is focused by cylinder lens  708  to form illumination plane  710 . A symmetric pair of LED sets and cylinder lenses illuminate each of image views  404 ,  406 ,  408 ,  412 ,  414 ,  416 ,  418 . The bottom illumination does not contribute to exception imaging and thus can be of any color. Red LEDs may be preferred, because of their increased efficiency and lower apparent brightness to human observers, but other suitable colors such as white LEDs may be provided. The cylinder lens array provides two planes of illumination for each side of a gap in the conveyer. The second illumination line is aligned with the imager view approximately 50 mm above the conveyor belt. Two illumination planes are used to maximize the reading depth of field allowing for the fact that illumination cannot readily be placed precisely on axis with the imager. 
     Though particular quantity of LEDs is illustrated and described for each of the illumination sets (e.g., illumination set  540  has 3 LEDs; illumination set  550  has two LEDs), each of these illumination sets may comprise one or more LEDs depending upon the desired intensity or other pertinent design considerations. 
     Though the size and specifications of the imagers may depend on the particular design, a preferred imager is a 1.3 megapixel CMOS imager with a resolution of 1280×1024 pixels. One preferred megapixel imager is the model EV76C560 1.3MP CMOS image sensor available from e2V of Essex, England and Saint-Egreve, France. This imager may be applicable to the data reader of any of the embodiments herein, however, any other suitable types of imager of various resolutions may be employed. 
     The image field of the imagers need not be square or rectangular and may, for example, be circular or have a profile of any suitable geometric shape. Similarly, the image field regions need not be square or rectangular and may, for example, have one or more curved edges. The image field regions may have the same or different sizes. 
     The focusing lenses that are proximate to the respective imagers, as well as the path lengths of the respective image path segments may provide control for the depth of field for the respective image within the view volume. 
     The image captured by the image field may be processed as a single image, but preferably however, the image captured by each image field region may be processed independently. The images from the different perspectives of the object  20  may reach the image field regions with the object being in the same orientation or in different orientations. Furthermore, the same image of the object  20  from the different (e.g., mirror image) perspectives of the object  20  may reach the different image field regions or different images of the object  20  may reach the different image fields. The different image field regions may have the same photosensitivities or be receptive to different intensities or wavelengths of light. 
     The optics arrangements described above may contain additional optical components such as filters, lenses, or other optical components that may be optionally placed in some or all of the image paths. The mirror components may include optical components such as surface treatments designed to filter or pass certain light wavelengths. In some embodiments, the image reflected by each mirror component can be captured by the entire image field or read region when pulsed lighting and/or different wavelengths are used to separate the images obtained by the different perspectives. The image reflection mirrors preferably have planar reflecting surfaces. In some embodiments, however, one or more curved mirrors or focusing mirrors could be employed in one or more of the imaging paths provided that appropriate lenses or image manipulating software is employed. In some embodiments, one or more of the mirrors may be a dichroic mirror to provide for selective reflection of images under different wavelengths. 
     The mirrors may have quadrilateral profiles, but may have profiles of other polygons. In some preferred embodiments, one or more of the mirrors have trapezoidal profiles. In some alternative embodiments, one or more of the mirrors may have a circular or oval profile. The mirrors may have dimensions sufficient for their respective locations to propagate an image large enough to occupy an entire image field of a respective imager. The mirrors may also be positioned and have dimensions sufficiently small so that the mirrors do not occlude images being propagated along any of the other image paths. 
     In some embodiments, the imagers may all be supported by or integrated with a common PCB or positioned on opposing sides of the common PCB. In some embodiments, the common PCB may comprise a flexible circuit board with portions that can be selectively angled to orient some or all of the imagers to facilitate arrangements of image paths. 
     In one example, the imagers may be selected with a frame rate of 30 Hz and one or more of the light sources used to illuminate the read region are pulsed at 90 Hz. Examples of light source pulsing is described in U.S. Pat. No. 7,234,641, hereby incorporated by reference. 
     In addition to the variations and combinations previously presented, the various embodiments may advantageously employ lenses and light baffles, other arrangements, and/or image capture techniques disclosed in US. Pat. Pub. No. 2007/0297021, which is hereby incorporated by reference. 
     A fixed virtual scan line pattern may be used to decode images such as used in the Magellan-1000i model scanner made by Datalogic ADC, Inc. (previously known as Datalogic Scanning, Inc.) of Eugene, Oreg. In some embodiments, an alternative technique based on a vision library may be used with one or more of the imagers. 
     In order to reduce the amount of memory and processing required to decode linear and stacked barcodes, an adaptive virtual scan line (VSL) processing method may be employed. VSLs are linear subsets of the 2-D image, arranged at various angles and offsets. These virtual scan lines can be processed as a set of linear signals in a fashion conceptually similar to a flying spot laser scanner. The image can be deblurred with a one dimensional filter kernel instead of a full 2-D kernel, thereby reducing the processing requirements significantly. 
     The rotationally symmetric nature of the lens blurring function allows the linear deblurring process to occur without needing any pixels outside the virtual scan line boundaries. The virtual scan line is assumed to be crossing roughly orthogonal to the bars. The bars will absorb the blur spot modulation in the non-scanning axis, yielding a line spread function in the scanning axis. The resulting line spread function is identical regardless of virtual scan line orientation. However, because the pixel spacing varies depending on rotation (a 45 degree virtual scan line has a pixel spacing that is 1.4× larger than a horizontal or vertical scan line) the scaling of the deblurring equalizer needs to change with respect to angle. 
     If the imager acquires the image of a stacked barcode symbology, such as GSI DataBar (RSS) or PDF-417 code, the imaging device can start with an omnidirectional virtual scan line pattern (such as an omnidirectional pattern) and then determine which scan lines may be best aligned to the barcode. The pattern may then be adapted for the next or subsequent frame to more closely align with the orientation and position of the barcode such as the closely-spaced parallel line pattern. Thus the device can read highly truncated barcodes and stacked barcodes with a low amount of processing compared to a reader that processes the entire image in every frame. 
     Partial portions of an optical code (from multiple perspectives) may be combined to form a complete optical code by a process known as stitching. Though stitching may be described herein by way of example to a UPCA label, one of the most common types of optical code, it should be understood that stitching can be applied to other types of optical labels. The UPCA label has “guard bars” on the left and right side of the label and a center guard pattern in the middle. Each side has 6 digits encoded. It is possible to discern whether either the left half or the right half is being decoded. It is possible to decode the left half and the right half separately and then combine or stitch the decoded results together to create the complete label. It is also possible to stitch one side of the label from two pieces. In order to reduce errors, it is required that these partial scans include some overlap region. For example, denoting the end guard patterns as G and the center guard pattern as C and then encoding the UPCA label 012345678905, the label could be written as G012345C678905G. 
     Stitching left and right halves would entail reading G012345C and C678905G and putting that together to get the full label. Stitching a left half with a 2-digit overlap might entail reading G0123 and 2345C to make G012345C. One example virtual scan line decoding system may output pieces of labels that may be as short as a guard pattern and 4 digits. Using stitching rules, full labels can be assembled from pieces decoded from the same or subsequent images from the same camera or pieces decoded from images of multiple cameras. Further details of stitching and virtual line scan methods are described in U.S. Pat. Nos. 5,493,108 and 5,446,271, which are hereby incorporated by reference. 
     In some embodiments, a data reader includes an image sensor that is progressively exposed to capture an image on a rolling basis, such as a CMOS imager with a rolling shutter. The image sensor is used with a processor to detect and quantify ambient light intensity. Based on the intensity of the ambient light, the processor controls integration times for the rows of photodiodes of the CMOS imager. The processor may also coordinate when a light source is pulsed based on the intensity of the ambient light and the integration times for the photodiode rows. 
     Depending on the amount of ambient light and the integration times, the light source may be pulsed one or more times per frame to create stop-motion images of a moving target where the stop-motion images are suitable for processing to decode data represented by the moving target. Under bright ambient light conditions, for example, the processor may cause the rows to sequentially integrate with a relatively short integration time and without pulsing the light source, which creates a slanted image of a moving target. Under medium light conditions, for example, the rows may integrate sequentially and with an integration time similar to the integration time for bright ambient light, and the processor pulses the light source several times per frame to create a stop-motion image of a moving target with multiple shifts between portions of the image. The image portions created when the light pulses may overlie a blurrier, slanted image of the moving target. Under low light conditions, for example, the processor may cause the rows to sequentially integrate with a relatively long integration time and may pulse the light source once when all the rows are integrating during the same time period. The single pulse of light creates a stop-motion image of a moving target that may overlie a blurrier, slanted image of the moving target. 
     In some embodiments, a data imager contains multiple CMOS imagers and has multiple light sources. Different CMOS imagers “see” different light sources, in other words, the light from different light sources is detected by different CMOS imagers. Relatively synchronized images may be captured by the multiple CMOS imagers without synchronizing the CMOS imagers when the CMOS imagers operate at a relatively similar frame rate. For example, one CMOS imager is used as a master so that all of the light sources are pulsed when a number of rows of the master CMOS imager are integrating. 
     Another embodiment pulses a light source more than once per frame. Preferably, the light source is pulsed while a number of rows are integrating, and the number of integrating rows is less than the total number of rows in the CMOS imager. The result of dividing the total number of rows in the CMOS imager by the number of integrating rows is an integer in some embodiments. Alternatively, in other embodiments, the result of dividing the total number of rows in the CMOS imager by the number of integrating rows is not an integer. When the result of dividing the total number of rows in the CMOS by the number of integrating rows is an integer, image frames may be divided into the same sections for each frame. On the other hand, when the result of dividing the total number of rows in the CMOS by the number of integrating rows is not an integer, successive image frames are divided into different sections. 
     Other embodiments may use a mechanical shutter in place of a rolling shutter to capture stop-motion images of a moving target. The mechanical shutter may include a flexible member attached to a shutter that blocks light from impinging a CMOS or other suitable image sensor. The shutter may be attached to a bobbin that has an electrically conductive material wound around a spool portion of the bobbin, where the spool portion faces away from the shutter. The spool portion of the bobbin may be proximate one or more permanent magnets. When an electric current runs through the electrically conductive material wound around the spool, a magnetic field is created and interacts with the magnetic field from the one or more permanent magnets to move the shutter to a position that allows light to impinge a CMOS or other suitable image sensor. 
     These and other progressive imaging techniques are described in detail in U.S. Published Patent Application No. US-2010-0165160 entitled “SYSTEMS AND METHODS FOR IMAGING” hereby incorporated by reference. 
     The system of the tunnel/portal scanner  100  preferably includes an object measurement system and related software that uses dead reckoning to track the position of items through the read region. Details of the object measurement system are further described in U.S. Application No. 61/435,686 filed Jan. 24, 2011 and U.S. Application No. 61/505,935 filed Jul. 8, 2011, hereby incorporated by reference. The software of the object measurement system records the times an item passes a leading light curtain  805   a  (at the upstream end of the front arch  110 ), as shown in  FIGS. 50-52  and a trailing light curtain  805   b  (at the downstream end of the rear arch  120 ) or is detected by sensors (e.g., positioning sensors) and assumes a constant known velocity of the conveyors  15 ,  16 . In one embodiment, the leading and trailing light curtains  805   a ,  805   b  are formed by sensor elements  5010  positioned vertically along arch leg sections  112 ,  114 ,  122 ,  124 . When an item passes through the leading and trailing light curtains  805   a ,  805   b , certain ones of the sensor elements  5010  are blocked dependent on the height (H) of the item. Multiple reads of the sensor elements provide light curtain data corresponding to a vertical object sensor (VOS) profile that represents the height and longitudinal length (L) of the item. The object measurement system also includes one or more lateral object sensors  5300   a ,  5300   b  positioned under conveyors  15 ,  16  that view the item through gap  50  as shown in  FIGS. 53-55 . For example, lateral object sensor  5300   a  produces a rearward directed view  5310   a  and the lateral object sensor  5300   b  produces a forward directed view  5310   b . In one embodiment, lateral object sensors  5300   a ,  5300   b  correspond to the cameras  410 ,  420  of the bottom scanner  400 . In another embodiment, lateral object sensors  5300   a ,  5300   b  may have associated illuminators  711   a ,  711   b  and may be separate from the cameras  410 ,  420 . As the item passes over gap  50 , the lateral object sensor(s) (either sensor  5300   a  or sensor  5300   b  or both) measures the footprint (e.g., longitudinal length and lateral width) of the item to produce lateral object sensor data corresponding to a lateral object sensor (LOS) profile. The VOS profile and the LOS profile are combined by the object measurement system to produce model data representing a three-dimensional model of the item. 
     When an item is scanned and decoded, the model data (produced as described above) is combined with the timing and trajectory of the detected barcode to correlate barcode data with the three-dimensional model of the item at an estimated item position. The correlation allows the tunnel/portal scanner to differentiate between multiple reads of the same item, and distinguish identical labels on multiple items. Dead reckoning may also allow the software to determine the presence of multiple distinct labels on individual items (such as an overpack label for a multi-pack of items). 
     As described above, the tunnel scanner  100  employs a plurality of 14 cameras, with some of the cameras (the top and side cameras) each having two image views on its imager and other cameras (the bottom cameras) each having four image views on its imager.  FIG. 44  illustrates an exemplary system architecture  800  for the tunnel scanner  100 . Images from the cameras in each scanner are decoded and the decoded information (decode packets and lateral sensor packets (e.g., information from lateral object sensors  5300   a ,  5300   b )) is sent to the interconnect processor  810 . Light curtain information from the light curtains  805   a ,  805   b  (pertaining to the size and position of item being passed through the read region) is processed and the corresponding information (light curtain state packets) is also sent to the interconnect processor  810 . The interconnect processor  810  applies time stamps to the packets and sends the time stamped packet data to the correlation processor  812 . The correlation processor  812  generates object models (e.g., three-dimensional models of objects) from the light curtain and lateral sensor packets and correlates object data with the decode packets to determine which objects correspond to the decoded data. Successfully correlated barcode information as well as exception data is then transmitted to the POS host. Exception data corresponds to any number of events when the object models and decode packets indicate that an error may have occurred. Examples of exceptions include, but are not limited to: (a) more than one barcode is correlated with an object; and (2) no barcode is correlated with an object model; (3) a barcode is read but is not correlated with an object model. 
       FIG. 45  is a flow chart of a side scanner and top scanner decode processor algorithm  820  according to one embodiment, having the following steps: 
     Step  822 —configuring camera for triggered mode. 
     Step  824 —checking for synchronization signal from interconnect processor. 
     Step  826 —if synchronization signal is detected, (Yes) proceed to Step  828 ; if No, return to Step  824 . 
     Step  828 —capturing image (trigger the camera to capture an image). 
     Step  830 —reading out image from the imager into processor memory image buffer. 
     Step  832 —processing image to locate and decode barcodes in image buffer. The image may be processed using a suitable image processing algorithm. 
     Step  834 —determining whether a barcode was successfully decoded: if Yes, proceed to Step  836 , if No, return to Step  824  to process additional images. For each barcode found in image buffer, record the symbology type (UPC, Code 39, etc), decoded data, and coordinates of the bounding box corners that locate the decoded label in the image. 
     Step  836 —creating decode packet (with the recorded symbology type, decoded data and coordinates). 
     Step  838 —sending recorded data (decode packet) to the interconnect processor and then returning to Step  824  to process additional images. 
       FIG. 46  is a flow chart of a bottom scanner decode processor algorithm  840  according to an embodiment, having the following steps: 
     Step  842 —Configuring the camera to continuously capture images and read out 4 rows of data. In a preferred reading method, the frame rate of reading out frames of 4 rows each is 2.5 KHz (2500 frames/second). 
     Step  844 —Setting decode and lateral sensor counters to zero. 
     Step  846 —Setting L to equal the desired periodicity for creation of lateral sensor packets. In one example the value of L=20. 
     Step  848 —capturing image and reading out each of the 4 rows of data from the lager (imager  411  or  424 ) into a temporary buffer. 
     Step  850 —storing each row of data into one of four circular image buffers containing 2N rows to generate four separate linescan images in processor memory. 
     Step  852 —increment decode and lateral sensor counters. 
     Step  854 —Determining if decode counter=N: if Yes proceed to Step  856 ; if No proceed to Step  862 . N represents how tall the decode buffer is. In one example, N=512, which corresponds to about 2.5 inches of belt movement (e.g., belt speed of 12 inches/sec, divided by a line scan speed of 2500 Hz times N of 512 equals 2.5 inches). 
     Step  856 —Processing each of the 4 image buffers sequentially (using the image processing algorithm) to locate and decode barcodes. The image processing algorithm analyzes an image using horizontal and vertical scan lines to find start and/or stop patterns of an optical code. The algorithm then traverses the image roughly in the direction of the optical code (also moving in a transverse direction as necessary) to decode the digits of the optical code similar to an adaptive VSL algorithm. 
     Step  858 —creating a decode packet if the decode is successful. If the number of rows in the circular buffer is 2N, then for every N rows, an image of the previous 2N pixels is decoded as a frame. For each barcode found in image buffer, record the symbology type (UPC, Code 39, etc), decoded data, and coordinates of the bounding box corners that locate the decoded label in the image. The recorded symbology type, decoded data and coordinates constitute the decode packet. 
     Step  860 —setting decode counter to zero. The decode counter represents a variable that counts the number of rows that have been put into the circular buffer. 
     Step  862 —determining if lateral sensor counter=L: if Yes, proceed to Step  864 ; if No, proceed to Step  868 . L represents the number of rows to skip between outputting lateral sensor data. In one example, the resolution of the lateral object sensors  5300   a ,  5300   b  is about 5 mils (e.g., 12 inches/sec divided by 2500 Hz). An L value of 20 provides a spacing of the lateral sensor data of about 0.1 inch. 
     Step  864 —creating lateral sensor packet. As an example, periodically (for example every 20 rows of data captured) a lateral sensor packet is created by: selecting a subset of the columns in the 4 rows of data (e.g., every 20 columns) and binarizing the data by comparing the pixel intensity to a fixed threshold. This creation of the lateral sensor packet process provides a coarse resolution binary representation of the objects passing by the bottom scanner. This binary representation corresponds to a footprint of the object. For any object viewable by the lateral object sensor, the object&#39;s longitudinal length is determined by the number of rows in the object footprint multiplied by the object footprint pixel size. 
     Step  866 —setting lateral sensor counter to zero. 
     Step  868 —sending recorded data (decode packets and lateral sensor packets) to the interconnect processor and then returning to Step  848  to capture/read out more images. 
       FIG. 47  is a flow chart of a light curtain processor algorithm  870  according to an embodiment, having the following steps: 
     Step  872 —checking for synchronization signal for the interconnect processor. The light curtain sensor elements  422  are monitored to determine the height of an object. For example, an object&#39;s height is determined by tallest light curtain sensor element that was blocked when the object is passed by. The light curtain sensor elements  422  may also be used to determine the longitudinal length of the object. For example, for objects tall enough to block at least one beam in the light curtain, object length is determined by time difference (as measured by Frame Count difference) between trailing light curtain being first blocked to being unblocked multiplied by assumed object velocity (typically the conveyor belt velocity). 
     Step  874 —monitoring light curtain beams and waiting for a change of state (where a beam is just interrupted or just cleared). 
     Step  875 —determining if a change of state has not occurred: if No, returning to Step  872 ; if Yes, proceeding to Step  876 . 
     Step  876 —creating light curtain state packet that represents the current light curtain state (e.g., corresponding to a bit pattern (for example, 1=vertically aligned sensors blocked, 0=vertically aligned sensors unblocked)). 
     Step  878 —transmitting light curtain state packet (indicating current state of light curtain beams) to the interconnect processor and then returning to Step  872 . 
       FIG. 48  is a flow chart of an interconnect processor algorithm  880  according to an embodiment, having the following steps: 
     Step  882 —Generating a periodic synchronization signal and sending it to the decode processors. This periodic synchronization signal sets the frame rate of the system. In a preferred example herein, periodic synchronization signal is 30 Hz (30 frames/second). 
     Step  884 —incrementing a counter (a frame count) each time the synchronization pulse is emitted. In one example, the synchronization pulse is emitted periodically at 30 Hz. 
     Step  886 —determining whether data is available: if No, returning to Step  882 ; if Yes, proceeding to Step  888 . 
     Step  888 —receiving decode packets from the top, side, and bottom decode processors. 
     Step  888  (cont&#39;d)—receiving lateral sensor packets from the bottom decode processors and the light curtain state packets from the light curtain processor. 
     Step  890 —recording the decode packets and the lateral sensor packets and recording the value of the frame count when the packets were received (referred to as time stamping of the packets). 
     Step  892 —sending the time stamped packet data to the correlation processor. 
       FIG. 49  is a flow chart of an example correlation processor algorithm  900  according to an embodiment, having the following steps: 
     Step  902 —waiting to receive packets (i.e., the lateral sensor packets from the bottom decode processors and the light curtain state packets from the light curtain processor) from the interconnect processor. 
     Step  904 —generating a three-dimensional object model (e.g., from an object footprint and side profile (LOS and VOS profiles)) from the light curtain state packets and lateral sensor packets. An object model is a volume solid with base equivalent to the object footprint, or simplified representation thereof (such as a rectangle) and a height as measured by the light curtain sensor data. 
     Step  906 —determining if the object has left the read region: if No, return to Step  902 ; if Yes, proceeding to Step  908 . Whether the object has left the read region may be determined in various ways. For example, the light curtain state packet or lateral sensor packet may indicate that an object has left the scan volume. In one example, transition of the trailing light curtain from a blocked state to an unblocked state indicates that an object has left the scan volume. In other examples, the leading light curtain and/or the lateral object sensor may be used to determine when an object leaves the read region. If data from the leading light curtain or lateral object sensor is used, the location of the object model is translated by the distance between the locations of the leading light curtain (and/or lateral object sensor) and the trailing light curtain so that the object model is at the edge of the trailing light curtain. 
     Step  908 —analyzing decode packet locations to determine if any of the locations correspond to the object. For example, a decode trajectory or a back projection ray is generated for each decode packet by considering the camera parameters of the camera that decoded the barcode and bounding box coordinates. Generation of back projection rays is further discussed in U.S. Patent Application Nos. 61/435,686 and 61/505,935, incorporated by reference above. Back projection rays are translated by the assumed movement of the object that would have occurred from the decode time until the present moment (by computing the time difference as measured by frame count difference between the moment the object left the scan volume and the moment when the decode occurred). After the back projection rays are translated, it is determined whether any back projection rays intersect the object model. 
     Step  910 —transmitting optical code data and exception information to host processor. If a single barcode value is associated with an object, a “Good Read” indication may be sent to the host processor. The exception information may correspond to one or more of various exceptions. In one example, the exception information may indicate that multiple different barcode values are associated with an object (e.g., a “Multiple Barcode Read” exception). In another example, the exception information may indicate that an object as seen but no barcode was associated with it (e.g., a “No Read” exception). In another example, the exception information may indicate that a barcode was decoded but no object was associated with it (e.g., a “Phantom Read” exception). 
     It is intended that subject matter disclosed in portion herein can be combined with the subject matter of one or more of other portions herein as long as such combinations are not mutually exclusive or inoperable. In addition, many variations, enhancements and modifications of the imager-based optical code reader concepts described herein are possible. 
     The terms and descriptions used above are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention.