Abstract:
An apparatus includes a light emitting diode operative to emit mostly invisible light within an invisible bandwidth, and a scattering surface configured to scatter a first portion of the invisible light from the light emitting diode out of the window. The scattering surface is also partially transparent to allow a second portion of the invisible light from the light emitting diode to pass through the scattering surface and strike the reflector that is configured to reflect at least some of the second portion of the invisible light towards the window. The apparatus further includes a photodetector configured to detect returned invisible light from the target object.

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to imaging-based barcode readers. 
     BACKGROUND 
     Various electro-optical systems have been developed for reading optical indicia, such as barcodes. A barcode is a coded pattern of graphical indicia comprised of a series of bars and spaces of varying widths. In a barcode, the bars and spaces having differing light reflecting characteristics. Some of the barcodes have a one-dimensional structure in which bars and spaces are spaced apart in one direction to form a row of patterns. Examples of one-dimensional barcodes include Uniform Product Code (UPC), which is typically used in retail store sales. Some of the barcodes have a two-dimensional structure in which multiple rows of bar and space patterns are vertically stacked to form a single barcode. Examples of two-dimensional barcodes include Code 49 and PDF417. 
     Systems that use one or more imaging sensors for reading and decoding barcodes are typically referred to as imaging-based barcode readers, imaging scanners, or imaging readers. An imaging sensor generally includes a plurality of photosensitive elements or pixels aligned in one or more arrays. Examples of imaging sensors include charged coupled devices (CCD) or complementary metal oxide semiconductor (CMOS) imaging chips. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments. 
         FIG. 1A  and  FIG. 1B  depict an imaging scanner in accordance with some embodiments. 
         FIG. 2  is a schematic of an imaging scanner in accordance with some embodiments. 
         FIGS. 3A-3B  depict an imaging scanner that includes an object detecting system behind the window of the imaging scanner. 
         FIG. 4A  depicts a bi-optic imager that includes a horizontal window and a vertical window in accordance with some embodiments. 
         FIG. 4B  depicts a bi-optic imager that also includes a customer-side window in accordance with some embodiments. 
         FIGS. 5-7  depict an improved object detecting system in accordance with some embodiments. 
     
    
    
     The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     DETAILED DESCRIPTION 
       FIG. 1A  and  FIG. 1B  depict an imaging scanner  50  in accordance with some embodiments. The imaging scanner  50  has a window  56  and a housing  58 . The imaging scanner  50  is typically a portable reader that has a base for supporting itself on a flat surface  30 , such as, a countertop. The window  56  generally faces an operator at the workstation. As shown in  FIG. 1A , the operator can slide or swipe the product  40  past the window  56  from right to left, or from left to right, in a “swipe” mode, to let an image of the barcode  40  on the product  42  be captured by the imaging scanner  50 . Alternatively, the operator can present the barcode  40  on the product  42  to the center of the window  56  in a “presentation” mode. The choice depends on operator preference or on the layout of the workstation. 
       FIG. 2  is a schematic of an imaging scanner  50  in accordance with some embodiments. The imaging scanner  50  in  FIG. 2  includes the following components: (1) an imaging sensor  62  positioned behind an imaging lens arrangement  60 ; (2) an illuminating lens arrangement  70  positioned in front of an illumination light source  72 ; (3) an aiming pattern generator  80  positioned in front of an aiming light source  82 ; and (4) a controller  90 . In  FIG. 2 , the imaging lens arrangement  60 , the illuminating lens arrangement  70 , and the aiming pattern generator  80  are positioned behind the window  56 . The imaging sensor  62  is mounted on a printed circuit board  91  in the imaging scanner. 
     The imaging sensor  62  can be a CCD or a CMOS imaging device. The imaging sensor  62  generally includes multiple pixel elements. These multiple pixel elements can be formed by a one-dimensional array of photosensitive elements arranged linearly in a single row. These multiple pixel elements can also be formed by a two-dimensional array of photosensitive elements arranged in mutually orthogonal rows and columns. The imaging sensor  62  is operative to detect light captured by an imaging lens arrangement  60  along an optical path or axis  61  through the window  56 . Generally, the imaging sensor  62  and the imaging lens arrangement  60  are designed to operate together for capturing light scattered or reflected from a barcode  40  as imaging data over a two-dimensional imaging field of view (FOV). 
     The barcode  40  generally can be located anywhere in a working range of distances between a close-in working distance (WD 1 ) and a far-out working distance (WD 2 ). In one specific implementation, WD 1  is in a close proximity to the window  56 , and WD 2  is about a couple of feet from the window  56 . Some of the imaging scanners can include a range finding system for measuring the distance between the barcode  40  and the imaging lens arrangement  60 . Some of the imaging scanners can include an auto-focus system to enable a barcode be more clearly imaged with the imaging sensor  62  based on the measured distance of this barcode. In some implementations of the auto-focus system, the focus length of the imaging lens arrangement  60  is adjusted based on the measured distance of the barcode. In some other implementations of the auto-focus system, the distance between the imaging lens arrangement  60  and the imaging sensor  62  is adjusted based on the measured distance of the barcode. 
     In  FIG. 2 , the illuminating lens arrangement  70  and the illumination light source  72  are designed to operate together for generating an illuminating light towards the barcode  40  during an illumination time period. The illumination light source  72  can include one or more light emitting diodes (LED). The illumination light source  72  can also include a laser or other kind of light sources. The aiming pattern generator  80  and the aiming light source  82  are designed to operate together for generating a visible aiming light pattern towards the barcode  40 . Such aiming pattern can be used by the operator to accurately aim the imaging scanner at the barcode. The aiming light source  82  can include one or more light emitting diodes (LED). The aiming light source  82  can also include a laser, LED, or other kind of light sources. 
     In  FIG. 2 , the controller  90 , such as a microprocessor, is operatively connected to the imaging sensor  62 , the illumination light source  72 , and the aiming light source  82  for controlling the operation of these components. The controller  90  can also be used to control other devices in the imaging scanner. The imaging scanner  50  includes a memory  94  that can be accessible by the controller  90  for storing and retrieving data. In many embodiments, the controller  90  also includes a decoder for decoding one or more barcodes that are within the imaging field of view (FOV) of the imaging scanner  50 . In some implementations, the barcode  40  can be decoded by digitally processing a captured image of the barcode with a microprocessor. 
     In operation, in accordance with some embodiments, the controller  90  sends a command signal to energize the illumination light source  72  for a predetermined illumination time period. The controller  90  then exposes the imaging sensor  62  to capture an image of the barcode  40 . The captured image of the barcode  40  is transferred to the controller  90  as imaging data. Such imaging data is digitally processed by the decoder in the controller  90  to decode the barcode. The information obtained from decoding the barcode  40  is then stored in the memory  94  or sent to other devices for further processing. 
     The illumination light source  72  usually is energized to address low ambient light conditions and to minimize hand jitter impact or swiping objects though the FOV on reading performance. On the other hand having bright illumination of an imaging scanner in constantly on state is annoying and bothersome for the user. It is also not efficient from power management perspective. Therefore it is beneficial to have an object sensing system which energizes illumination system when the object of interest is presented within the predetermined FOV of the imaging scanner  50  and at a certain distance from the scanner. 
       FIGS. 3A-3B  depict an imaging scanner  50  that includes an object detecting system behind the window  56 . The object detecting system in  FIG. 3B  includes an infrared LED  110  and a photodetector  120 . In some existing implementations, the infrared light projecting out of the window  56  mainly originates from one particular area—LED chip which may or may not have an auxiliary lens. These implementations place some limitation on the effectiveness of the object detecting system. This limitation becomes apparent in case of reading barcodes from cell phones, a user application that has recently become very popular. Typically, cell phone screen is designed in such a way which minimizes reflected light from its surface. Therefore reflected/scattered light of the object sensor LED is very low, which is nearly impossible for detection at larger distances. In general cell phones have very strong specular reflection from the screen. Therefore in a particular orientation of the cell phone, the returned specular reflection signal is quite strong and the object sensor can be activated at a longer distance. Unfortunately, this occurs if the cell phone is presented at a particular orientation only within a limited range of angle. 
     In general, as shown in  FIGS. 4A-4B , an imaging scanner  50  can be an bi-optic imager that includes a horizontal window  56 H and a vertical window  56 V, and the bi-optic imager can include one object detecting system behind the horizontal window  56 H and another object detecting systems behind the vertical window  56 V. When the barcode  40  on the product  42  is present or swiped across the windows  56 H or  56 V, the process of capturing one or more images of the barcode  40  can be triggered by the object detecting system behind the windows  56 H or  56 V. In some implementations, as shown in  FIG. 4B , the bi-optic imager  50  can also include a customer-side window  56 C, an object detecting system behind the customer-side window  56 C can be used to detect the presence of an object  42  in front of the customer-side window  56 C. In some situations, when the product  42  in  FIG. 4A  has a glassy surface or when the object  42  in  FIG. 4B  is a cell phone, the specular reflections from the glassy surface or from the flat screen of the cell phone can adversely affect the performance of the object detecting systems in the bi-optic imager. It is generally desirable to provide an improved object detecting system. 
       FIGS. 5-7  depict an improved object detecting system in accordance with some embodiments. The object detecting system in  FIGS. 5-7  includes an infrared LED  110 , a photodetector  120 , a reflector  130 , and a scattering surface  140  that is also partially transparent. The object detecting system in  FIGS. 5-7  is used for detecting the presence of an object in front of a window  56 . Such object detecting system can also be used for detecting the presence of an object in front of the horizontal window  56 H, the vertical window  56 V, or the customer-side window  56 C of a bi-optic imager as shown in  FIGS. 4A-4B . Also shown in  FIGS. 5-7  are some of the key components of the imaging scanner  50 , such as, the imaging sensor  62 , the imaging lens arrangement  60 , the illuminating lens arrangement  70 , and the illumination light source  72 . In addition, the field of view (FOV) of the imaging scanner  50  is also shown in  FIGS. 5-7 . 
     The object detecting system in  FIGS. 5-7  is configured to make such wakeup sensor system less sensitive to specular surface orientation in the far field. In  FIGS. 5-7 , the outgoing light for the wakeup sensor system are split into both directional and scattered light paths. This will increase the number of possible light path angles leaving the system which in turn will increase the probability that one of these light paths will reflect from the specular surface and reenter the wakeup system&#39;s field of view. 
     As shown in  FIG. 5 , the IR emitter has one component of its intensity that hits a mirror, providing highly directional outgoing path. This aids the system in illuminating far field objects. In  FIG. 5 , because the scattering surface  140  is partially transparent, a portion of the invisible light from the infrared LED  110  passes through the scattering surface  140  and strikes the reflector  130  that is configured to reflect at least some of such invisible light towards the window  56 . For example, some portion of the invisible light  210  from the infrared LED  110  passes through the scattering surface  140 , strikes the reflector  130 , and is reflected towards the window  56  as light  219 ; in addition, some portion of the invisible light  220  from the infrared LED  110  passes through the scattering surface  140 , strikes the reflector  130 , and is reflected towards the window  56  as light  229 . Similarly, some portion of light rays from the infrared LED  110  propagating in a direction between the ray of light  210  and the ray of light  220  will be reflected out of the window  56  as light rays propagating in a direction between the ray of light  219  and the ray of light  229 . 
     As shown in  FIG. 6 , the IR emitter has another component of its intensity that hits a scattering surface, which provides outgoing light in many different directions. This aids the system in illuminating nearby specular surfaces at many different angles. In  FIG. 6 , some portion of the invisible light from the infrared LED  110 , after scattered by the scattering surface  140 , propagates out of the window  56  directly or out of the window  56  indirectly after further scattered by other surfaces. For example, some portion of the invisible light  210  from the infrared LED  110 , after scattered by the scattering surface  140 , propagates out of the window  56  directly as light  212 . But some portion of the invisible light  210  from the infrared LED  110  is scattered by the scattering surface  140  as light  211 ; subsequently, some of the light  211 , after further scattering by one or more surfaces, propagates out of the window  56  indirectly as light  213 , light  215 , or  216 . Similarly, some portion of the invisible light  220  from the infrared LED  110 , after scattered by the scattering surface  140 , propagates out of the window  56  directly as light  221  and light  222 . 
     Additionally, in  FIGS. 5-7 , the wakeup system&#39;s field of view can be broken down into more than one component, each pointing in a generally different direction. This can increase the chance that it will see a highly directional returning light ray that has reflected from a specular surface. For example, as shown in  FIG. 7 , the field of view of the object detecting system includes at least two components—a first sub-field of view  300  and a second sub-field of view  400 —each pointing in a generally different direction. In  FIG. 7 , the first sub-field of view  300  falls upon the reflector  130  which angles the field of view to receive incoming rays that are generally parallel to the imaging path and downward angled incoming rays; furthermore, the front aperture  150  for the IR detector  120  is left open so that the photodetector  120  can see upward angled incoming rays in the second sub-field of view  400 . Specifically, light ray  330  within the first sub-field of view  300  is reflected by the reflector  130  as light ray  331  that is detected by the photodetector  120  after passing through the front aperture  150 . Light ray  430  within the second sub-field of view  400 , after passing through the front aperture  150 , is also detected by the photodetector  120 . The wakeup system can include additional apertures positioned in front of the infrared LED  110  or the photodetector  120  for defining the first sub-field of view  300  and the second sub-field of view  400 . 
     The object detecting system as shown in  FIGS. 5-7  can retain good performance on far field objects of a non-specular nature, and also have good performance on near field objects of a specular nature. This is ideal for a scanner that wants to detect reflective objects that are presented to it in the near field, such as a customer facing scanner that wants to wake up when a highly specular phone surface is presented to it. 
     In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. 
     The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed. 
     It will be appreciated that some embodiments may be comprised of one or more generic or specialized processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used. 
     Moreover, an embodiment can be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (e.g., comprising a processor) to perform a method as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.