Abstract:
Described is an image capture device with an adjustable range and related methods. The device comprises an illumination element, an array imager and a microcontroller. The illumination element is initialized to a first illumination intensity and a first illumination pulse duration. The array imager utilizes a first exposure time. The array imager achieves a first imaging range based on the first illumination intensity, the first illumination pulse duration and the first exposure time. The microcontroller changes at least one of (i) the first illumination intensity to a second illumination intensity (ii) the first illumination pulse duration to a second illumination pulse duration and (iii) the first exposure time to a second exposure time. The array imager achieves a second imaging range as a function of at least one of the second illumination intensity, the second illumination pulse duration and the second exposure time.

Description:
FIELD OF INVENTION 
       [0001]    The present invention generally relates to an image capture device having an adjustable range and related methods. 
       BACKGROUND 
       [0002]    A conventional bar code presentation scanner may be mounted on, for example, a checkout counter and allow a user to scan bar codes by presenting items in an imaging field thereof. A conventional bar code swipe scanner allows a user to scan bar codes by “swiping” items through an imaging field thereof. Swiping refers to an act of dynamically moving the items through the imaging field of the swipe scanner, whereas the items are simply held stationary in front of the presentation scanner. 
         [0003]    Both presentation and swipe scanners may be continuously powered and constantly attempting to decode bar codes which are detected in their respective scanning ranges. However, to ensure that all bar codes are scanned, the scanners are typically configured for a maximum scanning range. Thus, because the scanners are constantly attempting to decode the bar codes detected within their maximum scanning ranges, the scanners may detect and attempt to decode bar codes which were previously scanned (duplicate scans) and/or bar codes which are not intended to be scanned (inadvertent scans). The duplicate and inadvertent scans can frustrate the user and lead the user to believe that the scanners are malfunctioning. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to an image capture device with an adjustable range and related methods. The device comprises an illumination element, an array imager and a microcontroller. The illumination element is initialized to a first illumination intensity and a first illumination pulse duration. The array imager utilizes a first exposure time. The array imager achieves a first imaging range based on the first illumination intensity, the first illumination pulse duration and the first exposure time. The microcontroller changes at least one of (i) the first illumination intensity to a second illumination intensity (ii) the first illumination pulse duration to a second illumination pulse duration and (iii) the first exposure time to a second exposure time. The array imager achieves a second imaging range as a function of at least one of the second illumination intensity, the second illumination pulse duration and the second exposure time. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  shows an exemplary embodiment of an image capture device having an adjustable range according to the present invention. 
           [0006]      FIG. 2  shows an exemplary embodiment of a method for adjusting a range of an image capture device according to the present invention. 
           [0007]      FIG. 3  shows an exemplary embodiment of an architecture of an image capture device having an adjustable range according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The present invention may be further understood with reference to the following description and the attached drawings, wherein like elements are referred to with the same reference numerals. The present invention describes an image capture device with an adjustable range and related methods. While the exemplary embodiments of the present invention will be described with reference to an imager-based scanner using an array imager, those of skill in the art will understand that the present invention may be utilized by any image capture device, e.g., an imager-based scanner, a digital camera, a camera phone, a camera PDA, a web cam, a video camera, etc. 
         [0009]      FIG. 1  shows an exemplary embodiment of a scanner  10  having an adjustable scanning range according to the present invention. As is known by those of skill in the art, the scanner  10  may be immovably mounted on a checkout counter, a stanchion/wall in a retail store or a warehouse, etc. and be used for presentation and/or swipe scanning. That is, the scanner  10  may be configured to constantly attempt to decode bar codes within its scanning range. Thus, a user may simply swipe an item  15  past the scanner  10  or present the item  15  to the scanner  10  to decode a bar code  20  on the item  15 . 
         [0010]    In the exemplary embodiment, the scanner  10  may comprise an array imager  25  and an illumination element (e.g., one or more LEDs  30 ). The array imager  25  may be formed from an array or matrix of pixels and be used to decode both one- and two-dimensional bar codes, as well as generate images of other indicia (e.g., text, graphics, etc.). The LEDs  30  provide illumination (e.g., visible light, infrared light, etc.) to illuminate items, e.g., the item  15 , in the scanning range of the scanner  10 . The array imager  25  collects illumination reflected from the item  15 , and converts the reflected illumination into an analog signal. The analog signal is then converted into a digital image which the scanner  10  attempts to decode. For example, the image may include an image of the bar code  20 , which is decoded by the scanner  10  (or a remote processing device coupled thereto). 
         [0011]    The scanning range of the scanner  10  may extend from a minimum range R min  (e.g., ˜6 inches) to a maximum range R max  (e.g., ˜18 inches). Preferably, the scanning range extends from approximately twelve to fifteen inches. When the bar code  20  is within the scanning range, the scanner  10  may generate a decodable image thereof. However, when the bar code  20  is beyond the R max , the bar code  20  may not be sufficiently illuminated by the illumination from the LEDs  30  to generate the decodable image. When the bar code  20  is closer than the R min , the image of the bar code  20  may be too large to be decoded. Thus, the scanning range is conventionally initialized to the R max  (e.g., maximum intensity for LEDs  30 ) to ensure that all bar codes which are swiped-past/presented-to the array imager  25  receive sufficient illumination to generate decodable images. 
         [0012]    According to the exemplary embodiments of the present invention, the scanning range may be adjusted by varying one or more settings of the scanner  10 . The settings may include, for example, a raw intensity of the illumination emitted by the LEDs  30 , an illumination pulse duration of the LEDs  30 , an exposure time of the array imager  25 , etc. The settings may be varied singularly or in combination to adjust the scanning range of the scanner  10 .  FIG. 3  shows an exemplary embodiment of an architecture of the scanner  10  which includes a microcontroller  305 , an LED circuit  310  and a decoder  315 . The microcontroller  305  may vary the settings of the scanner  10  to achieve a desired scanning range, as will be described further below. 
         [0013]    The raw intensity of the LEDs  30  may correspond to a brightness of the illumination emitted by the LEDs  30 . In one exemplary embodiment, the LEDs  30  may be continually powered, while in other exemplary embodiments, the LEDs  30  may be pulsed substantially in synchronization with the decoder  315 , as described below. A decrease in the raw intensity may cause a corresponding decrease in the scanning range, because, when the item  15  is beyond the scanning range, the bar code  20  will not reflect a sufficient amount of illumination to the array imager  25  to generate a decodable image. Similarly, an increase in the raw intensity may cause a corresponding increase in the scanning range. The raw intensity may be configured during set-up of the scanner  10 , automatically by the scanner  10  or manually by a user, as will be explained further below. 
         [0014]    The illumination pulse duration of the LEDs  30  may be predefined time intervals for which the LEDs  30  (or selected ones thereof) are alternately powered up and powered down. By exposing the item  15  to the illumination only for the predefined time intervals (“flashing” the LEDs  30 ), the illumination available to be reflected by the item  15  may be reduced, limiting the scanning range. Additionally, limiting the time that the item  15  is exposed to the illumination may reduce and/or eliminate an effect of ambient light in the decoding process. That is, the ambient light (e.g., natural light, fluorescent light, etc.) may be reflected, along with the illumination from the LEDs  30 , onto the array imager  25  and included in the digital image. In the exemplary embodiment, the microcontroller  305  may control the LED circuit  310  (e.g., a current limiter) to vary current going through the LEDs  30  in accordance with the predefined time intervals. The LED circuit  310  may also vary the current to control the raw illumination intensity of the LEDs  30 . 
         [0015]    The exposure time is a predetermined time period for which the array imager  25  receives light (e.g., the reflected illumination and ambient light) and generates the digital image for the decoder  315  to decode. Those of skill in the art will understand that the exposure time may vary depending on a scanning mode utilized by the scanner  10 . For example, in a presentation scanning mode where the bar code  20  is substantially stationary relative to the scanner  10 , the exposure time may be on the order of approximately tens of milliseconds. However, in a swipe scanning mode where the bar code  20  is in motion relative to the scanner  10 , the exposure time may be on the order of hundreds of microseconds. Preferably, the exposure time is short enough to limit or eliminate an effect of ambient light in the decoding process. By using a short exposure time, the scanner  10  may limit the effect of the ambient light such that the illumination available for reflectance by the item  15  is essentially limited to the illumination provided by the LEDs  30 . 
         [0016]    Those of skill in the art will understand that the microcontroller  305  typically synchronizes the illumination pulse duration with the exposure time. Activation of the array imager  25  to receive light may immediately follows or be substantially simultaneous with the flash of the LEDs  30  (i.e., the illumination pulse duration time interval). Synchronization of the exposure time to the illumination pulse duration may virtually eliminate any ambient light in the image generated by the array imager  25 . 
         [0017]      FIG. 2  shows an exemplary embodiment of a method  200  for adjusting the scanning range of the scanner  10 . As noted above, the scanning range is conventionally configured to the R max  of the scanner  10  regardless of the use and/or location of the scanner  10 . For example, even when the scanner  10  is used on a checkout counter, the scanning range may be set to R max  even though items may not be swiped/presented any farther than eight inches from the scanner  10 . According to the exemplary embodiments of the present invention, the scanning range may be adjusted automatically by the scanner  10  or manually by the user. Automatic adjustment of the scanning range by the scanner  10  may be effected as described in U.S. patent application Ser. No. 11/007,403, entitled “Pulsed Illumination in Imaging Reading”, the entire disclosure of which is expressly incorporation herein by reference. As understood by those of skill in the art, the initial setting of the scanning range may be any setting and need not be the R max . For example, the scanning range may be the R min  and not register scans of items swiped beyond the R min . However, the exemplary embodiment of the method  200  will be described as though the scanning range is initially set to the R max . 
         [0018]    In step  205 , the scanner  10  captures an image of the bar code  20 . If the decoding is unsuccessful, the scanner  10  may capture and attempt to decode a further image, described above as the process of swipe scanning. When the image is decodable and the bar code  20  on the item  15  is decoded, it is determined whether the scanning range should be adjusted. 
         [0019]    In step  210 , it is determined whether the scanned bar code is the result of a duplicate scan or an inadvertent scan. Alternatively, it may be determined whether the scanner  10  is registering scans of the item  15  (e.g., when the scanning range is initially set to a range less than the R max ). As described above, the scanner  10  may be continuously powered and constantly attempting to decode. Thus, the scanner  10  may detect and attempt to decode bar codes in its scanning range which were previously scanned (duplicate scans) and/or bar codes which are not intended to be scanned (inadvertent scans). For example, the scanner  10  may be implemented as a kiosk in a retail store. A customer may scan the bar code  20  on the item  15  to obtain information about the item  15 . However, because the scanner  10  is constantly attempting to decode, it may detect other bar codes within its scanning range (e.g., another customer walking by the scanner  10  holding a further item with a further bar code). As such, other information corresponding to the further item may appear which is not desired by the customer. 
         [0020]    Whether the bar code scanned is the result of the duplicate or inadvertent scan may be determined by the user and/or by the scanner  10 . In the former case, the user may provide an indication to the scanner  10  that the bar code should not have been scanned. For example, the scanner  10  and/or a processing device coupled to the scanner  10  may include a data input device (e.g., a touch panel, a keypad, etc.) on which the user may provide feedback to the scanner  10 . The scanner  10  may utilize the feedback from the user to determine that the bar code is the result of a duplicate or inadvertent scan and adjust the scanning range accordingly. 
         [0021]    In step  215 , the scanning range of the scanner  10  is reduced (or otherwise adjusted). The reduction of the scanning range may be effected as described above. For example, the raw intensity of the illumination emitted by the LEDs  30 , the illumination pulse duration of the LEDs  30  and/or the exposure time may be adjusted. The adjustments may be accomplished via a software interface with the scanner  10 . For example, a processing device coupled to the scanner  10  may provide an application for configuring the settings of the scanner  10 . The user may enter changes to the settings of the scanner  10  on the application. 
         [0022]    Alternatively, the scanning range may be adjusted using one or more hardware components on the scanner  10 . For example, a knob, dial, switch, etc. may be disposed on the scanner  10  which is used to adjust the scanning range. Turning the knob/dial or repositioning the switch may increase/decrease the scanning range. That is, the microcontroller  305  may respond to changes in the knob/dial/switch by making corresponding changes to the raw intensity of the illumination from the LEDs  30 , the illumination pulse duration and/or the exposure time. For example, if the user tunes the knob to a scanning range of five inches, a corresponding reduction of the raw intensity, illumination pulse duration and/or exposure time may be affected to decrease the scanning range from, in the exemplary embodiment, the R max  to five inches. 
         [0023]    Those of skill in the art will understand that the present invention may provide several advantages. For example, as described above, the present invention reduces and/or eliminates duplicate and/or inadvertent scans. Thus, the user may not think that the scanner  10  is malfunctioning. False indications of malfunction may be problematic in that the scanner  10  is typically taken offline for diagnostic exams and may be returned to the manufacturer or a third-party for repair. However, the scanning range may simply have been too great. Therefore, by implementing the exemplary embodiments of the present invention, the user can adjust the scanning range during set-up or on-the-fly. 
         [0024]    The present invention has been described with the reference to the above exemplary embodiments. However, those of skill in the art will understand that various modifications and changes may be made to the embodiments without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings, accordingly, should be regarded in an illustrative rather than restrictive sense.