System for, and method of, detecting the presence of a mobile communication device in proximity to an imaging reader and for automatically configuring the reader to read an electronic code displayed on the device upon such detection

A printed code associated with a product is illuminated with light having a first lighting characteristic, and is readable in a default mode of an imaging reader. An electronic code displayed on a mobile communication device is readable in another mode of the reader, with a different second lighting characteristic that is designed to minimize specular reflection from a screen of the device. When the presence of the device in close proximity to the reader is detected, the reader is automatically configured to switch from the default mode to the other mode to enable the electronic code to be read.

BACKGROUND OF THE INVENTION

The present invention relates generally to a system for, and a method of, electro-optically reading a printed code associated with a product, and an electronic code displayed on a mobile communication device, and, more particularly, to detecting the presence of the device, such as a smartphone, in close proximity to an imaging reader, and for automatically configuring the reader to read the electronic code upon such detection.

Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read targets, such as one- and two-dimensional bar code symbols, and/or non-symbols, such as documents, over a range of working distances relative to each reader. An imaging reader includes a housing for supporting an imaging module, also known as a scan engine. In a hands-free mode, such as at a fixed position kiosk or at a stationary, point-of-transaction workstation, the imaging module is mounted in a housing having at least one window to which products associated with, e.g., bearing, the symbols to be read are either presented, or across which the symbols are swiped. The workstation may have a single, horizontal or upright, window as in a flat-bed or slot-scanner workstation, or a pair of horizontal and upright windows as in a bi-optical workstation, and be located at a countertop of a checkout stand in supermarkets, warehouse clubs, department stores, and other kinds of retailers, as well as at other kinds of businesses, such as libraries and factories.

The imaging module includes an imaging assembly having a solid-state imager or imaging sensor with an array of photocells or light sensors, which correspond to image elements or pixels in an imaging field of view of the imager, and an imaging lens assembly for capturing return light scattered and/or reflected from the symbol being imaged over a range of working distances relative to the module, and for projecting the return light onto the array to initiate capture of an image of each symbol. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, with global or rolling exposure shutters, and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the imaging field of view. In order to increase the amount of the return light captured by the array, for example, in dimly lit environments or for far-out symbols located relatively far from the window, the imaging module generally also includes an illuminating light assembly for illuminating the symbol with illumination light over an illumination field for reflection and scattering from the symbol.

Each symbol is typically printed with ink on such media as paper, foil or film labels that are directly applied to the products, or on such media as paper, foil or film packaging that cover and contain the products, or directly on membership or customer loyalty cards, coupons, and drivers' licenses that are carried by customers remotely from the products. In recent years, it has become increasingly advantageous to display symbols on information display screens, such as display screens of wireless telephones (“cellphones” or “smartphones”), personal digital assistants (“PDAs”), and like mobile communication devices, such as e-readers, portable tablets, slates, wearable glasses or watches, and computers. Displaying such symbols, also known as “electronic codes”, on such display screens has become increasingly desirable at such venues as airports and theaters, because they relieve consumers from needing to carry symbol-coded, paper tickets, coupons, and cards.

Although generally satisfactory for their intended purpose of reading printed codes, some of the known imaging readers have not proven to be altogether satisfactory when reading the above-described electronic codes due to specular reflection of the illumination light off the display screens. Display screens can be reflective, i.e., they alter their reflectivity to ambient light to form an image, typically from light and dark pixels, such as passive black and white liquid crystal displays (“LCDs”), or can be emissive, such as backlit LCDs, i.e., they internally generate the light emitted therefrom. Whether reflective or emissive, each display screen includes a glass pane or cover, and the electronic code is displayed behind the glass pane. A portion of the illumination light incident on the glass pane is reflected therefrom back into the imaging field of view of the imager. This reflected portion of the illumination light creates undesirable one or more hot spots in the imaging field of view that at least partially and locally blinds the imager, and may significantly compromise reading performance. If the electronic code cannot be successfully read in an initial attempt, the scan engine typically tries again and again. Often, the reading fails, and the user must take additional time to manually enter the data that would have otherwise been automatically read and entered into the imaging reader.

Accordingly, there is a need to efficiently, rapidly and reliably read electronic codes, and to generally improve overall reading performance of such imaging readers when reading electronic codes.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present disclosure relates to a system for electro-optically reading a printed code, e.g., a one- or two-dimensional bar code symbol, associated with a product, and for electro-optically reading an electronic code displayed on a mobile communication device, such as a cellphone or a smartphone. The system comprises an imaging reader including a housing, a light-transmissive window supported by the housing, an imaging assembly supported by the housing and having a solid-state imager with an array of image sensors, e.g., a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, with global or rolling exposure shutters, and an imaging lens assembly, and an illuminating light assembly supported by the housing. A controller is operative, in a first mode of operation of the reader, for controlling the illuminating light assembly to illuminate the printed code with illumination light having a first lighting characteristic, for controlling the imaging assembly to capture illumination light returned from the illuminated printed code through the window over a field of view and to project the captured illumination light from the illuminated printed code onto the array, and for processing the captured illumination light from the illuminated printed code.

A device detector detects when the mobile communication device is proximal to the window by sensing a radio frequency (RF) signal radiated from the mobile communication device, and generates a mode control signal when the sensed RF signal exceeds a threshold value. Preferably, the device detector includes an antenna supported by the housing, and operative for receiving the RF signal radiated from the mobile communication device when the latter is searching for a wireless connection.

The controller is operative, in response to receipt of the mode control signal, for automatically configuring the reader to switch to a second mode of operation in which the controller controls the illuminating light assembly to change the illumination light from a first lighting characteristic to a second lighting characteristic, controls the imaging assembly to capture return light from the electronic code through the window over a field of view and to project the captured return light from the electronic code onto the array, and processes the captured return light from the electronic code. The second lighting characteristic is different from the first lighting characteristic to minimize specular reflection from the mobile communication device from compromising reading of the electronic code.

If the imager has a global shutter for simultaneously exposing all the image sensors over exposure times in successive frames, then the controller energizes the illuminating light assembly to emit the illumination light as pulses over pulse times in successive frames, synchronizes each exposure time with each pulse time in each frame for the first lighting characteristic, and timewise shifts each pulse time with each exposure time in each frame for the second lighting characteristic. Advantageously, each pulse time does not overlap each exposure time for the second lighting characteristic.

If the imager has a rolling shutter for sequentially exposing all the image sensors in successive rows or columns over successive exposure times, then the controller energizes the illuminating light assembly to emit the illumination light as a train of pulses over successive pulse times, synchronizes one of the pulse times to overlap one of the exposure times for the first lighting characteristic in the first mode, and timewise shifts each pulse time with each exposure time for the second lighting characteristic in the second mode. Advantageously, each pulse time partially overlaps each exposure time for the second lighting characteristic.

Another aspect of the present disclosure relates to a method of electro-optically reading a printed code associated with a product, and of electro-optically reading an electronic code displayed on a mobile communication device. The method is performed by controlling, in a first mode of operation of an imaging reader having a light-transmissive window, an illuminating light assembly to illuminate a printed code with illumination light having a first lighting characteristic, and controlling an imaging assembly having a solid-state imager with an array of image sensors to capture illumination light returned from the illuminated printed code through the window over a field of view and to project the captured illumination light from the illuminated printed code onto the array, and processing the captured illumination light from the illuminated printed code. The method is further performed by detecting when the mobile communication device is proximal to the window by sensing a radio frequency (RF) signal radiated from the mobile communication device, and generating a mode control signal when the sensed RF signal exceeds a threshold value. The method is still further performed by automatically configuring the reader, in response to generation of the mode control signal, to switch to a second mode of operation in which the illumination light from illuminating light assembly is changed from a first lighting characteristic to a second lighting characteristic, in which return light from the electronic code is captured by the imaging assembly through the window over a field of view and is projected onto the array, and in which the captured return light from the electronic code is processed. The second lighting characteristic is configured to be different from the first lighting characteristic to minimize specular reflection from the mobile communication device from compromising reading of the electronic code.

Reference numeral10inFIG. 1generally identifies a mobile, handheld reader for electro-optically reading targets by image capture. As illustrated, the imaging reader10has a lower handle12to be gripped in a user's hand, and an upper barrel14arranged in a gun-shaped housing16having a trigger18that is manually depressed by the user's forefinger to initiate reading of a target, such as a one- or two-dimensional symbol associated with a product, or an electronic code22displayed on a screen24of a mobile communication device30. A light-transmissive window20(best seen inFIG. 2) is mounted on the housing16at the front end region of the barrel14. The reader10can thus be used in a handheld mode in which the reader10is aimed at a target to be read, followed by depression of the trigger18to initiate reading.

AlthoughFIG. 1depicts a gun-shaped reader10, this is merely exemplary, because it will be understood that many other reader configurations may be employed in the practice of the invention disclosed herein. For example, the reader may alternatively be configured as a stationary workstation, such as a vertical slot scanner having a generally upright window, or as a horizontal slot scanner having a generally horizontal window, or as a bioptical workstation having both a generally horizontal window and a generally upright window. The workstation may be used in many diverse environments. In these stationary workstations, the targets are slid, swiped past, or presented to, a window on the workstation in a hands-free mode of operation.

The mobile communication device30inFIG. 1is depicted as a cellphone or smartphone, but it could equally well be a different device, such as a personal digital assistant (“PDA”), an e-reader, a tablet, a slate, a pair of wearable glasses, a watch, or a portable computer. The device30has, among other things, an electronic keyboard26, and, as best seen inFIG. 3, a microprocessor28, a radio frequency (RF) module32, and an RF antenna34, as described below. The illustrated electronic code22is a one-dimensional symbol, but it could equally well be a two-dimensional symbol.

FIG. 2schematically depicts an imaging assembly or scan engine mounted in the reader10behind the window20. The imaging assembly includes a solid-state, imager or image sensor36, and an imaging lens assembly38, which may have one or more imaging lenses, such as a Cooke triplet. The imager36has an array of pixels or light sensors and may be a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, having either a global or a rolling exposure shutter, and is analogous to the imagers used in electronic digital cameras. The imager36and the lens assembly38are together operative for capturing return light scattered and/or reflected from a target40to be read by image capture over a field of view along an optical path or axis42through the window20and over a range of working distances between a close-in working distance (WD1) and a far-out working distance (WD2). In a preferred embodiment, WD1is either at, or about a half inch away from, the window26, and WD2can be many feet from the window26, although other numerical values are contemplated. The target40may either be a printed code associated with a product, or the electronic code22displayed on the device30. As described below, the imager36may have a global shutter in which all the image sensors are simultaneously exposed in successive frames, or a rolling shutter in which all the image sensors are sequentially exposed in successive rows or columns.

The reader10also supports an energizable illuminating light assembly for illuminating the target with illumination light from an illumination light source when energized. The illuminating light assembly includes, as illustrated, a pair of illumination light sources or light emitting diodes (LEDs)44, and a corresponding pair of illumination lens assemblies46to uniformly illuminate the target40with illumination light when energized. The illumination LEDs44and the illumination lens assemblies46are preferably symmetrically located at opposite sides of the imager36. A controller or control circuit50controls operation of the electrical components of the assemblies, processes the captured return light from the target as a image, and decodes the captured image. A memory48is connected, and accessible, to the controller50.

As previously described, the reader10is very satisfactory for reading a printed code, but is less satisfactory when reading the electronic code22due to specular reflection of the illumination light off the display screen24. A portion of the illumination light incident on the display screen24is reflected therefrom back into the imaging field of view of the imager36. This reflected portion of the illumination light creates undesirable one or more hot spots in the imaging field of view that at least partially and locally blinds the imager36, and may significantly compromise reading performance. If the electronic code22cannot be successfully read in an initial attempt, the scan engine typically tries again and again, thus rendering the performance as sluggish.

To minimize, if not eliminate, the specular reflection problem associated with electronic codes and to expedite the reading of electronic codes, it is proposed to change the lighting characteristic of the illumination light when reading electronic codes. Thus, in a first mode of operation, the controller50energizes the illuminating light assembly to emit the illumination light to illuminate the printed code with a first lighting characteristic, and thereupon, the controller50processes the captured return light from the printed code to read the printed code by image capture with the first lighting characteristic. In a second mode of operation, the controller50configures the illuminating light assembly to have a different second lighting characteristic, and thereupon, the controller50processes the captured return light from the electronic code22to read the electronic code22by image capture with the second lighting characteristic. The difference between the first and second lighting characteristics is dependent on whether the imager36has a global exposure shutter or a rolling exposure shutter, as described below.

The change in the lighting characteristics of the illumination light is initiated by a device detector in the reader10for detecting when the mobile communication device30is proximal to the window20by sensing a radio frequency (RF) signal radiated from the mobile communication device30, typically when the device is searching for a wireless connection, and for generating a mode control signal when the sensed RF signal exceeds a threshold value. The controller50automatically switches from the first lighting characteristic to the second lighting characteristic in response to receipt of the mode control signal.

As best seen inFIG. 3, the device detector includes an antenna52for receiving the RF signal radiated from the antenna34of the mobile communication device30when the latter is searching for a wireless connection, a frequency bandpass filter54for filtering the received RF signal, preferably in the frequency band of 0.7 to 2.7 GHz, a rectifier56for rectifying the filtered RF signal to a DC voltage, an optional amplifier58with a fixed gain for amplifying the rectified RF signal, and a comparator60for comparing the DC voltage to a reference DC voltage constituting the threshold value. When the DC voltage exceeds the reference DC voltage, the mode control signal is generated, and sent to the controller50(seeFIG. 2).

The search for the wireless connection by a smartphone or a cellphone is periodically, and typically constantly, performed by the microprocessor28controlling the RF module32to send out from the antenna34short RF signals or “pings” as the phone searches for a Wi-Fi or a cellular network nearby. These pings include the phone's MAC address (a unique identifier associated with a specific device) and other non-personal information like RF signal strength that is used to determine rough location of the phone. The phone also sends out RF signals when connecting to a Bluetooth device, or a near field communication (NFC) device. The frequency of these RF signals generally lies in the band of the bandpass filter54. The antenna52of the detector receives these pings, and generates the mode control signal when the mobile communication device30is located in a near range of working distances away from the window20. The near range extends from the window20to about ten inches therefrom in a preferred embodiment.

As previously mentioned, when the imager36uses a global shutter in which all the image sensors are simultaneously exposed over exposure times in successive frames, then the controller50energizes the illumination LEDs44to emit the illumination light as pulses over pulse times in the successive frames. A typical imager needs about 16-33 milliseconds to read the entire target image and operates at a frame rate of about 30-60 frames per second. As shown inFIG. 4, the exposure times, as represented by pulses A1and A2, each have a duration of 1 millisecond, and the frame interval is 30 milliseconds, there being one exposure time per frame. Each illumination pulse, as represented by pulses B1and B2, has a pulse time of 1 millisecond, there being one pulse time per frame. When reading the printed code, the controller50synchronizes each exposure time with each pulse time in each frame. Thus, as shown on the left side ofFIG. 4, the pulses A1and B1overlap in time. When reading the electronic code22, the controller50timewise shifts each pulse time with each exposure time in each frame. Thus, as shown on the right side ofFIG. 4, the pulses A2and B2are offset in time. Put another way, when reading the electronic code22, the illumination pulse B2is not generated while the imager36is being exposed. Thus, the illumination pulse B2does not create any hot spots that could blind and interfere with the imager36.

As also previously mentioned, when the imager36uses a rolling shutter in which the image sensors, which are arranged in mutually orthogonal rows and columns, are sequentially exposed over exposure times in successive rows or columns, then the controller50energizes the illumination LEDs44to emit the illumination light as a train of pulses over pulse over successive pulse times. As shown inFIG. 5, the exposure times, as represented by pulses A3, A4, A5, A6and A7, each have a duration of 30 milliseconds, and the frame interval is 35 milliseconds, there being one exposure time per frame. Each illumination pulse, as represented by pulses B3, B4, B5and B6, has a pulse time of 35 milliseconds. When reading the printed code, the controller50synchronizes one of the pulse times B3to overlap, and extend past, one of the exposure times A3, as shown on the left side ofFIG. 5. This insures that the printed code is fully illuminated for the entire exposure time.

When reading the electronic code22with the rolling shutter, the controller50timewise shifts each pulse time with each exposure time. Thus, as shown inFIG. 5, the pulses A4and B4are offset in time, as are the pulses A5and B5, as are the pulses A6and B6, etc. Each pulse time partially overlaps each exposure time. Thus, in frame1, a leading part of the pulse B4overlaps two-thirds of the pulse A4, so that only the bottom two-thirds of the rows or columns of the array are exposed; in frame2, a trailing part of the pulse B4and a leading part of the pulse B5overlap the leading and trailing third of the pulse A5, so that only the top and the bottom thirds of the rows or columns of the array are exposed; and in frame3, a trailing part of the pulse B5overlaps two-thirds of the pulse A6, so that only the top two-thirds of the rows or columns of the array are exposed; and so on.

Turning now to the flow chart ofFIG. 6, a method of reading a printed code and an electronic code is performed by capturing and processing return light from the printed code illuminated with a first lighting characteristic in a first or default mode of operation of the imaging reader10in step100. When the device30is detected in close proximity to the reader10in step102, a mode control signal is generated, which, in turn, signals the controller50to configure the reader10to transition to a second mode of operation in which the lighting characteristic has been changed to a second lighting characteristic in step104. In the second mode, return light from the electronic code is captured and processed in step106. The second lighting characteristic is designed to minimize, if not eliminate, the specular reflection problem that occurs when reading the electronic code. Thus, the reader10has an accelerated, aggressive reading performance, because the system recognizes that an electronic code is desired to be read when the near presence of the device30is detected.