BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a portable electro-optical imaging reader operative in either a hand-held mode, or in the illustrated workstation mode, for reading indicia;
FIG. 2 is a block circuit diagram of various components of the imaging reader of the type shown in FIG. 1;
FIG. 3 is a schematic view of a portable electro-optical moving beam reader for reading indicia;
FIG. 4 is a perspective view of an operator-supported electro-optical reader for reading indicia;
FIG. 5 is a block circuit diagram of components for detecting a steady state of a moving beam reader; and
FIG. 6 is a block circuit diagram of components for detecting a steady state of an imaging reader.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference numeral 10 in FIG. 1 generally identifies an electro-optical imaging reader in a workstation mode for processing transactions and mounted on a checkout counter at a retail site at which products, such as a can 12 or a box 14, each bearing a target symbol, are processed for purchase. The counter includes a countertop 16 on which a box-shaped vertical slot reader 20 having a generally vertical window 18 rests. A checkout clerk or operator 22 is located at one side of the countertop, and the reader 20 is located at the opposite side. A cash/credit register 24 is located within easy reach of the operator. In the workstation mode, the operator presents the symbols on the products to the window 18. The reader 20 is portable and lightweight and may be picked up from the countertop 16 by the operator 22 in a handheld mode, and the window 18 may be aimed at a symbol preferably on a product too heavy, or too large, or too bulky to be easily positioned on the countertop in front of the window of the reader in the workstation mode.
As shown in FIG. 2, the imaging reader 20 includes an imager 40 and a focusing lens 41 that are mounted in an enclosure 43. The imager 40 is a solid-state device, for example, a CCD or a CMOS imager and has a linear or area array of addressable image sensors operative for capturing light through the window 18 from a target, for example, a one- or two-dimensional symbol, over a field of view and located in a working range of distances between a close-in working distance (WD1) and a far-out working distance (WD2). In a preferred embodiment, WD1 is about two inches from the imager array 40 and generally coincides with the window 18, and WD2 is about eight inches from the window 18. An illuminator 42 is also mounted in the reader and preferably includes a plurality of light sources, e.g., light emitting diodes (LEDs) 42, arranged around the imager 40 to uniformly illuminate the target symbol.
As also shown in FIG. 2, the imager 40 and the illuminator 42 are operatively connected to a controller or microprocessor 36 operative for controlling the operation of these components. Preferably, the microprocessor is the same as the one used for decoding light scattered from the indicia and for processing the captured target symbol images.
In operation, the microprocessor 36 sends a command signal to the illuminator 42 to pulse the LEDs for a short time period of 500 microseconds or less, and energizes the imager 40 to collect light from a target symbol substantially only during said time period. A typical array needs about 33 milliseconds to read the entire target image and operates at a frame rate of about 30 frames per second. The array may have on the order of one million addressable image sensors.
The imager 40 itself should have a global electronic shutter in which all the sensors are simultaneously exposed for light capture. Most CCD arrays are designed with a global electronic shutter. A typical CMOS array is designed with a rolling electronic shutter in which different sensors are exposed at different times. If a CMOS array is used, then it must be designed to allow a global electronic shutter.
Reference numeral 120 in FIG. 3 generally identifies an operator- and/or stand-supported, retro-collective moving beam reader for electro-optically reading a target, such as bar code symbol 124, located in a range of working distances therefrom. In response to actuation of the reader as described below, a light beam 123 is directed at the symbol 124. The reader 120 includes a housing 125 in which a light source 126, a light detector 127, signal processing circuitry 128, and a battery pack 129 are accommodated. A pistol grip handle 121 enables an operator to conveniently hold the housing in the palm of his or her hand. A light-transmissive window 130 at a front of the housing enables the light beam 123 to exit the housing, and allows light 131 scattered off the symbol to enter the housing. A keyboard 132 and a display 133 may advantageously be provided on a top wall of the housing for ready access thereto.
In one mode of use, the operator holds the handle 121 and aims the housing at the symbol. In another mode of use, the housing is placed in a countertop cradle or stand, and the housing is aimed at the symbol by the stand. When actuated, the light source 126 emits the light beam 123, which is optically modified and focused by focusing optics 135 to form a beam spot on the symbol 124. The beam travels to a scan mirror 136 which is repetitively oscillated at a scan rate of at least 20 scans a second by a motor drive 138. The scan mirror 136 reflects the beam incident thereon along an outgoing optical path to the symbol 124 for reflection therefrom and sweeps the beam spot across the symbol in a scan pattern. The scan pattern can be a line extending lengthwise along the symbol along a scan direction, or a series of lines arranged along mutually orthogonal directions, or an omnidirectional pattern, just to name a few possibilities.
The reflected light 131 has a variable intensity over the scan pattern and passes through the window 130 along a return path coincident with the outgoing path onto the scan mirror 136 where it is collected and reflected onto the photodetector 127 for conversion to an analog electrical signal. Signal processing circuitry 128 digitizes and decodes the signal under control of a microprocessor 140 to extract the data encoded in the symbol.
FIG. 4 depicts an operator-supported reader including a finger-mounted module 1 and a peripheral module 7. One or more of the components depicted in FIG. 2, but especially the array 40 and the imaging lens 41, are mounted in the module 1 in the case where the reader of FIG. 4 is an imaging reader, and the remaining components are mounted in the peripheral module 7. One or more of the components depicted in FIG. 3, but especially the laser 126, are mounted in the module 1 in the case where the reader of FIG. 4 is a moving beam reader, and the remaining components are mounted in the peripheral module 7. Peripheral module 7 also advantageously includes a battery 7a for supplying power, a receiver 7b for receiving the data from module 1 over a cable 5 connected between the modules, a transmitter 7c for sending data over the cable 5 to the module 1, a cable connector 7d, a microprocessor 7e for controlling operations of the components in module 7, an indicator 7f for indicating a successful reading of a symbol, a wireless transceiver 7g for bidirectional communication with a remote base station or host 13, a keyboard 7h for manual entry of data, a display 7i for displaying information, and a memory 7j for data storage. The cable 5 may be replaced by a wireless link.
Hence, either imaging reader components or moving beam components can be provided in each reader depicted in FIGS. 1-2, 3 and 4, as well as other configurations. In accordance with this invention, the controller 36 of FIG. 2, or the controller 140 of FIG. 3, as depicted in FIGS. 5 and 6, is supported by a mobile reader, and is programmed for sensing when the mobile reader is supported in a steady state by the operator for a predetermined time period, and for automatically actuating the mobile reader in response to sensing the steady state to read indicia such as a symbol while the mobile reader is supported in the steady state by the operator. As earlier defined, the term “steady state” is defined as “stationary or nearly stationary,” that is, the reader and/or the symbol are ideally held motionless relative to each other. However, in practice, this is rarely achieved, since an operator's hand, for example, may shake and introduce, either accidentally or intentionally, at least some component of motion along one or all three mutually orthogonal axes along which the reader and/or the symbol are free to move. Thus, the term “steady state” also encompasses some slight relative motion between the reader and the symbol, the motion being insufficient to blur the symbol during reading.
In a preferred embodiment, as shown in FIG. 5, the photodetector 127 of the moving beam reader 120 generates successive analog electrical signals indicative of the light detected from the symbol 124, and the signal processor 128 includes a digitizer 134 for digitizing the successive analog electrical signals to generate successive digitized signals. The programmed controller 140 is operative for comparing the successive digitized signals over the predetermined time period, preferably about one-fourth of a second to one second in duration, as determined by a timer 150, and for automatically generating a trigger output signal for actuating the reader when the successive digitized signals being compared differ from one another by no more than a predetermined amount. Preferably, the successive digitized signals being compared are identical, or nearly so. A memory 122 is provided for storing the successive digitized signals, and the programmed controller 140 is operative for accessing the memory 122 to retrieve the successive digitized signals stored in the memory 122.
In another preferred embodiment, as shown in FIG. 6, the array 40 of image sensors is operative for generating successive electrical image signals of successive images indicative of the light captured from the symbol 124, and a digital image processor 152 is operative for generating successive digitized image signals therefrom. The programmed controller 36 is operative for comparing the successive digitized image signals and, hence, the successive images over the predetermined time period, preferably about one-fourth of a second to one second in duration, as determined by the timer 150, and for automatically actuating the reader 10 when the successive images being compared differ from one another by no more than a predetermined amount. Preferably, the successive images being compared are identical, or nearly so. The memory 122 is provided for storing the successive images, and the programmed controller 36 is operative for accessing the memory 122 to retrieve the successive digitized image signals and, hence, the successive images stored in the memory 122.
Hence, one feature of this invention is that the mobile reader has no physical trigger subject to breakage as in the prior art. Also, despite the lack of a physical trigger, the mobile reader is not energized all the time, but is only energized when the steady state is detected. This saves electrical energy and increases the lifetime of an on-board battery to power the reader. Energizing the mobile reader when the reader is in the steady state also prevents image blurring since the operator is now forced to present the symbol and/or the reader in a stationary manner relative to each other; otherwise, no reading will occur.
Another energy savings feature of this invention is to automatically shut off the reader after the elapse of a predetermined time period in which the reader is in the steady state. The mobile reader may be placed on a countertop or in a stand and left there for a time waiting for its next use. Rather than allowing the reader to continuously trigger and attempt to read indicia, the programmed controller shuts off the reader after say five minutes of remaining in the steady state.
The triggerless reader of this invention is of particular benefit to parcel delivery personnel. They are typically moving while handling parcels, and maintaining the reader off during such movement saves a great deal of electrical energy. When reading is required, all they need do is hold the reader steady, thereby automatically triggering the reader without using a physical trigger. Preferably, the finger-supported embodiment of FIG. 4 is employed to enable the parcel delivery personnel to have both hands free.
It will be understood that each of the elements described above, or two or more together, also may find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in a triggerless electro-optical reader and method, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. For example, any mobile unit including, but not limited to, computers, may be equipped with the motion stop sensor.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
Patent Application
20080087734
