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What is claimed is:
1. An automatic bar code symbol reading system having an object detection mode of operation, a bar code symbol detection mode of operation, and a bar code symbol reading mode
of operation, said automatic bar code symbol reading system, comprising;
a housing mountable relative to a countertop surface, and having a light transmission aperture through which visible light can exit and enter said housing;
object detection means disposed in said housing for automatically detecting an object located within a portion of a scan field defined external to said housing;
laser beam source in said housing for producing a visible laser beam within said housing;
laser beam directing means in said housing, for directing said visible laser beam through said light transmission aperture and into a scan field defined external to said housing;
scanning mechanism in said housing for scanning said visible laser beam across said scan field and a bar code symbol on said detected object, said scanned visible laser beam flickering in said scan field at a rate in the range from about 0.1 Hz
to about 16 Hz so as to improve the visual conspicuousness of said visible laser beam in said scan field during said bar code symbol detection mode of operation;
light detection means in said housing, for detecting the intensity of laser light reflected off said bar code symbol as said visible laser beam is scanned across said scan field and said bar code symbol, and for automatically producing scan data
indicative of the detected intensity of said reflected laser light;
scan data processing means for processing produced scan data so as to detect and decode said bar code symbol on said detected object, and upon detecting and decoding said bar code symbol on said detected object, automatically producing symbol
character data representative of said decoded bar code symbol; and
control means for controlling the operation of said automatic bar code symbol reading system.
2. The automatic bar code symbol reading system of claim 1, wherein said bar code symbol has first and second envelope borders, and wherein said scan data processing means comprises
means for detecting said first and second envelope borders of said bar code symbol, and
means for decoding said detected bar code symbol.
3. The automatic bar code symbol reading system of claim 1, wherein said housing comprises a hand-supportable structure supported within a stand, and said hand-supportable structure has a head portion and a handle portion, and wherein said laser
beam source, said laser beam directing means, said scanning mechanism, and said light detection means are disposed in said head portion.
4. A method of reading bar code symbols using an automatic laser scanning unit having an object detection mode of operation, a bar code detection mode of operation, and a bar code symbol reading mode of operation, said method comprising the
steps;
(a) supporting said automatic laser scanning unit stationary relative to a countertop surface;
(b) bringing an object in a non-contacting relationship with said automatic laser scanning unit so that said object is located within a least a portion of a scan field defined external to said automatic laser scanning unit;
(c) during said object detection mode, automatically generating an activation signal in response to the detection of said object located in said scan field;
(d) in response to the generation of said activation signal during step (c) and automatically entering said bar code symbol detection mode of operation;
(1) automatically activating a laser beam source and an electrically driven scanning element in said automatic laser scanning unit so as to produce a visible laser beam which (i) is directed through a light transmission aperture in said automatic
laser scanning unit and scanned across said scan field and a bar code symbol on said detected object, and (ii) flickers in said scan field at a rate in the range from about 0.1 Hz to about 16 Hz so as to improve during said bar code symbol detection
mode, the visual conspicuousness of said visible laser beam in said scan field during said bar code detection mode of operation;
(2) automatically detecting at said automatic laser scanning unit, the intensity of laser light reflected off said bar code symbol on said detected object, and automatically producing scan data indicative of the detected intensity of said
reflected laser light, and
(3) automatically processing produced scan data in order to detect said bar code symbol on said detected object;
(e) upon detecting said bar code symbol, automatically entering said bar code symbol reading mode of operation, and continuing to produce scan data indicative of the detected intensity of laser light reflected of said detected bar code symbol,
and automatically processing produced scan data in order to decode said laser bar code symbol on said detected object, and
(f) upon decoding said detected bar code symbol, automatically producing symbol character data representative of said decoded bar code symbol.
5. The method of claim 4 wherein said bar code symbol has first and second envelope borders, and wherein substep (d)(3) comprises detecting said first and second envelope borders of said bar code symbol and decoding said detected bar code
symbol.
6. An automatic bar code symbol reading system for countertop use by a user endowed with a human vision system having a critical flicker frequency, said automatic bar code symbol reading system having an object detection mode of operation, a bar
code symbol detection mode of operation, and comprising:
a housing mountable relative to a countertop surface, and having a light transmission aperture through which visible light can exit and enter said housing;
object detection means in said housing, for automatically detecting, during said object detection mode, the presence of an object within at least a portion of a scan field defined external to said housing;
laser beam source in said housing for producing, a visible laser beam within said housing;
laser beam directing means in said housing, for directing said visible laser beam through said light transmission aperture and into said scan field;
a scanning mechanism in said housing for scanning, during said bar code symbol detection mode and said bar code symbol reading mode, said visible laser beam across said scan field an a bar code symbol on said detected object,
said scanned visible laser beam flickering in said scan field during said bar code symbol detection mode, at a rate below the critical flicker frequency of the user's human visual system so as to improve the visual conspicuousness of said visible
laser beam in said scan field during said bar code symbol detection mode of operation;
light detection means in said housing, for detecting the intensity of laser light reflected off said bar code symbol as said visible laser beam is scanned across said scan field and said bar code symbol during said bar code symbol detection and
bar code symbol reading modes, and for automatically producing scan data indicative of the detected intensity or said reflected laser light;
scan data processing means for processing produced scan data during said bar code symbol detection mode and said bar code symbol reading mode, so as to detect and decode said bar code symbol on said detected object, and upon detecting and
decoding said bar code symbol, automatically producing symbol character data representative of said decoded bar code symbol; and
control means for controlling the operation of said automatic bar code symbol reading system.
7. The automatic bar code symbol reading system of claim 6, wherein said housing comprises a hand-supportable structure supportable in a stand and said hand-supportable structure comprises a head portion and a handle portion, and wherein said
laser beam source, said laser beam directing means, said scanning mechanism, and said light detection means are disposed in said head portion.
8. A method of reading bar code symbols using an automatic laser scanning unit having an object detection mode, a bar code symbol detection mode and a bar code symbol reading mode, said method comprising the steps:
(a) supporting said automatic laser scanning unit stationary relative to countertop surface and a user endowed with a human vision system having critical flicker frequency;
(b) bringing an object in a non-contacting relationship with said automatic laser scanning unit so that said object is located within at least a portion of a scan field defined external to said automatic laser scanning unit and said automatic
laser scanning unit automatically detects said object with at least a portion or said scan field;
(c) automatically generating an activation signal in response to the detection of said object located in said scan field so that said automatic laser scanning unit is induced into said bar code symbol detection mode;
(d) in response to the generation of said activation signal during step (c),
(1) automatically activating a laser beam source and an electrically driven scanning element in said automatic laser scanning unit so as to produce a visible laser beam which is directed through a light transmission aperture in said automatic
laser scanning unit and scanned across said scan field and a bar code symbol on said detected object, and said scanned visible laser beam flickers in said scan field at a rate less than the critical flicker frequency of the user's human visual system, so
as to improve the visual conspicuousness of said visible laser beam in said scan field as said user visually detection mode;
(2) automatically detecting at said automatic laser scanning unit, the intensity of laser light reflected off said bar code symbol on said detected object, and automatically producing scan data indicative of the detected intensity of said
reflected laser light, and
(3) automatically processing produced scan data in order to detect and decode said bar code symbol on said detected object; and
(e) upon detecting and decoding said bar code symbol, automatically producing symbol character data representative of said decoded bar code symbol.
9. The method of claim 8, wherein said bar code symbol has first and second envelope borders, and wherein substep (d)(3) comprises detecting said first and second envelope borders of said bar code symbol and decoding said detected bar code
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BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates generally to laser scanning systems, and more particularly to an automatic bar code symbol reading system having an automatic hand-supportable laser scanner which can be utilized in diverse lighting environments with
natural hand movements, while conserving electrical power.
2. BRIEF DESCRIPTION OF THE PRIOR ART
Bar code symbols have become widely used in many commercial environments such as, for example, point-of-sale (pos) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications.
To meet the growing demands of this recent innovation, bar code symbol readers of various types have been developed for scanning and decoding bar code symbol patterns. Typically, the symbol character data produced from such bar code readers is
provided as input to automated data processing systems.
In general, prior art hand-held bar code symbol readers using laser scanning mechanisms can be classified into three categories.
The first category of hand-held bar code symbol readers includes systems having manually-actuated laser scanners which can be supported in the hand of the user. The user positions the hand-held laser scanner at a specified distance from the
object bearing the bar code symbol, manually activates the scanner to initiate reading (e.g. by pulling a trigger), and then moves the scanner over other objects bearing bar code symbols to be read. Prior art bar code symbol readers illustrative of this
first category are disclosed in U.S. Pat. Nos. 4,387,297 to Swartz; 4,575,625 to Knowles; 4,639,606 to Boles et al., 4,845,349 to Cherry; 4,825,057 to Swartz, et al.; 4,903,848 to Knowles; 4,933,538 to Heiman, et al.; 5,107,100 to Shepard, et al.;
5,080,456 to Katz, et al.; and 5,047,617 to Shepard et al.
The second category of hand-held bar code symbol readers includes systems utilizing hand-held scanners which have (i) a tungsten bulb, a Xenon lamp, or light emitting diodes (LEDs) to radiate light onto a bar code symbol, and (ii) an
electronically scanned image sensor (e.g. CCD array) for converting the image of light reflected off the bar code symbol into a corresponding signal for decode processing. Exemplary systems of this type are disclosed in U.S. Pat. Nos. 4,570,057 to
Chadima, et al., 4,818,847 to Hara, et al and 4,877,949 to Danielson, et al.
The third category of hand-held bar code symbol readers include systems utilizing fully automated hand-held laser scanners having intelligent programs which control the operation device under diverse user operating conditions. Exemplary systems
of this type of bar code symbol reading technology are disclosed in pending U.S. application Ser. Nos. 07/898,919 and 07/761,123.
While prior art hand-held manually triggered and CCD type scanners have played an important role in the development of the bar code symbol industry, these devices, suffer from a number of shortcomings and drawbacks. For example, hand-held
manually-actuated laser scanners, although portable and lightweight, are not always convenient to use particularly in applications where the user must read bar coded objects over an extended period of time. In many applications, where bar coded objects
to be identified reside at arms length from the user's reach, hand-held CCD scanners are difficult to operate owing to their limited depth of field.
Unlike manually automated hand-held bar code scanners, fully automatic hand-held laser scanners do not cause fatigue due to their automatic operation. Also, owing to their extended depth of field, automatic hand-held laser scanners provide
increased flexibility by allowing the user to read bar coded objects residing at distances of six or more inches away from the scanner. However, even though automatic hand-held laser bar code scanners offer superior performance in most scanning
applications, it has been found that in intensely illuminated scanning environments, the user's ability to perceive the visible laser scanning beam is significantly diminished in the scan field of the device. Consequently, in such scanning environments,
it is difficult to visually align (i.e. register) the laser scanning beam with the bar code symbol to be scanned, thus hindering the automatic bar code symbol reading process. While the use of a higher power visible laser beam might render the beam more
easily perceptible, this approach is undesirable for laser safety and power consumption reasons.
Thus, there is a great need in the bar code symbol reading art for a hand-supportable laser bar code symbol reading system which overcomes the above described shortcomings and drawbacks of prior art devices and techniques, while permitting use
over a diverse range of laser scanning environments.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide an automatic hand-supportable laser scanning device which utilizes psychophysiological response characteristics of the human visual system in order to produce a visible laser
scanning beam that has improved user perceptibility over the scan field of the device.
A further object of the present invention is to provide such an automatic hand-supportable laser scanning device in which a visible laser beam is pulsed at a sufficient low frequency over the scan field of the device during its bar code presence
detection mode of operation, so as to increase the visual conspicuousness of the laser scanning beam.
It is another object of the present invention to provide such an automatic bar code symbol reading system in which one or more bar code symbols on an object can be consecutively read without requiring unnatural hand-movements of the automatic
hand-supportable laser scanning device.
A further object is to provide such an automatic bar code symbol reading system, in which the automatic hand-supportable bar code (symbol) scanning device has an infrared light object detection field which spatially encompasses at least a portion
of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the device during the automatic bar code reading process of the present invention.
Another object of the present invention is to provide an automatic bar code symbol reading system in which the hand supportable laser scanning device can be used as either a portable hand-supported laser scanner in an automatic hands-on mode of
operation, or as a stationary laser projection scanner in an automatic hands-free mode of operation.
Another object of the present invention is to provide such an automatic bar code reading system in which a support frame is provided for supporting the hand-supportable housing of the device in a selected mounting position, and permitting
complete gripping of the handle portion of the hand-supportable housing prior to removing it from the support frame.
A further object of the present invention is to provide such an automatic bar code symbol reading system in which the hand-supportable bar code reading device has long and short-range modes of object detection within its object detection field.
In one illustrative embodiment, the long and short-range modes of object detection are manually selectable by the user by manual activation of a switch on the hand-supportable housing of the device. In another illustrative embodiment, the long-range
mode of object detection is automatically selected when the hand-supportable bar code reading device is placed within the support s;and during the hands-free mode of operation. In this illustrative embodiment the short-range mode of object detection is
automatically selected whenever the hand-supportable bar code reading device is picked up from the support stand and used in its hands-on mode of operation. A further object of the present invention is to provide such an automatic bar code symbol
reading system, in which the hand-supportable bar code reading device has long and short-range modes of bar code presence detection within its scan field. In one illustrative embodiment, the short-range mode of bar code presence detection is manually
selectable by manual activation of a switch on the hand-supportable housing of the device. In another illustrative embodiment, the short-range mode of bar code presence detection is automatically selected when the hand-supportable bar code reading
device is placed within the support stand, or alternatively, upon decoding a predesignated bar code symbol preprogrammed to induce the short-range mode of bar code presence detection. In the short-range mode of bar code presence detection, the automatic
bar code reading device not only detects the presence of a bar code within the scan field by analysis of collected scan data, but it further processes the collected scan data to produce digital count data representative of the measured time interval
between bar and/or space transitions. Bar code symbols present within the short-range of the scan field, produce scan data having time interval characteristics falling within a prespecified timing data range. Using the results of this analysis, only
bar code symbols scanned within the short-range field are deemed "detected," and only bar code symbols detected within the short-range of the scan field activate the decoding module of the device and thus enable bar code symbol reading.
A further object of the present invention is to provide such an automatic bar code symbol reading system in which the hand-supportable bar code reading device has long and short-range modes of bar code symbol reading within its scan field.
In one illustrative embodiment, the long and short-range modes of bar code symbol reading are manually selectable by the user by manual activation of a switch on the hand-supportable housing of the device.
It is a further object of the present invention to provide such an automatic bar code symbol reading system, in which the long-range mode of object detection is automatically selected when the hand-supportable bar code reading device is placed
within the support stand during the hands-free mode of operation, or alternatively, upon decoding a predesignated bar code symbol preprogrammed to induce the mode of bar code symbol reading. In this illustrative embodiment, the short-range mode of
object detection is automatically selected whenever the hand-supportable bar code reading device is picked up from the support stand and used in its hands-on mode of operation. In this short-range mode of bar code symbol reading, the only decoded bar
code symbols residing within the short-range portion of the scan field, are deemed "read".
It is another object of the present invention to provide an automatic hand-supportable bar code reading device which has both long and short-range modes of object detection and bar code symbol reading, automatically selectable by placing the
hand-supportable device within its support stand and removing it therefrom. With this particular embodiment of the present invention, the automatic bar code symbol reading system can be used in various bar code symbol reading applications, such as, for
example, charge coupled device (CCD) scanner emulation and bar code "menu" reading in the hands-on short-range mode of operation, and counter-top projection scanning in the hands-free long-range mode of operation.
An even further object of the present invention is to provide an automatic hand-supportable bar code reading device which prevents multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon a bar code symbol for
an extended period of time.
A further object of the present invention is to provide a point-of-sale station incorporating the automatic bar code symbol reading system of the present invention.
It is a further object of the present invention to provide an automatic hand-supportable bar code reading device having a control system which has a finite number of states through which the device may pass during its automatic operation, in
response to diverse conditions automatically detected within the object detection and scan fields of the device.
It is yet a further object of the present invention to provide a portable, fully automatic bar code symbol reading system which is compact, simple to use and versatile.
Yet a further object of the present invention is to provide a novel method of reading bar code symbols using a automatic hand-supportable laser scanning device.
These and further objects of the present invention will become apparent hereinafter and in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the objects of the present invention, the Detailed Description of the Illustrated Embodiment of the Present Invention will be taken in connection with the drawings, wherein:
FIG. 1 is a perspective view of the illustrative embodiment of the automatic bar code symbol reading system of the present invention, showing the hand-supportable laser bar code symbol reading device supported within the scanner support stand for
automatic hands-free operation;
FIG. 1A is an elevated front view of the automatic bar code symbol reading system of FIG. 1, showing the light transmission window of the hand-supportable bar code symbol reading device while supported within the scanner support stand;
FIG. 1B is a plan view of the automatic bar code symbol reading system shown in FIG. 1;
FIG. 1C is a bottom view of the automatic bar code symbol reading system shown in FIG. 1;
FIG. 2 is a perspective view of the automatic hand-supportable bar code symbol reading device of the system hereof, shown being used in the automatic hands-on mode of operation;
FIG. 2A is a elevated, cross-sectional side view taken along the longitudinal extent of the automatic bar code symbol reading device of FIG. 2, showing various hardware and software components utilized in realizing the illustrative embodiment of
the automatic hand-supportable bar code symbol reading device of the present invention;
FIG. 2B is a cross-sectional plan view taken along line 2B--2B of FIG. 2A, showing the various components used in realizing the illustrative embodiment of the automatic bar code symbol reading device;
FIG. 2C is an elevated partially fragmented cross-sectional view of the head portion of the automatic hand supportable bar code symbol reading device of the present invention, illustrating an electro-optical arrangement utilized in transmitting
pulsed infrared light signals over the object detection field of the device;
FIG. 2D is an elevated partially fragmented cross-sectional view of the head portion of the automatic hand-supportable bar code symbol reading device of the present invention, illustrating the electro-optical arrangement utilized in producing the
object detection field of the device;
FIG. 3 is an elevated side view of the hand-supportable bar code symbol reading device of the illustrative embodiment of the present invention, illustrating the spatial relationship between the object detection and scan fields of the device, and
the long and short-ranges of programmed object detection, bar code presence detection, and bar code symbol reading;
FIG. 3A is a plan view of the automatic hand-supportable bar code symbol reading device taken along line 3A--3A of FIG. 3;
FIG. 4 is a system block functional diagram of the automatic hand-supportable bar code symbol reading device of the present invention, illustrating the principal components integrated with the system controller thereof;
FIG. 5 is a block functional diagram of a first embodiment of the object detection mechanism for the automatic hand-supportable bar code symbol reading device of the present invention;
FIG. 6 is a schematic diagram illustrating the intensity versus time characteristics of the visible laser scanning beam produced during the bar code presence detection mode of operation of the automatic hand-supportable bar code symbol reading
device of the present invention;
FIGS. 7A and 7B, taken together, show a high level flow chart of a system control program (i.e. Main System Control Routine) contained within the control system of the automatic bar code symbol reading device, illustrating various courses of
programmed system operation that the illustrative embodiment may undergo;
FIGS. 8A, 8B and 8B.sup.1 taken together, show a high level flow chart of an auxiliary system control program (i.e. Auxiliary System Control Routine with Range Selection), which provides the hand-supportable automatic bar code symbol reading
device of the present invention with several selectable modes of object detection, bar code presence detection and bar code symbol reading;
FIG. 9 is a state diagram illustrating the various states that the automatic hand-supportable bar code symbol reading device of the illustrative embodiment may undergo during the course of its programmed operation;
FIG. 10 is a perspective view of the support frame of the scanner support stand of the present invention;
FIG. 10A is a perspective view of the base plate of the scanner support stand of the present invention, with the adapter module mounted thereon;
FIG. 10B is a perspective, partially broken away view of the assembled scanner support stand of the present invention, showing the scanner cable, power supply cable and communication cable operably associated therewith and routed through
respective apertures formed in-the scanner support frame;
FIGS. 11A through 11D are perspective views of a point-of-sale system, showing the scanner support stand of the present invention supported on a horizontal countertop surface and operably connected to an electronic cash register, with the
automatic hand-supportable bar code symbol reading device being used in its hand-held short-range mode of operation;
FIGS. 12A and 12B are perspective views illustrating the steps carried out during the installation of the scanner support stand of the present invention onto a vertical counter wall surface;
FIG. 13 is an elevated side view of the automatic bar code symbol reading system of the present invention, shown mounted onto the vertical counter wall surface of FIGS. 12A and 12B;
FIG. 13A is a plan view of the automatic bar code symbol reading system of the present invention taken along line 13A--13A of FIG. 13;
FIG. 13B is a cross-sectional view of the scanner support stand of the present invention, taken along line 13B--13B of FIG. 13;
FIG. 13C is a cross-sectional view of the assembled scanner stand, taken along line 13C--13C of FIG. 15A;
FIG. 14 is perspective views showing the scanner support stand mounted on a vertical counter wall surface, and the automatic hand-supportable bar code symbol reading device being used in its automatic hands-free long-range mode of operation;
FIGS. 15A and 15B are perspective views showing the scanner support stand mounted on a vertical counter wall surface, and the automatic hand-supportable bar code symbol reading device being used in its automatic hand-held short-range mode of
operation;
FIG. 16 is a perspective view of a point-of-sale station according to the present invention, showing the scanner support stand pivotally supported above a horizontal counter surface by way of a pedestal base mounted under an electronic cash
register, and the automatic hand-supportable bar code symbol reading device received in the scanner support stand and being used in its automatic hands-free long-range mode of operation;
FIG. 17A and 17B are perspective views of a point-of-sale station according to the present invention, showing the scanner support stand pivotally supported above a horizontal counter surface by way of the pedestal base illustrated in FIG. 16, and
the automatic hand-supportable bar code symbol reading device being used in its automatic hand-held short-range mode of operation;
FIG. 18 is an elevated side view of the point-of-sale system of FIGS. 16A, 16B and 17, illustrating the rotational freedom of the scanner support stand about the x axis of the pivotal joint assembly;
FIG. 18A is an elevated, partially cross-sectional view of the base plate of the scanner support stand and the pivotal joint assembly connecting the scanner support stand to the pedestal base so as to provide three-degrees of freedom to the
scanner support stand with respect to the stationary pedestal base;
FIG. 18B is a partially fragmented view of the scanner support stand, pivotal joint assembly and pedestal base taken along the y axis of the pivotal joint assembly, illustrating the rotational freedom of the scanner support stand about the axis;
and
FIG. 18C is a perspective view of the scanner support stand and pedestal base assembly taken along the -z axis of the pivotal joint assembly, illustrating the rotational freedom of the scanner support stand about the z axis of the pivotal joint
assembly.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT OF THE PRESENT INVENTION
In FIGS. 1 and 11A through 11D, the automatic laser bar code symbol reading system of the present invention is illustrated. As shown, automatic bar code symbol reading system 1 comprises a portable, automatic hand-supportable bar code (symbol)
reading device 2 operably associated with support stand 3 of the present invention. Operable interconnection of hand-supportable bar code reading device 2 and scanner support stand 3 is achieved by a flexible multlwire scanner cable 5 extending from bar
code symbol device 2 into scanner support stand 3. Operable interconnection of scanner support stand 3 and a host system 6 (e.g. electronic cash register system, data collection device, etc.) is achieved by a flexible multiwire communications cable 7
extending from scanner support stand 3 and plugged directly into the data-input communications port of host system 6. In the illustrative embodiment, electrical power from a low voltage power supply (not shown) is provided to scanner support stand 3 by
way of a flexible power cable 8.
As illustrated in FIG. 1 through 1C, scanner support stand 3 is particularly adapted for receiving and supporting hand-supportable bar code reading device 2 in a selected position without user support, thus providing a stationary, automatic
hands-free mode of operation. In general, hand-supportable bar code reading device 2 includes an ultra-light weight hand-supportable housing 9 having a contoured handle portion 9A and a head portion 9B. As will be described in greater detail
hereinafter, head portion 9B encloses electro-optical components which are used to generate and project a visible laser beam through a light transmissive window 10, and to repeatedly scan the projected laser beam across a scan field 11 defined external
to the hand-supportable housing.
As illustrated in FIGS. 1 through 1C, scanner support stand 3 includes a support frame 12 which comprises a base portion 12A, a head portion support structure 12B, handle portion support structure 12C and a finger accommodating recess 12D. As
shown, base portion 12A has a longitudinal extent and is adapted for selective positioning with respect to a support surface, e.g.-countertop surface, counter wall surface, etc. Head portion support structure 12B is operably associated with base portion
12A, for receiving and supporting the head portion of the hand-supportable bar code reading device. Similarly, handle portion support structure 12C is operably associated with base portion 12A, for receiving and supporting the handle portion of the
hand-supportable bar code symbol reading device. In order that the user's hand can completely grasp the handle portion of the hand-supportable bar code reading device, that is prior to removing it off and away from the scanner support stand as
illustrated in FIG. 14A, finger accommodating recess 12D is disposed between head and handle portion support structures 12B and 12C and above base portion 12A of the support frame. In this way, finger accommodating recess 12D is laterally accessible as
shown in FIG. 13 so that when the handle and head portions 9A and 9B are received within and supported by handle portion support structure 12B and head portion support structure 12C, respectively, the fingers of a user's hand can be easily inserted
through finger accommodating recess 12D and completely encircle the handle portion of the hand-supportable device, as illustrated in FIG. 14A.
A more detailed description of the structure, functions and operation of the scanner support stand of the present invention will be provided hereinafter referring to FIGS. 10 through 16B. However, referring to FIGS. 1 and 10 through 13,
attention will be first accorded to the illustrative embodiment of the automatic hand-supportable bar code reading device of the invention.
As illustrated in FIGS. 2 through 2B in particular, head portion 9B continuously extends into contoured handle portion 9A at an obtuse angle which, in the illustrative embodiment, is about 146 degrees. It is understood, however, that in other
embodiments obtuse angle may be in the range of about 135 to about 180 degrees. As this ergonomic housing design is sculptured (i.e. form-fitted) to the human hand, automatic hands-on scanning is rendered as easy and effortless as waving ones hand.
Also, this ergonomic housing design eliminates the risks of musculoskeletal disorders, such as carpal tunnel syndrome, which can result from repeated biomechanical stress commonly associated with pointing prior art gun-shaped scanners at bar code
symbols, squeezing a trigger to activate the laser scanning beam, and then releasing the trigger.
As illustrated in FIGS. 2 through 3A, the head portion of housing 9 has a transmission aperture 13 formed in upper portion of front panel 14A, to permit visible laser light to exit and enter the housing, as will be described in greater detail
hereinafter. The lower portion of front panel 14B is optically opaque, as are all other surfaces of the hand supportable housing.
As illustrated in FIGS. 2, 3 and 3A in particular, automatic hand-supportable bar code reading device 2 generates two different fields external to the hand-supportable housing, in order to carry out automatic bar code symbol reading according to
the principles of the present invention. The first field, referred to as the "object detection field", indicated by broken and dotted lines, is provided externally to the housing for detecting energy reflected off an object bearing a bar code symbol,
located within the object detection field. The second field, referred to as the "scan field", having at least one laser beam scanning plane is provided external to the housing for scanning a bar code symbol on an object in the object detection field.
In the preferred embodiment, such scanning is achieved with a visible laser beam which, after reflecting off an object in the object detection field, produces laser scan data which is collected for the purpose of detecting the presence of a bar code
symbol within the scan field, and for subsequently reading (i.e. scanning and decoding) the detected bar code symbol.
In general, detected energy reflected from an object during object detection can be optical radiation or acoustical energy, either sensible Dr non-sensible by the user, and may be either generated from the automatic bar code reading device or an
external ambient source. As will be described in greater detail hereinafter, the provision of such energy is preferably achieved by transmitting a wide beam of pulsed infrared (IR) light away from transmission aperture 13, substantially parallel to
longitudinal axis 15 of the head portion of the hand-supportable housing. In the preferred embodiment, the object detection field, from which such reflected energy is collected, is designed to have a narrowly diverging pencil-like geometry of
three-dimensional volumetric expanse, which is spatially coincident with at least a portion of the transmitted infrared light beam. This feature of the present invention ensures that an object residing within the object detection field will be
illuminated by the infrared light beam, and that infrared light reflected therefrom will be directed generally towards the transmission aperture of the housing where it can be automatically detected to indicate the presence of the object within the
object detection field. In response, a visible laser beam is automatically generated within the head portion of the housing, projected through the transmission aperture and repeatedly scanned across the scan field, within which at least a portion of the
detected object will reside. At least a portion of the scanned laser light beam will be scattered and reflected off the object and directed back towards and through light transmissive window 10 for collection and detection within the head portion of the
housing, and subsequently processed in a manner which will be described in detail hereinafter. To ensure that the user can quickly align the visible laser beam with bar code symbol on the detected object, the object detection field is designed to
spatially encompass at least a portion of the scan field along the operative scanning range of the device, as illustrated in FIGS. 3 and 3A. This structural feature of the present invention provides the user with an increased degree of control, as once
an object is detected, minimal time will be required by the user to point the visible laser beam towards the bar code symbol for scanning. In effect, the laser beam pointing efficiency of the device is markedly improved during the automatic bar code
reading process, as it is significantly easier for the user to align the laser beam across the bar code symbol upon object detection.
To more fully appreciate the mechanisms employed in order to generate the object detection and scan fields of automatic bar code reading device of the present invention, reference is best made to the operative elements contained within the
hand-supportable housing of the device.
As shown in FIG. 4, automatic bar code reading device 2 comprises a number of system components, namely, an object detection circuit 16, laser scanning mechanism 17, photoreceiving circuit 18, analog-to-digital (A/D) conversion circuit 19, bar
code presence detection module 20, bar code scan range detection module 21, symbol decoding module 22, data format conversion module 23, symbol character data storage unit 24, and data transmission circuit 25. In addition, a magnetic field sensing
circuit 26 is provided for detecting scanner support stand 3, while a manual switch 27 is provided for selecting long or short-range modes of object detection, bar code presence detection and/or bar code symbol reading, which will be described in great
detail hereinafter. As illustrated, these components are operably associated with a programmable system controller 28 which provides a great degree of versatility in system control, capability an operation. The structure, function and advantages of
this system controller will become apparent hereinafter.
In the illustrated-embodiment, system controller 28, bar code presence detection module 20, bar code scan range detection module 21, symbol decoding module 22, and data format conversion module 23 are realized using a single programmable device,
such as a microprocessor having accessible program and buffer memory, and external timing circuitry. It is understood, however, that any of these elements may be realized using separate discrete components as will be readily apparent to those with
ordinary skill in the art.
Automatic hand-supportable bar code reading device 2 also includes power receiving lines 29 which lead to conventional power distribution circuitry (not shown) for providing requisite power to each of the system components, when and for time
prescribed by the system controller. As illustrated, power receiving lines 29 run alongside data communication lines 30 and are physically associated with multi-pin connector plug 31 at the end of flexible scanner cable 5. An on/off power switch or
functionally equivalent device (not shown) may be provided external the hand-supportable housing to permit the user to selectively energize and deenergize the device. In the illustrative embodiment, power delivered through flexible scanner cable 5 to
the bar code symbol reading device is continuously provided to system controller 28 so as to continuously enable its operation, while only biasing voltages and the like are provided to all other system components. In this way, each system component must
be activated (i.e. enabled) by the system controller in accordance with its preprogrammed system control routine.
In accordance with the present invention, the purpose of the object detection circuit is to determine whether an object (e.g., product, document, etc.) is present or absent from the object detection field over particular time intervals specified
by the system controller. When an object is detected within the object detection field, the object detection circuit produces first control activation signal A.sub.1 =1, which like all control activation signals, is provided as input to system
controller 28. As will be described in greater detail hereinafter, depending on the particular stage of the system control process, the system controller will respond to this event by causing the bar code reading device to undergo a transition from the
object detection state to the bar code symbol (presence) detection state.
In FIG. 5, a preferred technique is disclosed for detecting the presence of an object within the object detection field. In essence, object detection circuit 16A operates by transmitting a pulsed infrared (IR) light signal forwardly into the
object detection field. First control activation signal A is generated upon receiving a reflection of the transmitted signal from an object residing within the object detection field. As illustrated, object detection circuit 16A is realized as an IR
sensing circuit which comprises a synchronous receiver/transmitter 33 and an infrared LED 34 which generates a 940 nanometer pulsed signal at a rate of 20.0 KHZ. This pulsed IR signal is transmitted through focusing lens 35 to illuminate the object
detection field. When an object is present within the object detection field, a reflected IR pulse signal is produced from the surface of the object, spatially filtered by aperture stop 65B and focused through focusing lens 36 onto photodiode 37.
Notably, (i) selection of the optical characteristics of aperture stop 65B and lens 36 and (ii) the placement of photodiode 37 (with integrally formed lens 36) behind aperture stop 65B directly determine the geometric characteristics of the object
detection field. Consequently, these optical parameters are selected so as to provide an object detection field which, as hereinbefore explained, spatially encompasses at least a portion of the scanning field along the operative scanning range of the
device.
As illustrated in FIG. 5, the output of photodiode 37 is converted to a voltage by current-to-voltage amplifier 38, and the output thereof is provided as input to synchronous receiver/transmitter 33 which synchronously compares the received IR
signal with the transmitted IR signal to determine whether an object is present in or absent from the object detection field. If the object is present in the object detection field, then synchronous receiver/transmitter 33 produces first control
activation signal A.sub.1 =1, indicative of this condition. Upon generation of first control activation signal A.sub.1 =1, the system controller activates the operation of laser scanning mechanism 17, photoreceiving circuit 18, A/D conversion circuit
19, and bar code presence detection module 20 according to a preprogrammed system control routine, the details of which will be described hereinafter.
Alternatively, the automatic bar code reading device of the present invention can be readily adapted to sense ultrasonic energy reflected off an object present within the object detection field. In such an alternative embodiment, object
detection circuit 16 is realized as an ultrasonic energy transmitting/receiving mechanism. In the head portion of hand-supportable housing 9, ultrasonic energy is generated and transmitted forwardly of the housing head portion into the object detection
field. Then, ultrasonic energy reflected off an object within the object detection field is detected closely adjacent the transmission window using an ultrasonic energy detector. Preferably, a focusing element is disposed in front of the detector in
order to effectively maximize the collection of reflected ultrasonic energy. In such instances, the focusing element essentially determines the geometrical characteristics of the object detection field of the device. Consequently, as with the other
above-described object detection circuits, the energy focusing (i.e. collecting) characteristics of the focusing element will be selected to provide an object detection field which spatially encompasses at least a portion of the scan field.
For purposes of illustration, object detection circuit 16 shown in FIG. 5, is provided with two different modes of detection, namely, a long-range mode of object detection and a short-range mode of object detection. As shown in FIG. 4, these
modes are set by the system controller using mode enable signals E.sub.IRT =0 and E.sub.IRT =1, respectively. When induced into the long-range mode of object detection, the IR sensing circuit will generate first control activation signal A.sub.1 =1
whenever an object has been detected within the operative range of the object detection field, independent of the particular distance at which the object resides from the transmissive window. When induced into the short-range mode of object detection,
the IR sensing circuit will generate first activation control signal A.sub.1 =1 only when an object is detected at a distance within the short-range of the object detection field.
As schematically indicated in FIGS. 3 and 3A, the long-range specification for object detection is preferably preselected to be the full or entire range of sensitivity provided by IR sensing circuit 16A (e.g. 0 to about 10 inches). Preferably,
the short-range specification for object detection is preselected to be the reduced range of sensitivity provided by the IR sensing circuit when mode enable signal E.sub.IRT =1 is provided to the desensitization port of synchronous receiver/transmitter
33. In the illustrated embodiment, the short-range of object detection is a | | |
