US 6959871 B1
A compact assembly for electro-optically scanning indicia includes an oscillatable component operative for focusing, and for sweeping, a light beam across the indicia and, optionally, for correcting for scan aberration. A laser diode for emitting the beam is inserted into a central opening surrounded by an electromagnetic coil to conserve space. A magnet on the component interacts with the coil to effect oscillation. A floating flexure returns the component to an equilibrium position.
1. A terminal for executing a program, comprising: a reader for electro-optically reading machine-readable indicia constituting machine-executable instructions of the program; a processor for decoding the instructions and for self-executing the program to create a network site; and a display for displaying the network site.
2. The terminal as claimed in
3. The terminal as claimed in
4. The terminal as claimed in
5. The terminal as claimed in
6. The terminal as claimed in
7. The terminal as claimed in
8. The terminal as claimed in
9. The terminal as claimed in
10. A system for executing a program, comprising: a terminal including a computer network interface, a reader for electro-optically reading machine-readable indicia constituting machine-executable instructions of the program, a processor for decoding the instructions and for self-executing the program to obtain data to create a network site and a display for displaying the network site; and a storage medium on which the indicia is printed and read by the reader; and wherein the interface transmits the data via the interface to a computer network.
11. The system as claimed in
12. An optical reading and processing device for optically acquiring a computer-executable program encoded in the form of a two-dimensional bar code symbol on a storage medium, comprising:
a bar code reader for electro-optically reading the two-dimensional bar code symbol;
a transmitter for sending data over a communication link;
a processor for decoding the read two-dimensional bar code symbol to obtain the computer-executable program encoded therein, and for either executing the program to create a network site or causing the program to be transmitted via the communication link to a remote computer for execution to create the network site; and
a display for displaying the network site.
13. The device as claimed in
14. The device as claimed in
15. The device as claimed in
16. The device as claimed in
17. A method of optically acquiring and using a computer-executable program encoded in the form of a two-dimensional bar code symbol on a printed page via an optical reading and processing device, comprising the steps of:
reading the two-dimensional bar code symbol;
decoding the read two-dimensional bar code symbol to obtain the computer-executable program encoded therein;
executing the program to create a network site; and
displaying the network site.
18. The method as claimed in
This application is a continuation-in-part of pending U.S. patent application Ser. No. 09/379,153, filed Aug. 23, 1999 now U.S. Pat. No. 6,283,372, which in turn is a division of U.S. patent application Ser. No. 09/167,880, filed Oct. 7, 1998 now U.S. Pat. No. 6,412,697, which in turn is a continuation of U.S. patent application Ser. No. 08/595,162, filed Feb. 1, 1996, now U.S. Pat. No. 5,861,615, which in turn is a continuation of U.S. patent application Ser. No. 08/153,053, filed Nov. 17, 1993, now U.S. Pat. No. 5,504,316, which in turn is a continuation-in-part of U.S. patent application Ser. No. 07/868,401, filed Apr. 14, 1992, now U.S. Pat. No. 5,280,165, which in turn is a division of U.S. patent application Ser. No. 07/520,464, filed May 8, 1990, now U.S. Pat. No. 5,168,149. This application is also a continuation-in-part of U.S. patent application Ser. No. 08/037,143, filed Mar. 25, 1993, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 07/715,267, filed Jun. 14, 1991, now U.S. Pat. No. 5,235,167. This application is also a continuation-in-part of U.S. patent application Ser. No. 07/981,448, filed Nov. 25, 1992, now U.S. Pat. No. 5,478,997. This application is further a continuation-in-part of U.S. patent application Ser. No. 08/028,107, filed Mar. 8, 1993, now U.S. Pat. No. 5,408,081.
This invention relates generally to hand-held scanning systems which “read” indicia, such as barcode symbols, and in particular to systems and methods for scanning one-dimensional (1-D) and two-dimensional (2-D) barcode symbols with a first scan pattern that is relatively small and dense so as to be visible to the user, and thereafter a second, larger and more robust scan pattern for decoding. The invention also relates to scanners operable in both portable (hand-held) and surface mounted (hands-free) modes for reading various types of indicia. The invention further relates to novel miniature assemblies capable of 1-D and 2-D scanning.
Various optical readers and scanning systems have been developed for reading barcode symbols appearing on a label or the surface of an article. The barcode symbol itself is a coded pattern of indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light-reflecting characteristics. The readers and scanning systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alpha-numerical characters intended to be descriptive of the article or some characteristic of it. Such characters typically are represented in digital form, and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,360,798; 4,369,361; 4,387,297; 4,409,470 and 4,460,120, all assigned to the assignee of the present invention.
One embodiment of such a scanning system, as disclosed in some of the above patents, resides in, inter alia, a hand-held, portable laser scanning head supported by a user. The scanning head is configured to enable the user to aim the head at a target to emit a light beam toward a symbol to be read. The light source is a laser scanner typically in the form of a gas or semiconductor laser element. Use of semiconductor devices as the light source in scanning systems is particularly desirable because of the small size, low cost and low power requirements of semiconductor lasers. The laser beam is optically modified, typically by a lens, to form a beam spot of a certain size at the target distance. Preferably, the beam spot size at the target distance is approximately the same as the minimum width between regions of different light reflectivity, i.e., the bars and spaces of the symbol.
The barcode symbols are formed from bars or elements typically rectangular in shape with a variety of possible widths. The specific arrangement of elements defines the character represented according to a set of rules and definitions specified by the code or “symbology” used. The relative size of the bars and spaces is determined by the type of coding used, as is the actual size of the bars and spaces. The number of characters per inch represented by the barcode symbol is referred to as the density of the symbol. To encode a desired sequence of characters, a collection of element arrangements are concatenated together to form the complete barcode symbol, with each character of the message being represented by its own corresponding group of elements. In some symbologies a unique “start” and “stop” character is used to indicate where the barcode begins and ends. A number of different barcode symbologies exist. These symbologies include UPC/EAN, Code 39, Code 128, Codabar, and Interleaved 2 or 5.
In order to increase the amount of data that can be represented or stored on a given amount of surface area, several new barcode symbologies have recently been developed. One of these new code standards, Code 49, introduces a “two-dimensional” concept by stacking rows of characters vertically instead of extending the bars horizontally. That is, there are several rows of bar and space pattern, instead of only one row. The structure of Code 49 is described in U.S. Pat. No. 4,794,239, which is hereby incorporated by reference.
A one-dimensional single-line scan, as ordinarily provided by hand-held readers, functions by repetitively scanning the light beam in a line or series of lines across the symbol using a scanning component such as a mirror disposed in the light path. The scanning component may either sweep the beam spot across the symbol and trace a scan line across and past the symbol, or scan the field in view of the scanner, or do both.
Scanning systems also include a sensor or photodetector, usually of semiconductor type, which functions to detect light reflected from the symbol. The photo-detector is therefore positioned in the scanner or in an optical path in which it has a field of view which extends across and slightly past the symbol. A portion of the reflected light which is reflected off the symbol is detected and converted into an electrical signal, and electronic circuitry or software decodes the electrical signal into a digital representation of the data represented by the symbol that has been scanned. For example, the analog electrical signal from the photodetector may typically be converted into a pulse width modulated digital signal, with the widths corresponding to the physical widths of the bars and spaces. Such a signal is then decoded according to the specific symbology into a binary representation of the data encoded in the symbol, and to the alphanumeric characters so represented.
The decoding process in known scanning systems usually works in the following way. The decoder receives the pulse width modulated digital signal from the scanner, and an algorithm implemented in software attempts to decode the scan. If the start and stop characters and the characters between them in the scan were decoded successfully and completely, the decoding process terminates and an indicator of a successful read (such as a green light and/or an audible beep) is provided to the user. Otherwise, the decoder receives the next scan, performs another decode attempt on that scan, and so on, until a completely decoded scan is achieved or no more scans are available.
More sophisticated scanning, described in U.S. Pat. No. 5,235,167, assigned to the common assignee, and incorporated herein by reference, carries out selective scanning of 1-D and 2-D barcodes. Preliminary information, such as the barcode type and size, is preliminarily decoded during an aiming mode of operation when a relatively narrow and visible raster pattern is impinged on the target. Based upon the preliminary information, received by the scanner in the form of light reflected from the target, converted to an electrical signal and decoded, an appropriately sized raster scan pattern is generated. If the barcode pattern is found to be skewed or misaligned with respect to the direction of the raster scanning pattern, the pattern is generated with an orientation in alignment with the barcode. Aligning the scan pattern to the barcode is awkward, especially for long range scanning. If a barcode is not horizontally positioned on, for example, a container, the user is forced to position the scanner sideways in order to scan the barcode. One possible solution, described in the aforementioned U.S. Pat. No. 5,235,167, is to control the scanner to self-orient the scan pattern to the orientation of the barcode.
Scanning 2-D, or PDF, barcodes with a raster pattern also presents a similar problem. At certain distances, the visibility of a 2-D raster pattern is poorer than that of a single line, and orienting the barcode with the scan lines is not effortless. Assuming the pattern to be amply visible, the user may tend to position the 2-D barcode horizontally under a scan lamp. However, it would be ideal if no aligning is required. For example, a 2-D barcode may have been a photocopy vertically aligned onto a page. Upon scanning, the user may first subconsciously attempt to present the page horizontally, and thus present the barcode vertically. Without ability by the scanner to instantaneously sense barcode orientation, and then position a raster pattern to scan it, the user will be forced to realign the page vertically.
Following alignment of the scan pattern to the barcode, the pattern is then increased in width so as to fully span the length of the barcode, and if the pattern is determined to be a 2-D barcode, the height of the scan pattern is also increased so as to decode all of the barcode rows. However, the rate at which the raster pattern is increased in size is fixed and independent of the size of the barcode or the distance between the hand-held scanner and target. At a common rate of pattern size increase, depending upon the size of the barcode it may require from 0.1 to 2.0 seconds to open the scan pattern and decode the barcode. Distance to the target is another factor. Pattern size is incremented until the entire pattern is decoded. The size of each increment of increase is determined in part by the working range of the scanner. Very long range scanners, usable up to sixty feet, for example, may require smaller increments so that the patterns do not grow too fast at the end of a working range where much of the information, including start and stop codes, concerning attributes of the barcode resides. Hence, it would be desirable to control the rate at which the scan pattern grows to decode the barcode depending upon the characteristics of the barcode itself.
The scanner unit must be compact, energy efficient, and capable of scanning both 1-D and 2-D barcodes. The unit preferably will also be convertible between hand and surface support applications. The scan pattern will preferably be optimized in accordance with whether the unit is in hard held or surface supported modes of operation, whether it is in a presentation type of operation (wherein the indicia are passed under a scan lamp) or a pass through type of operation (supermarket type) and on the type of barcode or other indicia to be read.
This invention generally relates to a compact assembly for electro-optically scanning indicia, including a support, a light source such as a laser diode mounted on the support, an oscillatable optical component, and a drive for oscillating the component. The component includes a focusing element for focusing a light beam emitted by the source, and a scan element of one-piece with the focusing element for directing the light beam away from the support. The drive includes a permanent magnet mounted for joint oscillation with the component, and an energizable electrical coil mounted on the support. When energized by an energizing drive current, the field produced by the coil interacts with the field produced by the magnet to effect oscillation of the component for scanning the light beam over the indicia, for example, a bar code symbol.
The novel one-piece optical component is constituted of a light-transmissive material having a first curved surface constituting part of the focusing element and through which the beam enters the component, and a second reflecting surface from which the focused beam is reflected. The second surface is coated with a reflective coating and constitutes part of the scan element.
The component further includes a third curved surface through which the reflected beam exits the component. The third surface acts as a correcting element for scan aberration correction. The component still further includes extensions of one-piece with the elements. The extensions are operative for holding the permanent magnet.
The component is mounted on a shaft journaled at opposite ends on the support. A biasing element is operatively connected between the component and the support, for constantly exerting a restoring force on the component to return the latter to a neutral position. The biasing element is preferably an elongated leaf spring having one end fixed to the component, and an opposite spring end movably connected to the support. The opposite spring end passes between a pair of friction posts on the support and slides between the posts during oscillation of the component.
The light beam entering the component is at a right angle to the beam exiting the component in the neutral position. The second reflecting surface preferably lies in a plane oriented at a 45° angle to the beam entering the component. When the support is configured as a cylindrical housing having a longitudinal axis, the entering beam travels along the longitudinal axis, and the exiting beam travels radially and passes through an exit port formed in a side wall of the housing.
The light source is preferably a laser diode received in an open end of the housing. The drive coil surrounds the diode. A sensor for detecting light reflected from the indicia is mounted on the housing adjacent the coil and the diode.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.
As used in this specification, the terms “symbol” and “barcode” are intended to be broadly construed and to cover not only patterns composed of alternating bars and spaces of various widths, but also other one or two dimensional graphic patterns, as well as alphanumeric characters.
The invention provides a scanner system in which the scan pattern produced by a light beam is controlled to describe an omnidirectional scanning pattern, light reflected from a symbol is detected, and the scan pattern is thereafter controlled in response to the detected signals. The invention also provides a scanner system and method in which adjustment of the spatial coverage of the scan pattern of a scanning beam is automatically made at a responsively controlled rate to effect an appropriate type of scanning pattern depending upon the type of symbols to be read. The invention further provides a scanning system operation in which two different types of barcodes may be read, a standard linear barcode and a 2-D barcode. The invention provides a technique for determining the type of barcode, its angular orientation, and adjusts the spatial coverage or vertical sweep of the raster scanning beam to fully scan and read a 2-D barcode.
In accordance with a first aspect of the invention, the invention further produces scan patterns for reading indicia, optimized in dependence upon the operating mode of the scanner (portable or fixed) and other criteria. A portion of the barcode is initially scanned by projecting a light beam on the target containing the barcode, and scanning the beam using a pattern that is relatively small and dense so as to be visible to the user for aiming. A portion of the barcode is partially decoded to determine the type, and possible size, of the barcode, whether it is a 1-D or 2-D barcode and its angular orientation. A rotating Lissajous pattern is preferred for this purpose as it has been determined to be most robust, although other patterns can be used. If the symbol is found to be a 1-D barcode, the scan pattern is increased in size (opened) to a maximum size, at a prescribed rate, in conformance with the portion of the symbol previously decoded, and the rotating Lissajous pattern decodes the entire symbol. If the symbol is determined to be a 2-D barcode, the rotating Lissajous pattern is converted to a raster pattern, and increased in size at a prescribed rate to decode the barcode. In a preferred embodiment, the raster pattern precesses so as to align with the 2-D symbol and therefore read 2-D barcodes of different angular orientations with respect to the horizontal scanning pattern.
Thus, referring to
As further depicted in
The scanner 30 may be adapted to scan different types of articles or for different applications by interchanging the scanning head with another through use of electrical connectors. Furthermore, the scanning module may be implemented within a self-contained data acquisition system including one or more such components as keyboard, display, printer, data storage, application software and data bases (see, for example, U.S. Pat. No. 4,409,470), and may also include a radio or other type of communications interface for communication with a local area network, telephone exchange network or radio broadcast system.
The outgoing beam 36 is generated in the scanner 30 by a laser diode or the like, and directed to impinge upon the barcode symbol 32 that ordinarily is positioned a few inches from the front of the scanner. However, other applications may require scanning a target that is at a considerable distance, e.g., 60 feet from the scanner. The outgoing beam 36 is scanned using various patterns to be described later, one being a linear raster as shown in
For long range scanning, first aiming and then scanning the barcode to read the code is natural. These operations are termed the “aim mode” and “decode mode” hereinafter. Two trigger pull positions are normally provided, or the trigger is pulled twice to produce these respective modes of operation. In accordance with one aspect of the invention, and referring to
For example, the line scan pattern of
Upon the second trigger pull (or further pull of the trigger in the same stroke if the trigger is multi-purpose), or automatically, in the decode mode of operation, the scan pattern opens in the exact orientation of the barcode as determined by the peak detector, as shown in
The following example assumes an aim pattern in the form of a single scan line,
In order to cover all possible orientations of the barcode, the scan lines must be capable of rotating through 180 degrees, and preferably the entire symbol will be covered such that at least two scan lines traverse each row of bar patterns during reading. However, the resolution of rotation depends on the aspect ratio and size of the barcode.
If it is necessary to rotate the scan line once every s scans, at a resolution of r degrees, for a duration of d seconds in order to cover a total of 180 degrees, then
For example, if a complete 180 degree rotation should be accomplished within 0.1 second, at 10 degree resolution for every scan, then w/2π=90 Hz will suffice.
The orientation of the scan line alternatively may be determined more precisely than what is capable using the circuit of
The circuit of
Although the short single line pattern is the most visible, it is disadvantageous for aiming because it suggests orientation and may be psychologically distracting. Larger spots, those shown in
Another pattern which may be used for aiming, and which will be described in more detail later, is the rotating Lissajous pattern shown in
Another pattern for aiming found particularly effective is a bright rosette pattern of diameter less than the diameter of rosette to be used for decoding.
Once satisfied with aiming, the scanner begins to deflect the light beam with a scan pattern appropriate for decoding the barcode. The scan pattern for decode may be the same as for aim, or may be a different pattern or may be the same or different pattern with center of rotation that shifts upon transition between the two modes or during decoding. In a preferred embodiment, the decode scan pattern which is generated depends upon whether the barcode is found to be a 1-D barcode (when the preferred decode pattern is omni-directional) or a 2-D barcode (when the preferred decode pattern is raster). Pattern switching may be responsive to a second trigger pull, or may occur automatically.
For example, referring to
Upon determining, in this example, that the barcode is a 2-D barcode, the scan pattern is changed to a raster pattern, as shown in
Preferably, the specific pattern produced by the scanner, in accordance with an important aspect of the invention, is a pattern that is optimized for a particular classification of indicia and depending on whether the scanner is operating in a portable mode or is mounted in its fixture. A scan pattern is deemed to be optimized if it reads and decodes a prescribed pattern in a minimum amount of time, and within reasonable economic constraints.
If the scanner is operated in the fixed mode, with the palm held module 30 is mounted in bracket 114 and the module 30 directed to a region across which items bearing indicia, such as a barcode, to be read are passed, the rotational orientation of the scan pattern with respect to barcode is indeterminate. On the other hand, if the scanner is operated in the aim and shoot mode, with the module 30 separated from the bracket, the scanning pattern may be manually aligned with the barcode. The specific pattern produced should be optimized for decoding barcodes of the particular classification of barcode being read.
Hence, in accordance with an aspect of the invention, and referring to
Assume first that the scanner is in the fixed mode of operation and arranged to read a barcode symbol. The symbol is preliminarily read using the rotating Lissajous scan pattern to detect the start and stop codes of the barcode, so as to determine whether it is a 1-D or 2-D barcode. If the symbol being scanned is determined to be a 1-D barcode, the scanning pattern will remain defaulted in the form of a rotating Lissajous pattern, as shown in
Still referring to
The particular scanning patterns produced for decoding 1-D or 2-D barcodes when the scanner is operated in portable and fixed modes can be varied for specific applications and modules of particular optical characteristics. What is important is that the scanner is adaptive, controlled manually but preferably automatically, to produce decoding scan patterns that are optimized, that is, as robust as practical with respect to the operating mode selected and the classification of indicia being read.
Preferably, the scan pattern is also optimized in dependency on whether scanning is carried out by a presentation type (under a scan lamp) or a pass through (supermarket) type reader. In the presentation type reader, an article carrying a barcode or other symbol to be read is brought to the reader or the reader is brought to the article. Since reading is carried out in very close proximity to the barcode, there is no need for aiming. In the pass through reader, the article bearing a barcode is swiped past a scanning pattern produced by a fixed source of light beams. These two modalities present different decoding requirements to barcode readers (in the pass through mode of reading, the article swipes through the scan region relatively quickly, whereas in the presentation mode, the barcode is relatively stationary when read). Hence, if reading is carried out in the pass through mode, and the barcode is not very truncated (that is, the barcode is thin), a scanning pattern producing lines that are more sparsely spaced but more often repeated is preferred because it is more likely to traverse the barcode. That is, the faster the swipe, the thicker the barcode should be and hence a scanning pattern, such as a rotating Lissajous pattern, optimized for a relatively thick barcode pattern is preferred.
Assuming now that the rotating Lissajous pattern is generated (
The preferred Lissajous pattern for decoding, shown in
Single line rotation and scanning is produced, in accordance with the invention, by driving two mirrors (not shown) using the circuit 80 of
Amplitude control shown herein assumes that the Y-element will be driven somewhat harder than the X-element so as to compensate for any slightly leading resonant peak, as depicted in the amplitude response curves of
Resonant scan elements are known in the art. Such elements typically are provided with a flexural strip of Mylar or other material cantilever mounted to a base and supporting a miniature permanent magnet positioned within a coil. The coil is secured to a base, and a scan mirror is attached to the free end of the cantilever mounted flexural strip. By changing the dimensions or flexural characteristics of the cantilever mounted strip, the mass of the strip, the permanent magnet and mirror, or the distribution of mass on the flexural strip, different resonant frequencies can be established. See, for example, copending application Ser. No. 07/884,738, filed May 15, 1992 and incorporated herein by reference.
The resonant scan element can also be presented as a single element having different resonant frequencies in mutually orthogonal directions, and utilizing a single mirror to perform single line rotation and scanning. The circuit 80 of
To produce 2-D scanning patterns for symbologies such as PDF 417, described in U.S. patent application Ser. No. 07/461,881, filed Jan. 5, 1990, the resonant scan element must be capable of being simultaneously driven by at least two frequency components. Raster pattern rotation is achieved by driving a 2-D scanner such that the horizontal element is driven with the signal X(t) and the vertical element is driven with the signal Y(t), where
The above equations describe a rotating Lissajous pattern, and in fact, any Lissajous pattern may be rotated if the two sine functions are replaced by their Lissajous equivalent. If the resonant scan element has the desired equal amplitude and phase responsive at the two sinusoidal components of each drive axis, as illustrated in
A circuit 98 for developing drive signals for Lissajous pattern rotation, shown in
The four drive signals produced by circuit 98 of
A first pair 112, 114 of the mirrors 110 is optically combined as X-axis elements having two resonant frequencies. The second pair is arranged as a Y-axis element having two resonant frequencies that match those of the first pair. The mirrors may be oriented in either of the configurations of
Alternatively, each mirror pair may be combined on a single resonant element wherein a distinct resonant peak is available for each axis. The element hence can be driven at its resonance frequency by the higher frequency w2 and off resonance by the lower frequency w1, but with a larger amplitude and any necessary phase compensation. Resonance elements of dual resonant frequency response may be arranged orthogonally to produce the rotatable raster patterns in this case.
To compensate for rotational misalignment between the scan pattern and barcode, or droop in the scan pattern, another aspect of the invention precesses the raster so as to traverse barcode elements that are angularly displaced or are not oriented along a straight line. Referring to
The resultant zig-zag pattern causes the light beam to sweep the barcode symbols in a plurality of different angles, so that angularly offset lines of barcode up to about thirty degrees of offset can be read by the raster during precession. Similarly, even if the beam emitted by the scanner contains a degree of droop, the precessing raster will scan every barcode line during successive frames.
The processors 82 of
The scanner now waits for another trigger operation, and when the trigger has been manually operated for the second time, as determined in step 104, an omni-pattern for decoding is generated by the scanner (step 106). In the example of
If, however, the barcode has been fully decoded, determined in step 114, before the maximum size of the scan pattern is exceeded, the routine is completed.
The size of each pattern increment, and the rate at which the increments are generated, are preferably controlled in response to data read from the symbol during the aim mode to achieve an optimal rate of Y-direction expansion depending on the number of rows in and height of a label. If the 2-D code is not successfully decoded at step 114, then decoding is continued until either a successful decode has occurred or until a predetermined amount of time, typically on the order of three seconds, has elapsed.
In accordance with
In response to manual operation of the trigger, in step 120, a rotating line pattern (step 122), corresponding to what is shown in
A second manual operation of the trigger per step 128 is optional. Even if the trigger is not operated at this time, when the decoder has determined the optimum angle at which to emit a decode scan pattern, the pattern is produced (step 130). The line size is incremented (step 132) until it exceeds the length of the barcode (step 134). If the maximum size is exceeded, the size of the scan line is reduced to the minimum size for aiming (step 136) and the process repeats. During the time the length of the scan line is incremented, the barcode is being decoded, in step 138, and when decoding is completed, the routine is terminated.
In either the manual or automatic operations, the light beam directed toward the symbol to be read is transitioned between first and second scan paths in the aim and decode modes. In addition to transition between the scan paths described above, the first and second scan paths may differ from each other by rotation about an axis of rotation, by increase in scan path envelope diameter, by both rotation and envelope diameter increase and by displacement of the center of rotation of the first scan pattern.
The user can, therefore, simply aim an apparent spot on the barcode, without regard for the barcode's orientation, and then decode it upon the second trigger pull. It is also possible to provide automatic scan line opening without a second trigger pull. However, there is a danger that the scanner may unintentionally scan and decode the wrong barcode.
In accordance with another aspect of the invention, a first embodiment of a scanning element that may be used to produce the prescribed scan patterns is shown in
The circuit board 114 and support 118 are interconnected by four semi-rigid wires 126 that also carry electric current from a driver circuit to the four coils. By changing the connections between the coils, 1-D or 2-D scan patterns may be selectively achieved.
Wires 126 preferably are tin-soldered to the circuit board 114 and support 118. The material of the wires preferably is a phosphor-bronze alloy, although any other material that conducts electricity and provides semi-rigid support of the circuit board 114 and lens 112 with respect to support 118 may be used.
Magnet 124 is in the form of a ring, and in one embodiment may be magnetized axially. The central hole of magnet 124 serves as an aperture stop for the laser beam.
Alternatively, the permanent magnet 124 may be multiply poled around its circumference. For example, the poling of the permanent magnet may be such that there are four poles, with South poles being oriented at 0° and 180° and North poles at 90° and 270° along the circumference. By suitably energizing two of the four coils 116, the lens and coil assembly will rotate slightly, and hence the semi-rigid wires will begin to form a helix, reducing the distance between the lens 112 and laser beam source 122 to focus the beam. The other two coils are energized to oscillate the lens assembly to produce appropriate scanning.
Another embodiment of scanner, shown in
Pivotably mounted to the end of casing 130 at 146 is a piece of film 148, preferably made of Mylar. Upon the outer surface of the membrane, at a position in longitudinal alignment with core 140, is a reflector 150. The reflector 150, together with its supporting membrane 148, is maintained separated from the diaphragm plate 144 by another piece of film 152, again preferably formed of Mylar.
Except for Mylar films 148, 152, and reflector 150, the device shown in
Another embodiment of a scanning mechanism, in accordance with the invention, is shown in
Within the bracket 150, behind the magnet 158, is an electromagnetic coil 160 which, when energized, produces an electromagnetic field that interacts with the field of the permanent magnet to oscillate reflector 154 in one direction, for example, the X-direction.
An important advantage of the structure of the scanner mechanism shown in
To produce 2-D scanning using the mechanism of
Another embodiment of scanner, shown in
A U-shaped spring 178 is attached to the magnet 174 at one end, and the opposite end of the spring supports an optical element, preferably a reflector 180. Electrical leads (not shown) carry an energizing current or drive signal to the coil of electromagnet 174. The reflector 180 will oscillate in response to such electromagnet coil signal so as to scan in one or two dimensions, selectively. The spring 178 may be made of any suitable flexible materials, such as a leaf spring, a flexible metal coil or a flat bar having sufficient flexibility properties, and may be of a material such as a beryllium-copper alloy.
The reflector 180 is positioned between a laser beam source and lens assembly 182 and a target (not shown in
An important aspect of the embodiment of
The reflector 180 is capable of 2-D scanning. As described in copending application Ser. No. 07/943,232, filed on Sep. 10, 1992, the U-shaped spring 178, which may be formed of a plastic material, such as Mylar or Kapton, the arms of the U-shaped spring 178 and the planar spring 1.76 may be arranged to vibrate in planes which are orthogonal to each other. Oscillatory forces applied to permanent magnet 174 by the electromagnetic 172 can initiate desired vibrations in both of the springs 178 and 176 by carefully selecting drive signals applied to various terminals of the coil, as discussed in the copending application. Because of the different frequency vibration characteristics of the two springs 178 and 176, each spring will oscillate only at its natural vibration frequency. Hence, when the electromagnetic 172 is driven by a super position signal of high and low frequency components, the U-shaped spring will vibrate at a frequency in the high range of frequencies, and the planar spring 176 will vibrate at a frequency in the low range of frequencies.
An additional important aspect of the embodiment of
Another important aspect of
Optionally, the bracket 116 may be mounted on an extension tube 124, shown in
Hence, as described herein, the invention produces a rotating Lissajous scan pattern or other pattern that is easily seen by the user during aiming on a barcode, and then under manual control or automatically converts to a decode scan that is robust and opens at a rate, and to a size, that depends upon the barcode itself. If the barcode is a 1-D code, the decode pattern may be a precessing raster that is able to scan rows that are rotationally misaligned with the scan lines. Scanning is implemented by novel miniature 1-D and 2-D scanning assemblies, as described herein.
Another form of scanner that can produce the required two-dimensional scanning patterns is of a type implementing a scan element supported by a holder structure mounted on a mylar motor to produce oscillatory movements, the arrangement being mounted on a printed circuit board within a housing that can be manually held. The scanning motor and arrangement may be made of components formed essentially of molded plastic material, and utilizing of a Mylar leaf spring to limit scan. See, for example, U.S. patent application Ser. No. 07/812,923, filed Dec. 24, 1991, assigned to the assignee of this invention and incorporated herein by reference.
The support 202 has an annular collar 214 spaced axially from the flange 212. An electromagnetic coil 216 is wound around the support between the collar 214 and the flange 212. A sensor 218, preferably a photodiode, is mounted radially exteriorly of the flange and the collar, and overlies the coil 216 and the source 208. The sensor 218 detects light reflected off the indicia, and generates an electrical signal indicative of the variable intensity of the reflected light from the indicia. A filter 220 is positioned over the sensor, and may be a light-transmissive plastic or glass filter, or even a coating of a liquid filter material that is cured in place on the sensor.
The source 208 includes an aperture plate 22 having an aperture stop 224 through which the emitted beam passes. An oscillatable optical component 230 is mounted in the path of the beam, and on a shaft 226 whose opposite ends are journaled in bearings on opposite sides of the cylindrical housing. An exit window or port 228 is formed in the side wall of the housing.
The component 230 is formed of a light-transmissive, optically modifying material, such as synthetic plastic or glass, and includes a focusing element 232 having an outer convexly curved surface 234 through which the emitted beam first enters the component and is focused at a focal point within a working range of distances at which the indicia are located, and a scan element 236 having an outer planar surface 238 coated with a reflective coating preferably a metallic coating formed of nickel, gold or chromium, for reflecting the focused beam away from the coated surface 238. The coated surface 238 is oriented at a 45° angle to direct the reflected beam perpendicularly to the incident focused beam. The focusing and scan elements are of one-piece with each other.
The component 230 also preferably has a connecting element 240 having an outer convexly curved surface 242 through which the reflected beam exits the component and is focused for correction of scan aberration. The correcting element is likewise of one-piece with the component.
A permanent magnet 244 is fixedly mounted for joint oscillation with the component 230 on a pair of rear extensions or arms 246, 248, also of one-piece with the component. The magnet 244 generates a permanent magnetic field which interacts with the electromagnetic field generated by the coil 216 upon energization of the coil by an energizing drive current, such as a train of square waves, or any periodic drive signal. The component oscillates in alternate circumferential directions about the shaft over arc lengths on the order of 20°–25° in each direction from an equilibrium or neutral position depicted in
The neutral position is established by a biasing element or flexure 250, preferably a planar leaf spring, having one end 252 fixed to the component by a fastener, and an opposite end 254 slidably mounted between a pair of friction posts 256, 258 mounted on the support. The flexure end 254 is frictionally captured, but movable, between the posts. The flexure 252 constantly exerts a restoring force on the component to return the latter to the neutral position.
During energization of the coil by the drive current, the interacting magnetic fields causes the magnet and the component to oscillate, thereby flexing the flexure. The flexure bends in one, and then in an opposite, rounded shape. The flexure end 254 slides back and forth through the posts during the bending of the flexure. Preferably, the flexure is constituted of a resilient material such as Mylar™, a thin polyester film about 0.001″ thick.
Focusing of the beam is advantageously achieved by the same component that performs the scanning or sweeping of the beam across the indicia. The overall assembly occupies a compact volume on the order of 6.5 mm×6.5 mm×5.6 mm.
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 an electro-optical scanning assembly with one-piece, oscillatable, focusing/scan element, 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.
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.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.