Optical scanner

An optical scanner includes a scanner housing including a scan window, a laser light source, reflected light detector and a mirrored polygon spinner. The spinner is arranged both to spin around an axis of rotation and to move so as to displace said axis of rotation.

The present invention relates to an optical scanner and more specifically to an optical scanner having enhanced scan volume.

BACKGROUND OF THE INVENTION

Current bi-optic bar code scanner designs produce patterns arranged to read labels passed by the scanner. The patterns are such that action of an operator swiping a bar code across the scanner window will move a typical label of nominal truncation across several scan lines allowing the label to be read. However, with truncated or otherwise difficult bar code labels operators often present the label to the scanner window instead of swiping them. As there are a limited number of spatially separate scan lines it is possible for the label to miss them all and not be read. For example, if a label is presented adjacent a fan of scan lines, but not over the fan of scan lines, then the bar code will not be read.

Commonly assigned U.S. Pat. Nos. 5,229,588, 5,684,289, and 5,886,336 disclose a typical dual aperture optical scanner. The scanning light beams from a laser diode pass through substantially horizontal and vertical apertures to provide more item coverage than a single aperture scanner.

In an effort to increase item coverage, optics designers are increasing the number of scan lines, line length, and scan angles by increasing the number of lasers and pattern mirrors in the scanner. The addition of these components consequently increases cost.

Alternative approaches have been considered in which the scan lines are moved orthogonally to the direction of the lines. This has been achieved by the movement of the laser light source, within the scanner, or the movement of the output mirror. Both of these are mechanically complex solutions which are not suitable for multi-laser or large bi-optic scanners.

As will be illustrated in more detail below, with reference toFIGS. 1 to 6, present day scanners comprise, a laser assembly, spinner assembly, collection optics, pattern mirrors, detector assembly, electronics, a window and scanner housing which contains all the individual assemblies. In operation, the laser beam intercepts the polygon spinner rotating about a single axis and is subsequently scanned in a single plane towards a set of pattern mirrors which reflect the individual scan lines out the window and onto a barcode. The laser energy is then reflected off of the barcode and a portion is gathered by the collection optics and focused onto the detector generating a signal to be decoded by the electronics. The positions at which the scan lines exit the window are static, and are contained in a relatively small portion of the hemispherical volume available outside and adjacent to the window (FIG. 6).

SUMMARY OF THE INVENTION

It would be desirable to provide an optical scanner with a reduction in coverage gaps. It would also be desirable to provide a scan engine which can be utilized in an optically simpler barcode scanner (regardless of the number of scanner apertures) for improved manufacturability and reduced cost.

In accordance with a first aspect of the present invention there is provided an optical scanner comprising a scanner housing including a scan window, a laser light source, a reflected light detector and a mirrored polygon spinner which is arranged both to spin around an axis of rotation and to move so as to displace said axis of rotation.

Preferably, the spinner is moved linearly so as displace said axis of rotation. Most preferably, the spinner is mounted on a pivotable mount.

In one embodiment the pivotable mount is pivotably mounted to a fixed support on one side of the spinner and to a movable support on the other side of the spinner. In this embodiment the movable mount is a linear actuator, actuation of which causes the pivotable mount to pivot on the fixed support.

Preferably, the axis of rotation is directed substantially towards the scan window.

Most preferably the polygon spinner is externally mirrored.

In one embodiment the scanner further comprises pattern mirrors arranged to direct light from the polygon spinner through the scan window so as to produce scan lines.

Preferably the scanner further comprises an arrangement of pattern mirrors, or basket of mirrors, arranged to direct light from the polygon spinner through the scan window so as to produce scan lines.

Preferably, the optical scanner further comprises control circuitry in the scanner housing for obtaining bar code information from electrical signals from the reflected light detector.

According to a second aspect of the present invention there is provided a mirrored polygon spinner assembly, for use with an optical scanner, the assembly comprising a spinner and a means of rotating the spinner, the spinner being arranged both to spin around an axis of rotation and to move so as to displace said axis of rotation.

According to a third aspect of the present invention there is provided a method of scanning a bar code utilizing an optical scanner comprising a scanner housing including a scan window, a laser light source, reflected light detector and a mirrored polygon spinner arranged both to spin around an axis of rotation and to move so as to displace said axis of rotation, the method comprising positioning the bar code within the scan volume and moving the spinner so as to displace the axis of rotation which in turn causes movement of the scan lines orthogonally to the direction of said scan lines.

Preferably, the spinner is pivoted back and forth.

Scan engines in accordance with the present invention can not only be utilized in new optical bar code scanners, they can be retrofitted to existing scanners, as described with reference toFIGS. 1 to 6, in place of prior art scan engines. In addition scan engines in accordance with the present invention can be made small enough and in such a way that they can be a common module scan engine for any, or at least most, bar code scanners.

DETAILED DESCRIPTION

Referring now toFIG. 1, prior art dual aperture optical scanner10includes horizontal optics assembly12H and vertical optics assembly12V, and control circuitry36for controlling horizontal and vertical optics assemblies12H and12V. If one of optics assemblies12H and12V fails, scanner10retains partial operation.

Horizontal optics assembly12H projects a scan pattern through substantially horizontal aperture34H to scan bar codes42located on bottom, leading, trailing and checker side surfaces of item40. It will also scan bar codes42on intermediate surfaces including those between the bottom and customer side surfaces.

Laser16H includes one or more laser diodes or other suitable laser sources. Laser16H may include a laser having a wavelength of 650 nm.

Aiming mirror18H aims a laser beam from laser16H to polygon mirrored spinner20H. The laser beam passes through a hole25H in collection optic24H (FIG. 4).

Polygon mirrored spinner20H directs the laser beam to pattern mirrors22H. Polygon mirrored spinner20H also routes collected light to collection optic24H. Polygon mirrored spinner20H preferably includes four facets, but may include other numbers of facets. Facets are grouped into two pairs. Two opposite facets have angles of 74 degrees and 76 degrees from the spinner base. The other pair of opposite facets have angles of 86.5 degrees and 88.5 degrees. Motor32H rotates polygon mirrored spinner20H.

Pattern mirrors22H produce scanning light beams that emanate from substantially horizontal aperture34H to form a horizontal scan pattern for reading bar code42on item40. Pattern mirrors22H also collect light reflected from item40and direct it to polygon mirrored spinner20H.

Collection optic24H routes collected light from polygon mirrored spinner20H to routing mirror26H.

Routing mirror26H routes the collected light to detector assembly28H.

Detector assembly28H focuses, optically filters, and converts collected light into electrical signals.

Detection circuitry30H obtains bar code information from the electrical signals. Detection circuitry30H includes circuitry for digitizing bar code information.

Vertical optics assembly12V projects a scan pattern from substantially vertical aperture34V and primarily scans bar codes located on a customer side and top side of an item. Like horizontal optics assembly12H, vertical optics assembly12V scans the leading and trailing sides, as well as intermediate surfaces including those between the bottom and customer side surfaces. However, for simplicity the substantially similar vertical assembly will not be described in detail herein.

Control circuitry36processes the electrical signals from detector assemblies28H and assembly28V to obtain bar code information. Control circuitry36passes the bar code information to POS terminal14.

Control circuitry36controls operation of lasers16H and16V and motors32H and32V. Control circuitry36may remove power from lasers16H and16V and motors32H and32V to increase their longevity.

POS terminal14receives transaction data, for example, in the form of SKU numbers from scanner10and completes a transaction by finding price data for the SKU numbers in a price-lookup data file.

Scanner10as illustrated includes an integral scale60. Scale60includes weigh plate62, which includes substantially horizontal surface50and substantially horizontal aperture34H. Horizontal window64H is located within horizontal aperture34H.

Substantially vertical aperture34V is located within substantially vertical surface54. Substantially vertical window64V is located within substantially vertical aperture34V.

Scanner10includes housing52. Preferably, housing52may be easily adapted to fit in a typical checkout counter56. It is envisioned that substantially horizontal surface50be made substantially flush with top surface58of counter56. Scanner10is installed within checkout counter56so that substantially vertical aperture34V faces a store employee or other operator.

An illustrated reference X-Y-Z coordinate system determines orientations of pattern mirrors22H and22V within scanner10of the present invention. Origin O is defined such that:

X=0 is on the centerline of the scanner;

Z=0 is on the centerline of the scanner; and

Y=0 is on the substantially horizontal surface50.

Referring now toFIGS. 3-4, horizontal optics assembly12H and vertical optics assembly12V are shown in their positions within housing52.

Horizontal optics assembly12H and vertical optics assembly12V each have nearly all of the optical components of a functional bar code scanner. Horizontal optics assembly12H and vertical optics assembly12V each have their own housings66H and66V and printed circuit boards68H and68V. In the illustrated example, control circuitry36is located in horizontal optics assembly12H and signals vertical optics assembly12V are brought to control circuitry36via cables69.

Horizontal optics assembly12H includes horizontal aperture35H and window65H. Scale weigh plate62with horizontal aperture34H and window64H are located above window65H.

Horizontal optics assembly12H will scan all label orientations on the bottom and checker sides of item40, as well as certain orientations on the leading and trailing sides.

Optical pathing between laser16H and polygon mirrored spinner20H avoids contacting pattern mirrors22H along the way. Laser16H is located on a checker side of horizontal optics assembly12H and polygon mirrored spinner20H is located on the opposite side. Collection optic24H is located adjacent laser16H. The laser beam from laser16H passes through hole25H in collection optic24H. Detector assembly28H is located between collection optic24H and polygon mirrored spinner20H.

Spinners20H and20V are located where they are in order to generate suitable scan lines. In optics assembly12H, the generation of the front vertical lines requires arcs of light reflected from a spinner20H on the back side of the optical cavity.

Substantially vertical aperture34V is oriented at an acute angle T of about 86 degrees from substantially horizontal aperture34H. Other angular configurations, acute and obtuse, are also anticipated by the present invention.

Operationally, lasers16H and16V emit laser beams onto aiming mirrors18H and18V, which reflect the laser beams through holes25H and25V in collection optics24H and24V and then onto mirrored polygon spinners20H and20V. The polygon facets further reflect the laser beams up or down (for horizontal assembly12H) or forward or rearward (for vertical assembly12V), depending upon the facet struck. As the facets rotate, the laser beams are scanned in a shallow arc and reflected onto pattern mirrors22H and22V. In some cases, primary pattern mirrors reflect the laser beams through apertures34H and34V onto surfaces of item40. In other cases, the primary pattern mirrors reflect the laser beams onto secondary mirrors that reflect the laser beams through apertures34H and34V onto surfaces of item40.

As item40is moved through the scan zone (above horizontal aperture34H and in front of vertical aperture34V), scan lines generated by the laser beams from horizontal and vertical apertures34H and34V strike bar code label42, no matter where it is located on item42. A scan line will pass through all or part of bar code label40.

Item42scatters light back along the path of the incident laser light. The scattered light passes through horizontal and vertical apertures34H and34V, onto the secondary mirrors (if present), onto the primary mirrors and onto the polygon facets. The rotating facets reflect the scattered light onto collection optics24H and24V. Collection optics24H and24V focus the scattered light onto detector assemblies28H and28V by way of routing mirrors26H and26V. Detector assemblies28H and28V convert the scattered light into electrical signals for analog processing by pre-video circuitries30H and30V and digital processing by control circuitry36.

Referring now toFIG. 5, pattern mirrors22H are shown in detail. Horizontal pattern mirrors22H include primary pattern mirrors and secondary pattern mirrors. The primary pattern mirrors receive a laser beam directly from spinner20H. The secondary mirrors receive the laser beam from some of the primary pattern mirrors.

The term “front” as applied to mirrors means operator or checker side. The term “rear” as applied to mirrors means the side opposite to the operator or checker side. As illustrated, horizontal pattern mirrors22H exhibit substantially bilateral symmetry between the leading and trailing sides of horizontal optics assembly12H.

The primary pattern mirrors include left rear diagonal mirror86, right rear diagonal mirror88, left front vertical mirror78, right front vertical mirror80, left horizontal mirror82, right horizontal mirror84, left front picket mirror70, right front picket mirror72, left front diagonal mirror102, right front diagonal mirror104, left front bottom picket mirror74, and right front bottom picket76.

The secondary pattern mirrors include left rear diagonal mirror94, right rear diagonal mirror96, left front vertical mirror90, right front vertical mirror92, left horizontal mirror98, and right horizontal mirror100.

FIGS. 6 and 7illustrates a mirrored polygon spinner assembly120, for use with an optical scanner12described above. The assembly120comprises a spinner122and a means of rotating the spinner124in the form of a DC brushless motor. However, other motors or alternative means for rotating the spinner can be envisages by a person skilled in the art. The spinner122is arranged both to spin around an axis of rotation126and to move so as to displace said axis of rotation126, as will described below. The spinner122is an externally mirrored spinner.

The spinner122is mounted on a pivotable mount128, which is in turn mounted to a pair of fixed supports130on one side of the spinner122and to a movable mount132on the other side of the spinner122. The movable mount132is a linear actuator, actuation of which causes the pivotable mount to pivot on the fixed support.

When in use a bar code is scanned by a laser light produced by a light source and directed through the scanner window as described above. However in a scanner in accordance with the present invention the movement of the spinner causes a corresponding movement or oscillation of the scan lines in a direction orthogonal to the scan direction. In particular, the scanned ray fans move back and forth in a direction normal to their planes. This motion is maintained throughout the pattern generation process, so that (at a scanned bar code surface for example) a vertical scan line will move left and right, a horizontal scan line will move up and down, etc. The magnitude of this orthogonal scan is arranged to be such that the gaps between adjacent parallel scan lines are filled in by the orthogonal motion. Accordingly, previously missed bar codes will be scanned.