Optical scanning apparatus

Abstract: A compact optical scanning apparatus includes a motor driven hollow drive shaft (40) through which scanning light beams are projected. A mirror (66) mounted on one end of the drive shaft (40) deflects the light beams to the side of the drive shaft (40), said light beams impinge on the interior surfaces of a conically shaped ring of mirrors (62) which in turn deflect the light beams downwardly towards a circular mirror (32) mounted horizontally and which reflects the light beams towards a ring of pattern forming mirrors (82) mounted perpendicular to the circular mirror (32). The pattern forming mirrors (82) reflect the light beams through an aperture (22) in the scanning apparatus in the form of a scanning pattern. A gear mechanism (54,56,58) mounted between the ring of mirrors (62) and the drive shaft rotates the ring of mirrors (62) in a direction opposite to that of the drive shaft (40) and an advantageously dense pattern of scan lines is obtained.

Description: The present invention relates to optical scanning apparatus and in particular, but not exclusively, to an optical bar code scanning system which can be mounted within a checkout counter or other type of support member for scanning bar code labels on a merchandise item which is moved past a scanning aperture located in the bar code scanner. In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code printed on the merchandise item. In order to standardize the bar codes used in various point-of-sale checkout systems, the grocery industry has adapted a uniform product code (UPC) which is in the form of a bar code. Various reading systems have been constructed to read this type of bar code, including hand-held scanners which are moved across the bar code and stationary optical reader systems normally located within the checkout counter in which the bar code is read by projecting a plurality of scanning light beams through a window constituting the scanning area of the counter over which a bar code printed on a purchased merchandise item or on a bar code label attached to the merchandise item is moved. This scanning operation is part of the process of loading the item into a baggage cart. In scanning the bar code label, a scan pattern is generated by the scanning apparatus which consists of a plurality of individual scanning lines oriented in various directions so as to enable the scan pattern to scan the bar code label irrespective of its orientation with respect to the scan pattern. The most common prior art scan pattern is in the form of an X together with an horizontal line. One known stationary optical reader system is described in United States Patent 4 795 224, in which a lower beam is directed into a mirror which rotates within a prism ring which is itself rotatably driven in the same direction as the mirror. The laser beam is deflected to the prism by the rotating mirror and is then directed to a scan zone by a further mirror arrangement. Another known optical reader system is described in United States Patent 3 978 317, in which a light beam is reflected by a rotating mirror around a circular series of fixed mirrors and then onto a scan zone. A known optical reader according to the preamble of Claim 1 is described in United States Patent 4 971 410, which discloses a self contained optical scanning unit comprising a light source for projecting light onto a first deflecting means, which is mounted for rotation in a first direction. The unit further comprises a second deflecting means arranged to rotate in a direction opposite to that of said first deflecting means, and is formed by a plurality of mirror members conically arranged around said first deflecting means, so as to receive light deflected by said first deflecting means. However, such known systems are disadvantageous in that the provision of a high density of scan pattern in the scan zone is not possible with such apparatus and, indeed, would only become possible by employment of further complex, bulky and likewise expensive, light beam deflection apparatus. Even scanning systems currently found in checkout counters comprise a disadvantageously large structure mounted within the counter which have a number of mirrors mounted so as to occupy the internal area of the checkout counter. The present invention accordingly seeks to provide a compact optical scanner which is not only low in cost and does not occupy a large portion of the checkout counter, but which has the particular advantage of producing a scanning pattern composed of a dense pattern of scan lines. In accordance with the present invention there is provided, an optical scanning apparatus comprising a light source for projecting light on to first deflecting means mounted on a rotatable drive member for rotation therewith in a first direction, second deflecting means arranged to rotate in a direction opposite to that of said first deflecting means and comprising a first plurality of substantially flat mirror members conically arranged around said first deflecting means to receive light deflected by said first deflecting means, characterized by third deflecting means for deflecting light from said first plurality of mirror members to a second plurality of mirror members which surround said first plurality of mirror members, said third deflecting means being located beneath said first plurality of mirror members in a plane substantially perpendicular to the plane of each of said second plurality of mirror members and the rotation axis of said rotatable drive member, said second plurality of mirror members being arranged to deflect this light so as to form a scanning pattern for scanning coded indicia. As such, the invention provides for an advantageous increase in the scan line quality and density. In one embodiment an optical scanning unit which can be mounted adjacent the top surface of a checkout counter or any other type of support member which includes a laser source for projecting laser light beams through the hollow drive shaft of a motor which is mounted for support on a printed circuit board. Further, the motor can support a ring shape base support member on which is mounted by means of a plurality of bearing members, a ring support member which includes a plurality of arm members for supporting a conical shaped ring of deflecting mirrors enclosing the motor and the drive shaft. On the end of the hollow drive shaft there can be mounted a deflecting member for deflecting the laser light beam outwardly to the ring of mirrors which in turn deflect the laser light beams in a downward direction to a circular ring member. As such, the circular ring member deflects the laser light beams at a ring of vertically oriented pattern forming mirror members which deflect the received light beams through an aperture in the top of the checkout counter in a scanning direction for scanning a bar code label positioned in a scanning zone adjacent the aperture. A gear member can be secured to the drive shaft engaging a drive gear supported on the base member which engages the internal teeth of the ring support member for rotating the ring support member together with the ring of mirrors in a direction opposite to the direction of rotation of the drive shaft and the deflecting member. The invention advantageously provides for the generation of a scan pattern comprising a large number of rectilinear lines producing a highly dense scan pattern which is rotated in a circular direction enabling the scan pattern to scan a bar code label irrespective of its orientation. More particularly, the optical scanning apparatus generates a highly dense scan pattern comprising a plurality of straight scan lines oriented in a direction perpendicular to each other, while also providing an optical scanner which is compact in structure enabling the scanner to be installed in a very small supporting member and which is simple in construction and therefore low in cost. The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a perspective view of a housing member within which the optical scanning apparatus of the present invention is mounted which includes an aperture through which scanning light beams are projected for scanning a bar code label positioned adjacent the aperture; Fig. 2 is a schematic diagram of the optical scanning pattern generated by the preferred embodiment of the present invention; Fig. 3 is a cross-sectional view taken on line 3-3 of Fig. 1; Fig. 4 is a cross-sectional view of the scanning apparatus similar to Fig. 3 showing the light paths of the scanning light beams; Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 3 showing a top view of the ring of mirrors; Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 3 showing details of the drive gear mechanism; Fig. 7 is a view taken on lines 7-7 of Fig. 3 showing the base plate member and the location of the roller bearing members. Fig. 8 is a view taken on lines 8-8 of Fig. 3 showing details of the ring shaped reflecting mirror. Referring now to Fig. 1, there is shown a perspective view of a housing member 20 in which is located the optical scanning apparatus of the present invention. The housing member 20 includes an aperture 22 located in the cover portion 23 of the housing member in which is mounted a transparent cover member 24 such as a glass window through which are projected the scanning light beams generated by the scanning apparatus of the present invention. As best seen from Fig. 3, mounted within the housing member 20 is an optical scanning apparatus generally indicated by the numeral 26 which includes a printed circuit board 28 mounted to the floor portion 30 of the enclosure 20 by means of studs 31. Mounted to the printed circuit board 28 by means of studs 33 (Fig. 3) is a ring shaped reflecting mirror member 32 (Fig. 8) which encircles a motor member 34 mounted on a hollow support member 36 secured to the printed circuit board 28. The motor member 34 rotates a hollow drive shaft 40 in a manner that is well known in the art. The drive shaft 40 is mounted on two bearing members 42 mounted within the motor member 34. Mounted to the motor member 34 by means of screws 44 (Figs. 3 and 7) is a circular base plate member 46 (Fig. 7) which includes a circular slot 48 extending along the outer perimeter of the plate member 46. Located in the slot 48 are a plurality of needle bearing members 50 which slidably support a ring member 52 (Fig. 6) having its inner circumferential surface comprised of gear teeth 54. Secured to the drive shaft 40 is a drive member 56 (Figs. 3 and 6) which engages a second gear member 58 rotatably secured to the motor member 34 by means of a pin member 59 in the plate member 46, the gear member 58 engaging the gear teeth 54 of the ring member 52. As best seen in Fig. 3, mounted on the ring member 52 are three arm members 60 which are attached to and support a conically shaped ring 61 of mirror members 62. Secured to the end of the drive shaft 40 is an optical transceiver 64 which includes a deflecting portion 66 and a collection portion 68. For a complete description of the optical transceiver 64 reference should be made to U.S. patent US-A-4971410, corresponding to EP-A-0 412 680, which is assigned to the assignee of the present application. Mounted on the printed circuit board 28 adjacent the open end of the drive shaft 40 is a laser diode member 70 and a collimating and focusing lens member 72 both of which are in alignment with the spin axis 74 (Fig. 4) of the drive shaft 40. The laser diode member 70 outputs a diverging light beam which is collimated and focused on a reference plane (not shown) in front of the glass window 24 by the lens member 72. Secured to the glass window 24 in any conventional manner such as an adhesive coating is a photodetector 76 which, as will be described more fully hereafter, receives the light beams reflected from a scanned bar code label for generating electrical signals in response to the intensity of the reflective light beams received. Secured to the side wall portions 78 of the housing member 20 by means of studs 80 are eight vertically oriented pattern forming mirror members 82 (Figs. 2-7 inclusive) which will deflect scanning light beams received from the mirror member 32 in a direction through the glass window 24 to form a scanning pattern 84 (Fig. 2) which is composed of a plurality of rectilinear scanning lines. The motor member 34 is a 5-volt brushless DC motor which rotates the drive shaft at a speed of approximately 3200 rpm. In the operation of the scanning apparatus 26, the rotational movement of the drive shaft 40 will be transmitted through the gear members 56 and 58 to the ring member 52, rotating the ring member in a direction which is opposite to that of the rotation of the drive shaft 40. The laser diode member 70 will output a laser light beam through the drive shaft 40 which is deflected 90 degrees by the deflecting portion 66 of the optical transceiver 64. The light beams reflected by the deflecting portion 66 of the transceiver will strike the interior surface of the rotating mirror members 62, deflecting the light beams in a downward direction along a plurality of light paths 67 (Fig. 4) to strike the mirror member 32. The mirror member 32 deflects the light beams towards the pattern forming mirror members 82 which in turn deflect the received light beams through the glass window 24 in the aperture 22 in the form of the scan pattern 84 (Fig. 2) through which a bar code label is passed adjacent the glass window 24. The light beams reflected from the scanned bar code label are transmitted through the glass window 24 along light paths which are collected by the collection portion 68 of the optical transceiver 64 for focusing the reflected light beams on the photodetector 76. It will be seen from this arrangement that the reflected light beams are also directed towards the top opening of the ring 61 of mirror members 62 to be collected by the collection portion 68 of the transceiver 64 which is mounted adjacent the top opening of the ring of mirrors. The scan pattern 84 (Fig. 2) generated by the scanning apparatus of the present invention is the equivalent of 64 scan lines; 8 scan lines from 8 directions and from around 360 degrees assuming the use of eight pattern forming mirrors members 82 and eight mirror members 62 forming the ring 61. The exiting angles may vary between 40 and 90 degrees. The exiting scan lines in the scan pattern 84 from the top of the scanning apparatus are full length to give a large scan volume measured from the front of the scanning apparatus. A consideration of the present invention is that the 8/8 mirror arrangement will result in a plurality of partial scan lines as the full pattern effectively rotates around the drive shaft 40 as illustrated in Fig. 2. A wider scanning pattern is possible with different arrangement of the pattern mirror members 82 and the use of multiple bottom mirrors in place of the mirror member 32. While the present invention is shown disclosed in a portable housing member 20, it is obvious that the scanning apparatus can be mounted within a checkout counter as is normal in such checkout installations.

Claims: An optical scanning apparatus comprising a light source (70) for projecting light on to first deflecting means (66) mounted on a rotatable drive member (40) for rotation therewith in a first direction, second deflecting means arranged to rotate in a direction opposite to that of said first reflecting means (66) and comprising a first plurality of substantially flat mirror members (62) conically arranged around said first deflecting means (66) to receive light deflected by said first deflecting means (66), characterized by third deflecting means (32) for deflecting light from said first plurality of mirror members (62) to a second plurality of mirror members (82) which surround said first plurality of mirror members (62), said third deflecting means (32) being located beneath said first plurality of mirror members (62) in a plane substantially perpendicular to the plane of each of said second plurality of mirror members (82) and to the rotation axis of said rotatable drive member (40), said second plurality of mirror members (82) being arranged to deflect this light so as to form a scanning pattern for scanning coded indicia. Apparatus according to claim 1, characterized in that said drive member (40) is in the form of a tubular member through which light from said light source (70) is directed on to said first deflecting means (66). Apparatus according to either claim 1 or claim 2, characterized in that said third deflecting means (32) is annular and disposed substantially coaxially with said first plurality of mirror members (62). Apparatus according to any preceding claim, characterized in that said second deflecting means (62) is rotatably driven by gear means (58) engaging said drive member (40). Apparatus according to claim 4, characterized in that said second deflecting means (62) is mounted on a first support member (52) driven by said gear means (58) and which is mounted by way of a bearing surface (50) on a second support member (46). Apparatus according to any preceding claim, characterized in that the light from said source (70) is projected along the axis of rotation of said drive member (40). Apparatus according to claim 6, characterized by collector means (68) mounted on said drive member (40) adjacent said first deflecting means (66) for collecting light reflected from said coded indicia and focusing the collected light at a location on the axis of rotation of said drive member (40) at which is mounted opto-electronic detector means (76).

Inventors: WIKE CHARLES KENNETH JR, WIKE, CHARLES KENNETH, JR.
Applicants: NCR INT INC, NCR INTERNATIONAL INC.
Application year: 1991
Main classification: G06K7
IPC codes: G02B26, G06K7