Abstract:
A scanning device for recognizing and reading bar codes is configured to have a housing that can be mounted on a scanning surface or beneath the scanning surface. The housing contains an internal scanning face unit, which includes a source of laser light, a rotatable polygonal mirror for reflecting the laser light, a plurality of fixedly disposed flat mirrors and a pick-up element for detecting radiation deflected by the bar code. This internal scanning unit can be arranged within the outer housing in four different positions, thereby creating greater flexibility with respect to the mounting of the overall housing.

Description:
BACKGROUND OF THE INVENTION 
     At an increasing number of retail outlets use is being made at the checkout of scanning devices for bar codes which are arranged either lying in a table top or standing thereon. In the case of devices arranged lying in a table top the object to be paid for is moved over the transparent plate with the bar code downward whereby the transparent plate must be replaced frequently due to scratches. 
     In the case of scanning devices in standing position this problem does not occur. Here however the problem does occur that the space for such a scanning device in standing position is usually limited, particularly in the case that an existing scanning device must be replaced by a new version with improved operation. Scanning devices of the prior art are further designed in accordance with the desired direction of the objects for moving therealong, i.e. from left to right or from right to left. 
     SUMMARY OF THE INVENTION 
     The present invention provides a device for scanning and/or recognizing bar code, comprising: 
     a housing mountable standing in or on a surface; and 
     an internal unit comprising a source of laser light, a rotatable polygonal mirror for reflecting the laser light, a plurality of fixedly disposed flat mirrors and a pick-up element for picking up radiation scattered by the bar code, wherein the internal unit is placeable in the housing in two or more positions. 
     The scanning device according to the present invention can be applied in highly diverse existing situations and can be built into most existing locations owing to the possibility of changing the direction of the scan lines by rotating the internal unit through one or more quarter-turns and also owing to the compact dimensions thereof. 
     The rotatable polygonal mirror and the lying mirrors are preferably disposed relative to each other such that scan lines are projected outward in five different directions through a transparent plate of the housing. The length of the scan lines therein extends practically over the full width of the window. 
     The present invention further provides a module for a scanning device which is sealable in a dustproof manner and comprises a source of laser light, a rotatable polygonal mirror for reflecting the laser light, a plurality of fixedly disposed flat mirrors and a pick-up element for picking up radiation scattered by the bar code and an inner housing which is arrangeable in an outer housing of random dimensions greater than the inner housing and which seals the components of the internal unit in dustproof manner. 
     This module can be coupled to an application specific to a relevant customer, for instance a manufacturer of cash register systems; in that case a specially tailored interface can also be designed for this application. This module can also be built into many existing housings owing to the compact dimensions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages, features and details of the present invention will be elucidated on the basis of the following description of a preferred embodiment thereof with reference to annexed drawing, wherein: 
     FIGS. 1A-1L show schematic front views of a possible method of arranging a preferred embodiment of a device according to the invention; 
     FIG. 2 shows a front view of the device of FIG. 1; 
     FIG. 3 shows a cross-sectional view of the device of FIGS. 1 and 2; 
     FIG. 4 shows a top view of a fixing element for fixing the device of FIGS. 1,  2  and  3 ; 
     FIG. 5 shows a partly exploded and broken away view of diverse components of the device of FIGS. 1-4; 
     FIG. 6 shows an exploded view of the device according to FIGS. 1-5; 
     FIG. 7 is an exploded view of the internal unit of the device according to FIGS. 1-6; 
     FIG. 8 is a schematic view of the radiation beams from the device shown in FIGS. 1-7; and 
     FIG. 9 is a view in perspective of the adjustment of a focussing element of FIG.  8 . 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1A-1D show a device  1  according to the present invention, a lower part  2  of which is situated below the upper level of a table top T, is for instance flush-mounted therein. Situated in the lower part  2  is a board with digital electronics and an interface connected to an electric cable which extends downward through the table top. In FIGS. 1E-1H the device  1  is placed on the table top with the lower part  2 , while according to FIGS. 1I-1L the device  1  is tilted, i.e. the lower part  2  now extends sideways. Also in this tilted position of device  1  the cable for electrical connection is preferably carried downward through table top T. The tilted position according to FIGS. 1I-1L, in addition to the flush-mounted position according to FIGS. 1A-1D have the advantage relative to the positions according to FIGS. 1E-1H that an object for scanning does not have to be lifted from the table top but has only to be moved over the table top with the bar code directed toward device  1 . In FIGS. 1A-1L is shown a rotatable quadrangular mirror  3  as well as scan lines S which are projected outward at at least five different angles in sets of four lines each. The scanning pattern S as drawn is visible as laser lines on the transparent plate of the device. 
     As can be seen in FIGS. 1A-1D, the internal unit of the device as is designated using the position of the quadrangular mirror  3  can, in each position of the housing, be arranged therein in four different positions, whereby the scanning pattern is likewise adapted to the wishes of the user, for instance whether the objects are moved from left to right or from right to left or otherwise. 
     In FIG. 2 is shown the quadrangular mirror  3  which is preferably formed by a plastic element with mirror surfaces vapour-deposited thereon, in addition to fixedly disposed inclining mirrors  4 ,  5 ,  6  etc. The transparent plate  7  through which the view is taken is provided with a clear laser light-transmitting part opposite the mirrors and a dark part  8 . The transparent plate  7  preferably takes a single form and is provided with a scratch-resistant coating. 
     Further designated in FIG. 3 is a board  9  which is situated in the lower housing part  2 . The rotating mirror  3  and a plurality of flat mirrors are also shown. 
     FIG. 4 shows a mounting or console element  10  provided with a plurality of holes  11 ,  12 ,  13 ,  14 ,  15 ,  16 ,  17  and  18  for passage of mounting elements. A central opening  19  is the gate which results during injection moulding of the console element. 
     In FIGS. 5 and 6 can be seen that the holes for the mounting elements in console element  20  extend through respective standing parts  21 ,  22  of dovetail-like form into lower dovetail-like grooves  23  and  24  arranged in housing  25 . When device  1  is mounted in the position shown in FIGS. 1E-1H, the holes  11 ,  14 ,  15  and  18  are used for screws B and the mounting element  20  is screwed onto the table, whereafter housing  25  is pushed thereon. Finally, the pushed-on position of housing  25  is fixed using a closing cover  26  of L-shaped cross section which also fixes the housing  25  in rearward direction. Closing cover  26  is provided with counter elements which fit into dovetail-like grooves  40  and  41  as well as pins with a thickened end which can be snapped into oval holes in housing  25 . A flexible frame  27  is glued against frame  28 . Inside frame  27 , the transparent plate  7  is fitted and glued against frame  28 . Frame  28  is snapped fixedly onto inner housing  30 . Preferably situated between inner housing  30  and frame  28  is a labyrinth seal for dustproof sealing of the inner housing in which the mirrors and the like are situated. 
     Frame  27  is fitted fixedly into housing  25  during assembly. The rear plate  31  is provided with hooked ends  32  so that plate  31  can be fixed in a manner not shown with a single screw in order to further simplify assembly. In the embodiment shown in FIG. 5 an electric cable (not shown) for power supply and other electrical signals can be guided through an opening  33  in the outer housing to a board  9  on which digital electronics are situated. 
     In the flush-mounted positions shown in FIGS. 1A-1D use can be made of screw bolts B which are screwed into angular counter elements arranged in openings  12 ,  13 ,  16  and  17  of console  20 . 
     Both in the position shown in FIG.  5  and in the tilted position in which the grooves  40  and  41  engage on the standing parts  21  and  22 , the recess  33  is situated close to the table top, in an opening of which the cables can then be carried away. 
     With reference to FIG.  7  and also to FIG. 3, it is of further importance to note that a cable  51  is connected to a board  50  on which the laser light source and the receiver for the reflected laser light are situated, this preferably being a flat cable which must be connectable in all positions shown to the board  9  on which the digital electronics is situated. Arranged for this purpose on board  9  (see also FIG. 6) is an electrical connection  52  consisting of two connectors, so that contact with this connection is ensured in any rotated position of the flat cable. 
     Further shown in FIGS. 7,  8  and  9  is a focussing element  54 , which serves to focus scattered laser light radiation to a detector  60 . In order to improve the efficiency (to 99.98%) use is made here of a plastic element onto which a gold layer is vapour-deposited, whereby transmission losses such as occur in lenses are avoided. The components of the internal unit of FIG. 7 otherwise relate to the flat mirrors, the rotatable mirror, a motor therefor, and a component  55  on which all these elements are arranged and on which a dividing mirror  56  is also arranged which serves to separate the transmitted and reflected light and which, with the exception of a passage strip for the scattered laser light beams, is likewise provided with a gold coating. 
     For easy adjustment of focussing mirror  54  this latter is arranged using at least slightly resilient rods  61 ,  62 , while on one side a rotatable adjusting screw  64  with a slightly eccentrically arranged pin  65  is arranged through a flange  63  on mirror  54 . During assembly of the device according to the present invention a screw element  64  is turned using a screwdriver until the intensity of scattered laser light measured by the detector is at maximum. When adjusting element  64  is turned the mirror  54  is displaced counter to the spring action of rods  61  and  62 . 
     The above described preferred embodiment of the device according to the invention is extremely compact and provides a dense scanning pattern in all desired directions, also due to the high rotation speed of the quadrangular mirror, for instance 6,000 revolutions per minute and the speed of the electronics adapted thereto. 
     The rights applied for are however in no way limited by the above described preferred embodiment of the present invention; the rights applied for are defined by the following claims.