Laser module for reading optical codes

Abstract

There is described a compact laser module ( 1 ) for reading optical codes, comprising: a scanning illumination section having at least one source ( 8 ) for generating a laser beam, and means ( 9, 10 ) for scanning the optical code (C) to be read with a laser spot, and p1 a receiving section ( 20 - 24 ) for collecting at least a portion of the light diffused by the code (C) and detecting the collected light, the receiving section and the scanning illumination section being spatially distinct.

1 . Compact laser module ( 1 ) for reading optical codes, comprising: 
 a scanning illumination section having at least one source ( 8 ;  60 ) for generating a laser beam, and means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ) for scanning the optical code (C) to be read with a laser spot, and    a receiving section ( 20 - 24 ;  27 ;  27   a ) for collecting at least a portion of the light diffused by the code (C) and detecting the collected light,    the receiving section and the scanning illumination section being spatially distinct.    
     
     
         2 . Laser module ( 1 ) according to  claim 1 , characterised in that the scan means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ) comprises motor means ( 10 ;  40 ) and an optically reflecting member ( 9 ) moved by the motor means ( 10 ;  40 ) for receiving and deflecting the laser beam.  
     
     
         3 . Laser module ( 1 ) according to  claim 2 , characterised in that the optically reflecting member ( 9 ) is of a size (H S ) in the direction perpendicular to the scan plane that is less than 1.5 mm.  
     
     
         4 . Laser module ( 1 ) according to any one of claims  2  and  3 , characterised in that the motor means ( 10 ;  40 ) provides a continuously variable angular speed.  
     
     
         5 . Laser module ( 1 ) according to  claim 4 , characterised in that upon start up said motor means ( 10 ;  40 ) is driven with a ramp signal.  
     
     
         6 . Laser module ( 1 ) according to one or more of  claims 2  to  5 , characterised in that said motor means ( 10 ;  40 ) comprises a motor ( 10 ) selected between a brushless motor and a stepping motor.  
     
     
         7 . Laser module ( 1 ) according to  claim 6 , characterised in that said motor ( 10 ) is of a height (H M ) lower than 9 mm.  
     
     
         8 . Laser module ( 1 ) according to  claim 7 , characterised in that said motor ( 10 ) is of a height (H M ) lower than 6 mm.  
     
     
         9 . Laser module ( 1 ) according to  claim 8 , characterised in that said motor ( 10 ) is of a height (H M ) lower than 3 mm.  
     
     
         10 . Laser module ( 1 ) according to one or more of  claims 2  to  5 , characterised in that said motor means ( 10 ;  40 ) comprises a rotating magnetic disk motor and the optically reflecting member ( 9 ) is directly supported on the motor magnetic disk.  
     
     
         11 . Laser module ( 1 ) according to any one of  claims 2  to  5 , characterised in that said motor means ( 10 ;  40 ) comprises an electrostatic motor.  
     
     
         12 . Laser module ( 1 ) according to any of claims  2 - 11 , characterised in that the motor means ( 10 ;  40 ) is driven with pulse width modulation.  
     
     
         13 . Laser module ( 1 ) according to any of claims  2 - 12 , characterised in that the optically reflecting member ( 9 ) comprises at least a portion of the side faces ( 911 - 916 ) of a polygonal-base body, and is rotationally moved by the motor means ( 10 ).  
     
     
         14 . Laser module ( 1 ) according to  claim 13 , characterised in that the side faces ( 911 - 916 ) of the polygonal base body are sloping at respective different angles (α 1 -α 6 ) with respect to its axis.  
     
     
         15 . Laser module ( 1 ) according to one ore more of claims  2 - 12 , characterised in that the optically reflecting member ( 9 ) comprises a single surface, and is moved with an alternately oscillating motion along a circumference arc.  
     
     
         16 . Laser module ( 1 ) according to  claim 15 , characterised in that said motor means ( 10 ;  40 ) comprises an oscillating magnetic device ( 40 ).  
     
     
         17 . Laser module ( 1 ) according to  claim 16 , characterised in that the oscillating magnetic device ( 40 ) comprises, on a common insulating substrate ( 41 ): 
 a magnetic core ( 42 ) having a conductor winding ( 44 ) around it, and an air gap ( 43 ), and    an elongated magnetic element ( 45 ) having an end ( 47 ) that is free to oscillate towards and away from the air gap ( 43 ) of the magnetic core ( 42 ) and carrying the optically reflecting member ( 9 ).    
     
     
         18 . Laser module ( 1 ) according to  claim 1 , characterised in that the scan means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ) comprises a device ( 50 ) selected between an electro-optical device and an acousto-optical device.  
     
     
         19 . Laser module ( 1 ) according to  claim 1 , characterised in that the scanning illumination section comprises an array ( 60 ) of laser micro-sources ( 66 ) and the scan means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ) comprises a controller ( 61 ) for sequentially actuating the laser micro-sources ( 66 ) of a row ( 62 - 65 ) of the array ( 60 ).  
     
     
         20 . Laser module ( 1 ) according to  claim 19 , characterised in that the array ( 60 ) of laser micro-sources comprises more rows ( 62 - 65 ).  
     
     
         21 . Laser module ( 1 ) according to  claim 20 , characterised in that each row ( 62 - 65 ) of laser micro-sources ( 66 ) of the array ( 60 ) is of a respective colour.  
     
     
         22 . Laser module ( 1 ) according to any of the previous claims, characterised in that the scan means ( 9 ,  10 ;  40 ;  50 ) or the laser micro-sources ( 60 ) are arranged as far as possible from a front face ( 3 ) of the laser module ( 1 ).  
     
     
         23 . Laser module ( 1 ) according to any of the previous claims, characterised in that the scan means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ) exhibits a predetermined stand-by position, in which it projects the laser beam in at least one fixed laser spot at the code (C).  
     
     
         24 . Laser module ( 1 ) according to any of the previous claims, characterised in that the scan laser light is high frequency modulated.  
     
     
         25 . Laser module ( 1 ) according to  claim 24 , characterised in that the scan laser light is modulated so as to obtain a signal suitable to measure the optical code distance.  
     
     
         26 . Laser module ( 1 ) according to any of the previous claims, characterised in that the receiving section comprises at least one focusing lens ( 22 ) in the proximity of the front face ( 3 ) of the laser module ( 1 ), and at least one photo-detecting element ( 24 ) at the focus of the focusing lens ( 22 ).  
     
     
         27 . Laser module ( 1 ) according to  claim 26 , characterised in that there is a slit ( 23 ) between said at least one focusing lens ( 22 ) and said at least one photo-detecting element ( 24 ).  
     
     
         28 . Laser module ( 1 ) according to any of claims  26  and  27 , characterised in that there is a plurality of photo-detecting elements ( 24 ) and means ( 82 ,  83 ) for synchronising the actuation of the photo-detecting elements ( 24 ) of said plurality with said scan means ( 9 ,  10 ;  40 ;  50 ;  60 ,  61 ).  
     
     
         29 . Laser module ( 1 ) according to any of claims  26 - 28 , characterised in that the receiving section is essentially parallelepiped ( 27 ), said at least one photo-detecting element ( 24 ) being arranged in close proximity of a rear face ( 4 ) of the laser module ( 1 ).  
     
     
         30 . Laser module ( 1 ) according to  claim 29 , characterised in that the receiving section further comprises photo-detecting elements ( 24 ) arranged in close proximity of its side faces.  
     
     
         31 . Laser module ( 1 ) according to  claim 30 , characterised in that the receiving section comprises a plurality of photo-detecting elements ( 24 ) arranged along an optimum focus curve of a single focusing lens ( 22 ).  
     
     
         32 . Laser module ( 1 ) according to any of claims  26 - 28 , characterised in that the receiving section comprises a chamber ( 27   a ) having a front face ( 90 ), a lower face or respectively upper face ( 91 ) orthogonal to it, a sloping face ( 92 ) between them, and side faces ( 93 ,  94 ) shaped as right-angled triangles, said at least one focusing lens ( 22 ) being arranged at she front face ( 90 ), said at least one photo-detecting element ( 24 ) being arranged at the lower or respectively upper face ( 91 ), and there being provided an internally reflecting surface ( 95 ) at the sloping face ( 92 ).  
     
     
         33 . Laser module ( 1 ) according to  claim 32 , characterised in that the slope angle between the sloping face ( 92 ) and the front face ( 90 ) is less than  45  degrees.  
     
     
         34 . Laser module ( 1 ) according to any of claims  32  and  33 , characterised in that internally reflecting surfaces ( 96 ) are also provided at the side faces ( 93 ,  94 ) of the receiving chamber ( 27   a ).  
     
     
         35 . Laser module ( 1 ) according to  claim 34 , characterised in that the side faces ( 93 ,  94 ) are slightly converging away from the front face ( 90 ).  
     
     
         36 . Laser module ( 1 ) according to any of  claims 32  to  35 , characterised in that the receiving chamber ( 27   a ) is solid, made of an optically transparent material ( 97 ).  
     
     
         37 . Laser module ( 1 ) according to any of  claims 26  to  36 , characterised in that said at least one focusing lens ( 22 ) is selected between a cylindrical lens and a toric lens.  
     
     
         38 . Laser module ( 1 ) according to  claim 37 , characterised in that said at least one focusing lens ( 22 ) is a Fresnel cylindrical lens.  
     
     
         39 . Laser module ( 1 ) according to any of  claims 26  to  35 , characterised in that said at least one focusing lens ( 22 ) is made of a coloured plastic material with high-pass filter behaviour.  
     
     
         40 . Laser module ( 1 ) according to  claim 39 , characterised in that the receiving section comprises a common glass filter ( 21 ) having a low-pass treatment.  
     
     
         41 . Laser module ( 1 ) according to  claim 39 , characterised in that the focusing lens ( 22 ) is coloured with low-pass filter behaviour on its optically non-active face.  
     
     
         42 . Laser module ( 1 ) according to any of the previous claims, characterised in that the scanning illumination section and the receiving section are arranged in stacked planes.  
     
     
         43 . Laser module ( 1 ) according to  claim 36 , characterised in that the scanning illumination section comprises an emission window ( 11 ) having a height substantially equal to the laser beam diameter in that plane.  
     
     
         44 . Laser module ( 1 ) according to any of  claims 1  to  41 , characterised in that The scanning illumination section and the receiving section are arranged in a common plane.  
     
     
         45 . Laser module ( 1 ) according to  claim 44 , characterised in that said at least one photo-detecting element ( 24 ) of the receiving section partially extends in front of motor means ( 10 ;  40 ) of the scanning illumination section.  
     
     
         46 . Laser module ( 1 ) according to  claim 44  or  45 , characterised in that the scan means ( 9 ;  50 ) or the array of laser micro-sources ( 60 ) are arranged in close proximity of the front face ( 3 ) of the laser module ( 1 ).  
     
     
         47 . Laser module ( 1 ) according to any of the previous claims, characterised in that it comprises a support block ( 70 ) for commonly supporting the components of the receiving section, and of the components of the scanning illumination section.  
     
     
         48 . Laser module ( 1 ) according to  claim 47 , characterised in that the support block ( 70 ) and the components of the scanning illumination and receiving sections have conjugate means ( 12 ,  13 ,  13   a,    76 - 78 ) for assembling the components in predetermined positions.  
     
     
         49 . Laser module ( 1 ) according to any of claims  47  and  48 , characterised in that the support block ( 70 ) exhibits at least one wall ( 80 ,  81 ) extending transversally to the front face ( 3 ) for defining an insulated chamber for the scan laser light propagation.  
     
     
         50 . Laser module ( 1 ) according to any of  claims 47  to  49 , characterised in that the support block ( 70 ) exhibits at least one insulated light extraction path ( 82 ) at an end portion of the scan, and in that a photo-detecting element ( 83 ) is arranged at the end of each extraction path ( 82 ).