Laser scanning assembly having an improved scan angle-multiplication factor

• US 8,408,469 B2
• Filed: 10/07/2010
• Issued: 04/02/2013
• Est. Priority Date: 10/07/2010
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Good, Timothy
• Primary Examiner(s): Kim, Ahshik
• Application Number:
  US12/899,930
• Publication Number:
  US 20120085825A1
• Time in Patent Office: 908 Days
• Field of Search: 235/462.38, 235/462.39, 235/462.43, 235/462.24
• US Class Current: 235/462.38
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 26/12 using multifaceted mirrors
• CPC Class Codes: G02B 5/09 Multifaceted or polygonal mirrors , e.g. polygonal scanning mirrors; Fresnel mirrors
• CPC Class Codes: G06K 7/10613 by rotation, e.g. polygon
• CPC Class Codes: G06K 7/10623 Constructional details
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning

Abstract

A laser scanning system for generating a laser scanning pattern in a scanning field, while amplifying the scan-angle multiplication factor of rotating mirrors employed therein. The laser scanning system employs rotatable laser scanning assembly having an axis of rotation and first and second rotating mirrors with normal vectors that are coplanar with each other and said rotational axis, and which form an acute angle substantially less than 90 degrees so as to provide a laser scanning assembly with a scan angle multiplication factor that is greater than 2.0. A cluster of stationary mirrors mounted about the first and second rotating mirrors, for sweeping a laser beam off the cluster of stationary mirrors after a laser beam has been reflected off the first rotating mirror, then reflected off the second rotating mirror, and then directed outwardly towards an array of pattern mirrors, so as to generate a resultant laser scanning pattern within the scanning field.

Claims

1. A laser scanning assembly comprising:

first and second rotating mirrors supported on a support structure, rotatable about a common axis of rotation, by an electrical motor;

wherein said first and second rotating mirrors have normal vectors that are coplanar with each other and said rotational axis, and which form an acute angle substantially less than 90 degrees so as to provide said laser scanning assembly with a scan angle multiplication factor that is greater than 2.0.

2. The laser scanning assembly of claim 1, which further comprises:

a laser source for generating a laser beam and directing said laser beam along said rotational axis toward said first rotating mirror, reflecting off said first rotating mirror over to a stationary cluster of mirrors which produces a planar 360 degree sweep of said laser beam, and wherein said stationary cluster of mirrors intercepts said 360 degree sweep of said laser beam and reflects said laser beam up to said second rotating mirror, from which said laser beam is reflected off said second rotating mirror and exits outwardly towards a plurality of pattern forming mirrors, which generate a laser scanning pattern in a scan field.

3. The laser scanning assembly of claim 2, wherein laser light reflected and/or scattered off a bar code symbol in said scan field, returns along the same optical path of the exiting laser beam, reflecting off all the same mirrors in reverse order, at which point, the returned laser light is collected by a photo detector and processed by a scan data signal processor.

4. The laser scanning assembly of claim 1, wherein the angle of said first rotating mirror is approximately 45 degrees, measured with respect to said axis of rotation;

and wherein said second rotating mirror is about 15 degrees, measured with respect to said axis of rotation.

5. The laser scanning assembly of claim 2, wherein said stationary cluster of mirrors comprises up of 12 mirrors of equal size, such that each mirror intercepts 30 degrees of said beam sweep.

6. The laser scanning assembly of claim 5, wherein each said stationary mirror is tilted at an angle around 15 degrees, specifically, mirrors 1, 4, 7, and 10 are oriented at 15 degrees, mirrors 2, 5, 8, and 11 are oriented at an angle slightly greater than 15 degrees, and mirrors 3, 6, 9 and 12 are oriented at an angle slightly less than 15 degrees.

7. The laser scanning assembly of claim 1, wherein the resulting total scan angle multiplication factor of said laser scanning assembly is approximately 2.8.

8. The laser scanning assembly of claim 1, wherein the resulting laser scanning pattern is an almost continuous, 360 degree raster of three scanning lines with one scanning line being broken approximately every 30 degrees.

9. The laser scanning assembly of claim 8, wherein said 360 degree raster of three scanning lines are intercepted by a second cluster of stationary pattern mirrors, disposed outside said first cluster of stationary mirrors, and directed out into said scan field in which a bar code symbol is present.

10. The laser scanning assembly of claim 7, wherein said scan angle multiplication factor of the rotating mirrors provides very a uniform beam motion through a full 360 degrees around the laser scanning assembly.

11. The laser scanning assembly of claim 7, wherein the scan angle multiplication factor of the rotating mirrors allows said laser scanning assembly to be physically larger than any individual cluster mirror, and consequently, allows the light collection to be nearly uniform with scan angle.

12. A laser scanning system for generating a laser scanning pattern while amplifying the scan-angle multiplication factor of rotating mirrors employed therein, said laser scanning system comprising:

a rotatable laser scanning assembly having an axis of rotation and first and second rotating mirrors with normal vectors that are coplanar with each other and said rotational axis, and which form an acute angle substantially less than 90 degrees so as to improve said laser scanning system with a scan angle multiplication factor that is greater than 2.0; and

a cluster of stationary mirrors mounted about said first and second rotating mirrors, for sweeping a laser beam off said cluster of stationary mirrors after, a laser beam has been reflected off said first rotating mirror, then reflected off said second rotating mirror, and then directed outwardly towards an array of pattern mirrors, so as to generate a resultant laser scanning pattern within a scanning field.

13. A laser scanning system comprising:

a mirror support structure with a hollow center and supporting a double-side rotating mirror mounted along the axis of rotation, and pair of second rotating mirrors disposed about the axis of rotation above said double-sided rotating mirror;

a motor for rotating said, mirror support structure about said axis of rotation;

a first light collection mirror having a first aperture;

a first photodiode mounted below said motor;

a second light collection mirror having a second aperture;

a second photodiode mounted above said motor;

a first cluster of stationary mirrors arranged about said first rotating mirror for reflecting laser scanning beams towards said pair of second rotating mirrors.

14. The laser scanning system of claim 13, which further comprises:

a laser source for generating a first laser beam and directing said laser beam through said first aperture along said axis of rotation, and off the first surface of said double-sided mirror and out said first aperture towards said first cluster of mirrors, and then reflects off a second reflective surface and out towards a stationary array of beam folding mirrors and then off a scanned object, while return light rays off a scanned object travel along the same optical path, focused by said first collector mirror towards said first photodetector; and

a second laser source for generating a second laser beam and directing said laser beam through said second aperture along the axis of rotation, and off said second surface of said double-sided mirror and towards said first cluster of mirrors, and then reflects off a second reflective surface and out towards a stationary array of beam folding mirrors and then off a scanned object, while return light rays off a scanned object travel along the same optical path, focused by said second collector mirror towards said second photo-detector.

15. The laser scanning system of claim 13, which further comprises:

a laser source for generating a laser beam and then splitting said laser beam into first and second laser beams,

wherein said first laser beam is directed through said first aperture along said axis of rotation, and off the first surface of said double-sided mirror and out said first aperture towards said first cluster of mirrors, while return light rays off a scanned object travel along the same optical path, focused by said first collector mirror towards said first photodetector; and

wherein said second laser beam is directed through said second aperture along the axis of rotation, and off said second surface of said double-sided mirror and towards said first cluster of mirrors, while return light rays off a scanned object travel along the same optical path, focused by said second collector mirror towards said second photodetector.

16. Method of generating a scanning pattern for scanning a bar code symbol within a scanning field, said method comprising the steps of:

(a) rotating a laser scanning assembly about an axis of rotation,

wherein said laser scanning assembly has first and second rotating mirrors with normal vectors that are coplanar with each other and said rotational axis, and which form an acute angle substantially less than 90 degrees so as to provide said laser scanning assembly with a scan angle multiplication factor that is greater than 2.0;

(b) directing a laser beam onto said first rotating mirror as said first and second rotating mirror rotate about said axis of rotation;

(c) said first rotating mirror reflectively sweeping the reflected laser beam off a cluster of stationary mirrors mounted about said first and second rotating mirrors;

(d) said cluster of stationary mirrors reflecting the laser beam towards said second rotating mirror;

(e) said second rotating mirror reflectively sweeping the laser beam outwardly towards an array of stationary pattern mirrors;

(f) said array of stationary pattern mirrors reflecting the laser beam so as to generate a resultant laser scanning pattern within the scanning field.