LASER SCANNING CODE SYMBOL READING SYSTEM PROVIDING CONTROL OVER LENGTH OF LASER SCAN LINE PROJECTED ONTO A SCANNED OBJECT USING DYNAMIC RANGE-DEPENDENT SCAN ANGLE CONTROL

• US 20150144698A1
• Filed: 06/20/2012
• Published: 05/28/2015
• Est. Priority Date: 06/20/2012
• Status: Active Grant

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Teng, Zhipeng, Wang, Haixi
• Granted Patent: US 10,049,245 B2
• Time in Patent Office: Days
• US Class Current: 235/462.1
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10801 Multidistance reading

Abstract

Method of and system for reading bar code symbols using a hand-supportable laser scanning bar code symbol reading system supporting an improved level control over the length of laser scan lines projected onto scanned objects, at any instant in time, in a manner dependent the detected location, distance or range of the scanned object in the scanning field of the system during system operation. The length characteristics of the laser scan line are controlled by setting the laser scan sweep angle as a function of detected or estimated distance or range of the object from the system. In the illustrative embodiment, the laser scan sweep angle is controlled by supplying a drive current to the scanning mechanism, as a function of detected or estimated distance or range of the object from the scanning system.

Claims

1. A method of reading code symbols using a laser scanning code symbol reading system having a working distance, said method comprising the steps of:

(a) supporting adjacent an object with a code symbol, in proximity to a hand-supportable laser scanning code symbol reading system having a light transmission window, and a scan line data buffer;

(b) estimating the distance of said object from said light transmission window, and generating data representative of said estimated distance;

(c) projecting a laser scanning beam through said light transmission window, and having a scan angle that is determined by said estimated distance, or said data representative of said estimated distance;

(d) detecting the intensity of laser light reflected/scattered from said scanning field during the scan sweep of the laser scanning beam across said scanning field and any object in said scanning field, and generating scan data signal representative of the detected laser light;

(e) collecting a line of scan data over a sweep of the laser beam across the scanning field and any object therein, and buffering the collected line of scan data; and

(f) decode processing said line of scan data collected and buffered in step (e) in an attempt to read any code symbol represented in said line of scan data, and when a code symbol is read within said line of scan data, then generating and transmitting symbol character data, corresponding to said decoded code symbol, to its intended destination.

2. The method of claim 1, wherein said scan angle determined by said estimated distance in step (b) is selected to achieve a predetermined scan line length projected onto the object scanned by said laser scanning beam during step (c).

3. The method of claim 1, wherein the length of the scan line projected onto the object scanned by the laser scanning beam is substantially constant for a range of object distances from the light transmission window, over a substantial portion of the working range of said laser scanning code symbol reading system.

4. The method of claim 1, wherein the length of the scan line projected onto the object scanned by the laser scanning beam is substantially constant for a range of object distances from the light transmission window, over a limited portion of the working range of said laser scanning code symbol reading system.

5. The method of claim 1, wherein said code symbols are symbols selected from the group consisting of 1D bar code symbols, 2D stacked linear bar code symbols and 2D matrix code symbols.

6. The method of claim 1, wherein step (c) comprises using a scanner current drive circuit to supply different levels of drive current to an electromagnetically-driven scanning mechanism to achieve said scan angles in response to said distances estimated in step (b).

7. The method of claim 1, wherein step (b) comprises estimating the distance of an object in said scanning field from said light transmission window, by processing said generating scan data signal representative of the detected laser light.

8. A laser scanning code symbol reading system, comprising:

a housing with a light transmission window;

a laser scanning module, disposed in said housing, for scanning, during each scanning cycle, a laser beam across a laser scanning field defined external to said light transmission window, and along a laser scan line passing through a code symbol on a scanned object in said laser scanning field;

light collection optics, disposed in said housing, for collecting light reflected/scattered from the scanned object in said laser scanning field;

a photo-detector, disposed in said housing, for detecting the intensity of collected light from said laser scanning field, and generating an analog scan data signal corresponding to said detected light intensity during laser scanning operations, during each said scanning cycle;

a scan data signal processor, disposed in said housing, for processing said analog scan data signal generating, and generating a line of scan data for each said scanning cycle;

wherein said scan data signal processor further includes a module for processing said analog scan data signal so as to estimate the distance of an object in said scanning field from said light transmission window, and generate data representative of said estimated distance;

wherein said laser scanning module further projects said laser scanning beam through said light transmission window, and having a scan angle that is determined by said estimated distance, or said data representative of said estimated distance;

a scan data buffer, disposed in said housing, for buffering each said line of scan data during each said scanning cycle;

a programmed processor, disposed in said housing, for processing each said line of scan data buffered in said scan data buffer during each said scanning cycle to decode any code symbol represented in said scan data, and generate symbol character data representative of said decode code symbol, and transmitting said symbol character data to its intended destination; and

a system controller, disposed in said housing, for controlling operations within said laser scanning code symbol reading system.

9. The laser scanning code symbol reading system of claim 8, wherein said scan angle determined by said estimated distance is selected to achieve a predetermined scan line length projected onto the object scanned by said laser scanning beam.

10. The laser scanning code symbol reading system of claim 8, wherein the length of the scan line projected onto the object scanned by the laser scanning beam is substantially constant for a range of object distances from the light transmission window, over a substantial portion of the working range of said laser scanning code symbol reading system.

11. The laser scanning code symbol reading system of claim 8, wherein the length of the scan line projected onto the object scanned by the laser scanning beam is substantially constant for a range of object distances from the light transmission window, over a limited portion of the working range of said laser scanning code symbol reading system.

12. The laser scanning code symbol reading system of claim 8, wherein said code symbols are symbols selected from the group consisting of 1D bar code symbols, 2D stacked linear bar code symbols and 2D matrix code symbols.

13. The laser scanning code symbol reading system of claim 8, wherein said laser scanning modules comprises a scanner current drive circuit to supply different levels of drive current to an electromagnetically-driven scanning mechanism to achieve said scan angles in response to said distances.

14. The laser scanning code symbol reading system, of claim 8, wherein said analog scan data signal processor comprises a module for estimating the distance of an object in said scanning field from said light transmission window, by processing said generating scan data signal representative of the detected laser light.

15. The laser scanning code symbol reading system of claim 8, which further comprises:

an input/output (I/O) communication interface, disposed in said housing, for interfacing with a host system and transmitting symbol character data to said host system, via a communication link.

16. The laser scanning bar code symbol system of claim 15, wherein said communication link is either a wired or wireless communication link.

17. The laser scanning bar code symbol reading system of claim 8, wherein said housing is a hand-supportable housing.