CCD-based bar code scanner

• US 6,257,490 B1
• Filed: 11/09/1999
• Issued: 07/10/2001
• Est. Priority Date: 10/29/1997
• Status: Expired due to Term

• Current Assignee: SICK Incorporated (Sick)
• Original Assignee: PTO (Safe Fleet Holdings LLC)
• Inventors: Tafoya, Benny R.
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US09/436,630
• Time in Patent Office: 609 Days
• Field of Search: 235/462.24, 235/462.41, 235/383, 235/462.13, 235/462.09, 235/462.11, 235/462.01, 235/462.1, 235/462.21
• US Class Current: 235/462.24
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning

Abstract

A bar code scanning system for a conveyor system in which a first conveyor and a second conveyor are disposed apart from each other by a small gap region. A light emitting device is positioned in the gap underneath a top surface of the first and second conveyors, and the light emitting device shines light onto bar code labels on a bottom side of objects as the objects traverse from the first conveyor to the second conveyor. A light receiving device is also positioned in the gap, and the light receiving device receives reflected light from the bottom side of the objects due to the light being shined on the objects by the light emitting device. The gap is covered by a glass or plastic plate, so as to allow light to pass substantially therethrough.

Claims

1. A bar code scanning method, comprising the steps of:

a) scanning a particular location with at least one CCD camera having a plurality of pixels each positioned to receive reflected light from a distinct portion of the particular location;

b) providing separate control for a plurality of different scan lines to be generated, the different scan lines scanning the particular location at different angular scanning directions;

c) outputting data from different subsets of the plurality of pixels based on the separate control provided in the step b), so as to provide a plurality of virtual scan lines, respectively, each of the virtual scan lines corresponding to a particular angular scanning direction of the particular location; and

d) determining if a bar code has been scanned by simultaneously decoding the data from each of the different subsets,

wherein the separate control is provided by a master CPU providing a count value to be used as a trigger for creation of each of the plurality of scan lines, the count value being used to receive only certain data from the CCD camera that corresponds to certain pixels of the CCD camera, and

wherein the data for the plurality of subsets are respectively stored in axis memories before being read at predetermined instants by a corresponding slave processor to determine if a possible bar code label has been scanned.

2. An apparatus for reading bar codes, comprising:

a CCD camera configured to scan a particular location, the CCD camera having a plurality of pixels each positioned to receive reflected light from a distinct portion of the particular location;

a plurality of axis controllers respectively providing control for a plurality of different virtual scan lines to be generated;

a common logic unit configured to receive respective control signals from the plurality of axis controllers and to output data from different subsets of the plurality of pixels based on the control signals;

a plurality of axis memories connected to the common logic unit and configured to respectively receive the different subsets of the plurality of pixels output from the common logic unit;

a plurality of bit logic units respectively connected to the plurality of axis memories and each configured to output a count value corresponding to a number of sequential bits stored in the corresponding axis memory that are of a same logic value, for each data transition found in data stored in the corresponding axis memory; and

a plurality of slave processors respectively connected to the plurality of bit logic units and each configured to receive the count value from the corresponding bit logic unit and to determine if a possible bar code label has been scanned.

3. The apparatus according to claim 2, wherein the common logic unit comprises a plurality of buffers configured to receive and temporarily store pixel data from the CCD camera.

4. The apparatus according to claim 3, wherein the axis controllers provide for simultaneous creation of the plurality of virtual scan lines.

5. The apparatus according to claim 4, wherein the slave processors provide for simultaneous determination of data received from the plurality of virtual scan lines.

6. The apparatus according to claim 2, further comprising:

a master processor that is communicatively connected to the common logic unit, to each of the axis controllers, and to each of the slave processors,

wherein the master processor controls reading of the data output from the CCD cameras to the common logic unit,

wherein the master processor initializes each of the axis controllers for reading data from the common logic unit, and

wherein the slave processors only send data corresponding to the real bar code to the master processor and do not send non-real bar code data to the master processor.

7. The apparatus according to claim 6, wherein in intervals where no bar codes are detected, the master processor controls each of the axis controllers so as to place each of the axis controllers in a predetermined mode for performing diagnostic checks.

8. The apparatus according to claim 6, wherein the memory has a predetermined refresh cycle associated therewith, and wherein the master processor initiates a read cycle from the memory at a rate faster than the predetermined refresh cycle.

9. An apparatus for scanning a bar code label, comprising:

a CCD camera configured to provide a linear array of scan output corresponding to a particular region currently being scanned;

a memory for storing the linear array of scan output from the CCD camera;

a controller connected to the CCD camera and configured to output the linear array of scan output to a particular region of the memory;

a signal processor connected to the memory and configured to output data from particular memory locations of the memory so as to create a plurality of virtual scan lines that scan the particular region at different angular scanning directions;

a decoder configured to determine if data corresponding to the virtual scan lines corresponds to a real bar code; and

a read-only memory connected to the signal processor and configured to store an application program to be run by the signal processor, the application program providing the control by which the signal processor outputs the data from the particular locations of the memory,

wherein the memory includes a row pointer that indicates whether a particular row of the memory has been read into by the linear array of scan output, and

wherein the row pointer is used by the signal processor as a timing signal in order to determine when to cause the output of the data from the particular memory locations of the memory.

10. The apparatus according to claim 9, wherein the virtual scan lines correspond to two 45 degree lines that intersect with each other so as to form an X-shape scan pattern.

11. The apparatus according to claim 10, wherein the decoder is only capable of reading data corresponding to the X-shape scan pattern.

12. The apparatus according to claim 9, wherein the signal processor receives the linear array of scan output obtained at a certain point in time and stores the linear array of scan output in one respective column of the memory,

wherein, when all columns of the memory are written into by the at least one CCD camera, the signal processor receives a notification signal from the memory to read the stored scan output from the memory, and

wherein a first column of the memory that contains oldest stored scan output is rewritten with new stored scan output from the at least one CCD camera irrespective as to whether the signal processor has read the oldest stored scan output from the memory.

13. The apparatus according to claim 12, wherein the at least one CCD camera includes a first CCD camera and a second CCD camera,

wherein the first CCD camera provides scan output to only a first storage region of the memory, and

wherein the second CCD camera provides scan output to only a second storage region of the memory different from the first storage region.

14. The apparatus according to claim 9, further comprising:

a second CCD camera configured to provide a linear array of scan output corresponding to a second particular region currently being scanned;

a second memory for storing the linear array of scan output from the second CCD camera;

a second controller connected to the second CCD camera and configured to output the linear array of scan output to a particular region of the second memory;

a second signal processor connected to the second memory and configured to output data from the particular region of the second memory so as to create a plurality of virtual scan line segments,

wherein the decoder simultaneously receives data from the first and second signal processors, combines the data received from the first and second signal processors to create at least one combined virtual scan line from the plurality of scan lines and the plurality of scan line segments, and determines if data corresponding to the at least one combined virtual scan line corresponds to the real bar code.