Optical scanner alignment indicator method and apparatus

• US 6,330,521 B1
• Filed: 12/29/2000
• Issued: 12/11/2001
• Est. Priority Date: 05/01/1998
• Status: Expired due to Term

• Current Assignee: Microscan Systems Inc (Omron Corporation)
• Original Assignee: Robotic Vision Systems, Inc. (Acuity Brands, Inc.)
• Inventors: Kotlarsky, Anatoly, Bubnoski, David P., Hahn, James C.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Raymond, Edward
• Application Number:
  US09/752,390
• Time in Patent Office: 347 Days
• Field of Search: 702/150, 700/114, 700/115, 700/116, 700/117, 700/228, 700/229, 700/230, 700/259, 250/214, 250/363.02, 250/559, 250/200, 250/203.1, 335/06, 332/90, 348/94, 348/95, 369/275.1, 369/89, 369/373, 116/1, 359/197, 359/534, 359/642, 356/127, 356/138, 264/1.1, 395/12, 435/808, 333/248, 382/312
• US Class Current: 702/150
• CPC Class Codes: G06V 10/24 Aligning, centring, orientation detection or correction of the image

Abstract

A method and apparatus for aligning a target within a field of view of an optical scanner is provided. In an optical scanner having a field of view, apparatus for indicating whether a target is aligned within said field of view includes a microprocessor and an alignment indicator. The alignment indicator is electrically connected to the microprocessor and includes, for example, a light emitting diode. The microprocessor defines a first zone and a second zone within the field of view and determines whether the target is within the field of view. If the target is within the field of view, the microprocessor identifies a target alignment point on the target. The microprocessor determines whether the target alignment point is within either the first zone or the second zone and sends a signal to the alignment indicator. In response, the alignment indicator provides an indication indicating whether the target alignment point is located within the first zone, the second zone, or neither.

Claims

1. A method for aligning a target within a field of view of an optical scanner, said optical scanner comprising an alignment indicator, said method comprising the steps of:

defining a first zone within said field of view, said first zone being smaller than the field of view;

determining whether said target is within said field of view; and

if said target is within said field of view,

identifying a target alignment point on said target;

determining whether said target alignment point is within said first zone; and

if said target alignment point is within said first zone, said alignment indicator providing an indication thereof.

2. The method of claim 1, wherein the step of identifying said target alignment point comprises the steps of:

determining a geometric center point on said target; and

defining said geometric center point to be said target alignment point.

3. The method of claim 1, wherein the step of identifying said target alignment point comprises the steps of:

determining a center of gravity point on said target; and

defining said center of gravity point to be said target alignment point.

4. The method of claim 1, wherein the step of defining said first zone comprises the steps of:

identifying a field of view alignment point;

defining a reference target size;

determining an actual target size of said target;

determining a target radius of said target;

computing a first reference distance, said first reference distance being a function of said reference target size, said actual target size, and said target radius; and

defining said first zone to comprise a set of points within said field of view, wherein each point of said set of points is located less than one first reference distance from said field of view alignment point.

5. The method of claim 4, wherein the step of computing said first reference distance comprises the further steps of:

comparing said actual target size to said reference target size;

if said actual target size is less than or equal to said reference target size, defining said first reference distance to be about 90% of said target radius; and

if said actual target size is greater than said reference target size, defining said first reference distance to be about 90% of the target radius multiplied by a scale factor.

6. The method of claim 5, wherein said scale factor is approximately the square root of the ratio of said reference target size to said actual target size.

7. The method of claim 5, comprising the further step of:

if said first reference distance is defined to be less than about 25% of said target radius, defining said first reference distance to be about 25% of said target radius.

8. The method of claim 4, wherein the step of determining whether said target alignment point is within said first zone comprises the further steps of:

computing an actual distance between said target alignment point and said field of view alignment point;

comparing said actual distance to said first reference distance;

if said actual distance is less than said first reference distance, determining that said target alignment point is within said first zone; and

if said actual distance is not less than said first reference distance, determining that said target alignment point is not within said first zone.

9. The method of claim 1, wherein said alignment indicator comprises a light emitting diode, and wherein the step of said alignment indicator providing an indication comprises lighting said light emitting diode.

10. The method of claim 1, comprising the further steps of:

defining a second zone within said field of view; and

if said target is within said field of view,

determining whether said target alignment point is within said second zone; and

if said target alignment point is within said second zone, said alignment indicator providing another indication.

11. The method of claim 10, wherein said alignment indicator comprises a light emitting diode, and wherein the step of said alignment indicator providing another indication comprises blinking said light emitting diode.

12. The method of claim 4, comprising the further steps of:

defining a second zone within said field of view; and

if said target is within said field of view,

determining whether said target alignment point is within said second zone; and

if said target alignment point is within said second zone, said alignment indicator providing another indication.

13. The method of claim 12, wherein the step of defining said second zone comprises the steps of:

computing a second reference distance, said second reference distance being a function of said reference target size, said actual target size, and said target radius; and

defining said second zone to comprise a set of points within said field of view, wherein each point of said set of points is located less than one second reference distance from said field of view alignment point.

14. The method of claim 13, wherein said second reference distance is about three times said first reference distance.

15. The method of claim 10, comprising the further step of:

if said target alignment point is not within said first zone, and if said target alignment point is not within second zone, said alignment indicator providing still another indication.

16. The method of claim 15, wherein said alignment indicator comprises a light emitting diode, and wherein the step of said alignment indicator providing said still another indication comprises turning off said light emitting diode.

17. The method of claim 12, comprising the further step of:

if said target alignment point is not within said first zone, and if said target alignment point is not within second zone, said alignment indicator providing still another indication.

18. The method of claim 17, wherein said alignment indicator comprises a light emitting diode, and wherein the step of said alignment indicator providing said still another indication comprises turning off said light emitting diode.

19. In an optical scanner having a field of view, apparatus for indicating whether a target is aligned within said field of view, said apparatus comprising:

a microprocessor, said microprocessor defining a first zone within said field of view, said first zone being smaller than said field of view, and determining whether said target is within said field of view, and

if said target is within said field of view, said microprocessor identifying a target alignment point on said target and determining whether said target alignment point is within said first zone; and

if said target alignment point is within said first zone, said microprocessor sending a first signal indicating that said target alignment point is located within said first zone; and

an alignment indicator, said alignment indicator electrically connected to said microprocessor, said alignment indicator receiving said first signal from said microprocessor and, in response to said first signal, said alignment indicator providing an indication, said indication indicating that said target alignment point is located within said first zone.

20. The apparatus of claim 19, wherein said microprocessor defines a second zone within said field of view, and

if said target is within said field of view, said microprocessor determining whether said target alignment point is within said second zone; and

if said target alignment point is within said second zone, said microprocessor sending a second signal indicating that said target alignment point is located within said second zone; and

wherein said alignment indicator receives said second signal from said microprocessor and, in response to said second signal, said alignment indicator providing another indication, said another, indication indicating that said target alignment point is located within said second zone.

21. The apparatus of claim 20, wherein if said target alignment point is not located within either said first zone or said second zone, said microprocessor sends a third signal indicating that said target alignment point is not located within either said first zone or said second zone;

and

wherein said alignment indicator receives said third signal from said microprocessor and, in response to said third signal, said alignment indicator providing still another indication, said still another indication indicating that said target alignment point is not located within either said first zone or said second zone.

22. The apparatus of claim 19, wherein said alignment indicator comprises a light emitting diode.