Dot peen mark image acquisition

• US 9,881,194 B1
• Filed: 09/19/2016
• Issued: 01/30/2018
• Est. Priority Date: 09/19/2016
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Desvernay, Jean Hubert, Esponde, Jol, Bessettes, Vincent
• Primary Examiner(s): Kim, Ahshik
• Application Number:
  US15/269,020
• Time in Patent Office: 498 Days
• Field of Search: 23545409, 23546209, 2354621
• CPC Class Codes: G06K 19/06121 the marking having been punched or cut out, e.g. a barcode machined in a metal work-piece
• CPC Class Codes: G06K 19/06159 the marking being relief type, e.g. three-dimensional bar codes engraved in a support
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06K 7/1439 including a method step for retrieval of the optical code
• CPC Class Codes: G06K 7/146 the method including quality enhancement steps

Abstract

A mark reader apparatus has a lens and an autofocus system that manipulates the lens in accordance with control signals. An image acquisition system measures a distance from the lens to a dot peened mark. A processor is programmed to: calculate a focus position for the autofocus system that focuses the lens on the dot peened mark; apply an offset to the calculated focus position to produce an offset focus position; control the autofocus system by positioning the autofocus system to the offset focus position; and via the image acquisition system, acquire an image of the mark with the autofocus system set to the offset focus position.

Claims

1. A method, comprising:

measuring a distance from a lens to a dot peened mark;

calculating a focus position for an autofocus system that focuses the lens on the dot peened mark;

applying an offset to the calculated focus position to produce a focus motor position;

setting the autofocus system to the offset focus position; and

acquiring an image of the mark with the autofocus system set to the offset focus position.

2. The method according to claim 1, where the offset causes adjacent dots in the dot peened mark to appear merged in the acquired image.

3. The method according to claim 1, further comprising determining the offset prior to applying the offset.

4. The method according to claim 3, where determining the offset comprises determining an offset value by reference to stored values.

5. The method according to claim 3, where determining the offset comprises calculating the offset using one of the following equations:

$\mathrm{Offset}=\frac{\mathrm{\alpha <br><br>}\times <br><br>\mathrm{distance}<br><br><br><br>\mathrm{between}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{dots}<br><br><br><br>\mathrm{of}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}}{\mathrm{distance}<br><br><br><br>\mathrm{to}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}};<br><br>$

Offset=β

×

distance between the dots of the mark×

(γ

+motor position); and

Offset=η

×

measured distance between the clots;

where the values of α

, β and

γ

, η

are constants that depend on the autofocus mechanism and the lens.

6. The method according to claim 1, comprising determining whether or not the image to be acquired is that of a dot peened mark and if the image lacks a dot peened mark:

measuring a distance from a lens to a non-dot peened mark;

calculating a focus position for an autofocus system that focuses the lens on the non-dot peened mark; and

applying an offset setting of zero to the calculated focus position.

7. The method according to claim 1, further comprising decoding the dot peened mark by using the acquired image of the dot peened mark.

8. A method, comprising:

measuring a distance from a lens to a dot peened mark;

calculating a focus position for an autofocus system that focuses the lens on the dot peened mark;

determining an offset to the calculated focus position;

applying the offset to the calculated focus position to produce an offset focus position;

positioning the autofocus system to the offset focus position;

acquiring an image of the mark with the autofocus system set to the offset focus position; and

decoding the mark at a decoder by using the acquired image of the mark.

9. The method according to claim 8, where the offset is adequate to cause adjacent dots in the dot peened mark to appear merged in the acquired image.

10. The method according to claim 8, where determining the offset comprises determining an offset value by reference to stored values.

11. The method according to claim 8, where determining the offset comprises calculating the offset using one of the following equations:

$\mathrm{Offset}=\frac{\mathrm{\alpha <br><br>}\times <br><br>\mathrm{distance}<br><br><br><br>\mathrm{between}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{dots}<br><br><br><br>\mathrm{of}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}}{\mathrm{distance}<br><br><br><br>\mathrm{to}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}};<br><br>$
Offset=β

×

distance between the dots of the mark×

(γ

+motor position); and

Offset=η

×

measured distance between the clots;

where the values of α

, β and

γ

, and η

are constants that depend on the autofocus mechanism and the lens.

12. The method according to claim 8, comprising determining whether or not the image to be acquired is that of a dot peened mark and if the image lacks a dot peened mark:

measuring a distance from a lens to a non-dot peened mark;

calculating a focus position for an autofocus system that focuses the lens on the non-dot peened mark; and

applying an offset setting of zero to the calculated focus position.

13. A mark reader apparatus, comprising:

a lens;

an autofocus system that manipulates the lens in accordance with control signals;

an image acquisition system that measures a distance from the lens to a dot peened mark;

a processor that is programmed to;

calculate a focus position for an autofocus system that focuses the lens on the dot peened mark;

apply an offset to the calculated focus position to produce an offset focus position;

position the autofocus system to the offset focus position; and

via the image acquisition system, acquire an image of the mark with the autofocus system set to the offset focus position.

14. The apparatus according to claim 13, where the offset causes adjacent dots in the dot peened mark to appear merged in the acquired image.

15. The apparatus according to claim 13, where the processor is further programmed to determine the offset prior to applying the offset.

16. The apparatus according to claim 15, where determining the offset comprises determining an offset value by reference to stored values.

17. The apparatus according to claim 15, where a value of the offset is determined by calculating the offset using one of the following equations:

$\mathrm{Offset}=\frac{\mathrm{\alpha <br><br>}\times <br><br>\mathrm{distance}<br><br><br><br>\mathrm{between}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{dots}<br><br><br><br>\mathrm{of}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}}{\mathrm{distance}<br><br><br><br>\mathrm{to}<br><br><br><br>\mathrm{the}<br><br><br><br>\mathrm{mark}};<br><br>$

Offset=β

×

distance between the dots of the mark×

(γ

+motor position); and

Offset=η

×

measured distance between the clots;

where the values of α

, β and

γ

, and η

are constants that depend on the autofocus mechanism and the lens.

18. The apparatus according to claim 13, where the processor is further programmed to determine whether or not the image to be acquired is that of a dot peened mark and if the image lacks a dot peened mark:

measure a distance from a lens to a non-dot peened mark;

calculate a focus position for an autofocus system that focuses the lens on the non-dot peened mark; and

apply an offset setting of zero to the calculated focus position.

19. The apparatus according to claim 13, further comprising a decoder where the decoder decodes the dot peened mark by using the acquired image of the dot peened mark.

20. The apparatus according to claim 13, where the autofocus system comprises a motor, and where the offset comprises an offset to the motor position.