Method and apparatus for providing a focus indication for optical imaging of visual codes

• US 20070170259A1
• Filed: 01/25/2006
• Published: 07/26/2007
• Est. Priority Date: 01/25/2006
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nunnink, Laurens, Equitz, William, Kuechen, Joerg
• Granted Patent: US 8,181,878 B2
• Time in Patent Office: Days
• US Class Current: 235/462.210
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/10811 Focalisation

Abstract

A method and apparatus for indicating an in-focus or an out-of-focus condition for an imaging device (1, 2) in an optical reading and decoding apparatus (20) for receiving a coded image from a target area (29) on an article or package. In the method of the invention, two beams of light (27, 28) are generated to provide two illuminated aiming marks (32, 33) on the target. An in-focus condition is indicated when the two aiming marks are in a pre-defined spatial relationship relative to each other on the target. The in-focus condition or an out-of-focus condition can be signaled by controlling attributes of aiming marks (32, 33) or by controlling attributes of status indicator LEDs (12) on the apparatus (20) or by controlling an audible sound.

Claims

1. A method of indicating an in-focus condition for a two-dimensional imaging device that senses a coded pattern on a target, the method comprising:

generating two beams of light from two spaced apart aiming light sources;

aiming and shaping the two beams of light to produce two spaced apart illuminated aiming marks on the target without an intersection of said two respective beams with each other or with a central axis passing through a center of a field of view on the target; and

signaling at least one of an in-focus condition or an out-of-focus condition when the two illuminated aiming marks are in a pre-defined relationship relative to each other on the target and inside the field of view.

2. The method of claim 1, wherein the two beams of light are shaped into two illuminated bar-shaped aiming marks on the target which are aligned along a common axis, and wherein an in-focus condition is signaled by a space between the two bar-shaped marks along said axis, when said space is approximately equal in length to at least one, or to each, of the two illuminated bar-shaped aiming marks.

3. The method of claim 1, wherein the two beams of light are shaped into two illuminated bar-shaped aiming marks on the target that are parallel and spaced above and below a center of a field of view on the target, respectively, and wherein an in-focus condition is signaled by an end-to-end alignment of the two illuminated bar-shaped aiming marks.

4. The method of claim 1, wherein the two beams of light are shaped into two aiming marks of a shape determined by an in-focus condition, a beyond-focus-distance condition, or a shorter-than-focus-distance condition of the target in relation to the imaging device.

5. The method of claim 1, 2 or 3, wherein an in-focus condition is signaled by a change of color of at least one of the two illuminated aiming marks.

6. The method of claim 1, 2, 3 or 4, wherein an in-focus condition is signaled by a change of color of at least one light-emitting device other than the two spaced apart aiming light sources.

7. The method of claim 1, 2 or 3, wherein an out-of-focus condition is signaled by a blinking condition of at least one of the two illuminated aiming marks.

8. The method of claim 1, 2, 3 or 4, wherein an out-of-focus condition is signaled by a blinking condition of a light-emitting device other than the two spaced apart aiming light sources.

9. The method of claim 1, 2, 3 or 4, wherein the in-focus condition is indicated by an audible sound.

10. The method of claim 1, 2, 3 or 4, wherein the in-focus condition or an out-of-focus condition is signaled through a digital output to an external host.

11. An imaging apparatus for reading a coded pattern on a target, the imaging apparatus comprising:

a two-dimensional imaging device for sensing the coded pattern on the target within a field of view for the imaging device;

two spaced apart, aiming beam devices which transmit at least two respective beams of light to provide two spaced apart aiming marks on the target; and

a processor for receiving images of the coded pattern from the imaging device, the processor calculating an in-focus condition based on a parameter of an image sensed by the imaging device, and the processor signaling at least one of an in-focus condition or an out-of-focus condition based on a relative position of the aiming marks inside the field of view.

12. The apparatus of claim 11, further comprising shaping devices for shaping the two aiming marks as bar-shaped marks, and wherein an in-focus condition is signaled by alignment of the two bar-shaped aiming marks along a common axis, and by a gap between the two bar-shaped aiming marks being approximately equal in length to at least one, or to each, of the two bar-shaped aiming marks.

13. The apparatus of claim 11, further comprising aiming and shaping devices for shaping the two respective beams of light to provide two spaced apart and parallel aiming marks on the target that are positioned respectively above and below a center of the field of view for the imaging device;

and wherein an in-focus condition is signaled by an end-to-end parallel alignment of the two bar-shaped aiming marks.

14. The apparatus of claim 11, further comprising shaping devices for shaping the two respective beams of light to a respective shape determined by an in-focus condition, a beyond-focus-distance condition, or a shorter-than-focus-distance condition of the target in relation to the imaging device.

15. The apparatus of claim 11, 12 or 13, wherein an in-focus condition is signaled by a change of color of at least one of the two aiming marks.

16. The apparatus of claim 11, 12 or 13, wherein an out-of-focus condition is signaled by a blinking of at least one of the two aiming marks.

17. The apparatus of claim 11, 12, 13 or 14, further comprising a status-indicating light-emitting device, other than the aiming beam devices, that is controlled by the processor, and wherein an in-focus condition is signaled by a change of color of said status-indicating light-emitting device.

18. The apparatus of claim 11, 12, 13 or 14, further comprising a status-indicating light-emitting device, other than the aiming beam devices, that is controlled by the processor, and wherein an out-of-focus condition is signaled by a blinking of the status-indicating light-emitting device.

19. The apparatus of claim 11, 12, 13 or 14, wherein the in-focus condition is indicated by an audible sound.

20. The apparatus of claim 11, wherein the two beams are aimed so as not intersect each other or so as not to intersect a center line through a center of the field of view for the imaging device.