Modular focus system alignment for image based readers

• US 8,803,060 B2
• Filed: 03/05/2012
• Issued: 08/12/2014
• Est. Priority Date: 01/12/2009
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Nunnink, Laurens, Reuter, Richard
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US13/411,906
• Publication Number:
  US 20120161041A1
• Time in Patent Office: 890 Days
• Field of Search: 250/208.1, 250/216, 250/234, 250/235, 2502011-2015, 250/239, 235/462.42, 235/462.22, 235/462.36, 235/462.43, 359554-557, 396277-280, 396/301, 396/302
• US Class Current: 250/208.1
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G02B 7/026 using retaining rings or springs G02B7/027 takes precedence
• CPC Class Codes: G02B 7/04 with mechanism for focusing or varying magnification
• CPC Class Codes: G02B 7/10 by relative axial movement of several lenses, e.g. of varifocal objective lens
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

A modular focus system for image based code readers includes swappable lens attachments enables fixed focus, manual focus, and variable focus operation from a single reader. A manual focus lens cap includes a manually adjustable focus ring to change the focus of the reader. A variable focus lens module includes a liquid lens that is manipulated by a voltage delivered via a pair of electrodes to adjust the focus of the reader. The lens attachments can be swapped out and replaced as needed.

Claims

1. An image based code reader comprising:

a lens mount secured within a lens mount housing, the lens mount including at least one aligning tab;

a lens barrel received by the lens mount;

a sensor for capturing image data reflected from a target object;

an imager lens assembly coupled to the lens barrel and configured to focus the image data onto the sensor; and

a removable lens attachment including at least one key slot configured to couple to the at least one aligning tab such that the lens attachment can only be placed onto or removed from the lens mount at one predetermined angular position of the imager lens.

2. The image based code reader of claim 1 wherein the removable lens attachment further comprises a focus ring disposed at a target-facing end and a retaining flange disposed at a sensor-facing end.

3. The image based code reader of claim 1 wherein the removable lens attachment further comprises:

a manual focus lens module configured to be secured to the lens barrel such that rotation of the manual focus lens module translates into an axial movement of the imager lens relative to the sensor.

4. The image based code reader of claim 1 wherein the removable lens attachment further comprises:

a variable focus lens module configured to be secured to the lens barrel and electrically connected to a controller such that an output from the controller adjusts the focus of the code reader.

5. The image based code reader of claim 1, further comprising a cover comprising a locking tab, wherein the locking tab is configured to be received within a slot in the removable lens attachment when connected to the lens mount housing so as to prevent rotation of the removable lens attachment.

6. The image based code reader of claim 1, wherein the at least one aligning tab corresponds to a predetermined focus distance of the imager lens.

7. The image based code reader of claim 2, wherein the at least one aligning tab is formed in a receptacle disposed in the lens mount and the at least one key slot is formed in the retaining flange.

8. The image based code reader of claim 4, wherein the controller is configured to detect when the variable focus lens module is coupled to the code reader.

9. The image based code reader of claim 8, wherein the controller is further configured to detect at least one of out-of-focus image data, a target distance, and an operator input, and to generate an output voltage for the variable focus lens module when one of an out-of-focus image data, a target distance, and an operator input is detected.

10. The image based code reader of claim 3, wherein the manual focus lens module further comprises a mechanical stop for limiting rotation of the lens barrel to a predetermined range.

11. The image based code reader of claim 4, wherein the variable focus lens module comprises a liquid lens.

12. The image based code reader of claim 11, wherein the variable focus lens module further comprises a biasing member for holding the liquid lens and electrodes together.

13. The image based code reader of claim 1, wherein the lens mount further comprises at least one inwardly extending aligning tab.

14. The image based code reader of claim 1, wherein the lens mount further comprises a cutout for receiving an extension formed in the removable lens attachment.

15. The image based code reader of claim 1, wherein at least one alignment feature of the lens mount and the removable lens attachment are configured such that the lens mount and the removable lens attachment are received in only substantially one orientation.

16. The image-based code reader of claim 1, wherein the removable lens attachment comprises:

a first removable lens attachment configured to be secured to the lens barrel; and

a second removable lens attachment comprising;

a variable focus element adapted to be secured to an element housing; and

a pair of electrodes in electrical communication with the variable focus element, wherein the code reader is focused by supplying a voltage to the variable focus element when the second lens attachment is coupled to the lens barrel.

17. An image based code reader comprising:

a lens mount housing, the lens mount including a first alignment feature formed in a receptacle disposed in the lens mount housing;

a lens barrel received by the lens mount;

a sensor for capturing image data reflected from a target object;

an imager lens assembly fixedly secured within the lens barrel about an optical axis, wherein the imager lens assembly focuses the image data onto the sensor; and

a removable lens attachment having a second alignment feature, wherein the first alignment feature is aligned with the second alignment feature when the removable lens attachment is placed onto and removed from the lens barrel, and wherein the first alignment feature corresponds to a predetermined focal length of the imager lens assembly.

18. The image based code reader of claim 17 wherein the first alignment feature is an aligning tab and the second alignment feature is a key slot.

19. An image-based code reader comprising:

a lens mount secured within a lens mount housing, the lens mount including at least one aligning tab;

a lens barrel received by the lens mount;

a sensor for capturing image data reflected from a target object;

an imager lens assembly coupled to the lens barrel; and

a modular focusing system comprising;

a manual focus removable lens attachment having a focus ring disposed at a target facing end and a retaining flange having a notch in the retaining flange, the retaining flange disposed at a sensor facing end; and

a variable focus removable lens attachment.

20. An image based code reader comprising:

a lens mount secured within a lens mount housing, the lens mount including at least one aligning tab;

a lens barrel received by the lens mount;

a sensor for capturing image data reflected from a target object;

an imager lens assembly coupled to the lens barrel and configured to focus the image data onto the sensor; and

a removable lens attachment including mechanical features such that the lens attachment can only be placed onto or removed from the lens mount at one predetermined focus distance of the imager lens.