Illumination assemblies for use in barcode readers and devices and methods associated therewith

• US 10,268,854 B1
• Filed: 04/13/2018
• Issued: 04/23/2019
• Est. Priority Date: 04/13/2018
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Zebra Technologies Corporation
• Inventors: Tan, Chinh, Chen, Caihua, Wittenberg, Carl D., Potter, Jason Y.
• Primary Examiner(s): Vo, Tuyen K
• Application Number:
  US15/952,786
• Time in Patent Office: 375 Days
• Field of Search: 23546242, 23546243, 23546245
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: G06K 7/1096 the scanner having more than one scanning window, e.g. two substantially orthogonally placed scanning windows for integration into a check-out counter of a super-market

Abstract

At least some embodiments of the present invention are directed toward optical arrangements for use in providing illumination light emitted by a barcode reader. In some embodiments, the arrangement includes an illumination source, a lens positioned within the path of the illumination light emitted by the illumination source where the lens is operable to collimate the light and redirect its central axis, and a window positioned within the path of the redirected and collimated light where the window is operable to alter the illumination light such that the resulting illumination light beam has a height-to-width ratio of less than 8 to 25.

Claims

1. An illumination assembly for use in a barcode reader, comprising:

an illumination source operable to emit an illumination light along a first path, the illumination light having a central axis;

a lens positioned within the first path of the illumination light,

the lens configured to redirect the central axis resulting in a redirected central axis and propagate the illumination light along a second path, the central axis and the redirected central axis being non-parallel with respect to each other, the redirected central axis defining a line of intersection between a first plane and a second plane, the first plane being perpendicular to the second plane,

the lens including a first lens surface proximal to the illumination source, the first lens surface being positioned within the first path and being defined by a first freeform polynomial,

the lens further including a second lens surface distal to the illumination source, the second lens surface being positioned within the second path and being defined by a second freeform polynomial; and

a window positioned within the second path of the illumination light, the window including a first window-portion and a second window-portion,

the first window-portion being configured to propagate a first portion of the illumination light along a third path, the first portion of the illumination light being a portion of the of the illumination light that impinges on the first window-portion, the third path having a divergence angle of at least 25 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane,

the second window-portion configured to propagate a second portion of the illumination light along a fourth path, the second portion of the illumination light being a portion of the of the illumination light that impinges on the second window-portion, the fourth path having a divergence angle of at most 20 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane.

2. The illumination assembly of claim 1, wherein the first window-portion includes a lens array having a plurality of lens elements, each of the plurality of lens elements having a first lens-element surface that varies in a first direction and remains constant in a second direction, the first direction being parallel with the first plane and the second direction being parallel with the second plane.

3. The illumination assembly of claim 2, wherein the first lens-element surface is defined by a semi-circular shape having a curvature radius between 0.4 and 0.6 mm.

4. The illumination assembly of claim 2, wherein each of the plurality of lens elements has a pitch of 0.4 mm to 0.6 mm.

5. The illumination assembly of claim 2, wherein each of the plurality of lens elements further has a second surface that varies in the first direction and remains constant in the second direction, the second surface being opposite the first surface.

6. The illumination assembly of claim 5, wherein the second lens-element surface is defined by a semi-circular shape having a curvature radius between 1.4 and 1.6 mm.

7. The illumination assembly of claim 1, wherein a ratio of the first window-portion to the second window-portion is between 3 to 2 and 4 to 1.

8. The illumination assembly of claim 1, wherein at least one of the first surface and the second surface is defined by:

9. The illumination assembly of claim 1, wherein the lens provides an on-axis gain between 25×

and 35×

.

10. The illumination assembly of claim 1, wherein a combination of the lens and the window provides an on-axis gain between 8×

and 22×

.

11. The illumination assembly of claim 1, wherein, upon the illumination light exiting the window, between 50% and 75% of a total amount of radiant intensity of the illumination light is within +/−

5 degrees of the redirected central axis, the radiant intensity being measured along a cross-sectional sample extending parallel to the first plane.

12. The illumination assembly of claim 1, wherein the lens is a collimating lens.

13. The illumination assembly of claim 1, wherein the barcode reader includes a linear imaging assembly having field of view (FOV) that extends along a FOV plane, and wherein the FOV plane is parallel to the first plane.

14. The illumination assembly of claim 1, wherein the first lens surface and the second lens surface are arranged such that a first tangential plane that is tangential to the first lens surface along the central axis and a second tangential plane that is tangential to the second lens surface along the redirected central axis intersect at an oblique angle.

15. The illumination assembly of claim 14, wherein the oblique angle is between 25 and 40 degrees.

16. An illumination assembly for use in a barcode reader, comprising:

an illumination source operable to emit an illumination light along a first path, the illumination light having a central axis; and

a lens positioned within the first path of the illumination light,

the lens configured to redirect the central axis resulting in a redirected central axis and propagate the illumination light along a second path, the central axis and the redirected central axis being non-parallel with respect to each other, the redirected central axis defining a line of intersection between a first plane and a second plane, the first plane being perpendicular to the second plane,

the lens including a first lens surface proximal to the illumination source, the first lens surface being positioned within the first path and being defined by a first freeform polynomial,

the lens further including a second lens surface distal to the illumination source, the second lens surface being positioned within the second path and being defined by a second freeform polynomial,

wherein the first lens surface and the second lens surface are arranged such that a first tangential plane that is tangential to the first lens surface along the central axis and a second tangential plane that is tangential to the second lens surface along the redirected central axis intersect at an oblique angle.

17. The illumination assembly of claim 16, wherein at least one of the first surface and the second surface is defined by:

18. The illumination assembly of claim 16, wherein the lens provides an on-axis gain between 25×

and 35×

.

19. The illumination assembly of claim 16, wherein the lens is a collimating lens.

20. The illumination assembly of claim 16, wherein the oblique angle is between 25 and 40 degrees.

21. The illumination assembly of claim 16, further comprising:

a window positioned within the second path of the illumination light, the window including a first window-portion and a second window-portion,

the first window-portion being configured to propagate a first portion of the illumination light along a third path, the first portion of the illumination light being a portion of the of the illumination light that impinges on the first window-portion, the third path having a divergence angle of at least 25 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane,

the second window-portion configured to propagate a second portion of the illumination light along a fourth path, the second portion of the illumination light being a portion of the of the illumination light that impinges on the second window-portion, the fourth path having a divergence angle of at most 20 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane.

22. The illumination assembly of claim 16, wherein the lens has a height and a width, and wherein a height-to-width ratio is between 1.25 to 1 and 1.75 to 1.

23. A method of illuminating a target to be read by a barcode reader, the method comprising:

providing an illumination source operable to emit an illumination light along a first path, the illumination light having a central axis;

passing the illumination light through a lens positioned within the first path of the illumination light,

the lens configured to redirect the central axis resulting in a redirected central axis and propagate the illumination light along a second path, the central axis and the redirected central axis being non-parallel with respect to each other, the redirected central axis defining a line of intersection between a first plane and a second plane, the first plane being perpendicular to the second plane,

the lens including a first lens surface proximal to the illumination source, the first lens surface being positioned within the first path and being defined by a first freeform polynomial,

the lens further including a second lens surface distal to the illumination source, the second lens surface being positioned within the second path and being defined by a second freeform polynomial; and

upon the operation of passing the illumination light through the lens, passing the illumination light through a window positioned within the second path of the illumination light, the window including a first window-portion and a second window-portion,

the first window-portion being configured to propagate a first portion of the illumination light along a third path, the first portion of the illumination light being a portion of the of the illumination light that impinges on the first window-portion, the third path having a divergence angle of at least 25 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane,

the second window-portion configured to propagate a second portion of the illumination light along a fourth path, the second portion of the illumination light being a portion of the of the illumination light that impinges on the second window-portion, the fourth path having a divergence angle of at most 20 degrees along the first plane and a divergence angle of at most 8 degrees along the second plane.

24. The method of claim 23, wherein at least one of the first surface and the second surface is defined by:

25. The method of claim 23, wherein, upon the illumination light exiting the window, between 50% and 75% of a total amount of radiant intensity of the illumination light is within +/−

5 degrees of the redirected central axis, the radiant intensity being measured along a cross-sectional sample extending parallel to the first plane.

26. The method of claim 23, wherein the barcode reader includes a linear imaging assembly having field of view (FOV) that extends along a FOV plane, and wherein the FOV plane is parallel to the first plane.

27. The method of claim 23, wherein the first lens surface and the second lens surface are arranged such that a first tangential plane that is tangential to the first lens surface along the central axis and a second tangential plane that is tangential to the second lens surface along the redirected central axis intersect at an angle between 25 and 40 degrees.