Solid elastic lens element and method of making same

• US 8,366,002 B2
• Filed: 05/26/2010
• Issued: 02/05/2013
• Est. Priority Date: 05/26/2010
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Wang, Ynjiun Paul, Feng, Chen
• Primary Examiner(s): VO, TUYEN KIM
• Application Number:
  US12/787,665
• Publication Number:
  US 20110290887A1
• Time in Patent Office: 986 Days
• Field of Search: 235/454, 23546201-46249, 23547201-47203, 264/1.7, 264/2.6, 359642-797, 359/819, 359/821, 359/822, 359/829, 359/830
• US Class Current: 235/454
• CPC Class Codes: G02B 13/0075 having an element with variable optical properties
• CPC Class Codes: G02B 26/0875 by means of one or more refracting elements
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G02B 7/04 with mechanism for focusing or varying magnification
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A lens element is provided that includes a housing defining a center bore and an optical axis, and a light transmissive cover coupled to the housing. A first elastic solid lens is disposed within the housing adjacent the light transmissive cover, and is characterized by a first thickness and a first durometer hardness. A second elastic solid lens is disposed in the housing adjacent to and substantially conforming to the first elastic solid lens, and is characterized by a second thickness and a second durometer hardness. The second lens thickness is less than the first lens thickness, and the second durometer hardness is greater than the first durometer hardness. In one embodiment, the first durometer hardness is less than OO60 as measured by the Shore method, and the second durometer hardness is in the range of A20 to A60 as measured by the Shore method.

Claims

1. A lens element comprising:

a housing defining a center bore there through, the bore defining an optical axis;

a light transmissive cover coupled to the housing;

a first elastic solid lens disposed within the housing along the optical axis and characterized by a first durometer hardness, the first elastic solid lens having a first surface oriented toward a light source and an opposing second surface adjacent the light transmissive cover, the first and second surfaces of the first lens defining a first lens thickness;

and a second elastic solid lens having a first surface oriented toward the light source and an opposing second surface adjacent and substantially conforming to the first surface of the first elastic solid lens, the first and second surfaces of the second lens defining a second thickness, the second lens characterized by a second durometer hardness;

wherein the second lens thickness is less than the first lens thickness and the second durometer hardness is greater than the first durometer hardness.

2. The lens element of claim 1, wherein the first durometer hardness of the first elastic solid lens is less than OO60 as measured by the Shore method, and the second durometer hardness of the second elastic solid lens is in the range of A20 to A60 as measured by the Shore method.

3. The lens element of claim 2, wherein the first durometer hardness is less than OO30.

4. The lens element of claim 3, wherein the first durometer hardness is less than OO10.

5. The lens element of claim 2, wherein the second durometer hardness is in the range of A25 to A35.

6. The lens element of claim 1, wherein the thickness of the second elastic solid lens is less than half the thickness of the first elastic solid lens.

7. The lens element of claim 1, wherein the first thickness is in the range of 0.5 millimeters to 0.8 millimeters and the second thickness is in the range of 12.5 micrometers to 0.20 millimeters.

8. The lens element of claim 1, wherein the first elastic solid lens comprises polydimethylsiloxane cross linked with an agent in a ratio of greater than 20:

1.

9. The lens element of claim 8, wherein the first elastic solid lens comprises polydimethylsiloxane cross linked with an agent in a ratio of greater than 50:

1.

10. The lens element of claim 1, wherein the second elastic solid lens comprises polydimethylsiloxane cross linked with an agent in a ratio less than 10:

1.

11. The lens element of claim 10, wherein the second elastic solid lens comprises polydimethylsiloxane cross linked with an agent in a ratio less than 5:

1.

12. The lens element of claim 1, wherein the second elastic solid lens comprises fluorinated ethylene propylene.

13. The lens element of claim 1, further comprising a third elastic solid lens adjacent to the second elastic solid lens, the third elastic solid lens having a durometer hardness in the range of A20 to A60.

14. The lens element of claim 13, wherein the second elastic solid lens comprises polydimethylsiloxane and the third elastic solid lens comprises fluorinated ethylene propylene.

15. An indicia reading terminal comprising:

an imaging assembly including an image sensor having a plurality of pixels;

a memory for storing image data, and a controller for processing the image data for attempting to decode decodable indicia represented in the image data;

a lens assembly for focusing an image of a target onto the image sensor, the lens assembly comprising a light transmissive cover, a first elastic solid lens disposed adjacent the light transmissive cover, and a second elastic solid lens disposed adjacent to and substantially conforming to the first elastic solid lens, the first elastic solid lens characterized by a first thickness and a first durometer hardness, the second elastic solid lens characterized by a second thickness and a second durometer hardness, the first lens thickness being greater than the second thickness and the first durometer hardness being less than the second durometer hardness;

wherein the indicia reading terminal is operative to move a lens setting of the lens assembly between at least first and second different lens settings, the lens assembly having a first plane of optimum focus at the first lens setting and a second plane of optimum focus at the second lens setting, the indicia reading terminal further being operative to expose a first frame of image data with the lens assembly at the first lens setting and a second frame of image data with the lens assembly at the second lens focus setting, and wherein the terminal is further configured so that the terminal is operative to subject each of the first and second frames of image data to a decode attempt for decoding of a decodable indicia.

16. The indicia reading terminal of claim 15, wherein the first durometer hardness of the first elastic solid lens is less than OO60 as measured by the Shore method, and the second durometer hardness of the second elastic solid lens is in the range of A20 to A60 as measured by the Shore method.

17. The indicia reading terminal of claim 16, wherein the first durometer hardness is less than OO30 and the second durometer hardness is in the range of A25 to A35.

18. The indicia reading terminal of claim 15, wherein the terminal is operative to move a lens setting of the lens assembly between the first and the second lens settings of the lens assembly during a time that the terminal executes an operator activated read attempt of the terminal, the terminal further being operative so that the first and second frames are exposed during a single operator activated read attempt of the terminal.

19. The indicia reading terminal of claim 15, wherein the terminal is operative to maintain a lens setting of the lens assembly at a certain lens setting during a time that the terminal executes an operator activated read attempt of the terminal, the terminal being operative to move the lens setting in accordance with an operator input command input subsequent to a first operator activated read attempt and prior to a second operator activated read attempt, the terminal further being operative so that the first frame and the second frame are exposed during separate first and second separate operator activated read attempts of the terminal.

20. An indicia reading terminal comprising:

a laser source emitting laser light;

a scanning apparatus for scanning the laser light across the target, wherein the terminal is operative so that a plane of optimum focus of the laser light scanned across the target varies based on a present lens setting of the lens assembly;

a lens assembly for focusing laser light emitted from the laser source, the lens assembly comprising a light transmissive cover, a first elastic solid lens disposed adjacent the light transmissive cover, and a second elastic solid lens disposed adjacent to and substantially conforming to the first elastic solid lens, the first elastic solid lens characterized by a first thickness and a first durometer hardness, the second elastic solid lens characterized by a second thickness and a second durometer hardness, the first lens thickness being greater than the second lens thickness and the first durometer hardness being less than the second durometer hardness;

wherein the terminal is operative to move the lens assembly between a first lens setting and a second lens setting, and is further operative to generate a first signal corresponding to a first scan with the lens assembly at the first lens setting and a second signal corresponding to a second scan with the lens assembly at the second lens setting, and wherein the terminal is further operative to attempt to decode a decodable indicia utilizing the first signal and the second signal.

21. The indicia reading terminal of claim 20, wherein the first durometer hardness of the first elastic solid lens is less than OO60 as measured by the Shore method, and the second durometer hardness of the second elastic solid lens is in the range of A20 to A60 as measured by the Shore method.

22. The indicia reading terminal of claim 21, wherein the first durometer hardness is less than OO30 and the second durometer hardness is in the range of A25 to A35.

23. The indicia reading terminal of claim 20, wherein the terminal is operative to move a lens setting of the lens assembly between the first lens setting and the second lens settings of the lens assembly during a time that the terminal executes an operator activated read attempt of the terminal, the terminal further being operative so that the first and second signals are generated during a single operator activated read attempt.

24. The indicia reading terminal of claim 20, wherein the terminal is operative to maintain a lens setting of the lens assembly at a certain lens setting during a time that the terminal executes an operator activated read attempt of the terminal, the terminal being operative to move the lens setting in accordance to an operator input command input subsequent to a first operator activated read attempt and prior to a second operator activated read attempt, the terminal further being operative so that the first signal and the second signal are output during separate first and second operator activated read attempts of the terminal.

25. A method for manufacturing a lens element, comprising the steps of:

providing a housing and a light transmissive cover;

forming a first elastic solid lens from polydimethylsiloxane cross linked with an agent in a ratio of greater than 20;

1;

securing the first elastic solid lens within the housing adjacent to the light transmissive cover;

forming a second elastic solid lens from fluorinated ethylene propylene; and

securing the second elastic solid lens within the housing adjacent to the first elastic solid lens.

26. The method of claim 25, further comprising the step of plasma treating a surface of the second elastic solid lens to improve the adhesion to the first elastic solid lens.

27. The method of claim 25, wherein a thickness of the first elastic solid lens is in a range of 0.5 millimeters to 0.8 millimeters, and a thickness of the second elastic solid lens is in the range of 12.5 micrometers to 25 micrometers.

28. A method for manufacturing a lens element, comprising the steps of:

providing a housing and a light transmissive cover;

forming a first elastic solid lens from polydimethylsiloxane cross linked with an agent in a ratio of greater than 20;

1;

securing the first elastic solid lens within the housing adjacent to the light transmissive cover;

forming a second elastic solid lens from polydimethylsiloxane cross linked with an agent in a ratio less than 10;

1; and

securing the second elastic solid lens within the housing adjacent to the first elastic solid lens.

29. The method of claim 28, wherein a thickness of the first elastic solid lens is in a range of 0.5 millimeters to 0.8 millimeters, and a thickness of the second elastic solid lens is in the range of 0.10 millimeters to 0.20 millimeters.