Imaging module for optical reader comprising refractive diffuser

• US 20030213847A1
• Filed: 05/27/2003
• Published: 11/20/2003
• Est. Priority Date: 03/08/2001
• Status: Abandoned Application

• Current Assignee: Welch Allyn Incorporated
• Original Assignee: Welch Allyn Incorporated
• Inventors: Hunter, Vivian L., Havens, William H., Barber, Charles P., McCall, Melvin D., Hennick, Robert J., Coleman, Eric, Ehrhart, Michael
• Application Number:
  US10/445,524
• Publication Number:
  US 20030213847A1
• Time in Patent Office: Days
• US Class Current: 235/462.42
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10742 including a diffuser for diffusing the light from the light source to create substantially uniform illumination of the target record carrier
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence

Abstract

The present invention is an imaging module including various optical components and a circuit board, which, in one embodiment, carries essentially an entirety of illumination and aiming LEDs of the module. The module includes a combination of features which result in the size of the module being reduced. The module may comprise a refractive optic diffuser plate manufactured using a textured surface mold.

Claims

1. A method for making an imaging module for an optical reader, said module having a plurality of light emitting elements, said method comprising the steps of:

providing a mold;

applying a texture substantially throughout a surface of said mold;

making an optical plate using said mold, whereby said plate comprises a textured diffuser surface substantially uniformly formed throughout a surface of said plate; and

disposing said optical plate forward of at least one of said plurality of light emitting elements.

2. The method of claim 1, wherein said applying step includes the step of applying a micro cylinder texture substantially throughout a surface of said mold.

3. The method of claim 1, wherein said applying step includes the step of a applying a texture to said mold such that during said making step, a refractive optic diffuser surface is formed on said plate.

4. The method of claim 1, wherein said applying step includes the step of applying a texture to said mold such that during said making step, a refractive optic diffuser surface is formed on said plate, said diffuser surface comprising a plurality of substantially cylindrical microlenses.

5. The method of claim 1, wherein said applying step includes the step of applying a texture to said mold such that during said making step, a refractive optic diffuser surface is formed on said plate, said diffuser surface comprising a plurality of substantially cylindrical microlenses formed in a randomized pattern.

6. The method of claim 1, wherein said applying step includes the step of applying a texture to said mold such that during said making step, a refractive optic diffuser surface is formed on said plate, said diffuser surface comprising a plurality of substantially adjacent cylindrical microlenses of varying sizes.

7. The method of claim 1, wherein said applying step includes the step of applying a texture to said mold such that during said making step, a refractive optic diffuser surface is formed on said plate, said diffuser surface comprising a plurality of substantially cylindrical microlenses and occasional cross connections connecting valleys between an adjacent pair of cylindrical microlenses.

8. The method of claim 1, wherein said applying step comprises an acid resist process.

9. The method of claim 1, wherein said optical plate comprises polycarbonate.

10. An illumination system for an optical reader having an imaging axis, said illumination system comprising:

a plurality of light emitting diodes; and

an optical plate positioned forward of said plurality of light emitting diodes, said optical plate having a diffuser surface formed on a light exit surface there of.

11. The illumination system of claim 10, wherein diffuser surface is a substantially cylindrical mircolense diffuser surface.

12. The illumination system of claim 10, wherein said diffuser surface comprises substantially cylindrical microlenses adapted to diffuse light substantially via refractive optics.

13. The illumination system of claim 10, wherein said plurality of spaced apart light sources comprise at least one vertically oriented column of light emitting diodes, and wherein said diffuser surface comprises substantially vertically oriented substantially cylindrical microlenses for diffusing light substantially horizontally with respect to said substantially cylindrical microlenses.

14. The illumination system of claim 10, wherein said plurality of spaced apart light sources comprise at least one horizontally oriented row of spaced apart light sources and wherein said diffuser surface comprises substantially horizontally oriented substantially cylindrical microlenses for vertically diffusing light transmitted through said optical plate.

15. The illumination system of claim 10, wherein said plurality of light sources comprise a plurality of vertically arranged columns of light sources, and wherein said diffuser surface comprises vertically oriented substantially cylindrical microlenses for diffusing light substantially horizontally with respect to said substantially cylindrical microlenses.

16. The illumination system of claim 10, wherein said optical plate includes at least one wedge for directing light from any of said light emitting elements to a corner of a target area.

17. A method of making an optical diffuser plate comprising the steps of:

providing a mold, said mold having at least one textured surface;

providing a material that is moldable and transmissive of light at predetermined wavelengths; and

forming an optical diffuser plate, wherein the step of forming the optical diffuser plate includes injecting the material into the mold.

18. The method of claim 17, wherein the step of providing a mold includes the step of forming said at least one textured surface by etching.

19. The method of claim 17 wherein the at least one textured surface includes a plurality of cylindrical lenses.

20. The method of claim 19 wherein the plurality of cylindrical lenses includes a plurality of cylindrical microlenses.

21. The method of claim 19 wherein the plurality of cylindrical lenses are randomly oriented with respect to one another.

22. The method of claim 17 wherein said textured surface includes a plurality of substantially parallel valleys.

23. The method of claim 22 wherein said textured surface further includes a plurality of cross-connections, each of said plurality of cross-connections connecting adjacent valleys thereby forming a plurality of microlenses.

24. An optical reader comprising:

an image sensor;

a light source disposed proximate to said image sensor; and

a diffuser plate disposed to receive light from said light source;

wherein said diffuser plate includes a plurality of microlenses.

25. The optical reader of claim 24 wherein said diffuser optical plate further includes a targeting optical element.

26. The optical reader of claim 25 wherein said targeting optical element includes a plurality of cylindrical lenses.

27. The optical reader of claim 25 wherein said targeting optical element is adapted to project a single horizontal aiming line.

28. The optical reader of claim 25 wherein said light source includes a plurality of light sources.

29. The optical reader of claim 26 wherein said plurality of light sources includes a plurality of light emitting diodes.

30. The optical reader of claim 28 wherein said targeting optical element includes:

a plurality of aiming pattern wedges; and

a plurality of cylindrical lenses,

wherein each of said plurality of cylindrical lenses is optical coupled to a respective aiming pattern wedge of said plurality of aiming pattern wedges. each of which is coupled to one of said plurality of light sources.

31. An optical reader comprising:

a printed circuit board; and

a housing disposed about said printed circuit board,

wherein said printed circuit board includes;

an electronic circuit for capturing an image;

an electronic circuit for storing said image;

an electronic circuit for decoding said image; and

an electronic circuit for providing illumination.

32. The optical reader of claim 31 wherein said electronic circuit for capturing an image includes an image sensor chip.

33. The optical reader of claim 32 wherein said electronic circuit for providing illumination includes a light source disposed proximate to said image sensor chip.

34. The optical reader of claim 33 wherein said light source includes a plurality of light emitting diodes, wherein at least two light emitting diodes of said plurality of light emitting diodes are disposed on opposite sides of said image sensor chip.

35. The optical reader of claim 34 wherein said plurality of light emitting diodes are disposed in a substantially linear array.

36. The optical reader of claim 32 further including a diffusing optical plate disposed proximate to said light source.

37. The optical reader of claim 36 further including a lens assembly optically coupled to said image sensor chip.

38. The optical reader of claim 37 wherein said diffusing optical plate includes a light entry surface and a light exit surface, wherein said light exit surface includes a plurality of substantially cylindrical microlenses.

39. The optical reader of claim 38 wherein said plurality of substantially cylindrical microlenses includes a plurality of substantially cylindrical microlenses oriented in a horizontal direction.

40. The optical reader of claim 33 wherein said printed circuit board includes a flexible printed circuit board.

41. The optical reader of claim 40 wherein said light source includes at least one light pipe.