Method of inspecting ophthalmic lenses

• US 5,828,446 A
• Filed: 09/13/1996
• Issued: 10/27/1998
• Est. Priority Date: 12/21/1992
• Status: Expired due to Term

• Current Assignee: Johnson & Johnson Vision Products, Inc.
• Original Assignee: Johnson & Johnson Vision Products, Inc.
• Inventors: Davis, Thomas G.
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/712,658
• Time in Patent Office: 774 Days
• Field of Search: 356/124-127, 356/237, 356/239, 356/240, 356/430, 356/244, 356/246, 264/2.6, 250/562, 250/572, 250/223 B, 358/101, 358/106, 358/107, 382/8, 382/65
• US Class Current: 356/124
• CPC Class Codes: G01M 11/0214 Details of devices holding the object to be tested
• CPC Class Codes: G01M 11/0235 by measuring multiple properties of lenses, automatic lens meters
• CPC Class Codes: G01M 11/0278 Detecting defects of the object to be tested, e.g. scratches or dust investigating the presence of flaws or contamination on materials by optical means G01N21/88

Abstract

A method of continuously and automatically inspecting ophthalmic lenses. The lenses are continuously moved along a predetermined path to move each of the lenses, one at a time, into a lens inspection position. Each time one of the lenses moves into the lens inspection position, a light source is activated to generate a one light pulse, that light pulse is directed through the one lens and onto an array of pixels and a set of signals is generated representing the intensity of light incident on the pixel array. The set of signals is processed according to a predetermined program to determine at least one condition of the lens, and an output signal is generated representing that one condition.

Claims

1. A method of automatically inspecting ophthalmic lenses, comprising:

continuously moving a transparent lens carrier containing a multitude of lenses along a predetermined path to position each of the lenses, one at a time, into a lens inspection position;

each time one of the lenses moves into the lens inspection position,

i) activating a light source to generate a respective one pulse of collimated light,

ii) directing the collimated light pulse through said transparent carrier and said lens contained therein and onto an array of pixels,

iii) capturing selected portions of said light pulse on said array of pixels and generating a respective one set of digital data values representing the intensity of light incident on said array, said selected portions of said light pulse representing one or more lens defect conditions,

iv) processing said set of digital data values according to a predetermined program to determine at least one lens defect condition, and

v) generating an output signal representing at least one lens defect condition.

2. A method according to claim 1, wherein the moving step further includes the steps of:

positioning each of the multitude of lenses in a respective one location in therefor, lens carrier; and

continuously moving the lens carrier along a predetermined path.

3. A method according to claim 2, wherein:

the lens carrier contains a fluid solution;

the positioning step includes the step of positioning the lenses in said solution; and

the step of continuously moving the lens carrier includes the step of keeping the solution surface optically non-distorting during the continuously moving step.

4. A method according to claim 1, wherein the moving step includes the step of moving the lenses into the inspection position at a substantially uniform rate.

5. A method of inspecting ophthalmic lenses, comprising:

positioning one or more ophthalmic lenses on a transparent lens carrier containing a fluid solution;

continuously moving said lens carrier along a predetermined path to move each of the lenses, one at a time, into a lens inspection position;

each time one of the lenses moves into the lens inspection position,

i) activating a light source to generate a respective one light pulse of collimated light,

ii) directing the collimated light pulse through said transparent cup and said lens contained therein and onto an array of pixels,

iii) capturing selected portions of said light pulse on said array of pixels and generating a respective one set of digital data values representing the intensity of light incident on said array,

iv) processing said set of digital data values according to a predetermined program to determine at least one lens defect condition, and

v) generating an output signal representing said at least one lens defect condition;

wherein the directing step includes the steps of

i) exposing the array of pixels for a first predetermined time prior to activating the light source, and

ii) exposing the pixel array to the collimated light pulse for a second predetermined time after the light source is activated to insure that all pixels on the array are able to receive said light pulse.

6. A method according to claim 5, wherein the light source includes a controller, and the activating step includes the steps of:

generating a start signal each time one of the lenses moves into the lens inspection position; and

transmitting said start signal to said controller to activate the light source.

7. A method according to claim 6, wherein the pixel array is disposed inside a housing including a shutter having a normally closed position, and wherein the generating step includes the step of transmitting said start signal to the shutter to open the shutter to expose the pixel array to the light pulse.

8. A method according to claim 7, wherein the activating step includes the step of activating the light source a preset period of time after the shutter is opened.

9. A method according to claim 8, wherein the step of activating the light source a preset period of time after the shutter is opened includes the step of delaying the transmission of the start signal to the controller for said preset period of time.

10. A system for automatically inspecting ophthalmic lenses, comprising:

a transparent lens carrier adapted to transport one or more ophthalmic lenses;

means to continuously move said lens carrier along a predetermined path to move each of the lenses, one at a time, into a lens inspection position;

lighting means to generate a respective one collimated light pulse each time one of the lenses moves into the lens inspection position;

a pixel array to generate a respective one set of signals representing the intensity of light incident on said array;

means to direct the collimated light pulse through the lenses at said inspection position and onto the array of pixels; and

processing means connected to the pixel array to receive said sets of signals therefrom, to generate a set of digital data values from each set of said signals, to process said digital data values according to a predetermined program, and to generate an output signal representing at least one condition of each of the lenses.

11. A system for automatically inspecting ophthalmic lenses according to claim 10, wherein the means to continuously move the multitude of lenses includes means to move the lenses into the inspection position at a substantially uniform rate.

12. A system for automatically inspecting ophthalmic lenses according to claim 11, wherein the means to continuously move a multitude of lenses further includes:

means to position each of the multitude of lenses in a respective one location in a lens carrier, and

means to continuously move the lens carrier along therefor predetermined path.

13. A system for inspecting ophthalmic lenses according to claim 12, wherein:

the lens carrier contains a fluid solution; and

the means to continuously move the lens carrier includes means for keeping the solution surface optically non-distorting as the lens carrier is moved along the predetermined path.

14. A system according to claim 10, further comprising a housing having a shutter, and wherein:

the pixel array is disposed inside the housing;

the shutter has a normally closed position to prevent light from being transmitted to the pixel array; and

the lighting means includes a flashlamp to generate the light pulses.

15. A system according to claim 14, further comprising control means to selectively actuate the flashlamp to generate the light pulses, and to selectively move the shutter to an open position to expose the pixel array to the light pulses.

16. A system according to claim 15, wherein the control means includes means to move the shutter to the open position prior to activating the flashlamp, and to maintain the shutter in the open position for a predetermined period of time after the flashlamp is actuated.

17. A system according to claim 10, wherein the means to continuously move the lenses includes

means to generate a start signal each time one of the lenses moves into the lens inspection position;

and

means to transmit the start signal to the lighting means to generate one of the light pulses.

18. A system for automatically inspecting ophthalmic lenses, comprising:

a transparent lens carrier containing a fluid solution and adapted to transport one or more ophthalmic lenses in said fluid solution;

means to continuously move said transparent lens carrier along a predetermined path to move each of the lenses, one at a time, into a lens inspection position;

lighting means to generate a respective one pulse of collimated light each time one of the lenses moves into the lens inspection position;

a pixel array to generate a respective one set of signals representing the intensity of each light pulse incident on said array;

means to direct the collimated light pulses through the transparent carrier and said lens and onto the array of pixels for capturing selected portions of said light pulse incident on said array of pixels;

processing means connected to the pixel array to receive said sets of signals therefrom, to process said signals according to a predetermined program, and to generate an output signal representing at least one condition of each of the lenses; and

control means to expose the pixel array for a first predetermined period of time prior to generating each light pulse for a second predetermined period of time to insure that all pixels of the array are able to receive said each light pulse.

19. A system according to claim 18, further comprising a housing having a shutter, and wherein:

the pixel array is disposed inside the housing;

the shutter has a normally closed position to prevent light from being transmitted to the pixel array;

the lighting means includes a flashlamp to generate the light pulses, and a controller to control the flashlamp; and

the control means includes

i) means to generate a start signal each time one of the lenses moves into the lens inspection position,

ii) means to transmit the start signal to the shutter to open the shutter to expose the pixel array to the light pulses, and

iii) means to transmit the control signal to the controller to actuate the flashlamp, including means to delay the transmission of the control signal to the controller to actuate the flashlamp to generate a respective one of the light pulses a preset period of time after each time the shutter is opened.

20. A system according to claim 19, wherein the means to delay the transmission of the control signal includes a delay circuit located in series between the means to generate the start signal and the controller.

21. A method of automatically inspecting ophthalmic lenses, comprising the steps of:

centering each of said ophthalmic lenses in a respective transparent inspection cup of a lens carrier;

continuously moving said carrier to position said ophthalmic lenses, one at a time, into a lens inspection position;

each time one of said ophthalmic lenses moves into the lens inspection position, performing the steps of;

(a) activating a light source to generate a collimated light beam pulse for illuminating said transparent cup containing a said one ophthalmic lens;

(b) limiting a cross sectional area of said light beam pulse to form a light beam having cross-sectional area greater than an area of said ophthalmic lens at said lens inspection position;

c) directing said limited light beam through said transparent cup and said ophthalmic lens and to a stop located between said one ophthalmic lens and an array of pixels;

(d) capturing selected portions of said light pulse on said array of pixels by directing any portion of said light beam deflected by a defect in said one ophthalmic lens onto said array of pixels, said limiting step substantially reducing light deflected from said transparent inspection cup to improve contrast of an image of deflected light incident on said pixel array;

(e) converting said image on said array to digital data; and

(f) processing said digital data to determine at least one lens defect condition from said deflected light beam.

22. The method of claim 21, wherein the limiting step limits said cross sectional area of said light beam to illuminate an area which is approximately 10% to 15% larger than an area of said one ophthalmic lens.

23. The method of claim 21, wherein step (c) focusses said Limited light beam on said stop through a focussing lens.

24. The method of claim 21 further comprising the step of collimating by a collimating lens said image onto a focussing lens for focussing said collimated image onto said array of pixels, said collimating lens focussing said limited light beam onto said stop.

25. A system for automatically inspecting ophthalmic lenses, comprising:

transparent carrier means to carry each of said ophthalmic lenses in a centered position within a fluid solution;

moving means to continuously move said transparent carrier means to position said ophthalmic lenses, one at a time, into a lens inspection position;

a lighting means to generate a light beam of collimated light for illuminating said ophthalmic lens each time one of said ophthalmic lenses moves into the lens inspection position;

limiting means to limit a cross sectional area of said light beam to form a collimated light pulse of a limited cross-sectional area greater than an area of said ophthalmic lens at said lens inspection position;

directing means to focus said collimated light pulse of limited cross-sectional area through said transparent carrier and said ophthalmic lens and to a stop located between said one ophthalmic lens and an array of pixels, said array of pixels for capturing selected portions of said light pulse deflected by said ophthalmic lens onto said array of pixels, said limiting means substantially reducing light deflected from said carrier to improve contrast of a lens defect image incident on said pixel array;

converting means to convert said lens defect image on said array to digital data;

processing means to process said digital data for determining at least one condition of said one ophthalmic lens from said deflected light beam.

26. The system of claim 25, wherein the limiting means limits said cross sectional area of said light beam to illuminate an area which is approximately 10% to 15% larger than an area of said one ophthalmic lens.

27. The system of claim 25, wherein the directing means comprises a first focussing lens located between said one ophthalmic lens and said stop which is placed at a focal point of said first focussing lens, said first focussing lens focussing said limited light beam which passes unaffected through said one ophthalmic lens on said stop.

28. The system of claim 27, wherein said first focussing lens focusses said image formed from said deflected light onto said pixel array.

29. The system of claim 27, wherein the directing means further comprises a second focussing lens located between said stop and said pixel array, said second focussing lens receiving collimated beams of said image from said first focussing lens, and focussing said collimated light beams onto said pixel array.

30. The system of claim 25, wherein the directing means comprises first and second focussing lenses separated by a tube having baffles therein, said first focussing lens focussing said limited light beam on said stop and collimating said image onto said second focussing lens, said baffles improving collimation of said image, and said second focussing lens receiving said collimated image and focussing said image onto said pixel array.

31. A method for automatically inspecting ophthalmic lenses comprising the steps of:

continuously moving a plurality of said ophthalmic lenses which are each centered in a respective transparent inspection cup containing a fluid solution;

activating a light source to generate a collimated light beam pulse to illuminate one of said ophthalmic lenses contained in said fluid solution in said transparent inspection cup when said one ophthalmic lens reaches an inspection position;

directing said one pulse light beam through said transparent cup and one ophthalmic lens to a stop located between said one ophthalmic lens and a pixel array;

capturing selected portions of said light pulse deflected by a defect in said one ophthalmic lens onto said pixel array to form a lens defect image;

generating signals responsive to said lens defect image; and

processing said signals to determine a lens defect condition of said one ophthalmic lens.

32. The method of claim 31, wherein the continuously moving step maintains said fluid solution substantially level.

33. The method of claim 31 further comprising the step of limiting a cross sectional area of said one pulse light beam to approximately 10% to 15% larger than an area of said one ophthalmic lens.

34. The method of claim 31 further comprising the step of limiting a cross sectional area of said pixel array to approximately 10% to 15% larger than an area of said one ophthalmic lens.

35. The method of claim 31 further comprising the step of collimating said light deflected from said one ophthalmic lens prior to directing thereof to said pixel array.

36. The method of claim 31 further comprising the step of decoupling a position of said stop from a position of said pixel array.

37. The method of claim 36, wherein the decoupling step includes the step of collimating said light deflected from said one ophthalmic lens prior to directing thereof to said pixel array.

38. The method of claim 31, wherein the step of directing said one pulse light beam provides a collimated light beam through said one ophthalmic lens, and focusses said collimated light on said stop.

39. The method of claim 31, wherein the step of directing said one pulse light beam focusses said one pulse light beam on said stop through said one ophthalmic lens.

40. The method of claim 31, wherein the step of generating said signals generates digital data.

41. The method of claim 31, wherein the processing step indicates a defect of said one ophthalmic lens when one of a bright spot is detected in a dark inner zone of said image and a dark spot is detected in a bright peripheral zone of said image that surrounds said dark inner zone.

42. The method of claim 31 further comprising the step of opening a normally closed shutter in synchronization with said one pulse light beam generating step to expose said pixel array to said deflected light.

43. The method of claim 42, wherein the opening step opens said shutter beginning front a first predetermined time prior to the step of generating said one pulse light beam until a second predetermined time after the step of generating said one pulse light beam.

44. A system for automatically inspecting ophthalmic lenses comprising:

means for continuously moving a plurality of said ophthalmic lenses which are each centered in a respective transparent cup containing a fluid solution;

means for generating a collimated light beam pulse that illuminates one of said ophthalmic lenses contained in said fluid solution when said one ophthalmic lens reaches an inspection position;

means for directing said collimated light beam pulse through said transparent cup and one ophthalmic lens to a stop located between said one ophthalmic lens and a pixel array;

means for directing light deflected from said one ophthalmic lens past said stop and onto said pixel array to form an image of said one ophthalmic lens on said pixel array;

means for generating signals responsive to said deflected light;

means for processing said signals to determine a condition of said one ophthalmic lens.

45. The system of claim 44, wherein the continuously moving means maintains said fluid solution substantially level.

46. The system of claim 44 further comprising a limiting means for limiting a cross sectional area of said one pulse light beam to approximately 10% to 15% larger than an area of said one ophthalmic lens.

47. The system of claim 44 further comprising a limiting means for limiting a cross sectional area of said pixel array to approximately 10% to 15% larger than an area of said one ophthalmic lens.

48. The system of claim 44 further comprising a collimating means for collimating said light deflected from said one ophthalmic lens prior to directing thereof to said pixel array.

49. The system of claim 44 further comprising a decoupling means for decoupling a position of said stop from a position of said pixel array.

50. The system of claim 49, wherein the decoupling means includes a collimating lens to collimate said light deflected from said one ophthalmic lens prior to directing thereof to said pixel array.

51. The system of claim 44 further comprising means for decoupling a position of said stop from a position of said pixel array.

52. The system of claim 51, wherein said decoupling means includes a tube having baffles, said tube separating said means for directing said one pulse light beam and said means for directing said deflected light, said baffles collimating said deflected light to provide collimated light to said means for directing said deflected light to said pixel array.

53. The system of claim 44 further comprising a tube having baffles, said tube separating said means for directing said one pulse light beam and said means for directing said deflected light, said baffles collimating said deflected light to provide collimated light to said means for directing said deflected light to said pixel array.

54. The system of claim 44 further comprising a collimating lens that collimates said one pulse light beam to illuminate said one ophthalmic lens with a collimated pulse light beam.

55. The system of claim 44, wherein the means for directing said one pulse light beam focusses said one pulse light beam on said stop through said one ophthalmic lens.

56. The system of claim 44, wherein the means for generating said signals generates digital data.

57. The method of claim 44, wherein the processing means indicates a defect of said one ophthalmic lens when one of a bright spot is detected in a dark inner zone of said image and a dark spot is detected in a bright peripheral zone of said image that surrounds said dark inner zone.

58. The method of claim 44 further comprising means for opening a normally closed shutter in synchronization with said means for generating said one pulse light beam to expose said pixel array to said deflected light.

59. The method of claim 58, wherein the means for opening opens said shutter beginning from a first predetermined time prior to generating said one pulse light beam until a second predetermined time after generating said one pulse light beam.