IMAGING DEVICE

Abstract

The imaging device includes an image sensor, a lens member adapted to focus external radiation towards the image sensor and a heat shield to inhibit thermal damage to the lens member. The heat shield may include an optical filter between the lens member and the external radiation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of an imaging device in accordance with features of the present invention;

FIG. 2 is a sectional side view of the imaging device of FIG. 1;

FIG. 3 is a perspective view of the imaging device of FIG. 1; and

FIG. 4 is a graph of the temperature with respect to time during a typical re-flow solder process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 show an imaging device 10 which comprises a solid state CMOS image sensor 20 and a lens 30 adapted to focus external light towards the image sensor 20. The image sensor 20 is provided on a base member or substrate 40.

An optical filter in the form of an IR filter 50 is provided in an optical path between the lens 30 and the external light. Also, an aperture 52 is provided at the lens 30. The IR filter 50 provides a heat shield or shielding means which inhibits thermal damage to the lens 30, in particular during the manufacturing process. The IR filter 50 may be formed by applying to a glass plate a number of coatings of a material which inhibits the transmission of infrared electromagnetic radiation.

The lens 30 is provided in a barrel 32 and the barrel 32 is partial y encapsulated in an opaque plastic housing 42 which is fixed to the substrate 40. The housing 42 and substrate 40 also provide heat shielding to the lens 30 as the lens 30 is only exposed to external radiation via the infrared filter 50.

The lens 30 may be formed from a polymer material having a relatively high melting temperature. This melting temperature is greater than 200° C., and preferably greater than 250° C. One suitable material is a modified polycarbonate, such as Sunex™.

FIG. 4 shows a graph of temperature against time during a typical re-flow solder process. The heating rate is designed to be no greater than 3° C., and the cooling rate no greater than 6° C. The peak temperature during the process is about 260° C. However, the time during which the imaging device 10 is subject to temperatures above 200° C. is less than 90 seconds, and preferably less than 70 seconds. Furthermore, the time during which the imaging device 10 is subject to temperatures above 250° C. is less than 30 seconds, and preferably less than 20 seconds.

The presence and location of the IR filter 50 is sufficient to provide a heat shield or shielding means which substantially prevents thermal damage to the lens 30 at high temperatures during the manufacturing process. The relatively high melting temperature of the lens material co-operates with the IR filter 50 to provide additional heat shielding.

The imaging device 10 of the invention can therefore be subject to the high temperatures of the typical manufacturing process. This eliminates the need for additional sockets or flexible circuits, as well as the additional assembly steps involved with these additional components.

Various modifications and improvements can be made without departing from the scope of the present invention.

Claims

1-32. (canceled)

33. An imaging device comprising: an image sensor;a lens member to focus external radiation towards the image sensor; anda heat shield to inhibit thermal damage to the lens member and comprising an optical filter positioned between the lens member and the external radiation.

34. An imaging device as claimed in claim 33, wherein the optical filter comprises an infrared (IR) filter.

35. An imaging device as claimed in claim 33, wherein the heat shield further comprises a housing for at least partially encapsulating the lens member.

36. An imaging device as claimed in claim 33, wherein the heat shield further comprises a base member for at least partially encapsulating the lens member.

37. An imaging device as claimed in claim 36, wherein the base member comprises a substrate.

38. An imaging device as claimed in claim 33, wherein the lens member comprises a relatively high melting temperature material to define a co-operating heat shield.

39. An imaging device as claimed in claim 38, wherein the melting temperature of the material is greater than 200° C.

40. An imaging device as claimed in claim 39, wherein the melting temperature of the material is greater than 250° C.

41. An imaging device as claimed in claim 33, wherein the lens member comprises a polymer material.

42. An imaging device as claimed in claim 33, wherein the image sensor comprises a solid state image sensor.

43. An imaging device as claimed in claim 42, wherein the image sensor comprises a CMOS image sensor.

44. An imaging device comprising: an image sensor;a lens member to focus external radiation towards the image sensor; anda heat shield to inhibit thermal damage to the lens member and comprising a material having a high melting temperature to define the lens member.

45. An imaging device as claimed in claim 44, wherein the melting temperature of the material is greater than 200° C.

46. An imaging device as claimed in claim 45, wherein the melting temperature of the material is greater than 250° C.

47. An imaging device as claimed in claim 45, including a co-operating heat shield comprising an optical filter positioned between the lens member and the external radiation.

48. An imaging device as claimed in claim 47, wherein the optical filter comprises an IR filter.

49. An electronic device comprising: an imaging device including an image sensor,a lens member to focus external radiation towards the image sensor, anda heat shield to inhibit thermal damage to the lens member and comprising an optical filter positioned between the lens member and the external radiation.

50. An electronic device as claimed in claim 49, wherein the electronic device defines an optical pointing device.

51. An electronic device as claimed in claim 50, wherein the optical pointing device defines an optical mouse.

52. An electronic device as claimed in claim 49, wherein the electronic device defines a mobile device.

53. An electronic device as claimed in claim 52, wherein the mobile device comprises a mobile cellular telephone.

54. An electronic device as claimed in claim 52, wherein the mobile device comprises a camera.

55. A method of manufacturing an imaging device, the method comprising: providing an image sensor;providing a lens member to focus external radiation towards the image sensor; andpositioning an optical filter between the lens member and the external radiation to inhibit thermal damage to the lens member.

56. A method as claimed in claim 55, wherein the optical filter comprises an IR filter.

57. A method as claimed in claim 55, further comprising forming the lens member from a material having a high melting temperature to further inhibit thermal damage to the lens member.

58. A method as claimed in claim 55, further comprising subjecting the imaging device to a re-flow solder process.

59. A method of manufacturing an imaging device, the method comprising: providing an image sensor;providing a lens member to focus external radiation towards the image sensor and comprising forming the lens member from a material having a high melting temperature to inhibit thermal damage to the lens member.

60. A method as claimed in claim 59, wherein the melting temperature of the material is greater than 200° C.

61. A method as claimed in claim 60, wherein the melting temperature of the material is greater than 250° C.

62. A method as claimed in claim 59, wherein the lens member is at least partially formed from a polymer material.

63. A method as claimed in claim 59, further comprising positioning an optical filter between the lens member and the external radiation to further inhibit thermal damage to the lens member.

64. A method as claimed in claim 63, wherein the optical filter comprises an IR filter.

65. A method as claimed in claim 59, further comprising subjecting the imaging device to a re-flow solder process.