DISPLAY

• US 20100110340A1
• Filed: 01/12/2010
• Published: 05/06/2010
• Est. Priority Date: 05/19/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Montgomery, David James, Lesage, Etienne, MATHER, Jonathan
• Granted Patent: US 7,920,226 B2
• Time in Patent Office: Days
• US Class Current: 349/65
• CPC Class Codes: G02B 30/30 involving parallax barriers
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: H04N 13/31 using parallax barriers
• CPC Class Codes: H04N 13/312 the parallax barriers being placed behind the display panel, e.g. between backlight and spatial light modulator [SLM]
• CPC Class Codes: H04N 13/32 using arrays of controllable light sources; using moving apertures or moving light sources
• CPC Class Codes: H04N 13/354 for displaying sequentially

Abstract

A display comprises: a transmissive pixellated spatial light modulator (21); and a backlight (22). The backlight has a light-transmissive waveguide (26), with a first face of the waveguide being opposed to the spatial light modulator (21). The first face of the waveguide comprises a plurality of regions that are not totally internally reflective for at least one polarisation of light propagating within the waveguide, and the remainder of the first face of the waveguide is totally internally reflective for light propagating within the waveguide. Light is extracted from the waveguide at the regions where first face of the waveguide is not totally internally reflective. The pitch of the regions where first face of the waveguide is not totally internally reflective is substantially an integer multiple of the pitch of the pixels of the spatial light modulator.

Claims

1-48. -48. (canceled)

49. A backlight comprising:

a waveguide; and

a structure overlying the waveguide, selected regions of the structure having birefringent properties whereby the interface between the waveguide and the selected regions of the structure is not totally internally reflective for at least one polarisation of light propagating within the waveguide.

50. A backlight as claimed in claim 49 wherein a plurality of birefringent protrusions are disposed on the first face of the waveguide of the backlight, each protrusion having a refractive index that, for light of a first polarisation, is not lower than the refractive index of the waveguide whereby the protrusion is not totally internally reflective for light of the first polarisation propagating within the waveguide.

51. A backlight as claimed in claim 50 wherein each protrusion has a refractive index, for light of a second polarisation different from the first polarisation, that is lower than the refractive index, for the second polarisation, of the waveguide whereby the protrusion is totally internally reflective for light of the second polarisation propagating within the waveguide.

52. A backlight as claimed in claim 50 wherein regions of the first face between neighbouring protrusions are coated with a material having a refractive index, for light of a first polarisation, that is lower than the refractive index, for light of a first polarisation, of the waveguide.

53. A backlight as claimed in claim 50 wherein the protrusions have light-directing surfaces shaped so as to direct light of the first polarisation transmitted out of the waveguide into first and second angular ranges, the first angular range not overlapping the second angular range.

54. A backlight as claimed in claim 53 wherein the first angular range is on an opposite side of the normal axis of the display to the second angular range.

55. A backlight as claimed in claim 53 wherein a cross-section through a light-directing surface of a protrusion has at least a portion that is linear.

56. A backlight as claimed in claim 55 wherein a light-directing surface of a protrusion has at least a portion that is planar.

57. A backlight as claimed in claim 55 wherein a light-directing surface of a protrusion has at least a portion that is at an angle of between 35°

to 55°

to the first face of the waveguide.

58. A backlight as claimed in claim 53 wherein a cross-section through a light-directing surface of a protrusion has at least a portion that is concave.

59. A backlight as claimed in claim 50 wherein each protrusion extends substantially over the entire height of the backlight.

60. A backlight as claimed in claim 50 wherein each protrusion has the form of a solid of revolution about an axis perpendicular to the front face of the waveguide.

61. A backlight as claimed in claim 60 wherein each protrusion is conical or frusto-conical.

62. A backlight as claimed in claim 50 wherein the refractive index of the protrusions, for light of the first polarisation, is equal to the refractive index of the waveguide of the backlight for light of the first polarisation.

63. A backlight as claimed in claim 50 wherein the refractive index of the protrusions, for light of the first polarisation, is greater than the refractive index of the waveguide of the backlight for light of the first polarisation.

64. A backlight as claimed in claim 50 wherein an input aperture of a protrusion is dependent upon the distance of the protrusion from a side edge of the waveguide.

65. A backlight as claimed in claim 50 wherein the light guide is birefringent.

66. A backlight as claimed in claim 50 and comprising:

a reflective polarisation converter disposed adjacent a side face of the waveguide.

67. A display comprising:

a transmissive image display layer; and

a backlight as defined in claim 50.

68. A display as claimed in claim 67 wherein the image display layer is a pixellated image display layer;

and wherein a plurality of regions where the interface between the structure and the waveguide is not totally internally reflective for at the least one polarisation of light are provided behind each pixel aperture of the image display layer.

69. A display as claimed in claim 67 wherein the structure is provided between the image display layer and the waveguide.

77. A display as claimed in claim 67 and comprising a multiple view directional display.

78. A display as claimed in claim 77 and comprising a dual view display.

70-76. -76. (canceled)

79-80. -80. (canceled)