Light fixture and lens assembly for same

• US 20050281023A1
• Filed: 10/21/2004
• Published: 12/22/2005
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Acuity Brands, Inc.
• Inventors: Trott, Gary D., Gould, Carl T., Sharp, Christopher L., Mayfield, John T. III
• Granted Patent: US 7,261,435 B2
• Time in Patent Office: Days
• US Class Current: 362/217.05
• CPC Class Codes: F21S 8/04 intended only for mounting on a ceiling or the like overhead structures F21S8/02 takes precedence; details of ceiling bases F21V21/03
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 17/164 the parts being subjected to bending, e.g. snap joints
• CPC Class Codes: F21V 23/026 Fastening of transformers or ballasts
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: F21Y 2103/00 Elongate light sources, e.g. fluorescent tubes
• CPC Class Codes: F21Y 2113/00 Combination of light sources

Abstract

A light fixture or troffer for directing light emitted from a light source toward an area to be illuminated, including a reflector assembly within which the light source is positioned and a lens assembly detachably secured to a portion of the reflector assembly such that a lens of the lens assembly overlies the light source and such that substantially all of the light emitted from the light source passes through the lens assembly. In one example, the lens includes a curved prismatic surface that can be oriented toward or away from the underlying light source.

Claims

1. A lens assembly for directing light emitted from a light source toward an area to be illuminated, the light source being elongated along a light longitudinal axis, the lens assembly comprising:

an elongate lens extending along a lens longitudinal axis parallel to said light longitudinal axis and having a central lens portion curved in a transverse plane, the central lens portion having a plurality of elongate prismatic elements extending parallel to said lens longitudinal axis, each having a curved surface facing said light source,

wherein the elongate prismatic elements form an array that controls high angle glare in the longitudinal direction optically.

2. The lens assembly of claim 1, further comprising a diffuser inlay positioned between the light source and the central lens portion.

3. The lens assembly of claim 2, wherein the diffuser inlay has a bottom face spaced from at least a portion of the prismatic elements to define a linearly extending gap.

4. The lens assembly of claim 1, wherein all of said elongate prismatic elements have substantially the same shape.

5. The lens assembly of claim 1, wherein said curved surface subtends an angle of about 100°

.

6. The lens assembly of claim 1, wherein said curved surface subtends an angle of about and between 80°

to 120°

.

7. The lens assembly of claim 1, wherein the width of each elongate prismatic element is between about 0.5 inches and about 0.01 inches.

8. The lens assembly of claim 1, wherein the width of each elongate prismatic element is about 0.3 inches and about 0.03 inches.

9. The lens assembly of claim 1, wherein the width each elongate prismatic element between about 0.15 inches and about 0.05 inches.

10. The lens assembly of claim 1, wherein a pair of adjoining elongate prismatic elements form a common cusp edge.

11. The lens assembly of claim 1, wherein a reverse ray impacting an elongate prismatic element proximate the common cusp edge at an angle of incidence ω

of at least about 40°

will undergo total internal reflection and be reflected back into the room.

12. The lens assembly of claim 11, wherein the angle of incidence ω

is at least about 45°

.

13. The lens assembly of claim 11, wherein the angle of incidence is at least about 50°

.

14. The lens assembly of claim 10, wherein a reverse ray impacting an elongate prismatic element proximate the common cusp edge will undergo total internal reflection and be reflected back into the room.

15. The lens assembly of claim 1, wherein a section of the array of elongate prismatic elements, in a plane transverse to the lens longitudinal axis, has the shape of a continuous wave.

16. The lens assembly of claim 15, wherein the shape of the continuous wave is a periodic waveform.

17. The lens assembly of claim 16, wherein the periodic waveform has a substantially constant period.

18. The lens assembly of claim 16, wherein the periodic waveform is a substantially sinusoidal waveform.

19. The lens assembly of claim 16, wherein an arcuate section of each elongate prismatic element within each periodic waveform subtends an angle of about 100°

.

20. The lens assembly of claim 16, wherein an arcuate section of each elongate prismatic element within each periodic waveform subtends an angle of about and between 80°

to 120°

.

21. The lens assembly of claim 17, wherein the period of each periodic waveform is about and between 1.0 inches to 0.02 inches.

22. The lens assembly of claim 17, wherein the period of each periodic waveform is about and between 0.6 inches to 0.06 inches.

23. The lens assembly of claim 17, wherein the period of each periodic waveform is about and between 0.3 inches to 0.1 inches.

24. The lens assembly of claim 17, wherein each periodic waveform has a common cusp edge at the point of transition from positive amplitude to negative amplitude and at the point of transition from negative amplitude to positive amplitude.

25. The lens assembly of claim 24, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge at an angle of incidence ω

of at least about 40°

will undergo total internal reflection and be reflected back into the room.

26. The lens assembly of claim 25, wherein the angle of incidence ω

is at least about 45°

.

27. The lens assembly of claim 26, wherein the angle of incidence is at least about 50°

.

28. The lens assembly of claim 24, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements will undergo total internal reflection and be reflected back into the room.

29. The lens assembly of claim 1, wherein the lens is formed of a plastic material.

30. The lens assembly of claim 1, further comprising a troffer that houses the light source, and wherein the lens is constructed and arranged for being detachably secured to the troffer.

31. The lens assembly of claim 30, wherein the elongated lens has a first arm that is connected to a first lens edge of the central lens portion and a second arm that is connected to a second lens edge of the central lens portion.

32. The lens assembly of claim 31, wherein the troffer defines a trough that houses the light source, and wherein a portion of the first arm is constructed and arranged for detachably securing the portion of the first arm to a portion of the trough and a portion of the second arm is constructed and arranged for detachably securing the portion of the second arm to a portion of the trough.

33. The lens assembly of claim 30, wherein each of the respective first and second arms of the lens has a bottom portion connected to the respective first and second lens edges, each bottom portion extending substantially from the first end edge of the lens to the second end edge of the lens.

34. The lens assembly of claim 1, wherein the plane of symmetry extends through the area desired to be illuminated.

35. A lens assembly for directing light emitted from a light source toward an area desired to be illuminated, the light source being elongated along a light longitudinal axis, the lens assembly comprising:

an elongated lens having a first end edge, an opposed second end edge, a central lens portion that extends between the first and second end edges, and a lens longitudinal axis that is generally parallel to the light longitudinal axis, the central lens portion being curved in a plane transverse to the light longitudinal axis and being symmetric about a plane that extends through the light longitudinal axis, the central lens portion having a prismatic surface that defines a face oriented toward and spaced from the light source, wherein the prismatic surface of the lens defines an array of linearly extending prismatic elements, each prismatic element thereof extending generally longitudinally substantially between the first and second end edges of the lens, and wherein the lens controls high angle glare in the longitudinal direction optically.

36. The lens assembly of claim 35, wherein the lens assembly further comprises a diffuser inlay positioned between the light source and at least a portion of the prismatic surface of the central lens portion.

37. The lens assembly of claim 36, wherein the diffuser inlay is positioned in substantial overlying registration with the at least a portion of the prismatic surface, wherein the diffuser inlay has a bottom face, and wherein portions of adjoining prismatic elements of the array of prismatic elements and a portion of the bottom face of the diffuser inlay define a linearly extending gap.

38. The lens assembly of claim 35, wherein each prismatic element has substantially the same shape.

39. The lens assembly of claim 35, wherein, in section normal to the lens longitudinal axis, each prismatic element has a base and a rounded apex, wherein each prismatic element extends towards the apex substantially perpendicular with respect to a tangent plane that extends through the base.

40. The lens assembly of claim 39, wherein an arcuate section, normal to the lens longitudinal axis, of each prismatic element subtends an angle of about 100°

.

41. The lens assembly of claim 39, wherein an arcuate section, normal to the lens longitudinal axis, of each prismatic element subtends an angle of about and between 80°

to 120°

.

42. The lens assembly of claim 39, wherein the base of each prismatic element has a width of about and between 0.5 inches to 0.01 inches.

43. The lens assembly of claim 39, wherein the base of each prismatic element has a width of about and between 0.3 inches to 0.03 inches.

44. The lens assembly of claim 39, wherein the base of each prismatic element has a width of about and between 0.15 inches to 0.05 inches.

45. The lens assembly of claim 39, wherein a pair of adjoining prismatic elements of the array of prismatic elements have a common cusp edge.

46. The lens assembly of claim 45, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge at an angle of incidence w of at least about 40°

will undergo total internal reflection and be reflected back into the room.

47. The lens assembly of claim 46, wherein the angle of incidence w is at least about 45°

.

48. The lens assembly of claim 46, wherein the angle of incidence is at least about 50°

.

49. The lens assembly of claim 45, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements will undergo total internal reflection and be reflected back into the room.

50. The lens assembly of claim 35, wherein a section of the array of prismatic elements, in a plane normal to the lens longitudinal axis, has a shape of a continuous wave.

51. The lens assembly of claim 50, wherein the shape of the continuous wave is a periodic waveform.

52. The lens assembly of claim 51, wherein the periodic waveform has a substantially constant period.

53. The lens assembly of claim 51, wherein the periodic waveform is a substantially sinusoidal waveform.

54. The lens assembly of claim 51, wherein an arcuate section of each prismatic element within each periodic waveform subtends an angle of about 100°

.

55. The lens assembly of claim 51, wherein an arcuate section of each prismatic element within each periodic waveform subtends an angle of about and between 80°

to 120°

.

56. The lens assembly of claim 52, wherein the period of each periodic waveform is about and between 1.0 inches to 0.02 inches.

57. The lens assembly of claim 52, wherein the period of each periodic waveform is about and between 0.6 inches to 0.06 inches.

58. The lens assembly of claim 52, wherein the period of each periodic waveform is about and between 0.3 inches to 0.1 inches.

59. The lens assembly of claim 52, wherein each periodic waveform has a common cusp edge at the point of transition from positive amplitude to negative amplitude and at the point of transition from negative amplitude to positive amplitude.

60. The lens assembly of claim 59, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge at an angle of incidence ω

of at least about 40°

will undergo total internal reflection and be reflected back into the room.

61. The lens assembly of claim 60, wherein the angle of incidence ω

is at least about 45°

.

62. The lens assembly of claim 61, wherein the angle of incidence is at least about 50°

.

63. The lens assembly of claim 59, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements will undergo total internal reflection and be reflected back into the room.

64. The lens assembly of claim 35, wherein the lens is formed of a plastic material.

65. The lens assembly of claim 35, further comprising a troffer that houses the light source, and wherein the lens is constructed and arranged for being detachably secured to the troffer.

66. The lens assembly of claim 65, wherein the elongated lens has a first arm that is connected to a first lens edge of the central lens portion and a second arm that is connected to a second lens edge of the central lens portion.

67. The lens assembly of claim 66, wherein the troffer defines a trough, which houses the light source, and wherein a portion of the first arm is constructed and arranged for detachably securing the portion of the first arm to a portion of the trough and a portion of the second arm is constructed and arranged for detachably securing the portion of the second arm to a portion of the trough.

68. The lens assembly of claim 66, wherein each of the respective first and second arms of the lens has a bottom portion connected to the respective first and second lens edges, each bottom portion extending substantially from the first end edge of the lens to the second end edge of the lens.

69. The lens assembly of claim 35, wherein the plane of symmetry extends through the area desired to be illuminated.

70. A lens assembly for directing light emitted from a linear light source toward an area desired to be illuminated, the linear light source being elongated along a light longitudinal axis, the lens assembly comprising:

an elongated lens having a first end edge, an opposed second end edge, and a curved central lens portion that extends between the first and second end edges, the central lens portion being generally parallel to the light longitudinal axis and symmetric about a plane that extends through the light longitudinal axis, the central lens portion having a first surface and an opposed prismatic surface, the first surface defining a concave face spaced from and facing the light source, the prismatic surface being oriented away from the light source,

wherein the prismatic surface of the lens defines an array of linearly extending prismatic elements, each prismatic element thereof extending generally longitudinally substantially between the first and second end edges of the lens.

71. The lens assembly of claim 70, wherein the lens assembly further comprises a diffuser inlay positioned in substantial overlying registration with the first surface of the central lens portion.

72. A light fixture for directing light toward an area desired to be illuminated, comprising:

a reflector assembly comprising an elongated base member having a base longitudinal axis;

a linear light source for generating the light, the light source being elongated along a light longitudinal axis and being operatively supported by the base member; and

a lens assembly comprising an elongated lens having a curved central lens portion that extends generally parallel to the light longitudinal axis and is symmetric about a plane that extends through the light longitudinal axis, the central lens portion having a prismatic surface that defines a concave face spaced from and facing the light source, wherein the lens assembly is constructed and arranged for detachable connection to a portion of the base member of the reflector assembly.

73. The light fixture of claim 72, wherein the prismatic surface of the lens defines an array of linearly extending prismatic elements, each prismatic element generally extending longitudinally substantially between a first end edge of the lens and an opposed second end edge of the lens.

74. The light fixture of claim 73, wherein the lens assembly further comprises a diffuser inlay positioned in substantial overlying registration with the prismatic surface of the central lens portion.

75. The light fixture of claim 74, wherein the diffuser inlay has a bottom face, and wherein portions of adjoining prismatic elements of the array of prismatic elements and a portion of the bottom face of the diffuser inlay define a linearly extending gap.

76. The light fixture of claim 73, wherein each prismatic element has substantially the same shape.

77. The light fixture of claim 73, wherein the lens has a lens longitudinal axis extending between the first end edge and the second end edge, and wherein each prismatic element, in section normal to the lens longitudinal axis, has a base and a rounded apex, wherein each prismatic element extends substantially perpendicular towards the apex with respect to a tangent plane extending through the base.

78. The light fixture of claim 77, wherein an arcuate section, normal to the lens longitudinal axis, of each prismatic element subtends an angle of about 100°

.

79. The light fixture of claim 77, wherein an arcuate section, normal to the lens longitudinal axis, of each prismatic element subtends an angle of about and between 80°

to 120°

.

80. The light fixture of claim 77, wherein the base of each prismatic element has a width of about and between 0.5 inches to 0.01 inches.

81. The light fixture of claim 77, wherein the base of each prismatic element has a width of about and between 0.3 inches to 0.03 inches.

82. The light fixture of claim 77, wherein the base of each prismatic element has a width of about and between 0.15 inches to 0.05 inches.

83. The light fixture of claim 77, wherein a pair of adjoining prismatic elements of the array of prismatic elements have a common cusp edge.

84. The light fixture of claim 83, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge at an angle of incidence w of at least about 40°

will undergo total internal reflection and be reflected back into the room.

85. The light fixture of claim 84, wherein the angle of incidence ω

is at least about 45°

.

86. The light fixture of claim 84, wherein the angle of incidence is at least about 50°

.

87. The light fixture of claim 83, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements will undergo total internal reflection and be reflected back into the room.

88. The light fixture of claim 73, wherein the lens has a lens longitudinal axis extending between the first and second end edges of the lens, and wherein a section of the array of prismatic elements normal to the lens longitudinal axis has a shape of a continuous wave.

89. The light fixture of claim 88, wherein the shape of the continuous wave is a periodic waveform.

90. The light fixture of claim 89, wherein the periodic waveform has a substantially constant period.

91. The light fixture of claim 89, wherein the periodic waveform is a substantially sinusoidal waveform.

92. The light fixture of claim 89, wherein an arcuate section of each prismatic element within each periodic waveform subtends an angle of about 100°

.

93. The light fixture of claim 89, wherein an arcuate section of each prismatic element within each periodic waveform subtends an angle of about and between 80°

to 120°

.

94. The light fixture of claim 90, wherein the period of each periodic waveform is about and between 1.0 inches to 0.02 inches.

95. The light fixture of claim 90, wherein the period of each periodic waveform is about and between 0.6 inches to 0.06 inches.

96. The light fixture of claim 90, wherein the period of each periodic waveform is about and between 0.3 inches to 0.1 inches.

97. The light fixture of claim 90, wherein each periodic waveform has a common cusp edge at the point of transition from positive amplitude to negative amplitude and at the point of transition from negative amplitude to positive amplitude.

98. The light fixture of claim 97, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge at an angle of incidence ω

of at least about 40°

will undergo total internal reflection and be reflected back into the room.

99. The light fixture of claim 98, wherein the angle of incidence ω

is at least about 45°

.

100. The light fixture of claim 99, wherein the angle of incidence is at least about 50°

.

101. The light fixture assembly of claim 97, wherein a reverse ray impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements will undergo total internal reflection and be reflected back into the room.

102. The light fixture of claim 72, wherein the lens is formed of a plastic material.

103. The light fixture of claim 72, wherein the base member defines a trough, which houses the light source.

104. The light fixture of claim 103, wherein the elongated lens has a first arm that is connected to a first lens edge of the central lens portion and a second arm that is connected to a second lens edge of the central lens portion.

105. The light fixture of claim 104, wherein a portion of the first arm is constructed and arranged for detachably securing the portion of the first arm to a portion of the trough and a portion of the second arm is constructed and arranged for detachably securing the portion of the second arm to a portion of the trough.

106. The light fixture of claim 104, wherein each of the respective first and second arms of the lens has a bottom portion connected to the respective first and second lens edges, each bottom portion extending substantially from a first end edge of the lens to an opposed second end edge of the lens.

107. The light fixture of claim 106, wherein the bottom portion of each respective first and second arms of the lens is substantially planar.

108. The light fixture of claim 72, wherein the reflector assembly has a first longitudinal extending side edge and an opposed second longitudinally extending side edge, and wherein the lens assembly is positioned within the reflector assembly such that it is recessed above a substantially horizontal plane extending between the first and second longitudinal side edges and such that the lens assembly is not visible at high viewing angles in a vertical plane normal to the base longitudinal axis.

109. The light fixture of claim 108, wherein the lens assembly is recessed within the reflector assembly such that a plane bisecting one of the respective first and second longitudinal side edges and a tangential portion of the lens is oriented at an acute angle γ

to the substantially horizontal plane extending between the first and second longitudinal side edges.

110. The light fixture of claim 109, wherein the acute angle γ

is about and between 3° and

30°

.

111. The light fixture of claim 109, wherein the acute angle γ

is about and between 5° and

20°

.

112. The light fixture of claim 109, wherein the acute angle γ

is about and between 10° and

15°

.

113. The light fixture of claim 104, wherein the reflector assembly has a first longitudinal extending side edge and an opposed second longitudinally extending side edge, and wherein the lens assembly is positioned within the reflector assembly such that the light source is positioned below a plane bisecting one of the respective first or second longitudinally extending side edges and the adjacent respective first or second lens edges of the lens.

124. A method of illuminating an architectural space comprising mounting a plurality of light fixtures as set forth in claim 72 to the ceiling of the architectural space.

114. A method of controlling light emitted at angles close to a ceiling plane, comprising:

mounting a light fixture substantially parallel to the ceiling plane, the light fixture comprising;

a reflector assembly comprising an elongated base member having a base longitudinal axis, a first longitudinally extending side edge, and an opposed second longitudinally extending side edge;

a light source for generating the light, the light source being elongated along a light longitudinal axis, the light source being operatively connected to the base member; and

a lens assembly comprising an elongated lens having a lens longitudinal axis and a central lens portion that is curved in a plane transverse to the lens longitudinal axis, the central lens portion extending generally parallel to the light longitudinal axis and symmetric about a plane that extends through the light longitudinal axis, the central lens portion having a prismatic surface that defines a face spaced from and facing the light source; and

detachably connecting the lens assembly to a portion of the base member within the reflector assembly such that it is recessed above a substantially horizontal plane extending between the first and second longitudinal side edges and such that the lens assembly is not visible at high viewing angles in a vertical plane normal to the base longitudinal axis.

115. The method of claim 114, wherein the lens assembly is detachably connected to the reflector assembly such that substantially all of the light emitted by the light source passes through the lens.

116. The method of claim 115, further comprising recessing the lens assembly within the reflector assembly such that a vertical plane bisecting one of the respective first and second longitudinal side edges and a tangential portion of the lens is oriented at an acute angle γ

to the substantially horizontal plane extending between the first and second longitudinal side edges.

117. The method of claim 116, wherein the acute angle γ

is about and between 3° and

30°

.

118. The method of claim 116, wherein the acute angle γ

is about and between 5° and

20°

.

119. The method of claim 116, wherein the acute angle γ

is about and between 10° and

15°

.

120. The method of claim 114, wherein the face of the prismatic surface defines an array of linearly extending prismatic elements, each prismatic element extending substantially between a first end edge of the lens and an opposed second end edge of the lens, and wherein a pair of adjoining prismatic elements of the array of prismatic elements have a common cusp edge.

121. The method of claim 120, further comprising impacting the prismatic surface of the array of prismatic elements proximate the common cusp edge of the pair of adjoining prismatic elements with a reverse ray so that the reverse ray will undergo total internal reflection and be reflected back into the room, whereby the lens assembly appears to dim at high viewing angles in a vertical plane substantially parallel to the base longitudinal axis.

122. A method of illuminating an area and controlling light emitted at high angles, comprising:

mounting an elongate light fixture to extend substantially horizontally, the light fixture comprising;

a reflector assembly comprising an elongated base member;

a linear light source operatively connected to the base member and extending along a light longitudinal axis; and

an elongated lens releasably connected to the base member and having a prismatic surface that defines a curved face that is spaced from the light source;

wherein said lens is releasably connected to the base member such that it is recessed above a substantially horizontal plane containing bottom side edges of the reflector assembly such that the lens is not visible at high viewing angles in a vertical plane normal to the base longitudinal axis.

123. A method of illuminating an architectural space comprising:

providing a plurality of horizontally spaced light fixtures arranged to illuminate a horizontal area below the light fixtures, each light fixture comprising;

a reflector assembly;

a light source recessed in the reflector assembly for controlling glare at high viewing angles in the transverse direction; and

an elongated lens supported by the reflector assembly and configured to control glare at high viewing angles in the longitudinal direction optically.