Germicidal Lighting Device

Abstract

A germicidal lighting device includes an ultraviolet (UV) light source, a planar waveguide with a first surface, a second surface opposite to the first surface, and at least one edge surface perpendicular to the two parallel surfaces, and an optical filter. The UV light source is positioned adjacent to the edge surface of the planar waveguide to shine its UV light into the planar waveguide through the edge surface, and the UV light travels in the planar waveguide via total internal reflection. The first surface of the planer waveguide has a mechanism to reflect the UV light at an exit angle to exit the planar waveguide through the second surface. The optical filter filters a portion of the UV. Moreover, the light emitting area of the second surface of the planar waveguide is bigger than the light emitting surface area of the UV light source.

Claims

1. A germicidal lighting device, comprising an ultraviolet (UV) light source configured to emit a UV light in a wavelength range of 200˜400 nm; a planar waveguide with a first surface, a second surface opposite to the first surface, and at least one edge surface perpendicular to the first and the second surfaces; and an optical filter, wherein: the UV light source is positioned adjacent to the edge surface of the planar waveguide to shine the UV light into the planar waveguide through the edge surface, the UV light travels in the planar waveguide via total internal reflection, the first surface of the planer waveguide comprises a mechanism configured to reflect the UV light at an exit angle to exit the planar waveguide through the second surface, the optical filter filters a portion of the UV light, and a light emitting area of the second surface of the planar waveguide is bigger than a light emitting surface area of the UV light source.

2. The lighting device of claim 1, wherein the optical filter comprises a lowpass optical filter with a cutoff wavelength in a wavelength range of 225˜235 nm.

3. The lighting device of claim 2, wherein the optical filter is positioned between the UV light source and the edge surface of the planar waveguide to filter the UV light before the UV light enters the planar waveguide.

4. The lighting device of claim 2, wherein the optical filter is positioned over the second surface of the planar waveguide, directly or indirectly, to filter the UV light after the UV light exits the second surface of the planar waveguide.

5. The lighting device of claim 1, wherein the mechanism configured to reflect the UV light on the first surface at the exit angle to exit the planar waveguide through the second surface comprises an etched pattern on the first surface.

6. The lighting device of claim 1, further comprising: a first optical reflector surrounding the UV light source and configured to redirect the UV light emitted out of the UV light source through the edge surface of the planar waveguide.

7. The lighting device of claim 1, further comprising: exit a second optical reflector on the first surface of the planar waveguide and configured to redirect any portion of the UV light exit out of the first surface back through the planar waveguide.

8. The lighting device of claim 7, wherein the second optical reflector comprises a reflective coating on the first surface.

9. The lighting device of claim 1, further comprising: a brightness enhancement film (BEF) over the second surface of the planar waveguide and configured to adjust the exit angle of the UV light off the second surface to result in the exit angle being more perpendicular to the second surface.

10. The lighting device of claim 1, the planar waveguide is made of quartz.

11. The lighting device of claim 1, the planar waveguide is made of cyclic block copolymer (CBC).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are included to aid further understanding of the present disclosure, and are incorporated in and constitute a part of the present disclosure. The drawings illustrate a select number of embodiments of the present disclosure and, together with the detailed description below, serve to explain the principles of the present disclosure. It is appreciable that the drawings are not necessarily to scale, as some components may be shown to be out of proportion to size in actual implementation in order to clearly illustrate the concept of the present disclosure.

[0014] FIG. 1 The Threshold Limit Values (dosage) according to ACGIH UV Safety Guidelines.

[0015] FIG. 2 schematically depicts a diagram of the present disclosure where the optical filter is located between the UV light source and the planar waveguide.

[0016] FIG. 3 schematically depicts another diagram of the present disclosure where the optical filter is positioned over the second surface of the planar waveguide.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Overview

[0017] Various implementations of the present disclosure and related inventive concepts are described below. It should be acknowledged, however, that the present disclosure is not limited to any particular manner of implementation, and that the various embodiments discussed explicitly herein are primarily for purposes of illustration. For example, the various concepts discussed herein may be suitably implemented in a variety of germicidal lighting devices having different form factors.

[0018] The present disclosure includes an ultraviolet (UV) light source, a planar waveguide with a first surface, a second surface opposite to the first surface, and at least one edge surface perpendicular to the two parallel surfaces, and an optical filter. The UV light source is positioned adjacent to the edge surface of the planar waveguide to shine its UV light into the planar waveguide through the edge surface, and the UV light travels in the planar waveguide via total internal reflection. The first surface of the planer waveguide has a mechanism to reflect the UV light at an exit angle to exit the planar waveguide through the second surface. The optical filter filters a portion of the UV. Moreover, the light emitting area of the second surface of the planar waveguide is bigger than the light emitting surface area of the UV light source. When using a far-UVC light source, the optical filter may be a lowpass filter with a cutoff wavelength in the 225˜235 nm wavelength range for removing the harmful UV wavelengths.

Example Implementations

[0019] FIG. 2 is an embodiment of the germicidal lighting device of the present disclosure 100. The device 100 includes an omnidirectional UV light source 101, a planar waveguide 102, and an optical filter 106. The planar waveguide 102 has a first surface 103, a second surface 104, and an edge surface 105 which is perpendicular to the first surface 103 and the second surface 104. The reflector 110 directs the UV light emitted by the UV light source 101 toward the planar waveguide 102. An optical filter 106 is placed between the UV light source 101 and the edge surface 105 of the planar waveguide. The filter 106 is a lowpass filter with a cutoff wavelength at 230 nm. It blocks the wavelength above 230 nm and only permits the UV light less than 230 nm wavelength to pass through. The filtered UV light enters the planar waveguide 102 through the edge surface 105, and then travel within the planar waveguide via total internal reflection. A reflective coating 108 is used to improve the total internal reflection of the planar waveguide. The first surface 103 has an etched pattern 107 made of vertical and horizontal lines (though not shown) created by V-cutting. The UV light reflects off the etched pattern 107 at an exit angle that can exit the planar waveguide 102 through the second surface 104. The etched V-cuts 107 are more sparsely spaced when they are closer to the UV light source and become more densely spaced when they are away from the UV light source. This spacing pattern of the V-cuts helps producing a more uniformly distributed UV light out of the second surface 104. The UV light exiting out of the second surface 104 is at an exit angle not directly perpendicular to the second surface. A BEF 109 is used to adjust the exit angle of the UV light off the second surface 104 to result in the exit angle being more perpendicular to the second surface. The BEF 109 has two layers (though now shown) where one BEF layer corresponds to the UV light reflected by the vertical etched lines 107 on the first surface 103 and the other BEF layer corresponds to the UV light reflected by the horizontal etched lines on the first surface. The light emitting area of the second surface 104 of the planar waveguide is bigger than the light emitting surface area of the UV light source 101.

[0020] FIG. 3 is another embodiment of the present disclosure. This embodiment 200 is similar to the embodiment 100 in FIG. 2 with two differences. Firstly, the embodiment 200 uses a directional UV light source 201 with its light emitting surface facing the edge surface 205 of the planar waveguide 202. As such, it is not necessary to use a reflector to direct the UV light of the light source 201 toward the edge surface 205. Secondly, instead of placing a filter between the UV light source 201 and the edge surface 205 of the planar waveguide, a filter 206 is positioned over the second surface 204 of the planar waveguide 202 to filter indirectly the UV light after it exits the second surface and passes through the BEF 209.

Additional and Alternative Implementation Notes

[0021] Although the techniques have been described in language specific to certain applications, it is to be understood that the appended claims are not necessarily limited to the specific features or applications described herein. Rather, the specific features and examples are disclosed as non-limiting exemplary forms of implementing such techniques. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more,” unless specified otherwise or clear from context to be directed to a singular form.