# US 8,541,931 B2 · LED based lamp including reflective hood to reduce variation in illuminance

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- Number: US 8,541,931 B2
- Document ID: US8541931B2
- Status: Granted
- Kind: B2
- Application number: 12/721,311
- Filed: 2010-03-10
- Published: 2010-09-23
- Granted: 2013-09-24
- Earliest claimed: 2009-03-17
- Assignees: Intematix Corporation
- Applicants: Haitao Yang
- Inventors: Haitao Yang
- Web page: https://patentgrep.com/patent/US8541931B2

## CPC

- F21K 9/00: Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
- F21S 8/02: of recess-mounted type, e.g. downlighters (specially adapted for vehicle exteriors F21S41/00-F21S45/00)
- F21S 8/026: {intended to be recessed in a ceiling or like overhead structure, e.g. suspended ceiling}
- F21V 7/04: Optical design
- F21V 7/24: characterised by the material
- F21V 15/01: Housings, e.g. material or assembling of housing parts (F21V15/02 takes precedence {housings forming signs or letters G09F13/04})
- F21V 29/74: with fins or blades
- F21V 29/78: with helically or spirally arranged fins or blades
- F21V 29/83: the elements having apertures, ducts or channels, e.g. heat radiation holes
- F21V 13/04: the elements being reflectors and refractors {(for vehicle rear lights F21S43/40)}
- F21V 29/86: {Ceramics or glass}
- F21V 29/87: Organic material, e.g. filled polymer composites; Thermo-conductive additives or coatings therefor
- F21V 29/89: Metals
- F21Y 2105/10: comprising a two-dimensional [2D] array of point-like light-generating elements
- F21Y 2115/10: Light-emitting diodes [LED]
- F21K: NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
- F21S: NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21Y: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED

## Abstract

A lamp comprises: a thermally conductive body; a plurality of LEDs configured as an array and mounted in thermal communication with the body and a light reflective hood located in front of the plane of light emitting diodes. The hood has at least two frustoconical light reflective surfaces that surround the array of LEDs and are configured such that in operation light emitted by the lamp is within a selected emission angle (beam spread). The hood is configured such that in operation a variation in illuminance (luminous flux per unit area incident on a surface) is 10% or less over approximately a third to one half of the selected emission angle.

## Claims

### Claim 1

A lamp comprising:
a thermally conductive body;
a plurality of light emitting diodes configured as an array and mounted in thermal communication with the body; and
a light reflective hood located in front of the plane of light emitting diodes, wherein the hood has at least two frustoconical light reflective surfaces that surround the array of light emitting diodes and are configured such that in operation light emitted by the lamp is within a selected emission angle;
wherein a diameter of a first frustoconical light reflective surface is smaller than a diameter of a second frustoconical light reflective surface more distal to the light emitting diodes than the first frustoconical light reflective surface.

### Claim 2 (depends on 1)

The lamp according to claim 1, wherein the at least two light reflective surfaces are contiguous.

### Claim 3 (depends on 1)

The lamp according to claim 1, wherein the hood is configured such that in operation a variation in illuminance is 10% or less over approximately a third of the selected emission angle.

### Claim 4 (depends on 1)

The lamp according to claim 1, wherein the hood is configured such that in operation a variation in illuminance is 10% or less over approximately half of the selected emission angle.

### Claim 5 (depends on 1)

The lamp according to claim 1, wherein the hood is configured such that in operation a proportion of total light emission emitted within the selected emission angle is selected from the group consisting of: at least 90%, at least 95% and at least 98%.

### Claim 6 (depends on 1)

The lamp according to claim 1, and further comprising a light diffuser interposed between the array of light emitting diodes and the hood.

### Claim 7 (depends on 1)

The lamp according to claim 1, wherein the hood is generally cylindrical in form.

### Claim 8 (depends on 1)

The lamp according to claim 1, wherein the hood comprises a thermally conductive material.

### Claim 9 (depends on 8)

The lamp according to claim 8, wherein the hood has a thermal conductivity selected from the group consisting of at least 150 Wm−1K−1 and at least 200 Wm−1K−1.

### Claim 10 (depends on 8)

The lamp according to claim 8, wherein the hood is in thermal communication with the thermally conductive body.

### Claim 11 (depends on 1)

The lamp according to claim 1, wherein the hood comprises a material selected from the group consisting of: aluminum, an alloy of aluminum, a magnesium alloy, a plastics material, a metal loaded plastics material and a thermally conductive ceramic material.

### Claim 12 (depends on 1)

The lamp according to claim 1, and further comprising a light reflective material applied to the at least two light reflective surfaces.

### Claim 13 (depends on 1)

The lamp according to claim 1, wherein the selected emission angle is in a range 8° to 60°.

### Claim 14 (depends on 13)

The lamp according to claim 13, wherein the selected emission angle is selected from the group consisting of being of order: 20°, 30°, 45° and 60°.

### Claim 15 (depends on 1)

The lamp according to claim 1, wherein the body is configured such that the lamp can be fitted in an existing lighting fixture.

### Claim 16 (depends on 1)

The lamp according to claim 1, wherein the form of the body is selected from the group consisting of being: generally cylindrical, generally conical and generally hemispherical in form.

### Claim 17 (depends on 1)

The lamp according to claim 1, wherein the body is configured such that it has a form factor that resembles a standard form selected from the group consisting of: PAR38, PAR20, PAR30, PAR36, PAR56, PAR64, MR16 and MR11.

### Claim 18 (depends on 1)

The lamp according to claim 1, wherein the body comprises a material selected from the group consisting of: aluminum, an alloy of aluminum, a magnesium alloy, a plastics material, a metal loaded plastics material, a thermally conductive ceramic material and aluminum silicon carbide.

### Claim 19

A lamp comprising:
a thermally conductive body;
a plurality of light emitting diodes configured as an array and mounted in thermal communication with the body;
a light diffuser overlying the array of light emitting diodes; and
a light reflective hood overlying the light diffuser,
wherein the hood is configured to surround the array of light emitting diodes such that in operation light emitted by the lamp is within a selected emission angle, and
wherein a diameter of the hood is smaller at a first end proximal to the light emitting diodes than at a second end more distal to the light emitting diodes than the first end.

### Claim 20 (depends on 19)

The lamp according to claim 19, wherein the hood is configured such that a variation in illuminance is 10% or less over approximately a third of the selected emission angle.

### Claim 21 (depends on 1)

The lamp according to claim 1, wherein the hood is configured such that a variation in illuminance is 10% or less over approximately half of the selected emission angle.

### Claim 22 (depends on 19)

The lamp according to claim 19, wherein the hood is configured such that in operation a proportion of total light emission emitted within the selected emission angle is selected from the group consisting of: at least 90%, at least 95% and at least 98%.

### Claim 23 (depends on 19)

The lamp according to claim 19, wherein the hood comprises at least two frustoconical light reflective surfaces that surround the array of light emitting diodes.

### Claim 24 (depends on 23)

The lamp according to claim 23, wherein the light reflective surfaces are contiguous.

### Claim 25 (depends on 19)

The lamp according to claim 19, wherein the emission angle is in a range 8° to 60°.