Illumination – Light source and modifier – Including reflector
Reexamination Certificate
1999-06-25
2002-03-26
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S800000, C362S277000, C362S307000, C362S255000, C362S256000, C313S512000
Reexamination Certificate
active
06361190
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to a LED lighting device having a plurality of reflectors of improved shape and disposition to sequentially reflect a substantial portion of the light emitted by the LED element to effect a lighting device having a large lighted surface. The enlarged lighted surface created by the current invention provides a more visible lighting device with a reduction in the hot spot characteristic of normal LED lamps.
2. Description of Prior Art
FIG. 21
shows a diagrammatic partial sectional view of a conventional prior art LED lamp C
10
. In
FIG. 21
positive lead C
1
is the positive lead wire. Contact wire C
2
connects positive lead C
1
to LED element C
3
. Negative lead C
4
is the negative lead wire. Negative lead wire C
4
has reflective cup C
5
which partially surrounds LED element C
3
. LED body C
6
is formed of a transparent resin which encapsulates LED element C
3
and reflective cup C
5
. LED body C
6
forms converging lens C
7
which refracts and bends the light. If adequate electrical voltage is connected to positive lead wire C
1
and negative lead wire C
2
LED element C
3
is energized to emit light. The emitted light forms a spatial radiation pattern. The light is moderately diverging and substantially centered about a pattern axis CA of the spatial radiation pattern.
A first portion of the emitted light proceeds directly through lens C
7
. A second portion of the emitted proceeds into concave reflective cup C
5
whereat it is reflected and thereby redirected to also pass through concentrating lens C
7
. Both the first and second portions of light therefore are refracted at lens C
7
to emerge concentrated about lamp body axis CX of LED lamp C
10
. Lamp body axis CX is the geometric axis of lamp body C
6
and is coincident with pattern axis CA. Thus this prior art design of LED lamp C
10
emits light concentrated about body axis CX of LED lamp C
10
.
For some uses concentration of the light about body axis CX is desirable. Other uses require the emerging light to be less concentrated. Refracting lens C
7
can have a variety of shapes, however, it is not possible to reshape refractive surface C
7
to effect the required divergence of the light for many uses. For these uses prior art designs employ a body C
6
formed of a diffusing epoxy—usually milky white—to encourage the divergence of the light about the pattern axis CA. This design is inefficient as light is absorbed and lost within the diffusing epoxy.
FIG. 22
is an end view of the
FIG. 21
lamp as it would be seen by an observer along pattern axis CA. The size of the lamp as it appears to an observer is established by the size of LED body C
6
which is usually small ranging up to 10 millimeters in diameter. This small size creates a hot spot with a high value of light energy per square millimeter leaving lens C
7
. This hot spot can be a problem as it impresses an image on a viewers eye which takes time to recede. It can also damage the viewers eye. The size of the lighted area can be increased by increasing the diameter of body C
6
. This however increases the mass and the cost of the device. It also can reduce the efficiency as light energy is lost passing through thick sections of the transparent resin.
SUMMARY OF THE INVENTION
The current invention employs an interior and an exterior reflector to sequentially reflect the light emitted by an LED element to create an efficient enlarged lighted surface LED lighting device. The current invention can be configured so that it comprises a large lighted surface even when the device is of limited mass and thickness.
The current invention initially efficiently spreads the light emitted by a LED element by providing an interior reflector of a size and disposition adequate to intersect the first portion and for some embodiments including a cup reflector both the first and the second portion of light emitted by the LED element. For the following discussion the light reflected can be the sum of the first and second portions previously described for prior art or it can be either the first or the second portion of the light. The interior reflector of the current invention is usually designed to bend the light away from a pattern axis of the emitted light. The interior reflector could alternatively be considered as designed to reflect the light to bring it towards parallelism with a reference plane normal to the pattern axis of the light emitted by the LED element. The interior reflective surface is usually disposed in close proximity to the LED element so that it can intercept a large percentage of the emitted light. The efficiency of the design can be maximized by locating the interior reflective surface sufficiently close to the LED element and by employing an interior reflective surface having an acceptable contour.
In one embodiment of the current invention the interior reflective surface is achieved by contouring the resin body which encapsulates the LED element such that the reflective nature of the interior reflective surface is the result of an internal reflection of the light. This embodiment is desirable because designing the resin body of the device to employ internal reflection usually minimizes the cost of the device. The interior reflective surface can alternatively also be achieved by coating a contoured surface of the resin body with a metallic coating. The interior reflector can alternatively be a discrete reflector attached to the LED element.
For some uses it is desirable that the light emitted by the lighting device substantially evenly illuminate a hemisphere centered about the LED element. For this requirement one embodiment of the current invention permits a percentage of the emitted light to pass through the interior reflective surface so that the light will not be totally reflected thereby avoiding dark zones within the hemisphere. This can be achieved by contouring the interior reflective surface to create internal reflection but not total internal reflection. In this embodiment a percentage of the emitted light is permitted to pass through the interior reflective surface to thereby distribute some of the emitted light within a hemisphere having the pattern axis of the emitted light as its axis. Alternatively, this result can be achieved by coating the interior reflective surface with a very thin coat of a metallic reflective coating thereby permitting a percentage of the emitted light to pass through the reflector to abet a more uniform distribution of emitted light within the hemisphere while reflecting a large portion of the emitted light to increase its divergence from the pattern axis. The light which passes through the reflective surface is refracted to form the required spectral radiation pattern of the light emerging from the lighting device. Finally, partial reflection can be achieved if the interior reflective surface is roughened or sanded. In this embodiment, the interior reflective surface will no longer have the smooth finish necessary for total internal reflection permitting some light to pass through.
Other uses require most of the light to be brought into a substantially parallel relationship with the pattern axis of the light. For these uses, an additional embodiment of the current invention employs a substantially parabolic contour on the interior reflector. This results in a concentration of the light about a plane normal to the pattern axis. A conical exterior reflector is provided to subsequently reflect the light to bring it towards parallelism with the pattern axis.
Finally, there are other requirements where the light must be bent away from the pattern axis to increase its divergence about the pattern axis into a user defined specific energy pattern about the pattern axis. These requirements are met with an embodiment of the current invention comprising a contouring of the exterior reflector to correspond to the contour of the interior reflector to distribute the light into the specific energy pattern required.
The interior reflector can—for some emb
Carella Byrne et al.
Hand, Esq. Francis C.
O'Shea Sandra
Ton Anabel
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