LED lamp having a large illumination angle

An LED bulb includes a connecting member having an Edison male screw base and an LED module engaging with the connecting member. The LED module includes a circuit board, a first LED and a plurality of second LEDs mounted on the circuit board. The first LED is arranged on a center of the circuit board. The second LEDs are located surround the first LED. The LED bulb furthermore includes a plurality of lens. Each lens covers a corresponding second LED. Each lens includes a light-guiding portion which includes a light input surface and a light output surface. Light emitted from each of the second LEDs travels into the lens via the light input surface, and is refracted out to lateral directions of the LED bulb by the light output surface of the light-guiding portion to obtain a wider illumination range.

BACKGROUND

1. Technical Field

The disclosure relates to a light emitting diode (LED) lamp, and particularly to an LED bulb having a wider range of illumination.

2. Description of Related Art

LEDs have many beneficial characteristics, including low electrical power consumption, low heat generation, long lifetime, small volume, good impact resistance, fast response and excellent stability. These characteristics have enabled LEDs to be widely used as a light source in electrical appliances and electronic devices.

A conventional LED generally generates a smooth round light field with a radiation angle of 120 degrees (i.e. ±60 degrees). The light emitted from the LED is mainly concentrated at a center thereof. The light at a periphery of the LED is relatively poor in intensity and typically cannot be used to illuminate. Therefore the LED cannot be used in a lamp which requires a wide illumination range, for example, an explosion-proof lamp which may be fitted to a miner's safety helmet, or a gas station canopy lamp.

Therefore, what is needed, is an LED lamp which can overcome the limitations described above.

DETAILED DESCRIPTION

An embodiment of an LED lamp of the present disclosure will now be described in detail below and with reference to the drawings.

Referring toFIG. 1, an LED lamp100, in accordance with an exemplary embodiment, is provided. The LED lamp100is an LED bulb and includes a connecting member10for electrically connecting a power source (not shown) and an LED module30engaging with the connecting member10.

Also referring toFIG. 2, the connecting member10includes a holder11which in the shown embodiment is an E27 Edison male screw base, and a connector13engaging with a top end of the holder11. The holder11is configured for screwing to a socket (not shown) to electrically connects the power source. The LED module30includes a supporting member31engaging with a top end of the connector13, an LED unit33received in the supporting member31, and an envelope35mounted on the supporting member31and covering the LED unit33.

The holder11is a hollow tube with the bottom end thereof being closed. A metallic patch111is formed on an outside of the bottom end of the holder11. The metallic patch111functions as a positive electrode and a threaded periphery113of the holder11functions as a negative electrode to electrically connect the power source to drive the LED unit33to lighten. The holder11is a standard element, so the LED lamp100can be directly connect to a standard socket matching with the standard holder11to electrically connect with the power source. Thus, the LED lamp100of the present disclosure can replace the traditional incandescent bulb and compact fluorescent bulb.

The supporting member31is made of aluminum, copper or alloy thereof. The supporting member31includes a circular supporting plate311and a hollow, cone-shaped heat dissipating portion313extending downwardly from an outer periphery of the supporting plate311. A central portion of the supporting plate311defines a first through hole3111therein to allow wires (not shown) extending therethrough to electrically connect the holder11and the LED unit31. An outer diameter of the heat dissipating portion313axially decreases from a top end engaging with the LED unit33to a bottom end connecting the connector13. A plurality of fins3131radially extend from an outer circumferential surface of the heat dissipating portion313to dissipate heat of the heat dissipating portion313absorbed from the LED unit31.

The LED unit33includes a circuit board331, a first LED chip333and a plurality of second LED chips335arranged on the circuit board331, and a plurality of lenses40arranged on the circuit board331and covering the second LED chips335respectively.

The circuit board331is disc-shaped, and is mounted on a top surface of the supporting plate311. A size of the circuit board331substantially equals a size of the supporting plate311. The circuit board331thermally contacts with the supporting plate311. A second through hole3311is defined in a central portion of the circuit board331. The second through hole3311of the circuit board331is aligned with the first through hole3111of the supporting plate311. The second through hole3311of the circuit board331allows the wires to extend there through to electrically connect the LED unit33.

The first LED chip333is located at a center of the circuit board331, and is surrounded by the second LED chips335. In this embodiment, the LED lamp100includes one first LED chip333and three second LED chips335. The first LED chip333is aligned with the second through hole3311of the circuit board331. The three second LED chips335are located surrounding the first LED chip333, and are equidistantly spaced from each other. Each second LED chip335spaces a same distance with the first LED chip333. In this embodiment, the three second LED chips335are located on three vertices of an equilateral triangle respectively, and the first LED chip333is located at the center of the equilateral triangle. The first and second LED chips333,335can emit light with different colors if needed, and a brightness of each LED chip333,335can be adjusted by the circuit design of the circuit board331. In this embodiment, there is no lens covering the first LED chip333.

Also referring toFIGS. 3-4, each lens40is located on the top surface of the circuit board331, and covers one second LED chip335therein. The lens40is made of a transparent material with a good optical performance, such as PMMA (polymethyl methacrylate) or PC (polycarbonate). The lens40is symmetrical with respect to a central axis O-O′ line.

The lens40includes a light-guiding portion41, a rough portion43and a pair of retaining portions45.

The light-guiding portion41includes a curved top surface415, a flat bottom surface411and an annular side surface413interconnecting edges of the top surface415and the bottom surface411. A width of the top surface415along a direction parallel to the top surface of the circuit board331is larger than that of the bottom surface411. The side surface413is inclined, and extends downwardly and inwardly from an edge of the top surface415to a corresponding edge of the bottom surface411. The top surface415is employed as a light outputting surface of the corresponding second LED chip335. Most of the light emitted from the second LED chip335penetrates the lens40from the top surface415, and another part of the light penetrates the lens40from the side surface413.

The top surface415includes a pair of first curved surfaces4151cooperatively forming a wing-shaped configuration. The first curved surfaces4151are symmetrical about the central axis O-O′ line. Each of the first curved surfaces4151is convex. An outer edge of each first curved surface4151connects a top edge of a corresponding side surface413. Inner edges of the two first curved surfaces4151intersect at a joint4153. The joint4153is located on the central axis O-O′ line. A distance between each first curved surface4151and the bottom surface411of the light-guiding portion41is decreased from a central portion of the first curved surface4151to a periphery of the first curved surface4151.

A cavity417is recessed from a central portion of the bottom surface411to be aligned with the second LED chip335. The cavity417is surrounded by a second curved surface4171and an annular surface4173connecting the second curved surface4171. The second curved surface4171is convex to form a dome. The center of the second curved surface4171is aligned with the joint4153. The annular surface4173is perpendicular to the circuit board331. The second curved surface4171and the annular surface4173are employed as a light incident surface of the lens40. A width of the cavity417along the direction parallel to the top surface of the circuit board331substantially equals that of the second LED chip335.

The rough portion43and the two retaining portions45are protruded downwardly from the bottom surface411. The rough portion43includes a plurality of continuous protruding portions431. The protruding portions431are evenly arrayed on the bottom surface411and located around the cavity417. Each protruding portion431has the same shape and size. Each protruding portion431is inverted trapeziform, and a width of the protruding portion431decreases from a top end connecting the bottom surface411to a bottom end away from the bottom surface411. Edges of top ends of adjacent protruding portions431connect with each other, and the another parts of the adjacent protruding portions431are spaced from each other. The outer edges of the two protruding portions431located at outmost sides of the bottom surface411connect inner edges of the two retaining portions45respectively. In this embodiment, the lens40is fixed on the circuit board331by the two retaining portions45.

The envelope35is made of a light permeable material with a high refractive-index and has a hollow, hemispherical-shape. The envelope35is fixed on the top end of the supporting member31, and covers the LED units33therein. The envelope35can adjust the light emitted from the first and second LED chips333,335to a periphery of the envelope35divergently. In this embodiment, a center of a hemispherical-shaped surface of the envelope35is aligned with the first LED chip333.

Referring toFIGS. 4-5, when the LED lamp100is operated, light emitted from the first LED chip333travels directly into a central portion of the envelop35to illuminate with high light intensity. Simultaneously, light emitted from each second LED chip335travels into the lens40via the inner surface of the cavity417. For each lens40, most part of light from a central portion of the second LED chip335with high light intensity emits into the top surface415of the lens40, and this part of light is refracted by the top surface415to divergently emit into lateral directions of the envelope35with a larger light emission angle; another part of the light from a periphery of the second LED chip335emits into the annular side surface413, and this part of light is refracted by the annular side surface413to divergently emit into the lateral directions of the envelope35as well. And then, the light emitting into the lateral directions of the envelope35can be further refracted out by the envelope35divergently and uniformly, whereby the LED lamp100has a wider range of illumination. In this embodiment, the light emission angle of the LED lamp100is larger than 240 degrees.

In addition, because the lens40adjusts the light of the central portion of the second LED chip335to lateral directions of the second LED chip335, a light emission angle of each second LED chip335is enlarged, such that the number of the second LED chip335can be decreased compared to a conventional LED lamp with a wide range of illumination, whereby the manufacturing cost of the LED lamp100is reduced.

Further, because the light emission angle of the second LED chips335is enlarged by the lenses40, a distance between the second LED chips335can be arranged larger. When the distance between adjacent second LED chips335is increased, an overlapping area of the light from the second LED chips335will be decreased, and the total light intensity from the second LED chips335is decreased accordingly. However, because the first LED chip333is located in a center of the second LED chips335and the first LED chip333has no lens covering thereon, light emitted from the first LED chip333is concentrated on the central area of the LED lamp100to increase the total light intensity of the LED lamp100, whereby, a light emission angle of the LED lamp100is larger, while the light emitted out from the LED lamp100has sufficient intensity.

It is to be understood that the above-described embodiment is intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure as claimed. The above-described embodiment illustrates the scope of the disclosure but do not restrict the scope of the disclosure.