Light source and backlight module having the same

A light source includes a carrier, a plurality of solid-state light-emitting devices, a plate photo-coupler, a first reflector, and a plurality of second reflectors. The solid-state light-emitting devices and the light-incoupling component are configured on the carrier. The light-incoupling component has a bottom surface, a top surface, a plurality of side surfaces adjoining the bottom surface and the top surface, and a through hole extending from the bottom surface to the top surface. The solid-state light-emitting devices are located in the through hole. The first reflector covers the through hole. The second reflectors are configured on the side surfaces. Light emitted from the solid-state light-emitting devices enters the light-incoupling component via a sidewall of the through hole and leaves the light-incoupling component via the top surface thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a backlight module, and more particularly to a design of a light source in a backlight module.

2. Description of Related Art

In recent years, liquid crystal displays (LCDs) that have been developed to achieve full-color display gradually replace conventional cathode ray tube (CRT) displays and have become mainstream displays in the market due to the advantages of low operation voltages, non-radiation, light weight, small volume occupancy, and so forth. The LCDs are non-self-illuminating displays, and therefore display functions of the LCDs are achieved when the required light is provided by backlight modules. With increasing consciousness of environmental protection, cold cathode fluorescent lamps (CCFLs) serving as light-emitting devices in conventional backlight modules are gradually replaced by light-emitting diode (LED) devices that are more friendly to the environment.

FIG. 1is a schematic cross-sectional view illustrating a conventional backlight module. With reference toFIG. 1, a conventional backlight module100includes a light guide plate (LGP)110, a plurality of light sources120, and a plurality of optical clear adhesives130. The LGP110has a light-incident surface110aand a light-emitting surface110bopposite to the light-incident surface110a. Each of the light sources120is adhered to the light-incident surface110aof the LGP110via one of the corresponding optical clear adhesives130, respectively.

As shown inFIG. 1, each of the light sources120includes a carrier120a, a plurality of LED devices120b, a light-incoupling component120c, and a plurality of ring-shaped reflectors120d. The LED devices120band the light-incoupling component120care configured on the carrier120a. Light emitted from the LED devices120benters the light-incoupling component120cfrom side surfaces S of the light-incoupling component120cand leaves the light-incoupling component120cfrom a top surface T of the light-incoupling component120c. The ring-shaped reflectors120dcover the LED devices120band an edge of the top surface T. Besides, the top surface T of the light-incoupling component120cis adhered to the light-incident surface110aof the LGP110via the optical clear adhesive130.

As indicated in the region X ofFIG. 1, the light emitted from the light source120inFIG. 1is excessively concentrated on top of the light-incoupling component120c. In addition, a part of the light emitted from each of the LED devices120bpasses through the correspondingly optical clear adhesive130and is then reflected by the sidewall of each of the ring-shaped reflectors120d, which causes light leakage as indicated in the region Y ofFIG. 1. Accordingly, the conventional backlight module100has unfavorable optical uniformity, and said problem requires an effective solution.

SUMMARY OF THE INVENTION

The invention is directed to a light source and a backlight module that have favorable optical characteristics.

The invention provides a light source that includes a carrier, a plurality of solid-state light-emitting devices, a plate photo-coupler, a first reflector, and a plurality of second reflectors. The solid-state light-emitting devices and the light-incoupling component are configured on the carrier. The light-incoupling component includes a bottom surface, a top surface, a plurality of side surfaces adjoining the bottom surface and the top surface, and a through hole extending from the bottom surface to the top surface. The solid-state light-emitting devices are located in the through hole. The first reflector covers the through hole. The second reflectors are configured on the side surfaces. Light emitted from the solid-state light-emitting devices enters the light-incoupling component via a sidewall of the through hole and leaves the light-incoupling component via the top surface thereof.

According to an embodiment of the invention, the carrier is a circuit board, for instance.

According to an embodiment of the invention, the solid-state light-emitting devices are side-view LED packages, for instance.

According to an embodiment of the invention, each of the solid-state light-emitting devices has a light-emitting surface, and each of the light-emitting surfaces faces the sidewall of the through hole.

According to an embodiment of the invention, a shape of the first reflector and a shape of the through hole are substantially the same.

According to an embodiment of the invention, the through hole includes a circular through hole, an elliptical through hole, or a polygonal through hole.

According to an embodiment of the invention, the sidewall of the through hole includes a plurality of curved surfaces.

According to an embodiment of the invention, the first reflector is a reflective plate, and the first reflector and the top surface of the light-incoupling component are substantially on the same plane.

According to an embodiment of the invention, a gap is between the first reflector and the solid-state light-emitting devices.

According to an embodiment of the invention, the second reflectors include a plurality of reflective plates or a plurality of reflective coatings.

According to an embodiment of the invention, the light source can further include an optical filler that fills the through hole and encapsulates the solid-state light-emitting devices. A refractive index of the optical filler is different from a refractive index of the plate photo-coupler.

According to an embodiment of the invention, the light source can further include a third reflective layer configured between the carrier and the bottom surface of the plate photo-coupler. For instance, the third reflective layer is a white sheet.

The invention further provides a backlight module that includes at least one light source described above, an LGP, and at least one optical clear adhesive. The LGP has a light-incident surface and a light-emitting surface opposite to the light-incident surface. The first reflector of the light source and the top surface of the light-incoupling component are adhered to the light-incident surface of the LGP via the optical clear adhesive.

According to an embodiment of the invention, a top/bottom surface of the LGP has a plurality of optical micro-structures, and the optical micro-structures are dots, V-cuts, or other optical micro-structures suitable for scattering light, for instance.

The solid-state light-emitting devices are configured in the through hole of the plate photo-coupler, and the first reflector covering the through hole and the second reflectors configured on the side surfaces of the light-incoupling component allow the light to be emitted uniformly from the top surface of the light-incoupling component according to this invention. Hence, the light source and the backlight module mentioned above have favorable optical characteristics.

To make the above and other features and advantages of the invention more comprehensible, several embodiments accompanied with figures are detailed as follows.

DESCRIPTION OF EMBODIMENTS

FIG. 2Ais a schematic bottom view illustrating a backlight module according to an embodiment of the invention.FIG. 2Bis a schematic cross-sectional view illustrating a backlight module according to an embodiment of the invention.FIG. 2Cis a schematic top view illustrating a light source according to an embodiment of the invention. With reference toFIG. 2AtoFIG. 2C, the backlight module200of this embodiment includes an LGP210, one or more light sources220, and one or more optical clear adhesives230. The LGP210has a light-incident surface210aand a light-emitting surface210bopposite to the light-incident surface210a. Each of the light sources220is adhered to the light-incident surface210aof the LGP210via one of the optical clear adhesives230, respectively. In this embodiment, the number of the light sources220in the backlight module200can be properly adjusted based on actual product requirements. For instance, when the backlight module200is applied to a small-scale LCD panel, the backlight module200can have a single light source220. By contrast, when the backlight module200is applied to a medium-scale or a large-scale LCD panel, the backlight module200can have a plurality of light sources220arranged in arrays. As indicated inFIG. 2A, the light sources220are equidistantly arranged below the LGP210, and each of the light sources220corresponds to one sub-illuminating region L on the LGP210. In this embodiment, the distance between two adjacent light sources220is relevant to the optical design of the light sources220. People having ordinary skill in the pertinent art are able to adjust the distance between the adjacent light sources220based on the optical design of the light sources220, and the distance between the adjacent light sources220is not limited in this embodiment.

With reference toFIG. 2BandFIG. 2C, each of the light sources220of this embodiment includes a carrier220a, a plurality of solid-state light-emitting devices220b, a light-incoupling component220c, a first reflector220d, and a plurality of second reflectors220e. The solid-state light-emitting devices220band the light-incoupling component220care configured on the carrier220a. The light-incoupling component220chas a bottom surface B, a top surface T, a plurality of side surfaces S adjoining the bottom surface B and the top surface T, and a through hole H extending from the bottom surface B to the top surface T. The solid-state light-emitting devices220bare located in the through hole H. The first reflector220dcovers the through hole H. The second reflectors220eare configured on the side surfaces S of the light-incoupling component220c. Light emitted from the solid-state light-emitting devices220benters the light-incoupling component220cvia a sidewall SW of the through hole H and leaves the light-incoupling component220cvia the top surface T. Besides, the first reflector220dand the top surface T of the light-incoupling component220care adhered to the light-incident surface210aof the LGP210via the corresponding optical clear adhesive230.

The carrier220aof this embodiment is a circuit board, for instance. The circuit board is, for example, the well-known FR-4 printed circuit board, FR-5 printed circuit board, metal core printed circuit board (MCPCB), and so on. Besides, the circuit board can also be a flexible printed circuit (FPC).

The solid-state light-emitting devices220bare side-view LED packages, for instance. Additionally, the solid-state light-emitting devices220bare mounted on the carrier220aby surface mount technology (SMT), and the solid-state light-emitting devices220bare electrically connected to the carrier220a, for instance. Moreover, each of the solid-state light-emitting devices220bof this embodiment has a light-emitting surface E, and each of the light-emitting surfaces E faces the sidewall SW of the through hole H.

In this embodiment, the light-incoupling component220cis a square light-incoupling component that has a side length ranging from about 10 millimeters to about 20 millimeters, for example. The through hole H of the light-incoupling component220cis a circular through hole (shown inFIG. 2Cand having a diameter from about 5 millimeters to about 8 millimeters), an elliptical through hole (not shown), or a polygonal through hole (not shown), for example. According to other embodiments of the invention, the sidewall SW of the through hole H can include a plurality of curved surfaces and a plurality of crest lines exist can be observed between the curved surfaces, as shown inFIG. 3. In this case, the design of the through hole H enhances uniformity of light distribution. The shape of the first reflector220dcan be adjusted in accordance with the shape of the through hole H in this embodiment. That is to say, the shape of the first reflector220dand the shape of the through hole H are substantially the same. However, the shape of the first reflector220dis not limited in this embodiment.

Note that the first reflector220dshields and/or reflects the light emitted from the solid-state light-emitting devices220b, such that most of the light can enter the light-incoupling component220cfrom the sidewall SW of the through hole H and leave the light-incoupling component220cfrom the top surface T. The first reflector220dcan prevent parts of the light emitted from the solid-state light-emitting devices220bfrom being directly transmitted in an upward manner and passing through the corresponding optical clear adhesive230and the LGP210. Therefore, the first reflector220dcan resolve the issue of excessively concentrated light above the solid-state light-emitting devices220b. In this embodiment, the first reflector220dis a reflective plate, and the first reflector220dand the top surface T of the light-incoupling component220care substantially on the same plane. However, the horizontal position of the first reflector220dis not limited in this invention. Namely, the first reflector220dcan be slightly higher than or lower than the top surface T of the light-incoupling component220c.

As clearly shown inFIG. 2B, a gap is between the first reflector220dand the solid-state light-emitting devices220b. In other words, the through hole H for accommodating the solid-state light-emitting devices220bis not further filled with other materials. Since the medium (e.g., air) in the through hole and the light-incoupling component220chave different refractive indexes, refraction occurs when the light emitted from the solid-state light-emitting devices220bpasses through the sidewall SW of the through hole H, which is conducive to light scattering. Note that the through hole H can be partially or fully filled with an optical filter to cover the solid-state light-emitting devices220bin other embodiments of the invention, so as to further protect the solid-state light-emitting devices220b. The optical filler and the light-incoupling component220cshould have different refraction indexes, such that the light is refracted when passing through the sidewall SW of the through hole H.

In this embodiment, the second reflectors220econfigured on the side surfaces S are a plurality of reflective plates or a plurality of reflective coatings, for instance. The second reflectors220ereflect parts of the light entering the light-incoupling component220cto the top of the first reflector220dand the solid-state light-emitting devices220b. To be more specific, the light entering the light-incoupling component220cfrom the sidewall SW of the through hole H can be categorized into two types. The first type refers to the light directly passing through the top surface T of the light-incoupling component220c, the optical clear adhesive(s)230, and the LGP210. The second type refers to the light passing through the top surface T of the light-incoupling component220c, the optical clear adhesive(s)230, and the LGP210after the light is reflected by the second reflectors220e. If the proportion of the two types of light can be arranged appropriately, the uniform planar light source can be obtained according to this embodiment. For instance, people having ordinary skill in the art can selectively make some optical micro-structures on the top surface210band/or the bottom surface210aof the LGP210, so as to uniformize the light distribution on the top surface20bof the LGP210. The optical micro-structures are printed dots, V-cuts, or other optical micro-structures suitable for scattering light, for instance.

FIG. 4is a schematic cross-sectional view illustrating a backlight module according to another embodiment of the invention. With reference toFIG. 4, the backlight module200′ of this embodiment is similar to the backlight module200depicted inFIG. 2B, while the main difference therebetween lies in that the light source220′ of the backlight module200′ in this embodiment further includes a third reflective layer220fthat is configured between the carrier220aand the bottom surface B of the light-incoupling component220c. The third reflective layer220fis a white sheet or any other appropriate reflective plate, for example.

EXPERIMENTAL EXAMPLE

FIG. 5shows comparison between optical characteristics according to the related art and according to an embodiment of the invention, respectively. With reference to the upper-left and the upper-right irradiance distribution views inFIG. 5, the light source in this invention is designed to achieve better uniformity of light distribution in comparison with the conventional light source. In addition, with reference to the lower-left and the lower-right light leakage energy distribution views inFIG. 5, the light leakage issue of the light source in this invention is rather insignificant in comparison with that issue occurring in the conventional light source.

The solid-state light-emitting devices are configured in the through hole of the light-incoupling component, and the first reflector covering the through hole and the second reflectors configured on the side surfaces of the light-incoupling component allow the light to be emitted uniformly from the top surface of the light-incoupling component according to this invention. Hence, the light source and the backlight module of this invention have favorable optical characteristics.

Although the present invention has been disclosed by the above embodiments, they are not intended to limit the invention. Those skilled in the art may make some modifications and alterations without departing from the spirit and scope of the invention. Therefore, the protection range of the invention falls in the appended claims.