Patent Application
20140063846
The invention relates to backlighting technology of a display, more specifically, to a surface light source device and an edge-lit type backlight module.
A backlight module is an important component of a liquid crystal display (LCD). As LCDs do not produce light themselves, a function of the backlight module is to supply a light source with sufficient brightness and good uniformity, such that the LCD can display images normally. Currently, the backlight module is not only applied in LCD devices such as LCDs, LCD TVs but also used to provide light source for display devices such as digital photoframes, electronic paper, and mobile devices and the like.
Backlight modules may be classified into direct-lit type backlight module and edge-lit type backlight module, base on the location of the light source. In a direct-lit type backlight module, the light source is disposed below the light-exiting surface directly, and the light from the light source travels through a certain distance spatially and is diffused and mixed by the diffuser plate to exit as a surface light source. In an edge-lit type backlight module, the light source is disposed on an edge of the backlight module, and the light from the light source is transmitted to a light guide plate (LGP). The LGP may atomize light from a line light source (e.g., a Cold Cathode Fluorescent Lamp (CCFL)) or a dot light source (e.g. a Light Emitting Diode (LED)), so as to function as a uniform surface light source, and the light exiting the LGP are diffused and deflected by the diffuser plate and finally the emission angle of the light is adjusted via a converging prism.
As illustrated in
In a conventional edge-lit type backlight module, the light emitted by the luminant 1 is directly incident into the LGP 9. The LGP 9 is normally made of acrylic which has a larger refractive index relative to air. Therefore, the light suffers from several total internal reflections after incident into the LGP 9 and spreads in the whole interior of the LGP 9. When the light propagates to the optical grid 10, it undergoes diffuse reflection and exits the LGP 9 through the exiting surface. By adjusting the density of the optical grid 10, the brightness of the exiting light of the LGP 9 may be made uniform over the whole exiting surface.
However, in the above conventional edge-lit backlight module, due to the reason that acrylic generally has large weight and high price, the product cost is high. Moreover, special processes are required to form the optical grid 10 on the bottom surface of the LGP 9 and precise control of the distribution of the optical grid 10 is required, as a result, the processes are complicated and defective product may easily be produced.
In order to solve the problem of the LGP being heavy and pricy and the optical mesh being hard to fabricate, the present invention provides a surface light source and an edge-lit type backlight module.
A first aspect of the invention provides an surface light source device comprising: a luminant, a bottom reflector plate, a light leaking plate and a plurality of side reflector plates, wherein the bottom reflector plate and the plurality of side reflector plates form a light guide box with an upper opening, the luminant is disposed on at least one of the plurality of side reflector plates, the light leaking plate is disposed in the upper opening of the light guide box, such that light from the luminant is transformed into an exiting surface light via the light leaking plate.
A second aspect of the invention provides an surface light source device, comprising: a luminant, a bottom reflector plate, a light leaking plate, a plurality of side reflector plates, and a box-like frame, wherein the box-like frame has an opening, and a cavity surrounded by a plurality of sidewalls, the luminant is disposed on at least one of the plurality of sidewalls; the plurality of side reflector plates are disposed on the remaining sidewalls of the plurality of sidewalls; the light leaking plate is disposed in the opening of the box-like frame, such that light from the luminant is transformed into an exiting surface light via the light leaking plate.
A third aspect of the invention provides an edge-lit type backlight module comprising: the surface light source device described above, a diffuser plate, and an optical film plate, wherein a surface light from the surface light source device exits through the diffuser plate and the optical film plate.
In order to clearly illustrate the technical solution of the embodiments of the invention, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the invention and thus are not limitative of the invention.
1: luminant; 2: bottom reflector plate; 3: side reflector plate; 4: light leaking plate; 5: diffuser plate; 6: optical film plate; 7: stand; 8: frame; 9: light guide plate; 10: optical grid; 11: light leaking plate engage bore; 12: light leaking hole distal to the light source; 13: light leaking hole proximal to the light source; 14: light leaking plate engage portion; 15: ball-shaped extrusion.
In order to make objects, technical details and advantages of the embodiments of the invention apparent, the technical solutions of the embodiment will be described in a clearly and fully understandable way in connection with the drawings related to the embodiments of the invention. It is obvious that the described embodiments are just a part but not all of the embodiments of the invention. Based on the described embodiments herein, those skilled in the art can obtain other embodiment(s), without any inventive work, which should be within the scope of the invention.
Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms “first,” “second,” etc., which are used in the description and the claims of the present application for invention, are not intended to indicate any sequence, amount or importance, but distinguish various components. Also, the terms such as “a,” “an,” etc., are not intended to limit the amount, but indicate the existence of at lease one. The terms “comprises,” “comprising,” “includes,” “including,” etc., are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but do not preclude the other elements or objects. The phrases “connect”, “connected”, etc., are not intended to define a physical connection or mechanical connection, but may include an electrical connection, directly or indirectly. “On,” “under,” “right,” “left” and the like are only used to indicate relative position relationship, and when the position of the object which is described is changed, the relative position relationship may be changed accordingly.
In the present invention, the term “light leaking plate” refers to a sheet having at least one hole punched therethrough, and the sheet is made of an opaque material and light may pass through the at least one hole therein. In the present invention, the light leaking plate plays the following roles: 1) reflecting the light from the luminant a plurality of times on its internal surface, so that the light can be propagated in the whole light guide box; 2) making the light from the luminant to pass through the hole on the light leaking plate and exit in an emission direction of a surface light source; 3) making the brightness of the illuminant surface of the surface light source more uniform by adjusting the number and density of the holes on the light leaking plate.
As illustrated in
The light leaking plate 4 is a thin sheet made of an opaque material having a reflective function and has a thickness of 0-4 mm, for example, the light leaking plate 4 is made of PET or PC with microbubbles. As described in the following, the light leaking plate 4 provides a plurality of light leaking holes 12 and 13. and the surface of the light leaking plate 4 facing to the bottom reflector 2 is a total reflective surface, which has a function of repeatedly using the unleaked light to the most extent. Another surface of the light leaking plate 4 at the side opposed to the bottom reflector plate 2 is a diffuse reflective surface and is used to make the exiting (i.e. leaking) light as uniform as possible, such that the light exiting the light leaking plate is rendered as a surface light. Due to the fact that all the inner surfaces of the light guide box are reflective, the light emitted by the luminant 1 is totally reflected a plurality of times and diffused to the whole light guide box and then exits the light leaking holes 12, 13 of the light leaking plate 4 as a surface light.
As shown in
To fix the light leaking plate 4 in the upper opening of the light guide box, bonding and the like may be used to fix the light leaking plate 4 on the sidewalls of the light guide box. However, for better stability, it is preferably to use a mechanical structure to fix the light leaking plate 4 to the light guide box. For example, connecting members, such as an L-shaped connector, may be used to connect the upper or lower surface at peripheral edge of the light leaking plate 4 with the sidewalls of the light guide box. Alternatively, the light leaking plate 4 may be integrally formed with a plurality of protrusions for supporting. When fixing the light leaking plate 4 inside the light leaking box, the protrusions stand against the bottom reflector plate 2. As a further alternative, one or more stands 7 arranged on the bottom reflector plate 2 described in the following may also be used to fix the light leaking plate 4 inside the upper opening.
Preferably, the edge-lit type backlight module as shown in
In a variant embodiment, the luminant 1 may be disposed on an inner surface of at least one of the sidewalls of the frame 8 directly, using for example thermal-conductive adhesive tape or screw, the bottom reflector plate 2 may be disposed on the inner side of the bottom of the frame 8 using for example bonding, and the side reflector plates 3 may be disposed on the remaining sidewalls other than the one having the luminant of the frame 8 using for example bonding.
As described above, one or more stands 7 may be disposed on the bottom reflector plate 2, such that the light leaking plate 4 is fixed in the light guide box or its opening. Of course, many other approaches may be used to implement such fixation. One of the approaches is referred to as ‘shape engagement’, which is realized by the inherent shape of the stands 7. Specifically, as shown in
The stand 7 may be fixed to the bottom reflector plate 2 in many ways. For example, as shown in
Disposed above the light-exiting surface (i.e. the light leaking plate) of the surface light source device are a diffuser plate 5 and an optical film plate 6. The diffuser plate 5 is used for further diffusing the light exited from the light guide box such that the light is further homogenized in distribution. The optical film plate 6 is for changing the light shape. The term ‘light shape’ used herein refers to the intensity distribution of the light in different directions. The optical film plate 6 may include a prism film, a diffusion film, DBEF, a protection film, microlens and other film. In
More preferably, the top portion of the stand 7 has a hemispherical shape, thus the contact area between the stand 7 and the diffuser plate 5 is minimized to keep dark spots on the surface light source to the minimum and avoid the abrasion between the stand 7 and the diffusion 5.
The light-mixing distance between the light leaking plate 4 and the diffuser plate 5 is used to mask the optical meshes on the light leaking plate. The light-mixing distance is determined by the distance between the light leaking plate engage bore 11 of the light leaking plate 4 and the top end of the stand 7. Ideally, to make the finally manufactured backlight module as thin as possible, it is desirable that the light-mixing distance is zero. However, in real production it is difficult to realize zero in distance, the light-mixing distance is therefore about 0 to 20 mm.
It may be appreciated by those skilled in the art that the embodiments described above are only the preferable embodiments of the invention. In other embodiments of the invention, the surface of the sidewall of the frame which is provided with the luminant 1 may have or may not have a side reflector plate 3 disposed thereon. When both the luminant 1 and the side reflector plate 3 are disposed on one and same surface of the sidewall, the side reflector plate 3 are positioned between the luminant 1 and the surface, and the light impinged on this surface of the sidewall can be totally reflected. The light leaking holes on the light leaking plate 4 may have identical apertures, just that the density of the light leaking holes (i.e., the number of light leaking holes per unit area) proximal to the luminant 1 is lower while that of the light leaking holes far from the luminant 1 is higher. The shape of the stand is not necessarily a cone, and the support for both the light leaking plate 4 and the diffuser plate 5 is not necessary to achieve by merely using the same support member such as stands 7. Practically, two separate support members of any shape that formed on the frame 8 and light leaking plate 4 respectively may be used to support the light leaking plate 4 and the diffuser plate 5. Therefore, the shape and position of the components as described in the above embodiment are not limitative to the individual component of the invention.
It is demonstrated by the simulation test of the backlight module according to the above embodiments that the backlight module according to the embodiments of the invention may realize higher picture uniformity (a uniformity of 60% or higher by adjusting the optical meshes) and higher light usage (about 42% as opposed to 53% of a convention configuration, and may be further improved by optical mesh adjustment and surface improvement). Although the optical path in the light guide box is substantially the same as the optical path of the LGP in the conventional configuration, the propagation path of the light is mostly in the air, therefore, the absorption of the light by the acrylic is avoided. As a result, the light energy usage is generally comparable or better than that of the conventional LGP configuration.
The backlight module of the invention may be used in a display device, such as LCD panels, e-paper, OLED panels, LCD TVs, LCD, digital photoframes, mobile phones, tablet computer and any other product or component having a display function.
In the embodiments of the solutions of the invention, the light mixing of the edge-lit light source is realized through the design of the reflector plate and the light leaking pate, thereby omitting the design of LGP in the backlight module. In comparison with the conventional direct-lit type backlight module, the backlight module according to the embodiments of the invention significantly reduces thickness of the product by using edge-lit type and reduces the number of luminants, thereby reducing the power consumption and cost. Furthermore, in contrast with the convention edge-lit type backlight module, the backlight module of the invention can realize uniform exiting light simply without the LGP. With the omission of the LGP, the weight and cost of the backlight module are further reduced. Meanwhile, since the light propagates in the air, the absorption of the light by the LGP is avoided, thereby improving the usage of the light. Moreover, the manufacture of the light leaking plate and the optical meshes is simple which simplifies the manufacture processes.
What are described above is related to the illustrative embodiments of the disclosure only and not limitative to the scope of the disclosure; the scopes of the disclosure are defined by the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201220255322.7 | May 2012 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2013/072537 | 3/13/2013 | WO | 00 | 6/25/2013 |
