Patent Application
20140036534
This application claims priority to Korean Patent Application No. 10-2012-0084954 filed on Aug. 2, 2012, and all the benefits accruing therefrom under 35 U.S.C. §119, the entire contents of which are incorporated herein by reference.
(a) Field
The invention relates to a backlight unit.
(b) Description of the Related Art
Based on semiconductor technology which has been rapidly developed, demand for a flat panel display having more improved performance due to a small size and a light weight has explosively increased.
A liquid crystal display (“LCD”) which has been in the spotlight among the flat panel displays has merits of a small size, a light weight, low power consumption, and the like. Accordingly, the liquid crystal display has gradually gained more attention as an alternative display capable of overcoming demerits of a known cathode ray tube (“CRT”) and is used in a number of information processing devices where display devices are required.
In general, the liquid crystal display has a liquid crystal material between upper and lower panels of a liquid crystal panel. For example, the upper panel may include a common electrode, a color filter and the like, and the lower panel may include a thin film transistor and a pixel electrode. Different electrical potentials are applied to the pixel electrode and the common electrode of the liquid crystal panel of the liquid crystal display. Accordingly, the liquid crystal display generates an electric field and changes alignment of liquid crystal molecules of the liquid crystal material so as to control transmittance of light, thereby displaying images.
The liquid crystal panel of the liquid crystal display is a light receiving element which is not self-emitting, such that a backlight unit for supplying light to the liquid crystal panel is provided below the liquid crystal panel. The backlight unit includes a lamp, a light guide plate, a reflective sheet, an optical sheet and the like.
The optical sheet is positioned on the light guide plate, and a position fixing member which fixes a position and restricts movement of the optical sheet may be additionally included. As the position fixing member, an additional fixing member is disposed at a chassis (for example, a bottom chassis) and the optical sheet is fixed on the light guide plate.
However, since the additional fixing member at the chassis is accommodated in an area or width of the liquid crystal display and/or the backlight unit surrounding the optical sheet, reducing such area or width may be undesirably limited. This area or width surrounding the optical sheet may be referred to as a bezel of the backlight unit or the liquid crystal display.
Also, to form the additional fixing member at the chassis, a shape of the additional fixing member must be added to a mold of the chassis such that there are drawbacks since a manufacturing process is complicated, a manufacturing time is increased and a cost is increased.
One or more exemplary embodiment of the invention provides a backlight unit which fixes an optical sheet with a low manufacturing cost and process time.
An exemplary embodiment of a backlight unit according to the invention includes: a light source which supplies light; a light guide which transmits the light; an optical sheet on the light guide, and including a fixing member disposed at a side surface of the optical sheet; and a reflection sheet under the light guide. The reflection sheet reflects the light toward the optical sheet and includes a protrusion guide member which extends from a side surface of the reflection sheet and toward the light guide. The fixing member of the optical sheet is coupled to the protrusion guide member of the reflection sheet, and restricts movement of the optical sheet.
The fixing member of the optical sheet may comprise a protrusion guide member extending from the side surface of the optical sheet.
The fixing member of the optical sheet may further comprise a groove disposed between the protrusion guide members of the guide member.
A guide member unit restricts the movement of the optical sheet, and may include one protrusion guide member of the reflection sheet between two fixing members of the optical sheet.
The backlight unit may further include an adhesive member between a side surface of the light guide and the protrusion guide member of the reflection sheet, where the adhesive member couples the light guide and the protrusion guide member to each other.
A guide member unit restricts the movement of the optical sheet, and may include one fixing member of the optical sheet between two protrusion guide members of the reflection sheet.
The reflection sheet may further include a main body, and a bent portion which connects the protrusion guide member and the main body.
The reflection sheet may further include an opening at the bent portion of the reflection sheet, where the protrusion guide member and the main body are separated from each other by the opening.
The main body and the protrusion guide member may be separated by a predetermined distance.
The protrusion guide member may include a same material as the reflection sheet.
The reflection sheet may further include a protrusion guide member extension which extends from a distal end of the protrusion guide member, and the protrusion guide member extension overlaps the light guide.
The protrusion guide member extension may overlap the optical sheet.
The backlight unit may further include a first adhesive member between a side surface of the light guide and the protrusion guide member of the reflection sheet, where the first adhesive member couples the light guide and the protrusion guide member to each other.
The reflection sheet may further include a protrusion guide member extension, and the backlight unit may further include a second adhesive member between an upper surface of the optical sheet and the protrusion guide member extension. The second adhesive member may couple the optical sheet and the protrusion guide member extension to each other.
A guide member restricts the movement of the optical sheet, and includes the protrusion guide member of the reflection sheet and the fixing member of the optical sheet. The backlight unit may include two guide member units.
One of the two guide member units may be positioned at a first side of the light guide, and the other of the two guide member units may be positioned at a second side opposing the first side of the light guide.
The light source may be positioned at a side of the light guide excluding the guide member units.
The protrusion guide member of the reflection sheet may be spaced apart from the side surface of the optical sheet where the guide member is disposed
The protrusion guide member of the reflection sheet may contact the side surface of the optical sheet where the guide member is disposed.
As described above, in one or more exemplary embodiment, the optical sheet may be easily fixed through the protrusion guide member of the reflection sheet and a corresponding guide member of the optical sheet, such that a bezel of a liquid crystal display and/or the backlight unit may be narrows.
The above and other features of this disclosure will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which:
The invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the invention.
In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like elements throughout the specification. As used herein, connected may refer to elements being physically and/or electrically connected to each other. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the invention.
Spatially relative terms, such as “lower,” “under,” “above,” “upper” and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “lower” or “under” relative to other elements or features would then be oriented “above” relative to the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Hereinafter, the invention will be described in detail with reference to the accompanying drawings.
Now, an exemplary embodiment of a backlight unit according to the invention will be described with reference to
An exemplary embodiment of a liquid crystal display 100 according to the invention shown in
The backlight unit 20 shown in
The liquid crystal panel assembly 70 includes a liquid crystal panel 75, an integrated circuit (“IC”) chip 77 and a flexible printed circuit (“FPC”) board 79.
The liquid crystal panel 75 includes a thin film transistor (“TFT”) array panel 73 including a plurality of TFTs, an upper panel 71 facing the TFT array panel 73, and liquid crystal (not shown) between the panels. The TFT array panel 73 and the upper panel 71 may include one or more pixels which correspond to each other, respectively. The IC chip 77 may be mounted on the TFT array panel 73 to control the liquid crystal panel 75, but is not limited thereto or thereby.
The TFT array panel 73 may include a matrix of TFTs and a pixel electrode. A TFT may include a source terminal connected to a data line (not shown), and a gate terminal connected a gate line (not shown), on a transparent insulation substrate. The TFT may further include a drain terminal connected to the pixel electrode. The pixel electrode may include transparent indium tin oxide (“ITO”) as a conductive material.
Where the data line and gate line of the liquid crystal panel 75 are connected to the FPC board 79 and an electric signal from the FPC board 79 is input to the liquid crystal panel 75, the electric signal is transmitted to the source terminal and the gate terminal of the TFT. The electrical signal, otherwise referred to as a driving signal, may include a scanning signal and an image signal. In one exemplary embodiment, the TFT is turned on or turned off according to the scanning signal applied to the gate terminal of the TFT via the gate line such that the image signal applied to the source terminal of the TFT via the data line is transmitted to the drain terminal of the TFT or blocked. The liquid crystal panel 75 receives the driving signal from the FPC board 79 and the driving signal is respectively applied to the data line and the gate line of the liquid crystal panel 75.
The upper panel 71 is disposed on and facing the TFT array panel 73. In one exemplary embodiment, the upper panel 71 is a panel including one or more color filters, such as red, green and blue (“RGB”) color filters which may be formed through a thin film process, to thereby realize predetermined colors as the light passes therethrough. A common electrode including ITO may be deposited on an entire surface of the color filter. When electric power is applied to the gate and source terminals of the TFT to turn on the TFT, an electric field is formed between the pixel electrode of the TFT array panel 73 and the common electrode of the upper panel 71. An arrangement angle of the liquid crystal between the TFT array panel 73 and the upper panel 71 is changed by the electric field, and the light transmittances of the pixels are individually varied in accordance with the arrangement angles of the liquid crystal in the pixels, thereby obtaining a desired image.
The FPC board 79 generates the image signal and the scanning signal as signals to drive the liquid crystal display 100, and a plurality of timing signals used to apply the driving signals at an appropriate timing. The FPC board 79 applies the scanning signal and the image signal to the gate line and the data line of the liquid crystal panel 75, respectively.
An exemplary embodiment of the structure of the liquid crystal panel 75 according to the invention has been described above. However, different from the above exemplary embodiment, various exemplary embodiments of liquid crystal panels 75 may be used the liquid crystal display 100. In one exemplary embodiment, for example, the common electrode and the color filter above-described in the upper panel 71, may be instead in the TFT array panel 73. Also, an additional printed circuit board (“PCB”) may be further included, and the PCB and the TFT array panel 71 may be connected by the FPC board 79.
The backlight unit 20 uniformly provides light to the liquid crystal panel 75. The backlight unit 20 is provided under the liquid crystal panel assembly 70 and is received on the bottom chassis 28.
The backlight unit 20 includes a light emitting diode (“LED”) 12 (indicated by a dotted line), a substrate 14 supplying power to the LED 12 and on which the LED 12 is mounted, a light guide 10 such as a light guide plate guiding light emitted from the LED 12 and supplying the guided light to the liquid crystal panel assembly 70, a reflection sheet 26 positioned under and overlapping substantially a whole surface of the light guide 10, and reflecting light, and an optical sheet 24 receiving a light having a luminance characteristic from the LED 12 and providing the light having the luminance characteristic to the liquid crystal panel assembly 70. The LED 12 is fixed to the mold frame 22, and generates and supplies light to the liquid crystal panel assembly 70. The backlight unit 20 may include a plurality of LEDs 12. In the illustrated exemplary embodiment, the LED 12 is used as a light source, however, is not limited thereto, and a fluorescent lamp such as cold cathode fluorescent lamp (“CCFL”) may alternatively be used.
The liquid crystal display 100 may include a display area, and a non-display area excluding the display area. The optical sheet 24 may be disposed in the display area of the liquid crystal display 100, but is not limited thereto or thereby. An area or width surrounding the optical sheet 24 may be referred to as a bezel of the backlight unit 20 or of the liquid crystal display 100. In a plan view of the liquid crystal display 100, the bezel may include portions of an area taken from an edge of the optical sheet 24 or other internal component of the liquid crystal panel assembly 70 or the backlight unit 20, and extending to an outermost edge of the liquid crystal display 100.
Although not shown in
The top chassis 60 is provided on the liquid crystal panel assembly 70 and restricts movement of the liquid crystal panel assembly in a direction away from the bottom chassis 28, to reduce or effectively prevent the liquid crystal panel assembly 70 from breaking away from the bottom chassis 28 when the FPC board 79 is bent outside the mold frame 22. Although not shown in
The optical sheet 24 is positioned on the light guide 10 and a position thereof is fixed relative to other elements of the liquid crystal display 100. However, according to an alternative exemplary embodiment, the optical sheet 24 may be positioned so as to be movable by a predetermined distance or level. If the optical sheet 24 undesirably moves from the position of the predetermined level, light provided from the backlight unit 20 does not pass through the optical sheet 24 and is not provided to the liquid crystal panel 75.
The fixing of the optical sheet 24 will be described with reference to
Referring to
Referring to
Referring to
The guide member unit includes the protrusion guide member 26-1 and the protrusion guide member 24-2, and referring to
Referring to
Referring to
Also, in
In
As described, when the backlight unit 20 includes the guide member unit, movement of the optical sheet 24 is restricted in a horizontal (e.g., Y-axis) direction because of the coupling of the groove 24-1 with the protrusion guide member 26-1, and movement of the optical sheet 24 is restricted in a vertical (e.g., X-axis) direction because of the protrusion guide member 26-1 of the reflection sheet 26, thereby confirming the fixing of the optical sheet 24.
Differently from
When a guide member unit is at opposing sides of the light guide 10 as shown in
Also, the backlight unit 20 includes a plurality of protrusion guide members 26-1, the adhesive member 26-2 may not be necessary to fix the light guide 10 and the protrusion guide member 26-1 to each other. When the protrusion guide members 26-1 are attached to the light guide 10, the optical sheet 24 and/or the protrusion guide member 26-1 may be deformed by heat from the light source such that the optical sheet 24 and/or the protrusion guide member 26-1 become detached and undesirably form a margin.
The backlight unit 20 may include one or more optical sheets 24. The exemplary embodiment of
Next, alternative exemplary embodiments of a structure of a guide member unit according to the invention will be described with reference to
In the exemplary embodiment of
The cross-sectional view of
When the reflection sheet 26 includes a plurality of protrusion guide members 26-1, portions of the protrusion guide members 26-1 may be connected or fixed to the reflection sheet 26, and other portions of the protrusion guide members 26-1 may be fixed to the side of the light guide 10 by the adhesive member 26-2.
Even when portions of the protrusion guide members 26-1 are fixed to the side of the light guide 10 by the adhesive member 26-2 as illustrated in
The protrusion guide member 26-1 of the reflection sheet 26 shown in
The protrusion guide member extension 26-11 may reduce or effectively prevent movement of the optical sheet 24 in the Z-axis direction and toward the liquid crystal panel assembly 70.
As shown in
Also, as illustrated in the exemplary embodiment of
By the structure illustrated in
In
The guide member unit may be at various positions with respect to sides of the light guide 10, in addition to the position shown in
One among the various positions is shown in
Referring to
Movement of the optical sheet 24 is reduced or effectively prevented in the long and short side directions because the grooves 24-1 of the two coupled guide member units are at opposing sides.
Where the optical sheet 24 is fixed by one or more of the exemplary embodiments of the guide member units, a width of the bezel of the liquid crystal display 100 may be reduced compared with a conventional liquid crystal display including a special structure at a chassis to fix an optical sheet. That is, in one or more exemplary embodiment of the invention, a planar area of the chassis structure is significantly larger than a width defined by a thickness of the bent reflection sheet 26, thereby achieving a narrow bezel.
Also, a reflection sheet 26 of the conventional liquid crystal display is further elongated such as owing to a wide bezel. Since one or more exemplary embodiment of the invention includes a narrow bezel, the manufacturing cost and the process time of forming (e.g., providing) a liquid crystal display are not increased.
In order to verify a fixing performance, a liquid crystal display 100 including an exemplary embodiment of the fixing structure of the optical sheet 24 of the backlight unit 20 as shown in
Here, the front surface is a viewing side or screen side of the liquid crystal display where an image is displayed, and the rear surface is an opposite surface thereof. The upper surface is a surface of an upper side of the liquid crystal display when viewing the front surface, the lower surface is a surface of a lower side of the liquid crystal display when viewing the front surface, and the left surface and the right surface are surfaces of a left side and a right side of the liquid crystal display when viewing the front surface.
As shown in Table 1, three experimental examples of the liquid crystal display were manufactured, and the liquid crystal displays were dropped from heights of 15 centimeters (cm), 20 cm and 25 cm in each direction. As a result, at the heights of 15 cm and 20 cm, in all experimental examples, the optical sheet 24 is not separated such that there is no problem in fixing performance of the guide member unit according to the invention.
At the height of 25 cm, when the liquid crystal display is dropped in Experimental Example 2 with reference to the lower surface, and a condition of “NG” is generated. However, only the liquid crystal panel is broken, and the optical sheet 24 of the backlight unit 20 is not separated. That is, the fixing performance of the guide member unit according to the invention still passes. Therefore, the guide member unit according to the invention, maintains a position of the optical sheet 24 such that the optical sheet 24 remains fixed in a predetermined position.
It is noted that at the height of 25 cm, the liquid crystal panel is broken on the left surface and the right surface such that additional experiments are not performed and the result values are not provided.
Also, when using an optical sheet 24 for a relatively long time, the optical sheet 24 may be undesirably deformed or crumpled such as by heat from a light source within a backlight unit. Since the optical sheet 24 is most tightly or statically fixed in the exemplary embodiment of
In order to verify the extent of deformation of the optical sheet, an exemplary embodiment including all protrusion guide members 26-1 statically fixed to the light guide 10 by the adhesive member 26-2 was formed and the formed structure was stored in a chamber and operated for two hundred and fifty times. As a result, the optical sheet 24 and the reflection sheet 26 of the formed exemplary embodiment are not crumpled. Since the protrusion guide member 26-1 of the reflection sheet 26 includes the same material as a remainder of the reflection sheet 26, the reflection sheet 26 including the protrusion guide member 26-1 may to have an elastic property. When the reflection sheet 26 has the elastic property, a margin is provided within which the optical sheet 24 may move when a portion of the reflective sheet 26 deforms due to the elastic property.
As described above, the optical sheet 24 is sufficiently fixed by the protrusion guide member 26-1 of a same material as the reflection sheet 26 through the above experiments such that a satisfactory fixing performance is verified.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2012-0084954 | Aug 2012 | KR | national |
