Patent Application
20080117359
This application claims priority from Korean Patent Application No. 2006-0114733, filed on Nov. 20, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a backlight unit and a display apparatus having the same, and more particularly, to a backlight unit which provides improved brightness, and a display apparatus having the same.
2. Description of the Related Art
A display apparatus includes a liquid crystal display (LCD) panel and a backlight unit. The LCD panel includes a first substrate having a thin film transistor, a second substrate facing the first substrate and a liquid crystal layer interposed between the first and second substrates. The LCD panel does not emit light itself, and thus receives light from the backlight unit. The amount of transmission of light emitted by the backlight unit is adjusted by an alignment of liquid crystals.
A light source of the backlight unit includes a line light source such as cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL), and a surface light source such as flat fluorescent lamp (FFL).
The surface light source includes a light emitter to emit light, and a division formed between the light emitters that do not emit light. As the brightness differs between the light emitters and the divisions, a diffusion layer is provided to make the brightness uniform to supply light to the LCD panel.
However, a conventional diffusion layer includes a diffuser which lowers brightness or makes the emitted light uneven in brightness.
Accordingly, it is an aspect of the present invention to provide a backlight unit which improves brightness and brightness uniformity, and a display apparatus having the same.
Additional aspects of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present invention.
The foregoing and/or other aspects of the present invention can be achieved by providing a backlight unit, comprising: a surface light source which emits a light; and a diffusion collimation member which is provided in a path of the light emitted by the surface light source, and comprises a first diffusion sheet having a plurality of first reflectors arranged in a first direction and a second diffusion sheet formed on the first diffusion sheet and having a plurality of second reflectors arranged in a second direction forming a predetermined angle with respect to the first direction of the first diffusion sheet.
According to the embodiment of the present invention, the first diffusion sheet further comprises a first main body, and the plurality of first reflectors has a trapezoid section, and is disposed in a surface of the first main body in the first direction.
According to the embodiment of the present invention, the second diffusion sheet further comprises a second main body, and the plurality of second reflectors has a trapezoid section, and is disposed in a surface of the second main body in the second direction forming the predetermined angle with respect to the first direction.
According to the embodiment of the present invention, the trapezoid section of the first reflectors is different from the trapezoid section of the second reflectors.
According to the embodiment of the present invention, the first direction forms 90° angle with respect to the second direction.
According to the embodiment of the present invention, the first diffusion sheet and the second diffusion sheet comprise one of polymethyl methacrylate (PMMA), poly carbonate (PC), UV curing resin and polyethylene terephthalate (PET).
The foregoing and/or other aspects of the present invention can be achieved by providing a backlight unit, comprising: a surface light source which emits a light; and a diffusion collimation member which is provided in a path of the light emitted by the surface light source, and comprises a first diffusion sheet having a plurality of first reflectors arranged in a first direction and having a reflection surface to reflect light, and a second diffusion sheet formed on the first diffusion sheet and having a plurality of second reflectors arranged in a second direction forming a predetermined angle with respect to the first direction of the first diffusion sheet and having a reflection surface to reflect light; and a coating layer which is formed in at least one of the reflection surface of the first reflectors and the reflection surface of the second reflectors.
According to the embodiment of the present invention, the first diffusion sheet further comprises a first main body, and the plurality of first reflectors has a trapezoid section, and is disposed in a surface of the first main body in the first direction.
According to the embodiment of the present invention, the second diffusion sheet further comprises a second main body, and the plurality of second reflectors has a trapezoid section, and is disposed in a surface of the second main body in the second direction forming the predetermined angle with respect to the first direction.
According to the embodiment of the present invention, the coating layer is disposed in a pair of inclined sides which connect a lower side and an upper side of the trapezoid section of at least one of the first reflectors and the second reflectors.
According to the embodiment of the present invention, the first direction forms 90° angle with respect to the second direction.
The foregoing and/or other aspects of the present invention can be achieved by providing a display apparatus, comprising: a liquid crystal display panel; a surface light source which emits a light to the liquid crystal display panel; and a diffusion collimation member which is provided in a path of the light from the surface light source to the liquid crystal display panel, and comprises a first diffusion sheet having a plurality of first reflectors arranged in a first direction, and a second diffusion sheet formed on the first diffusion sheet and having a plurality of second reflectors arranged in a second direction forming a predetermined angle with respect to the first direction of the first diffusion sheet.
According to the embodiment of the present invention, the first diffusion sheet further comprises a first main body, and the plurality of first reflectors has a trapezoid section, and is disposed in a surface of the first main body toward the liquid crystal display panel in the first direction.
According to the embodiment of the present invention, the second diffusion sheet further comprises a second main body, and the plurality of second reflectors has a trapezoid section, and is disposed in a surface of the second main body toward the liquid crystal display panel in the second direction forming the predetermined angle with respect to the first direction.
According to the embodiment of the present invention, the trapezoid section of the first reflectors is different from the trapezoid section of the second reflectors.
According to the embodiment of the present invention, the first direction forms 90° angle with respect to the second direction.
According to the embodiment of the present invention, the first diffusion sheet and the second diffusion sheet comprise one of polymethyl methacrylate (PMMA), poly carbonate (PC), UV curing resin and polyethylene terephthalate (PET).
The foregoing and/or other aspects of the present invention can be achieved by providing a display apparatus, comprising: a liquid crystal display panel; a surface light source which emits a light to the liquid crystal display panel; and a diffusion collimation member which is provided in a path of the light from the surface light source to the liquid crystal display panel, and comprises a first diffusion sheet having a plurality of first reflectors arranged in a first direction and having a reflection surface to reflect light, and a second diffusion sheet formed on the first diffusion sheet and having a plurality of second reflectors arranged in a second direction forming a predetermined angle with respect to the first direction of the first diffusion sheet and having a reflection surface to reflect light; and a coating layer which is formed in at least one of the reflection surface of the first reflectors and the reflection surface of the second reflectors.
According to the embodiment of the present invention, the first diffusion sheet further comprises a first main body, and the plurality of first reflectors has a trapezoid section, and is disposed in a surface of the first main body toward the liquid crystal display panel in the first direction.
According to the embodiment of the present invention, the second diffusion sheet further comprises a second main body, and the plurality of second reflectors has a trapezoid section, and is disposed in a surface of the second main body toward the liquid crystal display panel in the second direction forming the predetermined angle with respect to the first direction.
According to the embodiment of the present invention, the coating layer is disposed in a pair of inclined sides which connect a lower side and an upper side of the trapezoid section of at least one of the first reflectors and the second reflectors.
According to the embodiment of the present invention, the first direction forms 90° angle with respect to the second direction.
The above and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompany drawings of which:
a and 7b illustrate a comparison of brightness uniformity in
a and 8b are graphs which illustrate an improvement in brightness in
Hereinafter, exemplary embodiments of the present invention will be described with reference to accompanying drawings, wherein like numerals refer to like elements and repetitive descriptions will be avoided as necessary.
A display apparatus may include a TV or a projector. Hereinafter, a flat panel TV will be described as an exemplary embodiment of the present invention.
As shown in
Hereinafter, each direction will be defined as follows. A ‘d’ direction refers to a light moving direction from the surface light source 140 to the liquid crystal display panel 110. An ‘x’ direction refers to a first direction which is perpendicular to the ‘d’ direction and in which a first reflector 153a of a first diffusion sheet 150a is arranged. A ‘y’ direction refers to a second direction which is perpendicular to the ‘d’ direction and in which a second reflector 153b of a second diffusion sheet 150b is arranged. Here, a light may move in the ‘x’ direction or ‘y’ direction. However, the light moving in ‘x’ or ‘y’ direction is not relevant to the display apparatus 100, and thus the description thereof will be avoided here. Alternatively, a light may move in a slant direction as well as a perpendicular direction to the x and y directions, i.e., a light moves in the ‘d’ direction and the liquid crystal display panel 110 forms an image thereon.
The liquid crystal display panel 110 includes a first substrate 111 having a thin film transistor and a second substrate 113 facing the first substrate 111. A liquid crystal layer (not shown) is disposed between the first substrate 111 and the second substrate 113. The liquid crystal display panel 110 forms an image by adjusting an arrangement of the liquid crystal layer. The liquid crystal display panel 110 does not emit light itself, and thus receives light from a backlight unit 130 disposed there behind.
A driver 115 is provided in one lateral part of the first substrate 111 to supply a driving signal. The driver 115 includes a flexible printed circuit board (FPC) 116 whose first side is connected with the first substrate 111, a driving chip 117 which is embedded in the FPC 116 and a printed circuit board (PCB) 118 which is connected with a second side of the FPC 116. The driver 115 according to the present invention employs a chip on film (COF) method, but is not limited thereto. Alternatively, the driver 115 may employ other known methods including a tape carrier package (TCP) method and a chip on glass (COG). Otherwise, a part of the driver 115 may be embedded in the first substrate 111 during a wire-forming process.
The backlight unit 130 includes the surface light source 140 which is disposed behind the liquid crystal display panel 110, the first diffusion sheet 150a and the second diffusion sheet 150b. The backlight unit 130 further includes an optical film 120.
The optical film 120 is provided behind the liquid crystal display panel 110, and includes a prism film 121 and a protection film 123.
The prism film 121 includes prisms, which has a trigonal shape, and are arranged uniformly thereon. The prism film 121 collects the light diffused or collimated by the diffusion collimation member 150, in a direction perpendicular to a surface of the liquid crystal display panel 110. There may be provided two prism films 121. In this case, a micro prism formed in the respective prism films 121 forms a predetermined angle. Most of the light which passes the prism films 121 travels vertically to provide uniform brightness.
The protection film 123 protects the prism films 121 which are easily scratched. The protection film 123 may include polyethyleneterephtalate (PET).
The surface light source 140 supplies the light to the diffusion collimation member 150. In the first exemplary embodiment of the present invention, the surface light source 140 includes a flat fluorescent lamp.
As shown in
The first light source substrate 141 is shaped like a plate. The second light source substrate 142 is a formed glass and are grooved repeatedly. Where the first and second light source substrates 141 and 142 are separated from each other is a light emitter. Where the first and second light source substrates 141 and 142 contact each other is disposed a division 246. The light emitter and the division 246 are elongated in the second direction ‘y’ of the reflector 153.
A light emitting space 143 which is formed on the light emitter is filled with a light emitting gas including mercury and neon. A fluorescent layer (not shown) is formed in the second light source substrate 142 to change ultraviolet rays generated by the light emitting gas into visible rays. A reflection layer (not shown) is formed in the first light source substrate 141 to reflect the light from the light emitting space 143 to the diffusion collimation member 150.
The second light source substrate 142 which is formed on the light emitting space 143 includes a flat surface 142a which is in parallel with the liquid crystal display panel 110.
The surface light source 140 has a wider width to emit the light and provides the light with relatively uniform brightness, compared to a line light source. However, the surface light source 140 requires the division 246 to keep a shape of the light emitting space 143 formed in the light emitter. The division 246 does not emit a light itself, and thus the surface light source 140 supplies the light with uneven brightness.
The brightness of the light emitted by the surface light source 140 becomes uniform and is improved through the diffusion collimation member 150 according to the first exemplary embodiment of the present invention.
As shown in
A light emitter (hereinafter, to be called pixel) is formed by the first and second light source substrates 241 and 242 and the wall 244 which are connected with each other, and a division 246 which does not emit a light is formed between the openings 245. The pixels divided by the division 246 are driven to express various gradations from a backlight unit 130. Boundary lines are shown in the wall 244 as a boundary between pixels, which should be alleviated.
Thus, a light emitted from the surface light source 140 to a liquid crystal display panel 110 should be diffused or collected.
A diffusion collimation member 150 according to
The first diffusion sheet 150a and the second diffusion sheet 150b have the same configuration so that a drawing of the second diffusion sheet 150b is avoided here.
Hereinafter, the diffusion collimation members 150 according to the first exemplary embodiment of the present invention will be described. The first main body 151a and the second main body 151b are to be called a main body 151, and the first reflector 153a and the second reflector 153b will be referred to as a reflector 153. A first reflection surface 157a and a second reflection surface 157b will be referred to as a reflection surface 157, and a first through surface 155a and a second through surface 155b will be called a through surface 155. The first diffusion sheet 150a and the second diffusion sheet 150b are sequentially stacked in the moving direction (d) of light, and do not have any difference in configuration. However, the shape and size of the reflector 153 may vary.
The main body 151 supports the reflector 153, and is arranged in parallel with the liquid crystal display panel 110 and toward the surface light source 140. The main body 151 has such a thickness so as to support the reflector 153. The thickness of the first main body 151a and the second main body 151b may be different from each other as necessary. Preferably, the main body 151 is formed integrally with the reflector 153. According to another exemplary embodiment of the present invention, the main body 151 and the reflector 153 may be adhered to each other with various known methods including using ultraviolet rays.
The plurality of reflectors 153 is disposed in the first direction (x) or the second direction (y) with respect to the main body 151, and diffuses or collimates a light emitted by the surface light source 140. The reflectors 153 include the plurality of first reflectors 153a which is in parallel with the first main body 151a in the first direction (x), and the plurality of second reflectors 153b which is provided in parallel with the second main body 151b in the second direction (y). The respective reflectors 153 include the reflection surface 157 and the through surface 155.
A section of the reflector 153 has a trapezoid shape. As shown in
The reflectors 153 are arranged in the first direction (x) or the second direction (y). Preferably, the first direction (x) forms 90° angle with respect to the second direction (y). The details and effects of the angle will be described later. The light which is diffused or collimated by the first reflector 153a provided in the first direction (x) is again diffused or collimated by the second reflector 153b disposed in the second direction (y).
The light emitted by the surface light source 140 is diffused or collimated by the diffusion collimation member 150, thereby improving brightness and brightness uniformity of an image formed on the liquid crystal display panel 110.
The reflection surface 157 includes a pair of inclined sides of the reflector 153 and is provided in the reflector 153. The reflection surface 157 is distinguished from the reflector 153. That is, the inside of the reflection surface 157 includes a denser medium than air in the outside thereof. The inside of the reflector 153 is a dense region while a corrugated part, the outside of the reflector 153, is a sparse density region. Total reflection occurs when incident angles θ1 to θ5 (refer to in
The path of the light which passes the reflector 153 of the diffusion collimation member 150 will be described with reference to
First, a path of the light A1 (refer to
Another path of the light A2 (refer to
Other paths of the light A3 and A4 (refer to
Other paths of the light A5 and A6 (refer to
Thus, the light emitted by the surface light source 140 passes the first diffusion sheet 150a through various paths. The light is mainly collimated by the reflector 153, and then diffused.
The diffused or collimated light is diffused or collimated by the second diffusion sheet 150b in a direction different from the first diffusion sheet 150a. The path of the light diffused or collimated by the second diffusion sheet 150b is the same as that by the first diffusion sheet 150a, and thus the description thereof will be avoided here.
The light emitted by the surface light source 140 is diffused or collimated by the diffusion collimation members 150, thereby improving brightness of light moving toward the liquid crystal display panel 110, and brightness uniformity thereof.
As described above, the path of the light emitted from the surface light source 140 may differ by adjusting the shape and pitch of the reflector 153. The diffusion and collimation direction of light may vary by adjusting the section of the first and second reflectors 153a and 153b.
Hereinafter, the display apparatus according to the first exemplary embodiment of the present invention will be described with reference to
As shown in
a and 7b illustrate a simulation result of the display apparatus 100 having the diffusion collimation members 150 arranged as shown in
The first diffusion sheet 150a in the first direction (x) in
As shown in
The coating layer 259 is coated to the first reflector 153a or the second reflector 153b in consideration of a path of the light. The coating layer 259 is formed as a thin layer on a reflection surface 157 of a reflector 153.
Thus, a light in the reflector 153 is not transmitted to the outside of the reflector 153 by refraction.
A path of the light which passes the reflector 153 of the diffusion collimation member 150 will be described with reference to
Paths of the light A2 to A6 in
First, a path of the light A1 (refer to
The collimated and diffused light is again diffused or collimated by a second diffusion sheet 150b in a direction different from the first diffusion sheet 150a. The path of the light diffused or collimated by the second diffusion sheet 150b is the same as that in first diffusion sheet 150b, and thus the description thereof will be avoided here. The coating layer 259 may be formed in the second diffusion sheet 150b as necessary.
The light emitted by the surface light source 140 is diffused or collimated by the diffusion collimation member 150, thereby improving brightness of light moving toward the liquid crystal display panel 110, and brightness uniformity.
According to the second exemplary embodiment of the present invention, the light emitted by the surface light source 140 is collimated more efficiently by the coating layer 259 formed in the reflector 153.
As described above, the present invention provides a display apparatus which includes a diffusion collimation member to diffuse or collimate light emitted by a surface light source and to improve brightness and brightness uniformity.
Also, according to the present invention, light which is emitted by the surface light source is collimated more efficiently.
Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0114733 | Nov 2006 | KR | national |
