KR101644002B1 - Backlight unit and display apparatus comprising the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a display device including the backlight unit, including a light source unit having at least one light source arranged in a predetermined direction; A light guide plate for transmitting the light emitted from the light source unit in a predetermined direction; And an elastic member for elastically biasing the light source unit toward the light guide plate, wherein the light source unit includes a gap maintaining unit for maintaining a constant distance between the light source and the light guide plate. According to the present invention, the distance between the light source and the light guide plate can be kept constant regardless of the expansion or contraction of the light guide plate due to heat, and the required light amount can be constantly maintained.

Edge type, backlight, light guide plate, elastic member

Description

BACKLIT UNIT AND DISPLAY APPARATUS COMPRISING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a display device including the backlight unit. More particularly, the present invention relates to a backlight unit and a backlight unit that can maintain a constant distance between the light source unit and the light guide plate, And a display device including the same.

The backlight unit can be divided into two types according to the position of the light source: a direct type and an edge type.

The direct-type backlight unit includes a reflection plate positioned at a lower portion of the lamp to reflect light, a light source positioned at a lower portion of the liquid crystal panel and directly illuminating the front surface of the liquid crystal panel, And an optical sheet for diffusing light. And can be provided with a large number of light sources and is mainly used for a large-screen liquid crystal display device requiring high brightness because of high light utilization efficiency.

On the other hand, the edge type backlight unit usually includes a light guide plate for guiding the light of the light source toward the liquid crystal panel on the side of the light source. The edge type is disadvantageous in that luminance is lowered when the liquid crystal display device is enlarged, but it is advantageous for thinning. The light guide plate scatters and uniformizes the light, and a reflector is disposed on the lower surface of the light guide plate. On the upper surface of the light guide plate, a pair of prism sheets for converting and converging light traveling paths and a diffusion sheet for increasing the uniformity of light incident on the liquid crystal panel are formed.

The light guide plate is usually made of PMMA (Polymer Methyl Methacrylate). PMMA materials are characterized by expansion and contraction in response to heat and humidity, and the coefficient of thermal expansion is also high among plastic materials.

 On the other hand, in the case of a large backlight unit, the LEDs should be arranged as close as possible to the light guide plate in order to secure a sufficient amount of light. This is because the light efficiency decreases as the distance between the LED and the light guide plate increases. When an LED edge type is employed in a large backlight unit that is larger than 40 inches, the size of the light guide plate also increases. Therefore, the amount of change in the length of expansion or contraction due to temperature and humidity changes increases. Therefore, when the LED is arranged close to the light guide plate for the light efficiency, the light guide plate and the LED may come into contact with each other due to the expansion in a high temperature operating environment. On the contrary, if the interval between the LED and the light guide plate is increased It is difficult to secure the light quantity.

The present invention solves the problem of adjusting the interval between the light guide plate and the LED, which occurs in the design of the large LED edge type backlight unit.

The present invention also provides a backlight unit capable of maintaining the brightness of a light source regardless of deformation of the light guide plate and a display device including the backlight unit.

A backlight unit according to the present invention includes: a light source unit having at least one light source arranged in a predetermined direction; A light guide plate for transmitting light emitted from the light source unit in a predetermined direction; And an elastic member for elastically biasing the light source unit toward the light guide plate. The light source unit may include a gap maintaining unit for maintaining a constant distance between the light source and the light guide plate.

The light source unit may further include a plurality of point light sources and a point light source substrate on which the point light sources are mounted, and the space maintaining unit may extend from the point light source substrate toward the light guide plate.

The gap maintaining part may be provided integrally with the point light source substrate.

”, “ㅏ”형상 중 어느 하나 일 수 있다. At this time, the cross section of the point light source substrate and the interval maintaining portion is a "C" shape, "

Quot ;, " a " shape.

Wherein the elastic member is provided between the accommodating member and the light source unit and the elastic member is coupled with the accommodating member and the light source unit so as to correspond to deformation of the light guide plate, .

The elastic member may include at least one of a coil spring, a rubber, a graphite tape, a graphite sheet and a sponge. Of course, the elastic member is not limited to a particular configuration and material as long as it can elastically bias the light source portion in response to deformation of the light guide plate.

The light source may be disposed along a side surface of the light guide plate.

The light source may include a light emitting diode device.

According to another aspect of the present invention, there is provided a display apparatus including: an image receiver for receiving a video signal; A signal receiver for processing the received video signal; A display panel on which the processed video signal is displayed; And a backlight unit for providing light to the display panel, wherein the backlight unit includes: a light source unit having at least one light source arranged in a predetermined direction; A light guide plate for transmitting light emitted from the light source unit in a predetermined direction; And an elastic member for elastically biasing the light source unit toward the light guide plate. The light source unit may include a gap maintaining unit for maintaining a constant distance between the light source and the light guide plate.

As described above, according to an embodiment of the present invention, a backlight unit capable of maintaining the luminance of a light source regardless of deformation of the light guide plate and a display device including the backlight unit are provided.

According to an embodiment of the present invention, there is provided a backlight unit and a display device including the backlight unit, wherein the light source unit and the light guide plate maintain a constant interval.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

FIGS. 1A and 1B are cross-sectional views of a backlight unit according to an embodiment of the present invention, illustrating shrinkage of an elastic member according to a light guide plate deformation.

As shown in the figure, the backlight unit according to the present embodiment includes a light source 110, a light guide 120, an optical sheet 130 arranged on the upper side of the light guide plate 120, (140), and a receiving member (150) for accommodating them. The backlight unit further includes a housing member 150 and an elastic member 160 provided in the light source unit 110. The backlight unit according to the present embodiment is of an edge type, and the light source units 110 are arranged in a line in a specific direction.

The light guide plate 120 is arranged on one side of the light source unit 110 so that light emitted from the light source unit 110 can be incident thereon. The light guide plate 120 is generally made of acrylic resin such as polymethylmethacrylate and serves to uniformly supply light from the light source unit 110 to the optical sheet 130. Although the light guide plate 120 is generally rectangular, it is not limited thereto and may have various shapes depending on the shape of the panel to which light is supplied.

The optical sheet 130 may include a diffusion plate, a prism film, a protective film, and the like, not shown, and uniformly diffuses the light emitted from the light guide plate 120.

The reflection plate 140 reflects the light incident on the lower portion of the light guide plate 120 and reflects the light toward the optical sheet 130 to supply the light to the light guide plate 120. The reflector 140 may be made of polyethylene terephthalate (PET) or polycarbonate (PC), or may be coated with silver or aluminum.

FIG. 2 is an enlarged view of the light source unit 110 and the elastic member 160 in FIG. 1A. As shown in FIG. 2, the light source unit 110 includes a point light source 111 as a light source, And a space maintaining unit 113, 114 extending from the point light source substrate 112. The spacers 113, The elastic member 160 is coupled to the light source unit 110 at one side of the light source unit 110.

The point light source 111 is mounted on the bar-shaped point light source substrate 112 and includes a plurality of light emitting diodes. The temperature of the point light source 111 may rise to several tens degrees due to light emission. The point light source 111 may form a group of a plurality of light emitting diodes that emit different colors and may be provided with light emitting diodes that emit white light. The point light source 111 may be implemented as a laser diode or the like in addition to the light emitting diode.

The point light source substrate 112 may be a circuit substrate having a circuit pattern for supplying power to the point light source 111, and may be formed using aluminum having a good heat transfer rate as a main material.

The interval maintaining portions 113 and 114 extend from the point light source substrate 112 in the direction of the light guide plate 120 and keep the distance between the light guide plate 120 and the point light source 111 constant. As shown in the figure, the gap holding portions 113 and 114 according to the present embodiment include a point light source substrate 112 and a "C" -shaped cross section opening in the direction of the light guide plate 120 while accommodating the point light source 111 . The gap maintaining parts 113 and 114 may be provided integrally with the point light source substrate 112. Of course, the point light source substrate 112 and the spacing portions 113 and 114 may be connected to each other so as to be able to be coupled with each other, though they are not integrated.

The end portions of the gap holding portions 113 and 114 extending from the point light source substrate 112 are in contact with one surface of the light guide plate 120 and the gap between the point light source 111 and the light guide plate 120 are maintained at a constant gap G1. That is, even if the light guide plate 120 is inflated by the gap maintaining portions 113 and 114, the gap between the point light source 111 and the light guide plate 120 arranged in the direction in which the light guide plate 120 expands is not narrowed, do. According to the present embodiment, the gap holding portions 113 and 114 and the light guide plate 120 are in contact with each other but not with each other.

The elastic member 160 is provided between the light source unit 110 and the accommodation member 150 and has both ends fixed to the light source unit 110 and the accommodation member 150. The elastic member 160 elastically biases the light source unit 110 toward the light guide plate 120 and supports the light source unit 110 while changing its length in conjunction with expansion or contraction of the light guide plate 120. When the light guide plate 120 is expanded and the pressure is applied to the light source unit 110, the elastic member 160 will be contracted. When the light guide plate 120 is contracted, the elastic member 160 expands to move the light source unit 110 Will support. 1A, when the length of the elastic member 160 is d1, the gap between the point light source 111 and the light guide plate 120 is maintained at G1 by the gap holding portions 113 and 114 as described above. If the light guide plate 120 expands in the direction of the light source unit 110 due to heat or humidity and the length thereof is increased by X, the elastic member 160 contracts as shown in FIG. 1B, and the length thereof becomes d2 smaller than d1. Even if the light guide plate 120 is deformed in this way, the gap between the point light source 111 and the light guide plate 120 is kept constant. Conversely, when the light guide plate 120 is contracted in the state of FIG. 1B, the length of the elastic member 160 increases, so that the light source unit 110 is properly supported between the receiving member 150 and the light guide plate 120.

3 is a cross-sectional view of a conventional backlight unit. As shown in the figure, the point light source 10 is fixed to the inside of the receiving member 150. [ The gap between the point light source 10 and the light guide plate 120 may be changed when the light guide plate 120 contracts or expands while the distance between the point light source 10 and the light guide plate 120 is G2. That is, the distance between the point light source 10 and the light guide plate 120 will be changed corresponding to the deformation of the light guide plate 120, which means a change in brightness of light. In addition, when the light guide plate 120 is expanded and the light guide plate 120 and the point light source 10 are in contact with each other, deformation of the light guide plate 120 due to heat generation of the point light source 10 and uneven brightness may be caused.

The distance between the point light source 111 and the light guide plate 120 is kept constant so that the luminance of the light emitted from the point light source 111 to the light guide plate 120 can be kept constant, 120 can flexibly support the light source unit 110 in conjunction with the deformation.

The elastic member 160 according to the present embodiment is a coil spring as shown. The material and structure of the elastic member 160 are not limited thereto and may include a rubber or a sponge provided between the light source unit 110 and the accommodation member 150 so as to apply an elastic bias to the light source unit 110. The elastic member 160 may be provided in multiple numbers and has heat resistance capable of maintaining elasticity against the heat generated by the point light source 111.

According to another embodiment of the present invention, the light source may be realized as a linear light source or a planar light source such as a lamp other than a point light source.

In addition, according to another embodiment of the present invention, the spacing portions 113 and 114 integrally formed with the point light source substrate 112 may be clamped and coupled to the light guide plate 120.

Also, according to another embodiment of the present invention, the backlight unit may be configured as a direct lower type instead of an edge type. In this case, the backlight unit includes a light guide part and a light source part arranged on the back surface of the light guide plate. Further, the light guide plate may include a space retaining part formed between the light guide plate and the light source part, and an elastic member provided between the light source part and the lower chassis.

FIG. 4 is a perspective view of a display device according to an embodiment of the present invention, and FIG. 5 is a control block diagram of a display device.

 The display device includes a display panel 200 and a backlight unit 100 provided below the display panel 200 to provide light to the display panel 200. The display device 200 includes a video receiver 300, And a processing unit (400).

4, a reflecting sheet 140 is housed in the housing member 150 and the light source unit 110, the light guide plate 120, the optical member 130, and the housing member 150 are spaced apart from each other. The light guide plate 120 will be arranged between the two point light source substrates 111 shown in the figure and the light emitted from the point light source 111 will be incident on the side surface of the light guide plate 120. The elastic member 160 formed between the point light source substrate 112 and the receiving member 150 elastically biases the light source unit 110 toward the light guide plate. Of course, the point light source 111 and the point light source plate 112 may be arranged along the long side surface of the light guide plate 120, or may be additionally arranged along the long side surface side of the light guide plate 120 .

The display panel 200 according to the present embodiment is implemented as a liquid crystal panel. In the display panel 200, a liquid crystal layer (not shown) is filled between two substrates, and an image is displayed by adjusting the arrangement of the liquid crystal layers. The display panel 200 receives light from the backlight unit 100 to display an image in the display area. The display panel 200 includes a panel driver 210 for receiving and displaying image signals. A signal processing block for providing a video signal to the panel driver 210 is mounted on a board (not shown) together with the power supply block and stored in the housing member 150.

The image receiving unit 300 of FIG. 5 receives an image to be displayed on the display panel 200. The image receiving unit 300 receives a radio frequency (RF) signal transmitted from a broadcasting station (not shown) Wirelessly, or can receive video signals of composite video, component video, super video, SCART, and HDMI (high definition multimedia interface) standards. Alternatively, when the display device is a computer monitor, the image receiving unit 300 may be configured to receive image signals such as D-SUB, DVI, and HDMI standards capable of delivering RGB signals according to the VGA method.

The signal processing unit 400 performs predetermined signal processing on the image signal transmitted from the image receiving unit 300. The type of the signal processing performed by the signal processing unit 400 is not limited to a specific process. For example, various kinds of decoating, encoding, deinterlacing, frame rate conversion, scaling, noise reduction for improving image quality, And the like. The signal processing unit 400 may be implemented as an individual configuration capable of independently performing each of these processes, or an integrated configuration in which various functions are integrated.

When the backlight unit 100 realizes local dimming, the signal processor 400 generates a control signal for the local dimming and outputs the control signal to the backlight unit 100. The backlight unit 100 may further include a light source driving unit (not shown) and a light source control unit for receiving the control signal and controlling the light source driving unit.

6 is a cross-sectional view of another backlight unit according to another embodiment of the present invention.

The backlight unit according to the present embodiment may include a graphite sheet 161 as an elastic member. The thickness of the graphite sheet 161 may range from approximately 1 to 3 mm. Graphite is a material having the same properties as diamond, and has conductivity and thermal conductivity. The graphite sheet 161 is a purified natural graphite product without addition of additives and has inherent properties of only graphite such as heat resistance and chemical resistance, and is excellent in flexibility and compression restoring force, i.e., elasticity, and can be used at high temperature. The backlight unit may include a graphite tape obtained by cutting a graphite sheet into a certain width instead of the graphite sheet 161 and wrinkling the surface.

7 is a cross-sectional view of a backlight unit according to another embodiment of the present invention.

”을 갖는다. 즉, 점광원(111)과 도광판(120) 사이의 간격을 일정하게 유지할 수 있는 형상이면 점광원 기판(112)과 간격유지부(115)는 “ㄷ”자 형상이 아니어도 무방하다. 따라서, 간격유지부(115)는 점광원(111)의 하부에서 점광원 기판(112)으로부터 도광판(120) 방향으로 연장될 수 있고, 이 경우 점광원 기판(112)과 간격유지부(115)의 단면은 “ㄴ”자 형상을 갖는다.The gap maintaining portion 115 according to the present embodiment extends from the point light source substrate 112 to the light guide plate 120 on the top of the point light source 111. The cross-section of the point light source substrate 112 and the interval maintaining portion 161 is "

&Quot; That is, the point light source substrate 112 and the gap retaining portion 115 may not have a " C " shape insofar as the gap between the point light source 111 and the light guide plate 120 can be maintained constant. The gap maintaining part 115 may extend from the point light source substrate 112 to the light guide plate 120 in the lower part of the point light source 111. In this case, Section has an " C " shape.

8 is a view illustrating a light source unit that may be included in another backlight unit. The light source unit 110 according to the present embodiment includes a gap maintaining unit 116 extending from the point light sources 111 toward the light guide plate 120. That is, the gap maintaining portion 116 does not extend from the edge of the point light source substrate 112 but extends in the direction of the light guide plate 120 on the surface of the point light source substrate 112. As shown in the figure, the interval maintaining portions 116 may be arranged between the point light sources 111, but they may be arranged between the plurality of point light sources 111. The gap holding portion 116 may have a cylindrical shape or a polygonal columnar shape.

Although several embodiments of the present invention have been shown and described, those skilled in the art will readily appreciate that many modifications may be made without departing from the spirit or scope of the invention . The scope of the invention will be determined by the appended claims and their equivalents.

1A and 1B are cross-sectional views illustrating shrinkage of an elastic member according to a light guide plate deformation of a backlight unit according to an embodiment of the present invention,

FIG. 2 is a detailed view of FIG. 1A,

3 is a cross-sectional view of a conventional backlight unit,

4 is a perspective view of a display device according to an embodiment of the present invention,

FIG. 5 is a control block diagram of the display device according to FIG. 4,

6 is a cross-sectional view of a backlight unit according to another embodiment of the present invention,

7 is a cross-sectional view of a backlight unit according to another embodiment of the present invention,

8 is a cross-sectional view of a backlight unit according to another embodiment of the present invention.

Description of the Related Art [0002]

100: backlight unit 110: light source unit

10, 111: point light source 120: light guide plate

130: optical sheet 140: reflector

150: storage member 160, 161: elastic member

200: display panel 300: image receiving unit

400: Signal processor

Claims (16)

In the backlight unit, A light guide plate; At least one light source for irradiating the light guide plate with light, a substrate on which the at least one light source is mounted, and a plurality of spaced apart portions extending from the substrate toward the light guide plate so as to form a predetermined gap between the at least one light source and the light guide plate, A light source unit including a holding unit; A receiving member for receiving the light source unit and the light guide plate; And an elastic member interposed between the accommodating member and the substrate and elastically biasing the substrate toward the light guide plate so that the gap remains constant when the light guide plate expands or contracts. delete The method according to claim 1, Wherein the gap holding portion is integral with the substrate. The method according to claim 1, Wherein the end face of the substrate and the spacing portion has a " C "shape, " C " shape,

Quot ;, " a " shape. ≪ / RTI > The method according to claim 1, Wherein the elastic member is coupled to the housing member and the substrate. The method according to claim 1, Wherein the elastic member comprises at least one of a coil spring, a rubber, a graphite tape, a graphite sheet and a sponge. The method according to claim 1, Wherein the light source is disposed along a side surface of the light guide plate. The method according to claim 1, Wherein the light source comprises a light emitting diode element. In the display device, An image receiving unit for receiving a video signal; A signal processor for processing the received video signal; A display panel on which the processed video signal is displayed; And a backlight unit for providing light to the display panel, The backlight unit includes: A light guide plate; At least one light source for irradiating the light guide plate with light, a substrate on which the at least one light source is mounted, and a plurality of spaced apart portions extending from the substrate toward the light guide plate so as to form a predetermined gap between the at least one light source and the light guide plate, A light source unit including a holding unit; A receiving member for receiving the light source unit and the light guide plate; And an elastic member interposed between the accommodating member and the substrate and elastically biasing the substrate toward the light guide plate so that the gap is constant when the light guide plate expands or contracts. delete 10. The method of claim 9, Wherein the interval holding portion is integral with the substrate. 10. The method of claim 9, Wherein the end face of the substrate and the spacing portion has a " C " shape, " C " shape,

Quot ;, " a " shape. 10. The method of claim 9, Wherein the elastic member is coupled to the housing member and the substrate. 10. The method of claim 9, Wherein the elastic member comprises at least one of a coil spring, a rubber, a graphite tape, a graphite sheet, and a sponge. 10. The method of claim 9, Wherein the light source is disposed along a side surface of the light guide plate. 10. The method of claim 9, Wherein the light source comprises a light emitting diode device.

Images