KR101102018B1 - Backlight unit - Google Patents

Abstract

The present invention relates to a backlight unit.

A backlight unit according to an embodiment of the present invention includes a plurality of lamps for generating light; A light guide plate for diffusing light generated from the lamp; A case accommodating the lamp and the light guide plate; Located at the top of the case characterized in that it comprises at least one support portion in contact with one side of the light guide plate.

Description

Back light unit {BACK LIGHT UNIT}             

1 is a view showing a conventional liquid crystal display device.

2 is a view showing in detail the lamp holder of FIG.

3A and 3B illustrate the backlight unit of FIG. 1 in detail.

4 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a cross-sectional view taken along the line VV ′ of FIG. 4.

6 is a view showing in detail the lamp holder of FIG.

FIG. 7 is a diagram illustrating the lamp holder of FIG. 6.

8 is a diagram illustrating a notebook structure in which a backlight unit structure according to an embodiment of the present invention may be used.

<Description of Symbols for Main Parts of Drawings>

2, 102: liquid crystal display panels 8, 18, 108, 118: polarizing sheet

10, 110: optical sheet 12, 112: light guide plate

14, 114: reflector 34, 134: case

36, 136: lamp 50, 150: driving part                 

38, 138: lamp holder 42: support part

46, 146: seating part 48, 148: horizontal support part

142: first support 144: second support

143: first fastening portion 145: second fastening portion

The present invention relates to a backlight unit, and more particularly, to a backlight unit having a lamp guide holder for supporting a lamp and supporting a diffuser plate.

In general, the display device is a cathode ray tube ("CRT") using a cathode ray tube, a plasma display panel ("PDP") and an electro lumini which displays an image through self-luminescence A sense (Electro Luminiscence: "EL"), a liquid crystal display ("LDC") for displaying an image using a backlight, and the like. Among such display devices, a liquid crystal display device may be a representative example having characteristics such as light weight, thinness, and low power consumption. Liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. On the other hand, the liquid crystal display device displays the desired image on the screen by adjusting the transmission amount of the light beam according to image signals applied to the plurality of control switches arranged in a matrix form.                         

Since the liquid crystal display device is not a self-luminous display device, a light source such as a back light is required. There are two types of backlight for the liquid crystal display device, an edge type type and a direct type type.

In the edge type system, a lamp is installed outside the flat panel to irradiate light to the medium and small liquid crystal display panels, and the light generated from the lamp is incident on the entire surface of the liquid crystal display panel through the transparent light guide plate.

In the direct type, a plurality of lamps are disposed on a flat surface and a diffuser plate is disposed between the lamps and the liquid crystal display panel in order to irradiate light to the large and medium type liquid crystal display panels. The lamp of the backlight unit for a direct type liquid crystal display device has a long length of the lamp to irradiate light to the large and medium liquid crystal display panels. Accordingly, the lamp guide holder is positioned at the center of the lamp to support the lamp.

1 is a view showing a conventional liquid crystal display device.

Referring to FIG. 1, a conventional liquid crystal display device includes a liquid crystal display panel 2, a backlight unit for irradiating light to the liquid crystal display panel 2, and a driving unit 50 for driving the backlight unit.

In the liquid crystal display panel 2, liquid crystal cells are arranged in an active matrix form between upper and lower glass substrates, and thin film transistors for switching video signals are installed in each of the liquid crystal cells. It is. In the liquid crystal display panel 2, an image corresponding to the video signal is displayed by changing the refractive index of each of the liquid crystal cells according to the video signal. On the lower substrate of the liquid crystal display panel 2, a tape carrier package (not shown) in which a driver integrated circuit for applying a driving signal to a thin film transistor is mounted is attached. In addition, polarizing sheets 8 and 18 are provided on the front and rear surfaces of the liquid crystal display panel 2, respectively. Here, the polarizing sheets 8 and 18 serve to improve the viewing angle of the image displayed by the liquid crystal cells.

The backlight unit receives power from an external power source and includes a plurality of lamps 36 for irradiating light to the liquid crystal display panel 2, a lamp holder 38 for supporting the plurality of lamps 36, and a plurality of lamps ( 36 and a case 34 for accommodating the lamp holder 38 and a reflector 14 provided between the lamp 36 and the case 34 to prevent and diffuse leakage of light generated from the lamp 36. And a plurality of light guide plates 12 for advancing the light generated from the lamp 36 toward the liquid crystal display panel 2, and a plurality of light sources for irradiating the liquid crystal display panel 2 with improved efficiency of the light emitted from the light guide plate 12. With optical sheets 10.

The lamp 36 is composed of a glass tube, inert gases inside the glass tube, and a cathode and an anode installed at both ends of the glass tube. Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube. When the lamp 36 is connected to the driving unit 50 through a wire and a synchronous cable, when an AC voltage generated from the driving unit 50 is applied to the high voltage electrode and the low pressure electrode, electrons are emitted from the low pressure electrode to inert gas in the glass tube. The collision with the field increases the amount of electrons exponentially. Thereafter, electric current flows inside the glass tube by the increased electrons, and ultraviolet rays are emitted by excitation of the inert gas by the electrons. The ultraviolet rays emitted in this manner collide with the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

The lamp holder 38 supports the lamp 34 and the light guide plate 12.

The reflective plate 14 is disposed between the upper surface of the case 34 and the plurality of lamps 36 to reflect the light generated from the lamps 36 and to be irradiated toward the liquid crystal display panel 2 to improve the light efficiency. .

The light guide plate 12 scatters the light generated from the plurality of lamps 36 by using a groove and / or protrusion-shaped light pattern formed in the light guide plate 12, so that the light is wide angled to the liquid crystal display panel 2. And enter.

The optical sheets 10 may reduce the power consumption by improving the front brightness of the liquid crystal display by increasing the brightness of the light emitted from the light guide plate 12. In addition, the optical sheets 10 cause the light incident at an oblique angle from the surfaces of the reflective sheet 14 and the light guide plate 12 to travel perpendicularly to the liquid crystal display panel 2. In other words, the optical sheets 10 serve to raise the propagation direction of light from the surface of the optical sheets 10.

The case 34 prevents light leakage of visible light emitted from each of the lamps 36 and reflects the visible light traveling toward the front and the light guide plate 12 toward the side and the back of the plurality of lamps 36. The efficiency of light generated in the field 36 is improved.

The driver 50 adjusts the current supplied to the lamp 36 according to a control signal for controlling the brightness of the lamp 36. The lamp 36 that receives the controlled current adjusts the brightness according to the magnitude of the current to control the brightness of the liquid crystal display panel 2.

A lamp holder 38 of the conventional liquid crystal display having the above structure will be described in detail with reference to FIG. 2.

Referring to FIG. 2, the lamp holder 38 has a triangular pyramid-shaped support portion 42 spaced apart from the light guide plate 12 at predetermined intervals, and a horizontal support portion 48 that is perpendicular to the support portion 42 and has a predetermined width. And two mounting parts 46 formed on one side of the horizontal support part 48 and on which the lamp 36 is seated. Here, the two seating parts 46 are located opposite to both sides with respect to the support part 42.

Meanwhile, the light guide plate 12 shown in FIG. 3A undergoes thermal expansion when light starts to be irradiated from the lamps 36 to have warpage as shown in FIG. 3B. Accordingly, the separation distance between the light guide plate 12 and the lamps 36 is changed, so that the brightness of the light emitted through the light guide plate 12 is changed. This change in light causes a fatal picture quality error when the liquid crystal panel 2 implements an image. In addition, since the curved portion of the light guide plate 12 exerts a pressure on the upper end of the support 42 of the lamp holder 38, deformation occurs in the lamp holder 38. As a result, the light generated from the lamp 36 is scattered by the deformed support part 42, thereby lowering the brightness of the light.

Accordingly, it is an object of the present invention to provide a backlight unit for preventing the warpage of the light guide plate to maintain a constant light generated from the lamp.

In order to achieve the above object, a backlight unit according to an embodiment of the present invention includes a plurality of lamps for generating light; A light guide plate for diffusing light generated from the lamp; A case accommodating the lamp and the light guide plate; Located at the top of the case and provided with at least one support portion in contact with one side of the light guide plate.

The support part is located at the center of the upper case.

The support part includes a first support part in contact with a rear surface of the light guide plate; A second support part coupled to the first support part and in contact with the case is provided.

The support portion has a horizontal support portion formed in parallel with the case having a predetermined width from at least one side of the first and second support portion; One side of the horizontal support is further provided with at least one seating portion in which the lamps are seated.

The support portion further includes a fastening portion for fastening the first support portion and the second support portion.

The fastening part is formed of at least one of a protrusion having a female thread and a male thread, and a fastening part having a groove and a hook and a groove engaged with the hook.

The first support part is formed of a silicone-based synthetic resin made of a transparent material, and the second support part is formed of a light reflection material that reflects light.

The silicon synthetic resin is HR2610, and the light reflection material is formed of a metal material such as aluminum.                     

The backlight unit may include a reflection plate positioned between the case and the lamp to prevent leakage of light generated from the lamp; And a light sheet mounted on the light guide plate to increase the efficiency of light emitted from the light guide plate.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

4 to 7 illustrate a liquid crystal display according to an exemplary embodiment of the present invention.

4 and 5, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 102 for implementing an image, a backlight unit for irradiating light to the liquid crystal display panel 102, and a backlight. A driving unit 150 for driving the unit is provided.

In the liquid crystal display panel 102, liquid crystal cells are arranged in an active matrix form between upper and lower glass substrates, and thin film transistors for switching video signals are provided in each of the liquid crystal cells. It is. The liquid crystal display panel 102 may display an image corresponding to the video signal by changing the refractive index of each of the liquid crystal cells according to the video signal. A tape carrier package (not shown) in which a driver integrated circuit for applying a driving signal to a thin film transistor is mounted on the lower substrate of the liquid crystal display panel 102 is attached. In addition, polarizing sheets 108 and 118 are provided on the front and rear surfaces of the liquid crystal display panel 102, respectively. Here, the polarizing sheets 108 and 118 function to improve the viewing angle of the image displayed by the liquid crystal cells.

The backlight unit is supplied with power from an external power source, and includes a lamp 136 for irradiating light to the liquid crystal display panel 102 and a light guide plate 112 for moving the light generated from the lamp 136 toward the liquid crystal display panel 102. ), A lamp holder 138 that supports the lamp 136, and supports the light guide plate 112, and a plurality of optical lights that irradiate the liquid crystal display panel 102 by improving the efficiency of light emitted from the light guide plate 112. Sheets 110, a reflector plate 114 disposed under the lamp 136 to prevent and diffuse leakage of light generated from the lamp 136, an optical sheet 110, a light guide plate 112, and a plurality of sheets. And a case 134 for housing the two lamps 136 and the reflecting plate 114.

The lamp 136 includes a glass tube, inert gases inside the glass tube, and a cathode and an anode installed at both ends of the glass tube. Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube. The lamp 136 is connected to the driving unit 150 through a wire and a synchronous cable, when the AC voltage generated from the driving unit is applied to the high voltage electrode and the low pressure electrode, electrons are emitted from the low pressure electrode and the inert gas in the glass tube and Collision increases the amount of electrons exponentially. Thereafter, electric current flows inside the glass tube by the increased electrons, and ultraviolet rays are emitted by excitation of the inert gas by the electrons. Ultraviolet rays emitted in this manner collide with the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

The light guide plate 112 scatters light generated from the plurality of lamps 136 by using a light pattern in the form of grooves and / or protrusions formed in the light guide plate 112, whereby the light is wide angled to the liquid crystal display panel 102. And have it enter.

The optical sheets 110 may reduce the power consumption by improving the front luminance of the liquid crystal display by increasing the luminance of the light emitted from the light guide plate 112. In addition, the optical sheets 110 cause the light incident at an oblique angle from the surfaces of the reflective sheet 114 and the light guide plate 112 to travel perpendicular to the liquid crystal display panel 102. In other words, the optical sheets 110 serve to raise the propagation direction of light from the surface of the optical sheets 110.

The lamp holder 138 is positioned at the center of the case 134 to support the lamp 136 and to contact the rear surface of the light guide plate 112 to prevent bending of the light guide plate 112.

The reflecting plate 114 is disposed between the upper surface of the case 134 and the plurality of lamps 136 to reflect the light generated from the lamps 136 to be irradiated toward the liquid crystal display panel 102 to improve the light efficiency. .

The case 134, which houses the lamp 136, the light guide plate 112, the reflector plate 114, and the optical sheet 110, prevents light leakage of visible light emitted from each of the lamps 136, and a plurality of lamps. By reflecting the visible light traveling toward the side and the back of 136 toward the front surface, that is, the light guide plate 112, the efficiency of light generated in the lamps 136 is improved.

The driver 150 adjusts the current supplied to the lamp 136 according to a control signal for controlling the brightness of the lamp 136. The lamp 136 supplied with the controlled current adjusts the brightness according to the magnitude of the current to control the brightness of the liquid crystal display panel 102.                     

A lamp holder 138 according to an embodiment of the present invention having such a structure will be described in detail with reference to FIG. 6.

Referring to FIG. 6, the lamp holder 138 contacts the rear surface of the light guide plate 112 to be coupled to the first support part 142 and the first support part 142 to support the light guide plate 112, and the case 134. A second support part 144 disposed on the second support part 144, a horizontal support part 148 extending vertically from the one side of the second support part 144 and having a predetermined width, and a side of the horizontal support part 148. At least one seating portion 146 extending therefrom to seat the lamp 136.

The first support part 142 is formed of a transparent material in the form of a triangular pyramid and contacts the rear surface of the light guide plate 112. Since the first support part 142 is formed of a transparent material, the first support part 142 does not affect the light diffusion of the light guide plate 112. In addition, the material of the first support part 142 is formed of a material resistant to heat and pressure. As such a material, a silicone-based synthetic resin is used. One of the silicone-based synthetic resins is HR2160. In addition, the lower end of the first support part 142 is formed with a first fastening part 143 to be engaged with the upper end of the second support part 144.

The back surface of the second support part 144 is in contact with the top surface of the case 134. The upper end of the second support part 144 is formed with a second fastening part 145 corresponding to the first fastening part 143 formed on the first support part 142. In addition, the second support 114 reflects the light generated from the lamp 136 to improve the brightness. As an example of the first fastening part 143 and the second fastening part 145, when a hook-like protrusion is formed on the second fastening part 145 as shown in FIG. 6, the first fastening part 143 is It has a groove that is engaged with the hook-shaped protrusion. In addition, as shown in FIG. 7, when a protrusion having a male thread is formed in the second fastening part 145, the first fastening part 143 may be a female thread corresponding to the male thread of the second fastening part 145. The branch is formed with a groove.

Here, the coupling form of the first support portion 142 and the second support portion 144 is in the form of a triangular pyramid with a uniform surface.

The horizontal support part 148 is perpendicular to the second support part 144 from one side of the second support part 144 and extends in parallel to the front surface of the case 134.

The mounting portion 146 is fixed to the lamp 136 is seated on one side of the horizontal support 148. The seating portion 146 is formed symmetrically with respect to the second support 144.

The lamp holder 138 has a structure in which the first support part 142 of the lamp holder 138 is formed by the light guide plate 112 when the light guide plate 112 is thermally expanded due to heat generated by the light from the lamp 136. By supporting the center, bending does not occur. Accordingly, since the distance between the light guide plate 112 and the lamp 136 is kept constant, the light generated from the lamp 136 is uniformly incident on the rear surface of the light guide plate 112. As a result, image quality defects due to the warpage of the light guide plate 112 do not occur. In addition, since the material of the first support part 142 contacting the light guide plate 112 and supporting the light guide plate 112 has characteristics of heat resistance and pressure resistance, deformation of the first support part 142 does not occur.

On the other hand, the lamp holder 138 according to an embodiment of the present invention having such a structure can be used in a portable information device, general information equipment, office information equipment, etc., as an example can also be used for the notebook shown in FIG. Can be.

As mentioned above. The backlight unit according to an exemplary embodiment of the present invention includes a first support part which is in contact with the rear surface of the light guide plate to directly support the light guide plate and a second support part which is fastened to the first support part and is in contact with the upper surface of the case to prevent bending of the light guide plate. do. Accordingly, in the backlight unit according to the exemplary embodiment of the present invention, the unevenness of the light guide plate and the lamp may occur due to the warpage of the light guide plate, and as a result, the uneven brightness of light irradiated onto the liquid crystal display panel may be prevented.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (9)

A plurality of lamps for generating light; A light guide plate for diffusing light generated from the lamp; A case accommodating the lamp and the light guide plate; At least one support part positioned on an upper portion of the case and in contact with one side of the light guide plate; The support portion A first support part in contact with a rear surface of the light guide plate and formed of a transparent material having heat resistance and pressure resistance; And a second support part coupled to the first support part and in contact with the case and reflecting light. The method of claim 1, The support portion The backlight unit, characterized in that located in the center of the upper case. delete The method of claim 1, The support portion A horizontal support part having a predetermined width from at least one side of the first and second support parts and formed in parallel with the case; And at least one seating portion on which the lamps are seated on one side of the horizontal support portion. The method of claim 1, The support portion And a fastening part for fastening the first support part and the second support part. The method of claim 5, The fastening portion A backlight unit, characterized in that it is formed with at least one of a protrusion having a female thread and a male thread, and a fastening part having a groove and a hook and a groove engaged with the hook. delete The method of claim 1, The first support unit is a backlight unit, characterized in that formed of a silicone-based synthetic resin. The method of claim 1, A reflection plate positioned between the case and the lamp to prevent leakage of light generated from the lamp; And a light sheet mounted on an upper portion of the light guide plate to increase the efficiency of light emitted from the light guide plate.

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