KR20100040765A - Backlight unit for display - Google Patents

Abstract

PURPOSE: A backlight unit for display is provided to reduce the whole thickness by uniting light guide plate, reflecting plate, and LED and reducing diffusing plate. CONSTITUTION: A light guide unit(10) comprises a light incident protruding unit. A light source unit(30) emits light to a light guide unit. A reflecting unit reflects the light to the light guide unit. An optical sheet uniformly distributes the light. At least one projection supports the optical sheet by being formed on the top surface of the light guide unit.

Description

Backlight unit for display

The present invention relates to a backlight unit for a display, and more particularly to a backlight unit for a display using a light emitting diode.

In general, liquid crystal displays (LCDs) are used in various devices ranging from televisions, notebook computers, desktop monitors, and mobile phones.

Since the LCD does not emit light by itself, a light emitting device capable of illuminating a liquid crystal panel is required to display image information.

The light emitting device of the LCD is coupled to the back of the liquid crystal panel and called a backlight unit. This backlight unit is a very important device because it needs to irradiate the liquid crystal panel by forming a uniform surface light source.

A general backlight unit includes a light source, a light guide plate, a diffusion sheet, a prism, a protective sheet, and the like, and as a light source, a fluorescent lamp such as a mercury cold cathode fluorescent lamp or a light emitting diode may be used.

However, since fluorescent lamps have to use environmental pollutants such as mercury, and have disadvantages such as slow response speed, recently, a backlight unit using a light emitting diode as a light source has been recently used.

The backlight unit using the light emitting diode light source mainly uses a direct method of arranging the light emitting diodes on the back of the liquid crystal panel and directly irradiating the liquid crystal panel.

The direct type light emitting diode maintains the uniformity of the screen by adjusting the light distribution through the lens design of the light emitting diode.

As described above, the direct type light emitting diode can secure the uniformity of the surface light source in the point light source by using a lens that enables wide distribution of the light exit angle.

However, such a direct light emitting diode still has not overcome the limitation of the point light source even when using a lens that enables wide distribution of light emission.

That is, although the uniformity of the surface light source can be secured by using a lens, there is a limit in reducing the distance between the light emitting diodes and a limit in reducing the distance between the light emitting diode light source and the diffusion plate for diffusing the light. It is a limiting factor in making the overall thickness thin.

The present invention is to provide a backlight unit for a display that can reduce the overall thickness by removing the diffusion plate, combining the light guide plate, the reflecting plate and the light emitting diode.

In addition, the present invention is to provide a display backlight unit suitable for a large screen display by combining a light guide plate, a reflecting plate and a light emitting diode to be modularized, and by assembling a plurality of modules in a tiling manner.

In addition, the present invention is to provide a backlight unit for a display that can form a gap of the air layer between the light guide plate and the optical sheet to reduce the mura phenomenon caused by the luminance difference generated at the boundary between the light guide plate and the adjacent light guide plate. .

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above are clearly understood by those skilled in the art from the following descriptions. Could be.

According to an embodiment of the present invention, a display backlight unit includes a light guide part having a light receiving protrusion on a part of a side surface, a light source part positioned at a side of the light receiving protrusion to emit light to the light guide portion, and a light coupled to the lower surface of the light guide portion. An optical sheet positioned above the light guide to reflect the light, the optical sheet to distribute the light uniformly, and an upper surface of the light guide to maintain a gap between the light guide and the optical sheet. It may comprise at least one projection supporting.

Here, among the surfaces of the projections, the surface in contact with the surface of the light guide portion may be flat, and the surface in contact with the surface of the optical sheet may have a curvature.

And, the height of the protrusion may be about 1-2 mm, and the distance between the protrusion and the adjacent protrusion may be about 2-3 cm.

In addition, the upper surface of the light guide portion is flat, and the lower surface of the light guide portion is formed to be inclined in the light exit surface direction from the light incident surface where the light projecting portion is located, the upper surface of the reflector is inclined in a direction opposite to the lower surface of the light guide portion, The lower surface of the portion may be formed to be flat.

In addition, a cover protrusion may be formed on a side of the reflector where the light emitting surface of the light guide is positioned to cover an upper portion of the light source of an adjacent backlight unit, and at least an edge of the reflector may be coupled to the light guide. One coupling member may be formed.

In addition, at least one coupling member may be formed at a side of the reflector to be coupled to an adjacent backlight unit, and at least one coupling member is coupled to a back cover of the backlight unit at a lower edge portion of the reflector. May be formed.

Other objects, features and advantages of the invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

The display backlight unit according to the present invention has the following effects.

First, the present invention can reduce the overall thickness by removing the diffusion plate, combining the light guide plate, the reflecting plate and the light emitting diode, it is possible to reduce the thickness of the display panel such as LCD.

Second, the present invention can provide a display backlight unit suitable for a large screen display by combining a light guide plate, a reflecting plate, and a light emitting diode into a module, and by assembling a plurality of modules in a tiling manner.

Third, the present invention can reduce the Mura phenomenon due to the luminance difference generated at the boundary between the light guide plate and the adjacent light guide plate by forming a gap of the air layer between the light guide plate and the optical sheet by using the projection of the light guide plate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1A to 1D are views illustrating a structure of a backlight unit for a display according to the present invention, in which FIG. 1A is a perspective view, FIG. 1B is a plan view, and FIG. 1C is a side view seen in a first direction of FIG. 1A, and FIG. 1D Is a side view as seen in the second direction of FIG. 1A.

As illustrated in FIGS. 1A to 1D, the backlight unit of the present invention may be largely configured of a light guide unit 10, a light source unit 30, a reflective unit 50, and at least one protrusion 70.

Here, the light guide portion 10 has a top surface is formed flat, the bottom surface is formed to be inclined, a portion of the side is made of a structure in which the light projecting portion 15 is formed.

The light guide portion 10 has a first side face 17a and a second side face 17b facing each other, and a third side face 17c and a fourth side face 17d facing each other.

In this case, the thickness of the light guide portion 10 is formed to become thinner from the first side surface 17a to the second side surface 17b, so that the lower surface of the light guide portion 10 has an inclined surface as a whole.

Subsequently, the light receiving protrusion 15 is formed on the first side surface 17a of the light guide portion 10, and the thickness of the light receiving protrusion 15 is thinner than the thickness of the first side surface of the light guide portion 10.

Therefore, the upper surface of the light projecting portion 15 and the upper surface of the light guide portion 10 are formed to be located on different planes.

In some cases, in order to uniformly transmit light to the entire light guide part, a part of the lower surface of the light projecting part 15 may be manufactured in an uneven form.

At this time, the upper surface of the circuit board 35 of the light source unit 30 coupled to the lower surface of the light projecting portion 15 may have a concave-convex shape at the same position.

In addition, at least one coupling protrusion 19 may be further formed at a lower edge portion of the light guide portion 10 as a coupling member for coupling with the upper surface of the reflective portion 50.

Here, the coupling protrusion 19 is inserted into and coupled to the coupling groove 52 formed on the upper surface of the reflecting portion 50, thereby being manufactured to withstand external shocks or vibrations.

In addition, at least one or more protrusions 70 are formed on the upper surface of the light guide portion 10.

Here, the protrusion 70 is formed to support the optical sheet 80 shown in FIG. 3, thereby maintaining a gap of the air layer between the light guide 10 and the optical sheet 80.

Of the surfaces of the protrusions 70, the surface contacting the surface of the light guide part 10 may be flat, and the surface contacting the surface of the optical sheet 80 may be formed in a semicircular shape to have a curvature.

At this time, the radius of curvature of the protrusion 70 in contact with the surface of the optical sheet 80 is preferably about 0.1-1mm.

The reason is that when the radius of curvature of the protrusion 70 is about 0.1 mm or less or about 1 mm or more, the loss of light reflected or refracted by the protrusion 70 becomes large.

Therefore, the light incident on the protrusion 70 is not lost, and the curvature of the protrusion 70 may be appropriately adjusted to be produced so that a large amount of light proceeds in the direction of the optical sheet 80.

In addition, it is preferable that the height h of the protrusion 70 is about 1-2 mm.

The reason is that when the height h of the projection 70 is about 1 mm or less, if the gap of the air layer is too small and the diffusion of incident light is not large, the efficiency is not good, and the height h of the projection 70 is about 2 mm or more, The overall thickness of the backlight unit may be thick and inefficient.

Subsequently, the distance d between the protrusion 70 and the protrusion 70 adjacent thereto is preferably about 1/3 of the distance from the light incident surface to the light exit surface of the light guide portion.

That is, the distance d between the protrusion 70 and the protrusion 70 adjacent thereto is preferably about 2-3 cm.

The reason is that when the distance d between the protrusion 70 and the protrusion 70 is about 2 cm or less, the number of the protrusions 70 formed on the surface of the light guide portion 10 increases, resulting in reflection and refraction of incident light. If there is a problem that the light loss is increased, and the distance d between the protrusion 70 and the protrusion 70 is about 3 cm or more, the optical sheet supported by the protrusion 70 stretches or falls and the light diffuses properly. A loss problem may occur.

Therefore, the protrusion 70 and the adjacent protrusion 70 should be formed symmetrically with respect to the surface of the light guide portion 10, and should be formed at appropriate intervals and numbers.

In some cases, the protrusion 70 is preferably a material having a small surface tension so that the protrusion 70 is easily bonded to the light guide 10.

For example, the protrusion 70 may be made of polymethylmethacrylate (PMMA), polycarbonate, cyclic olefin copolymer (Cyclic Olefin Copolymer), or the like, and may be formed of the same material as the light guide 10. May be

On the other hand, the light source unit 30 is located on the side of the light projecting portion 15 and serves to emit light to the light guide portion 10, consisting of at least one light emitting diode 32 and the circuit board 35 Can be.

Here, the light emitting diode 32 is positioned on the side surface of the light receiving protrusion 15 and generates light and emits the light to the light receiving protrusion 15.

In addition, the circuit board 35 supports and combines the lower surface of the light emitting diode 32 and the light receiving protrusion 15.

As such, the reason for forming the light receiving protrusion 15 from the side surface of the light guide portion 10 may be to remove the dark portion between the light emitting diodes 32, and to connect the light emitting diodes 32 to the light emitting diodes 32 at the joints between the backlight units. Direct light leakage caused by this can be prevented.

Subsequently, the reflector 50 is coupled to the lower surface of the light guide 10 to reflect light to the light guide 10, and the second, third, and fourth side surfaces 17b and 17c of the light guide 10 are provided. , 17d) may prevent light from the light guide 10 from being transmitted to the outside.

Here, the upper surface of the reflecting portion 50 has an inclined surface having an inclination opposite to the inclined surface formed on the lower surface of the light guide portion 10.

Therefore, when the upper surface of the reflecting portion 50 and the lower surface of the light guiding portion 10 overlap each other, the lower surface of the reflecting portion 50 and the upper surface of the light guiding portion 10 are in equilibrium.

That is, the reflector 50 has a first side and a second side facing each other, the thickness of the reflector 50 becomes thicker from the first side to the second side.

At this time, the light source unit 30 is positioned on the first side surface of the reflector 50, and a cover protrusion 54 for the cover is formed on the second side surface of the reflector 50.

Here, the cover protrusion 54 covers the upper part of the light source of an adjacent backlight unit when assembling a plurality of backlight units, so that the light emitting diode 32 is located at the light receiving protrusion 15 of the light guide portion 10. Can be prevented from appearing on the display screen.

In addition, at least one coupling groove 52 may be formed in the upper edge portion of the reflector 50 as a coupling member for coupling with the light guide 10.

As described above, the coupling protrusion 19 of the light guide portion 10 is inserted into and coupled to the coupling groove 52 of the reflecting portion 50, thereby being manufactured to withstand external shock or vibration.

In addition, the reflector 50 has a third side and a fourth side facing each other, the third side is a coupling member for engaging with the adjacent backlight unit when assembled with a plurality of backlight units, the side hook groove ( 56 is formed, and a side hook 58 may be formed on the fourth side as a coupling member for engaging with an adjacent backlight unit.

Here, if the backlight unit is modularized to assemble a plurality of backlight units, the grooves 56 for the side hooks of the reflecting unit 50 may be coupled by inserting the side hooks of other adjacent backlight units, and the reflecting unit ( The side hook 58 of 50 may be engaged by being inserted into the groove for the side hook of another adjacent backlight unit.

By using the side hook 58 and the side hook groove 56, a plurality of backlight units can be easily assembled by lateral alignment.

In addition, at least one lower surface hook 60 may be formed at a lower edge portion of the reflector 50 as a coupling member for coupling with a back cover (not shown) of the backlight unit.

Here, the lower surface hook 60 can be easily assembled without using a screw or the like to combine the back cover as conventional.

FIG. 2 is a diagram illustrating a large backlight unit in which a plurality of backlight units of FIG. 1 are modularized.

As shown in FIG. 2, the light guide unit 10 and the backlight unit having the reflective unit 50 coupled thereto are respectively modularized, and then the side hooks 58 of one modularized backlight unit are adjacent to each other. It may be fitted into the groove 56 for the side hook of the backlight unit.

Since the other backlight units are connected to the left and right of one backlight unit, the plurality of backlight units are aligned in the horizontal direction.

3, the projection units 54 for the cover of the reflector 50 of each backlight unit may be disposed on the upper portion of the light emitting diode 32 of the adjacent backlight unit, as illustrated in FIG. 3. The cover may prevent the light emitting diode 32 located in the light receiving protrusion 15 of the light guide 10 from being reflected on the display screen.

In addition, a lower side hook 60 is formed at the bottom of each backlight unit, and may be coupled to a back cover (not shown) of the backlight unit.

In addition, the protrusion 70 formed on the upper surface of the light guide portion 10 is formed to support the optical sheet 80, thereby maintaining a gap of the air layer between the light guide portion 10 and the optical sheet 80. have.

Here, the air layer may play a role of diffusing the light emitted from the light guide portion 10 like the conventional diffusion plate due to the difference in refractive index.

The light diffused by the air layer is incident to be uniformly distributed throughout the display panel while passing through the optical sheet 80, so that the display panel can obtain uniform luminance.

For example, the optical sheet 80 has a structure in which the diffusion sheet 80a, the prism sheet 80b, and the protective sheet 80c are sequentially stacked, and the diffusion sheet 80a is incident from the light guide part 10. By scattering the light to uniform the luminance distribution of the light, the prism sheet 80b to focus the light to the display panel, the protective sheet 80c serves to protect the prism sheet 80b.

As such, a number of backlight units coupled in the lateral and longitudinal directions are well suited for use as a backlight for large displays.

In addition, since the plurality of backlight units are easy to assemble with each other, there is an effect that the manufacturing cost is low.

In addition, since the backlight is manufactured by removing the diffusion plate and the like, the thickness of the backlight is greatly reduced, and the overall display thickness is not only reduced, but the number of parts is also economically effective.

In addition, the projection of the light guide plate may be used to form a gap of the air layer between the light guide plate and the optical sheet, thereby reducing the mura phenomenon caused by the luminance difference generated at the boundary between the light guide plate and the neighboring light guide plate.

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

1A to 1D show the structure of a backlight unit for a display according to the present invention.

FIG. 2 is a view illustrating a large backlight unit in which a plurality of modules are assembled by modularizing the backlight unit of FIG. 1.

3 is a view showing a gap of an air layer located between the light guide portion and the optical sheet of the backlight unit according to the present invention.

Claims (14)

A light guide portion having a light projecting portion on a side surface thereof; A light source unit disposed at a side surface of the light incident protrusion to emit light to the light guide unit; A reflector coupled to a lower surface of the light guide to reflect the light to the light guide; An optical sheet disposed above the light guide unit to uniformly distribute the light; And, Display backlights, characterized in that it comprises at least one projection formed on the upper surface of the light guide portion to support the optical sheet to maintain a gap of the air layer between the light guide and the optical sheet. unit. The backlight unit of claim 1, wherein a surface of the protrusion is in contact with the surface of the light guide portion and a surface of the protrusion is in contact with the surface of the optical sheet. The backlight unit of claim 2, wherein a radius of curvature of the protrusions contacting the surface of the optical sheet is 0.1 to 1 mm. The backlight unit of claim 1, wherein the protrusion has a height of about 1 mm to about 2 mm. The backlight unit of claim 1, wherein a distance between the protrusion and an adjacent protrusion is 1/3 of a distance from a light incident surface to a light emitting surface of the light guide portion. The display unit of claim 1, wherein a distance between the protrusion and an adjacent protrusion is 2-3 cm. The backlight unit of claim 1, wherein the protrusions and the protrusions adjacent thereto are formed symmetrically with respect to the surface of the light guide portion. The backlight unit of claim 1, wherein an upper surface of the light guide portion is flat, and a lower surface of the light guide portion is inclined in a light exit surface direction from a light incident surface on which the light projection protrusion is located. The backlight unit of claim 1, wherein at least one coupling member is formed at an edge portion of the lower surface of the light guide portion to be coupled to the reflective portion. The backlight unit of claim 1, wherein an upper surface of the reflector is inclined in a direction opposite to a lower surface of the light guide, and a lower surface of the reflector is flat. The backlight unit of claim 1, wherein a cover protrusion is formed at a side of the reflector where the light emitting surface of the light guide unit is positioned to cover an upper portion of the light source of an adjacent backlight unit. The backlight unit of claim 1, wherein at least one coupling member is formed at an edge portion of the upper surface of the reflector to engage the light guide portion. The backlight unit of claim 1, wherein at least one coupling member is formed at a side of the reflector to engage an adjacent backlight unit. The backlight unit of claim 1, wherein at least one coupling member is formed at an edge portion of the lower surface of the reflector to engage with a back cover of the backlight unit.

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