KR101309260B1 - Backlight unit - Google Patents

Abstract

PURPOSE: A backlight unit is provided to reduce a viewing angle by emitting light with a narrow angle from a light source to a light guide plate. CONSTITUTION: A light source unit (211) includes a light source and a first light path control member. A light guide plate (213) changes the light path horizontally emitted from the light source unit and emits the light incident. The light guide plate includes a second light path control element (213a) and a third light path control member (213b). The second light path control member is arranged in the entering part of the light guide plate. The third light path control member is arranged on the lower surface of the light guide plate.

Description

Backlight unit {BACKLIGHT UNIT}

The present invention relates to a backlight unit for a display panel, and more particularly, to a backlight unit for adjusting a viewing angle and reducing power consumption.

Liquid crystal displays are widely used because of their thinness, lightness, and low power consumption. The liquid crystal display device is composed of a liquid crystal display panel for displaying an image, a backlight unit for supplying light to the liquid crystal display panel, and a driving circuit portion for supplying a driving signal to the liquid crystal display panel.

The backlight unit is classified into a direct type and an edge type according to a method of supplying light to the liquid crystal display panel. In the direct type backlight unit, a plurality of light sources are positioned under the liquid crystal display panel, and supply light directly to the liquid crystal display panel. An edge type backlight unit has a light source positioned at a side of the liquid crystal display panel, and supplies light to the liquid crystal display panel using a light guide plate.

The edge type backlight unit is always lit brightly regardless of the brightness of the screen displayed on the liquid crystal display panel, so that light may be emitted even when unnecessary.

1 is a cross-sectional view showing a conventional liquid crystal display device. Referring to FIG. 1, the liquid crystal display device 100 is driven by a single edge-light method and includes a backlight unit 110 and a liquid crystal panel 120.

The backlight unit 110 includes a light source unit 111, a reflective film 113, a light guide plate 115, a diffusion sheet 117, and a prism sheet 119. The light source unit 111 includes a CCFL or LED 111a which is a light source and a mounting portion 111b. The light generated by the CCFL or the LED 111a is reflected by the mounting portion 111b composed of the reflector, the reflective film 113 and the scattering pattern 115a of the light guide plate 115, and the reflected light is shown in FIG. 1. As described above, the light guide plate 115 is uniformly dispersed throughout the light guide plate 115. Light uniformly diffused in the light guide plate 115 passes through the diffusion sheet 117. The diffusion sheet 117 diffuses or concentrates the light passing through the light guide plate 115 to make the luminance uniform and to widen the viewing angle. The light passing through the diffusion sheet 117 is sharply reduced in brightness, the prism sheet 119 is used to prevent this. The prism sheet 119 refracts the light emitted from the diffusion sheet 117 to form a wide viewing angle. The liquid crystal panel 120 includes a rear glass 121, a liquid crystal 123, a color filter 125, and a front glass 127. To be incident on.

As described above, the conventional backlight unit 110 has a reflective film 113, a scattering pattern 113a, a diffusion sheet 117 and the like to uniformly illuminate the entire screen of the liquid crystal panel 120 and secure a wide viewing angle. Several films or sheets, such as the prism sheet 119, are used. In this case, while the light passing through the light guide plate 115 passes through the diffusion sheet 117 and the prism sheet 119, a considerable amount of light is absorbed and the luminance of the light finally generated is lowered.

In addition, by using a plurality of sheets including the prism sheet 119 which is an expensive raw material, the manufacturing unit price of the backlight unit 110 was also expensive.

In addition, the thickness of the backlight unit 110 is increased because several sheets need to be attached to the backlight unit 110.

In addition, the wide viewing angle makes it difficult to generate high luminance.

Therefore, it is required to generate high brightness plane light using little light energy without using several sheets.

An embodiment of the present invention provides a light source unit, a light guide plate, a backlight unit including the same, and a liquid crystal display using the same to reduce power consumption by narrowing a viewing angle.

According to an embodiment of the present invention, a backlight unit includes: a light source unit emitting parallel light; And a light guide plate that exits by changing a path of light incident in parallel from the light source unit, wherein the light source unit includes first light path adjusting means for changing a path of light so that light is incident in parallel to the side of the light guide plate, The light guide plate may include: second light path adjusting means for bending the light emitted from the first light path adjusting means up and down on a side thereof; The third light path adjusting means, which is emitted from the second light path adjusting means and totally reflected from the upper surface of the light guide plate, and the light emitted from the second light path adjusting means, is emitted to the upper surface of the light guide plate. Include.

In one embodiment, the first optical path adjusting means may include at least one of a plurality of convex lenses or cylindrical lenses.

In example embodiments, the second light path adjusting means may include a prism for bending light incident in parallel to the top surface of the light guide plate to the top and bottom surfaces of the light guide plate.

In one embodiment, the prism may be provided in plurality in the thickness direction of the light guide plate.

In an embodiment, the third optical path adjusting means may include a plurality of triangular oblique reflection patterns.

In example embodiments, the light guide plate may further include a reflective layer on the lower surface.

In one embodiment, the triangular oblique reflection pattern may have an inclined surface having an angle of 5 ° to 45 ° with respect to the lower surface.

In one embodiment, the light source unit may include an LED light source for emitting light to the first light path adjusting means.

In one embodiment, the LED light source may be provided in plurality and the first light path adjusting means may include a plurality of convex lenses corresponding to the LED light source.

In one embodiment, the LED light source may be provided in plural and the first light path adjusting means may include a cylindrical lens or a lenticular lens.

In one embodiment, the light source unit may further include a linear light guide, a light source for emitting light to the light incident portion of the linear light guide, and a lens disposed between the light source and the light incident portion of the light guide.

In one embodiment, the light guide portion of the linear light guide further comprises a prism for bending the light incident from the light source to the left and right, and the light guide path is reflected by the light to the left and right by the prism parallel light A reflective pattern may be provided to emit light.

In one embodiment, the light source unit includes: a linear light guide path, a light source that emits light to a light incident part of the linear light guide path, and an inverted prism-shaped optical structure that is disposed in the light exit part of the light guide path to provide bulging light. It may include.

According to an exemplary embodiment of the present invention, since light having a narrow traveling angle is incident from the light source to the light guide plate, the viewing angle may be reduced and thus energy consumption may be reduced.

According to an exemplary embodiment of the present invention, high brightness plane light may be generated with one light guide plate without a diffusion sheet, a prism sheet, and a reflective film.

According to an exemplary embodiment of the present invention, a thickness of a product may be reduced by not using a plurality of sheets, and a backlight device of a liquid crystal display device capable of lowering a manufacturing cost of a product may be provided.

1 schematically shows a display device according to the prior art.
2 schematically illustrates a display device according to an exemplary embodiment.
3 to 5 schematically show a backlight unit according to an embodiment of the present invention.
6 and 7 illustrate a method in which the linear light guide path 300 of FIG. 5 provides the linear light to the first optical path adjusting means 211b.
8 is a perspective view of the backlight unit of FIG. 4.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

As used herein, the term "parallel" as used in connection with the "path of light" means parallel to the display panel plane. For example, parallel light refers to light parallel to the display panel surface. This shows that when the direction of parallel light is changed, for example, when it is bent up and down, the light can be provided to the display panel surface.

Embodiments of the present invention relate to a backlight unit and a display device using the same. The backlight unit according to an exemplary embodiment of the present invention relates to a technology for saving energy, and is characterized by reducing a viewing angle for energy saving. In order to reduce the viewing angle, the backlight unit according to an exemplary embodiment includes optical path adjusting means for emitting light in parallel, and optical path adjusting means for bending the parallel light up and down to provide the inside of the light guide plate. The light guide plate has light path adjusting means on its lower surface to provide the bent light to the display panel.

Hereinafter, with reference to the accompanying drawings will be described in detail.

2 schematically illustrates a display device according to an exemplary embodiment. Referring to FIG. 2, the display device 200 according to the exemplary embodiment includes a backlight unit 210 and a display panel 220. The display panel 220 may include a rear substrate 221 on which a thin film transistor is formed, a liquid crystal 223, and a front substrate 225 on which a color filter is formed. The liquid crystal 223 is positioned between the rear substrate 221 and the front substrate 227, and the rear substrate 221 is adjacent to the backlight unit 210.

The backlight unit 210 includes a light source unit 211 and a light guide plate 213. As compared with the conventional backlight unit 11 of FIG. 1, it can be seen that the number of sheets or plates constituting the backlight unit 210 according to an embodiment of the present invention is much smaller.

The backlight unit 210 according to an embodiment of the present invention includes optical path adjusting means, for example, at least three optical path adjusting means 211b, 213a, and 213b to reduce the viewing angle. At least one of the light path adjusting means 211b, 213a, and 213b may be provided in the light source unit 211 and at least one of the light guide plates 213. For example, the light path adjusting means 211b may be provided in the light source unit 211, and the light path adjusting means 213b may be provided in the lower surface of the light guide plate 213. The light path adjusting means 213a may be provided in the light source unit 211 or the light guide plate 213.

The light source unit 211 includes a light source 211a and a first light path adjusting means 211b. The light guide plate 213 includes a second light path adjusting means 211a at a light incident portion that is a side surface thereof, and a third light path adjusting means 213b at a lower surface thereof. In the present embodiment, the second light path adjusting means 211a is provided in the light guide plate 213, but may be provided in the light source unit 210 or may be provided separately from the light source unit 211 and the light guide plate 213.

The light source 211a may include a plurality of light sources disposed at regular intervals, for example, light emitting diodes (LEDs). For example, the light source 211a may include a plurality of LEDs spaced apart from the side surface of the light guide plate and disposed along the side surface. Alternatively, the light source 211a may be provided as one linear light source.

The first light path adjusting means 211b is provided so that the light emitted from the light source 211a travels in parallel to be incident on the light guide plate 213, that is, is provided to the light incident part of the light guide plate 213. The first light path adjusting means 211b may be configured as a parallel light lens or a parallel light lenticular lens that emits incident light in parallel. The parallel light lens can be a convex lens, for example. Although described in more detail with reference to FIGS. 3 to 5, the light path adjusting means 211b may be provided with a plurality of convex lenses disposed spaced apart from each other, or may be a cylindrical lens or a lenticular lens extending in a straight line.

The light guide plate 213 is made of a transparent material so that light emitted from the light source unit 211 located adjacent to the side (light incidence portion) is transmitted. For example, the light guide plate 213 may be formed of any one of acrylic (Acryl), polymethyl methacrylate (PMMA), polycarbonate (PC: PolyCarbonate), and polystyrene (PS: PolyStyrene).

The second light path adjusting means 213a turns the light incident in parallel by the first light path adjusting means 211b of the light source unit 211 in the vertical direction to enter the light guide plate 213.

Parallel light formed through the first light path adjusting means 211b in the light source 211a has a diffusion angle controlled by the size effect and the focus blur effect of the light source, and the diffusion angle is the second light path adjusting means. It remains until it passes 213a and the 3rd light intensity adjusting means 213b, and forms the viewing angle which injects into a liquid crystal panel. The second light path adjusting means 213a bends the light incident in parallel so that the light is totally reflected from the upper and lower surfaces of the light guide plate 213 in the vertical direction. The second light path adjusting means 213a may be composed of, for example, a plurality of prisms, and the oblique angle of the prism constituting the second light path adjusting means 213a is configured to be the third light path adjusting means configured on the lower surface of the light guide plate. Combined with the oblique angle of 213 to adjust the light to travel in the vertical direction.

When the light incident on the upper and lower surfaces of the light guide plate 213 is totally reflected, the third light path adjusting means 213b emits the light to the top surface of the light guide plate 213 to be incident on the display panel 220. For example, the light reflected from the upper surface of the light guide plate 213 may be emitted in a vertical direction, for example, within 90 ° or 90 ° ± 10 ° to 90 ° ± 60 ° with respect to the upper surface of the light guide plate. It is provided on the lower surface in a slope reflection pattern.

The third light path adjusting means 213b may be provided in a triangular shape, for example, and has a predetermined inclination angle α with the lower surface of the light guide plate 213. For example, the inclination angle α of the second light path adjusting means 213b may be 5 ° to 45 °. The third light path adjusting means 213b may be provided by patterning the bottom surface of the light guide plate 213, or by attaching a film having a reflective pattern to the bottom surface of the light guide plate 213 by transferring by an imprint process or by a roll process. have.

In the above-described embodiment, a reflective layer may be coated on the lower surface of the light guide plate 213. For example, the reflective layer may function to reflect the totally reflected light to the upper surface of the light guide plate 213 in the lower surface of the lower portion of the third light path adjusting means 213b.

3 to 5 illustrate a backlight unit according to various embodiments of the present disclosure. The light source, the first light path adjusting means, and the second light path adjusting means may be implemented in various forms.

Referring to FIG. 3, in the backlight unit according to an exemplary embodiment, the light source 211a includes a plurality of LEDs disposed along the side surface of the light guide plate 213, and the first light path adjusting unit 211b includes Consists of a plurality of convex lenses corresponding to the light source (211a) one-to-one, the second light path adjusting means (213a) may be provided with a straight prism extending along the side of the light guide plate (213).

Referring to FIG. 4, in the backlight unit according to an exemplary embodiment, the light source 211a includes a plurality of LEDs disposed along the side of the light guide plate 213, and the first light path adjusting means 211b includes It is composed of a cylindrical lens or a lenticular lens extending along the side of the light guide plate 213, the second light path adjusting means (213a) is a straight prism extending along the side of the light guide plate 213. It may be provided. A plurality of linear prisms may be provided along the thickness direction of the light guide plate.

Referring to FIG. 5, in the backlight unit according to an exemplary embodiment of the present disclosure, a linear light guide path 300 extending longer along the side surface of the light guide plate 213 is further provided than the backlight unit of FIGS. 3 and 4. The light source 211a is positioned at one end that is an incident part of the linear light guide path 300. In detail, the light emitted from the LED light source 211a is incident into the linear light guide path 300, and the direction is bent toward the incident part (side of the light guide plate) of the light guide plate 213 to be converted into a linear light source. The first light path adjusting means 211b is composed of, for example, a cylindrical lens or a lenticular lens extending alongside the light guide path 300, and the second light path adjusting means 213a extends alongside the light guide path 300. It can be provided with a straight prism lens.

6 and 7 illustrate a method in which the linear light guide path 300 of FIG. 5 provides the linear light to the first optical path adjusting means 211b.

Referring to FIG. 6, the light emitted from the LCD light source 211a becomes parallel light by the convex lens 320, and the left and right directions are formed by a plurality of prisms 310 formed at one end (incident portion) of the linear light guide path 300. It is converted to, and is reflected from the rain surface 330 installed in the linear light guide path 300 is converted to a linear light source by bending the direction 90 degrees. The inclined surface 330 may be provided in plural along the extending direction of the light guide path 300.

Referring to FIG. 7, light emitted from the LED light source 211a proceeds by total reflection inside the linear light guide path 300, and then has an inverse prism-shaped optical structure installed at one side (the exit surface) of the linear light guide path 300. It may be converted to a linear light source by bending 90 degrees by 350). The optical structure 350 may be provided in plural along the direction in which the light guide path 300 extends.

8 is a perspective view of the backlight unit of FIG. 4.

Referring to FIG. 8, the light source unit 211 includes a plurality of light sources 211a and first light path adjusting means 211b such as a cylindrical lens or a lenticle lens. The second light path adjusting means 213a includes a plurality of linear prisms 213a arranged along the thickness direction of the light guide plate 213. The third light path adjusting means 213b includes a plurality of line-shaped reflection patterns 213b.

210: Backlight unit
211: light source unit
213 light guide plate
211a: light source
211b: first light path adjusting means
213a: second light path adjusting means
213b: third light path adjusting means
300: light guide

Claims (13)

A light source unit including a light source for emitting light and a first light path adjusting means for changing a path of the light emitted from the light source so that light is incident in parallel to an incident part of the light guide plate; And
A backlight unit including a light guide plate that changes the path of light incident in parallel from the light source unit and exits.
The light-
The inclined surface which is disposed in the incidence portion of the light guide plate and parallelly enters the light incident in parallel with the inclined surface upwards so that the light emitted from the first light path adjusting means is totally reflected from the upper and lower surfaces of the light guide plate. A second light path adjusting means provided; And
Arranged on the lower surface of the light guide plate so as to reflect the light emitted by being folded upward from the second light path adjusting means and totally reflected from the upper surface of the light guide plate and the light emitted by bending downward from the second light path adjusting means and emitted to the upper surface. And a third light path adjusting means. The method according to claim 1,
The first optical path adjusting means includes a plurality of convex lenses spaced apart along the incidence portion of the light guide plate or a cylindrical lens extending along the incidence portion of the light guide plate. 3. The method according to claim 1 or 2,
The second light path adjusting means includes a prism for bending light incident in parallel with the top and bottom surfaces of the light guide plate to the top and bottom surfaces of the light guide plate. The method of claim 3,
The prism is provided in plurality in the thickness direction of the light guide plate. The method of claim 3,
The third optical path adjusting means includes a plurality of triangular oblique reflection patterns. 6. The method of claim 5,
The triangular oblique reflection pattern has a sloped surface having an angle of 5 ° to 45 ° with respect to the lower surface. The method of claim 3,
The light guide plate further comprises a reflective layer on the lower surface. 3. The method according to claim 1 or 2,
And the light source is an LED light source for emitting light to the first light path adjusting means. The method of claim 8,
The LED light source is provided in plurality and the first light path adjusting means comprises a plurality of convex lenses corresponding to the LED light source. The method of claim 8,
A plurality of LED light sources are provided, and the first light path adjusting means includes a cylindrical lens or a lenticular lens extending along a direction in which the plurality of LED light sources are arranged. 3. The method according to claim 1 or 2,
The light source unit is:
Straight light guide;
A light source for emitting light to the light incident part of the linear light guide path; And
And a lens disposed between the light source and the light incident part of the light guide path. 12. The method of claim 11,
A prism disposed at a light incident portion of the linear light guide path and bending the light incident from the light source to the left and right,
The light guide unit is provided with a reflective pattern for reflecting light bent left and right by the prism to emit parallel light. 3. The method according to claim 1 or 2,
The light source unit is:
Straight light guide;
A light source for emitting light to the light incident part of the linear light guide path; And
And an inverted prism-shaped light structure disposed in the light exit portion of the light guide to provide parallel light.

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