KR102708384B1 - Liquid Crystal Display device - Google Patents

Abstract

The present invention relates to a display device, and more particularly, to a display device capable of improving image quality by preventing mura (staining) while being lightweight and thin.
The present invention is characterized in that a first optical unit including a dichroic layer and a color conversion layer is positioned above a light source, a second optical unit including a pattern layer including first and second stereoscopic pattern layers and an optical pattern is positioned above the first optical unit, and a third optical unit including first and second light collecting units and a diffusion unit is positioned above the second optical unit.
Through this, the display device of the present invention can realize lightness and thinness with a narrow bezel, and at the same time, can provide a surface light source with high brightness and high color reproducibility from the backlight unit and improved visibility to the display panel, thereby preventing halo mura, lattice mura, and border mura from occurring.

Description

Display device {Liquid Crystal Display device}

The present invention relates to a display device, and more particularly, to a display device capable of improving image quality by preventing mura (staining) while being lightweight and thin.

Recently, with the development of information technology and mobile communication technology, display devices capable of visually displaying information are being developed, and display devices are largely classified into self-luminous displays with luminous properties and non-luminous displays that can display images by other external factors.

An example of a non-luminous display is the LCD (Liquid Crystal Display), which is a device that does not have its own light-emitting element.

Therefore, LCD, a non-luminous display, requires a separate light source, and a backlight unit with a light source on the back is provided to irradiate light toward the front of the LCD, thereby creating a discernible image.

The backlight unit uses a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp, and a light emitting diode (LED, hereinafter referred to as LED) as a light source.

Among these, LEDs are being widely used as display light sources due to their compact size, low power consumption, and high reliability.

Meanwhile, general backlight units are classified into side light type and direct light type depending on the arrangement structure of the LEDs, which are the light source. The side light type has a structure in which the LEDs are arranged on one or both sides of the light guide plate, and the light emitted from the LEDs through the light guide plate is converted into flat light and emitted to the display panel.

And the direct light type has multiple LEDs placed under the display panel to directly shine light on the front of the display panel.

Recently, research on large-area display devices is being actively conducted in response to consumer demand, and direct-light type is more suitable for large-area liquid crystal displays than side-light type.

In addition, the direct light type can improve the uniformity and brightness of light irradiated on the display panel, and can also implement local dimming operation, thereby improving the contrast ratio and reducing power consumption.

Meanwhile, in the case of the direct light type, when multiple light sources are turned on, a uniform surface light source is provided to the display panel, but when only one light source is turned on, the light is diffused to the surroundings, causing halo mura.

Accordingly, in order to prevent the occurrence of such halo mura, a reflective layer is positioned further between the light sources, and a thick diffusion plate is positioned further above the light sources. In the case where the reflective layer is positioned between the light sources in this way, the halo mura that occurs due to the peripheral diffusion of light when only some of the light sources are turned on can be reduced, but when multiple light sources are all turned on, the light is not supplied smoothly to the upper part of the reflective layer, and a lattice mura in which part of the reflective layer is visible occurs.

In addition, as the thick diffuser plate is positioned further above the light source, it is becoming difficult to provide a lightweight and thin display device that has recently been in demand.

In addition, since this type of direct light has the light source LED positioned below the display panel and directly irradiates light onto the display panel, there is a deviation in the light supplied between the center where the light source is located and the edge area where the light source is not located.

This causes a borderless bezel, and the importance of display devices with a narrow bezel has been increasing recently. In conventional display devices, the edge area where low-luminance light is provided could be completely covered through the bezel, but as the bezel becomes narrower, the edge area cannot be completely covered, so there is a problem that light unevenness occurs in the edge area of the display panel, forming a shadow and the user perceives this as darkness.

Therefore, it causes a problem of deterioration in the display quality of the display device.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a display device having a light weight, a thin body, and a narrow bezel, while preventing stains such as halo mura, grid mura, and border mura, thereby improving image quality.

In order to achieve the object as described above, the present invention provides a display device including a plurality of light sources mounted on a PCB, a resin layer covering the plurality of light sources on the PCB, a first optical unit positioned above the resin layer and including a dichroic layer and a color conversion layer, a second optical unit positioned above the first optical unit and including optical patterns positioned respectively corresponding to the plurality of light sources and a first stereoscopic pattern layer including a plurality of first inverted pyramid lenses, a third optical unit positioned above the second optical unit and including a diffusion portion and a first light collection portion, and a display panel positioned above the third optical unit.

Here, the light source emits blue light, the dichroic layer reflects light other than the blue light, the dichroic layer is positioned between the light source and the color conversion layer, and the color conversion layer converts the blue light into white light.

And, the first stereoscopic pattern layer includes a first base layer, and a first stereoscopic lens layer in which a plurality of first inverted pyramid lenses are protruded and arranged from a lower surface of the first base layer, and the plurality of first inverted pyramid lenses are formed of a lower surface formed in a square shape and four side surfaces each extending from an edge of the lower surface to form one corner, and a length of the lower surface is 20 to 40 um, and an angle formed by the corners is 90 to 130 degrees, and a second stereoscopic pattern layer including a second base layer, and a second stereoscopic lens layer in which a plurality of second inverted pyramid lenses are protruded and arranged from a lower surface of the second base layer is positioned above the first stereoscopic pattern layer.

In addition, the optical pattern is formed of a double-layered overlapping printing structure, and the diameter of the optical pattern is 4.3 to 5.6 times larger than the diameter of the light source.

And, the first light collecting unit is provided with a first support layer, and a first lens layer on the first support layer, the first lens layer has first prism mountains arranged in a band shape along the first longitudinal direction and protruding in a row, the second light collecting unit including a second support layer on the first light collecting unit and a second lens layer on the second support layer is positioned, and the second lens layer has second prism mountains arranged in a band shape along the second longitudinal direction perpendicular to the first longitudinal direction and protruding in a row.

At this time, the diffusion part includes a third support layer, and first and second diffusion layers on both sides of the third support layer, and a reflector including a through hole through which the light source passes is positioned on the PCB.

As described above, according to the present invention, by positioning a first optical unit including a dichroic layer and a color conversion layer above a light source, a second optical unit including a pattern layer including first and second stereoscopic pattern layers and an optical pattern above the first optical unit, and a third optical unit including first and second light collecting units and a diffusion unit above the second optical unit, a surface light source having high brightness and high color reproducibility and also improved visibility can be provided to a display panel from a backlight unit.

Through this, it is possible to prevent halo mura from occurring even when only one light source consisting of an LED or micro LED is turned on, and also has the effect of preventing lattice mura from occurring even when a reflector is positioned around the light source to prevent halo mura.

In addition, the display device according to the embodiment of the present invention has the effect of being lightweight and thin and having a narrow bezel, and also has the effect of preventing the occurrence of frame blur even when implementing a narrow bezel, and through this, also has the effect of preventing the occurrence of a problem of deterioration in the image quality of the display device.

In addition, since the thick diffuser plate can be omitted on top of the light source, this has the effect of implementing light weight and thinness, and also has the effect of reducing process costs and making assembly convenient.

FIG. 1 is an exploded perspective view schematically illustrating a display device according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view schematically illustrating a portion of the modularized display device of Fig. 1.
Figure 3 is a graph showing the reflectivity characteristics of the dichroic layer of the first optical unit.
Figure 4a is a rear perspective view schematically illustrating the second optical unit.
Figure 4b is a photograph showing a three-dimensional pattern layer of the second optical unit.
Figure 4c is a front view schematically illustrating the inverted pyramid pattern of the second optical unit.
Figures 5a and 5b are experimental results showing FOS evaluations that vary depending on the angle formed by the corners of the inverted pyramid lens of the second optical unit.
FIG. 6 is a front view schematically illustrating the relationship between the size of a light source and an optical pattern according to an embodiment of the present invention.
Figure 7a is a photograph schematically illustrating an example of an optical pattern.
Figure 7b is a photograph showing the appearance with the optical pattern applied.
Figure 8 is a schematic diagram schematically illustrating the light propagation path passing through the second optical unit.
Figure 9a is a schematic diagram illustrating how backscattering occurs.
FIG. 9b is a diagram schematically illustrating a display device according to an embodiment of the present invention in which backscattering does not occur.
Figure 10a is a photograph showing the appearance of dark spots generated by backscattering.
FIG. 10b is a photograph showing a display device according to an embodiment of the present invention in which dark spots are prevented.
Figure 11a is a graph showing the light transmittance spectrum of a display device without a dichroic layer.
FIG. 11b is a graph showing the light transmittance spectrum of a display device according to an embodiment of the present invention.
Figures 12a and 12b are graphs showing the luminance distribution according to the viewing angle depending on the presence or absence of the first and second stereoscopic pattern layers of the second optical unit.
Figure 13a is a photograph showing the appearance of a grid mura.
FIG. 13b is a photograph showing a display device according to an embodiment of the present invention in which no grid mura occurs.
Figure 14a is a photograph showing the appearance of a border mura.
FIG. 14b is a photograph showing an improved appearance of a display device with improved edge blur according to an embodiment of the present invention.

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

FIG. 1 is an exploded perspective view schematically illustrating a display device according to an embodiment of the present invention.

As illustrated, the display device (100) includes a display panel (110), a backlight unit (120) that irradiates light to the display panel (110), and a cover plate (150) on which the backlight unit (120) and the display panel (110) are mounted.

At this time, for the convenience of explanation, if the direction on the drawing is defined, the backlight unit (120) is placed at the rear of the display panel (110) under the assumption that the display surface of the display panel (110) faces forward, and the cover bottom (150) is positioned on the back of the backlight unit (120), so that the display panel (110) and the backlight unit (120) are modularized as one unit through the cover bottom (150).

Let's look at each of these in more detail.

The display panel (110) may be formed of one of a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), an electroluminescence display device (ELD), and an organic light emitting diode (OLED).

Here, for convenience of explanation, an LCD that transmits light irradiated from a backlight unit (120) to a display panel (110) and displays an image by controlling an electric field applied to a liquid crystal layer of the display panel (110) and changing the arrangement of the liquid crystals will be described as an example.

First, the display panel (110) is a part that plays a key role in image expression and includes first and second substrates (112, 114) that are bonded to each other with a liquid crystal layer in between.

At this time, under the premise of an active matrix method, although not clearly shown in the drawing, a plurality of gate lines and data lines intersect to define pixels on the inner surface of the first substrate (112), which is commonly called a lower substrate or array substrate, and a thin film transistor (TFT) is provided at each intersection point and is connected in a one-to-one correspondence with a transparent pixel electrode formed in each pixel.

And on the inner surface of the second substrate (114) called the upper substrate or color filter substrate, color filters of, for example, red (R), green (G), and blue (B) colors corresponding to each pixel and a black matrix surrounding each of these and covering non-display elements such as gate lines, data lines, and thin film transistors are provided. In addition, a transparent common electrode covering these is provided.

In addition, although not clearly shown in the drawing, upper and lower alignment films (not shown) that determine the initial molecular arrangement direction of the liquid crystal are interposed at the boundary between the two substrates (112, 114) of the display panel (110) and the liquid crystal layer, and a seal pattern is formed along the edges of the two substrates (112, 114) to prevent leakage of the liquid crystal layer filled in between.

At this time, upper and lower polarizing plates (not shown) are attached to the outer surfaces of the first and second substrates (112, 114), respectively.

Along one edge of the display panel (110), a printed circuit board (117) is connected via a connecting member (116) such as a flexible circuit board or a tape carrier package (TCP).

Accordingly, the display panel (110) turns on the thin film transistor selected for each gate line by the on/off signal of the thin film transistor injected into the gate line, and the image signal of the data line is transmitted to the corresponding pixel electrode, and the arrangement direction of the liquid crystal molecules changes due to the electric field generated between the pixel electrode and the common electrode, thereby exhibiting a difference in transmittance.

And, the display device (100) according to the present invention is equipped with a backlight unit (120) that supplies light from the rear surface of the display panel (110) so that the difference in transmittance indicated by the display panel (110) is expressed externally.

A high-brightness surface light source implemented from a backlight unit (120) is provided to a display panel (110), so that the display panel (110) displays an image.

The backlight unit (120) includes a light source unit (129), a resin layer (123) positioned to cover the light source unit (129), a reflector (125) positioned below the light source unit (129), and first to third optical units (210, 220, 230) positioned on the light source unit (129).

The light source unit (129) is a light source of the backlight unit (120), and includes a plate-shaped PCB (129b) that is mounted on the inside of the lower surface (151) of the cover bottom (150) and a plurality of light sources (129a) that are mounted at a set interval on the PCB (129b).

Each light source (129a) may be formed of a light emitting diode (LED), and the light source (129a) that is an LED may be formed of a mini LED having a size of several hundred μm or a micro LED (μLED) having a size of several tens μm. For convenience, the small mini/micro LEDs are collectively referred to as micro LEDs in the following.

Here, the light source (129a) according to the embodiment of the present invention is composed of a blue LED or micro LED including a multi-quantum well layer that emits blue light with excellent luminous efficiency and luminance to improve luminous efficiency and luminance.

The backlight unit (120) including a plurality of light sources (129a) includes a white or silver reflector (125) that covers the entire inner surface (151) of the PCB (129b) and the cover bottom (150) except for the plurality of light sources (129a), and is configured with a plurality of through holes (125a) through which the plurality of light sources (129a) can each pass.

And, a resin layer (123) is positioned on the upper part of the PCB (129b) to cover the entire upper surface of the PCB (129b) and the reflector (125). The resin layer (123) can be applied to the upper part of the PCB (129b) with a thickness thicker than that of the light source unit (129) so as to cover all light sources (129a) mounted on the PCB (129b).

This resin layer (123) serves to fix and protect a plurality of light sources (129a) and support the first to third optical units (210, 220, 230) positioned above the light source unit (129).

Accordingly, an optical gap or air gap is defined between the light source unit (129) and the first to third optical units (210, 220, 230).

An optical gap or air gap is a region where light emitted from two to three adjacent light sources (129a) overlap and mix with each other. If an optical gap or air gap is not secured, a dark area may occur between adjacent light sources (129a) where light does not overlap and mix with each other.

The first to third optical units (210, 220, 230) supported by the resin layer (123) and positioned at a certain interval above the light source unit (129) serve to diffuse and guide light incident from the light source unit (129) to the entire backlight unit (120), and provide a uniformly processed white surface light source to the display panel (110).

The first optical unit (210) includes a dichroic layer (211) and a color conversion layer (213). The first optical unit (210) processes light emitted from a light source (129a) into white light with improved color purity.

That is, since the backlight unit (120) according to the embodiment of the present invention emits blue light from the light source (129a), only clearer blue light is incident on the color conversion layer (213) in the process of transmitting the blue light emitted from the light source through the dichroic layer (211) of the first optical unit (210), and the blue light incident on the color conversion layer (213) is color-converted into white light with improved color purity in the process of transmitting the color conversion layer (213).

The second optical unit (220) positioned above the first optical unit (210) serves to diffuse the light transmitted through the first optical unit (210). The first and second stereoscopic pattern layers (221, 223) and the pattern layer (225) in which a plurality of optical patterns (227, see FIG. 2) are arranged at positions corresponding to the positions of the light source (129a) between the first and second stereoscopic pattern layers (221, 223) are positioned.

The clear white light created in the process of transmitting the first optical unit (210) through the second optical unit (220) together with the third optical unit (230) positioned above is uniformly spread throughout the entire backlight unit (120), thereby improving brightness and light uniformity.

The third optical unit (230) is a composite optical sheet and includes a diffusion section (231) and first and second light-collecting sections (233, 235). The third optical unit (230) diffuses or collects light passing through the first and second optical units (210, 220) to provide a uniform surface light source with high brightness and excellent visibility to the display panel (110).

Through this, the display device (100) according to the embodiment of the present invention realizes high color reproducibility and further improves high brightness and visibility. This will be examined in more detail later.

A cover plate (150) is positioned at the bottom of the backlight unit (120) to support the backlight unit (120). The cover plate (150) is formed of a plate-shaped lower surface (151) and a side surface (153) in which the edge of the lower surface (151) is vertically folded, thereby forming a predetermined space inside which the backlight unit (120) can be installed.

Here, although not specifically shown, the display device (100) may further include a guide panel that surrounds and supports the side of the backlight unit (120) and the display panel (110), and may further include a top cover that surrounds the upper edge of the display panel (110).

As described above, the display device (100) according to the embodiment of the present invention can prevent halo mura from occurring even when only one light source (129a) formed of an LED or micro LED is turned on, and can also prevent lattice mura from occurring even when a reflector (125) is positioned around the light source (129a).

In addition, the display device (100) according to the embodiment of the present invention can be lightweight and thin and have a narrow bezel, and can also prevent the occurrence of frame blur even when implementing a narrow bezel.

This is because the display device according to the embodiment of the present invention has high brightness and high color reproducibility from the backlight unit (120), and a surface light source with improved visibility is provided to the display panel (110).

Let's take a closer look at this with reference to Figure 2.

FIG. 2 is a cross-sectional view schematically illustrating a part of the modularized display device of FIG. 1, and FIG. 3 is a graph showing the reflectivity characteristics of the dichroic layer of the first optical unit.

And, Fig. 4a is a rear perspective view schematically illustrating the second optical unit, Fig. 4b is a photograph showing a three-dimensional pattern layer of the second optical unit, and Fig. 4c is a front view schematically illustrating an optical pattern of the second optical unit.

Figures 5a and 5b are experimental results showing FOS evaluations that vary depending on the angle formed by the corner of the inverted pyramid lens of the second optical unit.

As shown in Fig. 2, the backlight unit (120) is mounted on the upper portion of the plate-shaped lower surface (151) of the cover bottom (150), that is, the plate-shaped PCB (129b) of the backlight unit (120) can be attached to the lower surface (151) of the cover bottom (150) using an adhesive material (not shown) such as a double-sided tape.

A plurality of light sources (129a) are mounted on the PCB (129b) to form a light source unit (129).

The light source (129a) may be an LED or a micro LED, and the LED or micro LED (μLED) may be manufactured by crystallizing an inorganic material such as GaN on a semiconductor wafer substrate such as sapphire or silicon (Si).

LEDs or micro LEDs (μLEDs) are crystallized through an epitaxial growth process. The epitaxial growth process refers to the process of growing on the surface of a crystal while assuming a specific orientation relationship. In order to form the device structure of an LED or micro LED (μLED), a GaN-based compound semiconductor must be stacked on a substrate in the form of a pn junction diode, and each layer grows by inheriting the crystallinity of the layer below.

And, the LED or micro LED (μLED) may include an n-doped n-type semiconductor layer, one or more multi-quantum well layers (MQW) and a p-doped p-type semiconductor layer.

The n-type semiconductor layer is made of a semiconductor material such as GaN, AlGaN, InGaN, AlInGaN, etc., and may contain Si, Ge, Se, Te, or C as impurities, and the p-type semiconductor layer is made of a semiconductor material such as GaN, AlGaN, InGaN, AlInGaN, etc., and may contain Mg, Zn, Be, etc. as impurities.

And, the multi-quantum well layer can have a multi-quantum well structure such as InGaN/GaN, for example.

These multi-quantum well layers can emit light of one color among red, green, and blue, or light of a different color. For example, if the multi-quantum well layer includes an InGaAlP material, it can emit red light, and if the multi-quantum well layer includes an InGaN material with a different In content, it can emit green or blue light.

Meanwhile, although not shown, a reflective pattern layer (not shown) is positioned under the light source (129a) so that light emitted from the light source (129a) that is not incident on the display panel (110) can be reflected so that it is incident on the display panel (110). If a reflective pattern layer (not shown) is provided, the luminous efficiency of the light source (129a) can be increased.

Here, the light source (129a) according to the embodiment of the present invention is composed of a blue LED or blue micro LED including a multi-quantum well layer that emits blue light with excellent luminous efficiency and luminance in order to improve luminous efficiency and luminance.

And on the PCB (129b), a reflector (125) is positioned, which is configured with a plurality of through holes (125a) through which a plurality of light sources (129a) can pass. The reflector (125) covers the entirety of the PCB (129b) and the lower surface (151) of the cover bottom (150) except for the plurality of light sources (129a), thereby reflecting light emitted from the plurality of light sources (129a) toward the back and side surfaces of the light sources (129a) toward the first to third optical units (210, 220, 230), thereby improving the brightness of the light.

In addition, since these reflectors (125) reflect light toward the first to third optical units (210, 220, 230), they also prevent halo mura from occurring, in which light is diffused to the surroundings even when only one light source (129a) is turned on.

The reflector (125) can be attached to the PCB (129b) using an adhesive material (not shown) such as a double-sided tape.

A resin layer (123) covering the entire upper surface of the PCB (129b) and the reflector (125) is positioned on the upper side of the PCB (129b) including the reflector (125). The resin layer (123) is filled on the upper side of the light source unit (129) and is positioned to completely cover the light source unit (129).

This resin layer (123) can be applied to the upper portion of the PCB (129b) with a thickness thicker than the light source unit (129) so as to cover all light sources (129a) mounted on the PCB (129b).

This resin layer (123) serves to fix and protect a plurality of light sources (129a) and to support the first to third optical units (210, 220, 230) positioned above the light source unit (129). This resin layer (123) may use, for example, a photocurable or thermocurable resin, and the cured resin layer (123) may have a strength greater than a predetermined size, thereby enabling the protection of the plurality of light sources (129a) and the support of the first to third optical units (210, 220, 230).

It is preferable that such a resin layer (123) have a refractive index greater than the refractive index of air (n=1) so as to further improve the extraction efficiency of light emitted from the light source (129a).

That is, since each light source (129a) has a refractive index within the light source (129a) greater than that of air, light emitted from the light source (129a) may be reflected at the interface where it comes into contact with air, which may reduce light extraction efficiency.

At this time, by positioning the resin layer (123) having a refractive index greater than that of air above the light source (129a), the difference between the internal refractive index of the light source (129a) and the refractive index of the resin layer (123) becomes smaller than the difference between the internal refractive index of the light source (129a) and the refractive index of air, so that the reflection ratio of light emitted from the light source (129a) is lowered, and thus the light extraction efficiency can be increased.

The dichroic layer (211) of the first optical unit (210) positioned above the resin layer (123) is a layer formed by alternately laminating high refractive index inorganic materials with low light absorption and low refractive index inorganic materials, and acts as a light filter that selectively passes light according to wavelength.

Referring to the graph showing the reflectivity characteristics of the dichroic layer (211) of the present invention in the attached Fig. 3, the horizontal axis of the graph represents the wavelength of light (wavelength (nm)) and the vertical axis of the graph represents the reflectivity (R (%)).

And (a) represents the emission wavelength of blue light, (b) represents the emission wavelength of green light, (c) represents the emission wavelength of red light, and (d) represents the reflectivity of the dichroic layer (211) according to the wavelength of light.

Referring to the graph, it can be seen that it has a low reflectance for light with a wavelength ranging from 400 nm to 500 nm, while it has a high reflectance of over 90% for light with a wavelength ranging from 550 nm to 700 nm.

That is, the dichroic layer (211) prevents light of a color other than blue light from being transmitted from the blue light emitted from the light source (129a), thereby allowing only blue light with improved color purity to be incident on the color conversion layer (213) positioned above the dichroic layer (211).

Therefore, the blue light passing through the dichroic layer (211) becomes clear blue light with improved color purity.

And the color conversion layer (213) of the first optical unit (210) positioned above the dichroic layer (211) can convert color by including a mineral that can absorb light of a specific wavelength range (or color) and emit light of a wavelength range different from the specific wavelength range.

Here, since the light source (129a) is composed of a blue LED or blue micro LED that emits blue light, light having a wavelength range of about 420 nm to 490 nm corresponding to blue is emitted from the light source (129a).

In this way, when the light source (129a) is a blue LED or a blue micro LED, the color conversion layer (213) may convert light (blue light) in a wavelength range corresponding to blue emitted from the light source (129a) into white light.

More specifically, the light included in the color conversion layer (213) may absorb light in a wavelength range of about 420 nm to 490 nm corresponding to blue and emit light in a wavelength range of about 490 nm to 580 nm corresponding to green (green light), or absorb light in a wavelength range of about 420 nm to 490 nm corresponding to blue and emit light in a wavelength range of about 580 nm to 780 nm corresponding to red (red light).

In this way, when the blue light emitted from the light source (129a) is converted into green light and red light in the color conversion layer (213), white light, which is a combination of the green light, the red light, and the blue light emitted from the light source (129a), can be supplied to the display panel (110 in FIG. 1).

This is because blue light has a shorter wavelength than red light and green light, and the fluorescence efficiency of the color conversion layer (213) is slightly better for light of a shorter wavelength, and the color conversion layer (213) is slightly better in terms of lifespan, etc., in converting light of relatively long wavelengths into red light and green light than in converting light of relatively short wavelengths into blue light.

This color conversion layer (213) includes a color conversion material, and the color conversion material may be, for example, a quantum dot, a fluorescent dye, or a combination thereof. The fluorescent dye includes, for example, an organic fluorescent material, an inorganic fluorescent material, and a combination thereof.

Quantum dots can be selected from, but are not limited to, group II-VI compounds, group III-V compounds, group IV-VI compounds, group IV elements, group IV compounds, and combinations thereof.

Group II-VI compounds are binary compounds selected from the group consisting of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; It may be selected from the group consisting of ternary compounds selected from the group consisting of CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and mixtures thereof, and quaternary compounds selected from the group consisting of HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe and mixtures thereof.

The group III-V compound may be selected from the group consisting of a binary compound selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; a ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and mixtures thereof; and a quaternary compound selected from the group consisting of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof.

The group IV-VI compound may be selected from the group consisting of a binary compound selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe and mixtures thereof; a ternary compound selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe and mixtures thereof; and a quaternary compound selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe and mixtures thereof.

Group IV elements can be selected from the group consisting of Si, Ge, and mixtures thereof.

The group IV compound may be a binary compound selected from the group consisting of SiC, SiGe, and mixtures thereof.

At this time, the binary, ternary or quaternary compound may exist within the particle at a uniform concentration, or may exist within the same particle with the concentration distribution partially divided into different states. In addition, one quantum dot may have a core/shell structure surrounding another quantum dot.

The interface between the core and the shell can have a concentration gradient in which the concentration of elements present in the shell decreases toward the center.

These quantum dots can have a full width of half maximum (FWHM) of an emission wavelength spectrum of about 45 nm or less, preferably about 40 nm or less, more preferably about 30 nm or less, and can improve color purity or color reproducibility within this range.

In addition, the shape of the quantum dot is not particularly limited to the commonly used shape, but more specifically, it can be used in the shape of spherical, pyramidal, multi-arm, or cubic nanoparticles, nanotubes, nanowires, nanofibers, nanoplatelet particles, etc.

The fluorescent dye can be, for example, a red fluorescent dye, a green fluorescent dye, a dye that emits light of a third color, or a combination thereof.

A red fluorescent dye is a material that absorbs light in a blue wavelength range and emits light in a red wavelength range, and may be, for example, at least one of (Ca, Sr, Ba)S, (Ca, Sr, Ba)2Si5N8, CaAlSiN3, CaMoO4, Eu2Si5N8, K2SiF6, SrCaAlSiN3, CaS, and SrLiAlN3. In addition, the red fluorescent dye may be, for example, a material having a maximum emission peak at 617 nm to 637 nm and a full width at half maximum (FWHM) of 10 nm to 100 nm.

A green fluorescent dye is a material that absorbs light in the blue wavelength range and emits light in the green wavelength range, and may be, for example, at least one of yttrium aluminum garnet (YAG), (Ca, Sr, Ba)2SiO4, SrGa2S4, barium magnesium aluminate (BAM), alpha-SiAlON, beta-SiAlON, Ca3Sc2Si3O12, Tb3Al5O12, BaSiO4, CaAlSiON, Sr1-xBax)Si2O2N2, LuAG, (Ca, Sr, Ba)Si2O2N2, and GaS.

In addition, the green fluorescent dye may be, for example, a material having a maximum emission peak at 510 nm to 525 nm and a full width at half maximum (FWHM) of 60 nm to 70 nm. In a specific example, as the green fluorescent dye, a first green fluorescent dye having a maximum emission peak at 520 nm and a full width at half maximum (FWHM) of 62 nm and a second green fluorescent dye having a maximum emission peak at 511 nm and a full width at half maximum (FWHM) of 64 nm may be used. However, the green fluorescent dye is not limited to the examples described above.

Meanwhile, the fluorescent dyes listed so far can be made of inorganic fluorescent substances, and organic fluorescent substances can be made of BODIPY series fluorescent substances.

Additionally, Perovskite materials can also be applied.

Here, the dichroic layer (211) positioned below the color conversion layer (213) prevents back scattering of red and green light generated in the process of converting blue light into white light in the color conversion layer (213) from being emitted toward the light source.

Backscattering can cause dark spots in which the area where the light source (129a) is mounted appears relatively dark.

The dichroic layer (211) prevents light of other colors than blue light from being transmitted from the light source (129a), thereby preventing backscattering by allowing both red light and green light among the light converted from the color conversion layer (213) to be reflected toward the display panel (110 in FIG. 1). Through this, light loss can be minimized, thereby improving the brightness of the present invention.

Additionally, the occurrence of edge mura phenomenon can be prevented by enhancing the color mixing of red, green, and blue light.

Sample 1 Sample 2 Brightness enhancement rate (%) 100% 110 ~ 120% ↑

In the above (Table 1), Sample 1 is a configuration of a backlight unit that does not have a dichroic layer, and the luminance of the display device including the backlight unit in which blue light emitted from a light source is directly converted into color in the color conversion layer is defined as 100%. Sample 2 is a configuration of a display device (100 in FIG. 1) including a backlight unit (120) in which a dichroic layer (211) is provided below a color conversion layer (213) according to an embodiment of the present invention, and as can be seen in (Table 1), by positioning the dichroic layer (211) below the color conversion layer (213), it can be confirmed that the luminance of the display device (100 in FIG. 1) is improved by 10 to 20%.

This is because, as mentioned above, the dichroic layer (211) prevents backscattering of the red and green light converted in the color conversion layer (213) and allows them to be reflected toward the display panel (110 in FIG. 1), thereby minimizing the occurrence of light loss.

The second optical unit (220) positioned above the first optical unit (210) has a pattern layer (225) positioned between the first and second stereoscopic pattern layers (221, 223) and the first and second stereoscopic pattern layers (221, 223). The second optical unit (220) serves to diffuse high-purity white light transmitted through the first optical unit (210).

Looking at the second optical unit (220) in more detail with reference to the attached FIG. 4a, the second optical unit (220) includes first and second stereoscopic pattern layers (221, 223). The first stereoscopic pattern layer (221) includes a first base layer (221a) and a first stereoscopic lens layer (221b) for diffusing light on the lower surface of the first base layer (221a), and the second stereoscopic pattern layer (223) positioned above the first stereoscopic pattern layer (221c) includes a second base layer (223a) and a second stereoscopic lens layer (223b) for diffusing light on the lower surface of the second base layer (223a).

And the pattern layer (225) is positioned between the first and second stereoscopic pattern layers (221, 223), more precisely, between the first base layer (221a) of the first stereoscopic pattern layer (221) and the second stereoscopic lens layer (223b) of the second stereoscopic pattern layer (223). The pattern layer (225) includes a plurality of optical patterns (227) at positions corresponding to the positions of the light source (129a).

The first and second base layers (221a, 223a) of the first and second three-dimensional pattern layers (221, 223) are made of a light-transmitting polycarbonate series, polysulfone series, polyacrylate series, polystyrene series, polyvinyl chloride series, polyvinyl alcohol series, polynorbornene series, polyester series, etc.

And, the first and second stereoscopic lens layers (221b, 223b) formed on the lower portions of the first and second base layers (221a, 223a), respectively, are made of transparent acrylic resin, and the first and second stereoscopic lens layers (221b, 223b) have a plurality of first and second inverted pyramid lenses (221c, 223c) in a pyramidal shape arranged to protrude from the back surfaces of the first and second base layers (221a, 223a).

These plurality of first and second inverted pyramid lenses (221c, 223c) are formed in a shape in which the area decreases from the lower surface defined on the back surface of the first and second base layers (221a, 223a) toward the upper surface, and the plurality of first and second inverted pyramid lenses (221c, 223c) are arranged adjacent to each other in the longitudinal and transverse directions, and are arranged densely so that there is no empty space between the adjacent first and second inverted pyramid lenses (221c, 223c).

As illustrated in FIGS. 4b and 4c, the first and second inverted pyramid lenses (221c, 223c) are formed with a lower surface (222) formed in a square shape and four side surfaces (224) extending from edges of the lower surface (222) to form one corner, and the width (w) of the first and second inverted pyramid lenses (221c, 223c) corresponding to one length of the lower surface (222) of the first and second inverted pyramid lenses (221c, 223c) is formed to have a range of 20 to 40 um, and the angle (α) formed by the corners of the first and second inverted pyramid lenses (221c, 223c) can be formed to have a range of 90 to 130 degrees.

When the width (w) of the first and second inverted pyramid lenses (221c, 223c) is 20 um or less, it becomes difficult to form the first and second inverted pyramid lenses (221c, 223c) themselves, and when the width (w) of the first and second inverted pyramid lenses (221c, 223c) is 40 um or more, it becomes difficult to form the angle (α) formed by the corners of the inverted pyramid lenses (221c, 223c) to have a range of 90 to 130 degrees.

Corner angle of inverted pyramid lens 0 degrees 20 degrees 40 degrees 60 degrees 90 degrees 130 degrees Luminance Efficiency (%) 94% 95% 94% 96% 98% 100% Color change characteristics (Wx, Wy) Equivalent level Equivalent level Equivalent level Equivalent level Equivalent level Equivalent level FOS Evaluation NG NG NG NG OK OK

The above (Table 2) is the experimental result data measuring the luminance efficiency and FOS evaluation and color change characteristics according to the angle (α) formed by the corners of the first and second inverted pyramid lenses (221c, 223c) of the first and second stereoscopic lens layers (221b, 223b). The first and second inverted pyramid lenses (221c, 223c) were fixed to the same width (w), and only the angle (α) formed by the corners was varied to measure them. (Table 2) shows that the luminance efficiency is measured to be the highest when the angles (α) formed by the corners of the first and second inverted pyramid lenses (221c, 223c) are 90 degrees and 130 degrees, and it can be confirmed that the FOS evaluation is also judged as good only when the angles (α) formed by the corners of the inverted pyramid lenses (221c, 223c) are 90 degrees and 130 degrees.

Here, the FOS evaluation indicates the appearance (Front of Screen; FOS) status of the display device (100 in Figure 1), and the appearance status can be expressed by dividing it into levels 1 to 5, which are relative values. Levels 2 to 5 indicate a defective state in which the display quality is lowered due to the occurrence of stains such as halo mura.

When the angle (α) formed by the corners of the inverted pyramid lenses (221c, 223c) is 0 to 60 degrees, the FOS evaluation is at levels 2 to 3 as shown in FIG. 5a, resulting in a poor evaluation. However, when the angle (α) formed by the corners of the inverted pyramid lenses (221c, 223c) is 90 to 130 degrees as in the embodiment of the present invention, the FOS evaluation is at level 1 as shown in FIG. 5b, resulting in a good evaluation.

The pattern layer (225) positioned between the first and second stereoscopic pattern layers (221, 223) includes a number of optical patterns (227) at positions corresponding to the positions of the light source (129a). The optical pattern (227) reflects a portion of the light emitted upward from the light source (129a) positioned downward and disperses it in the lateral direction, and allows the remaining portion of the light to be transmitted and to proceed in the upward direction.

Accordingly, most of the light can be prevented from traveling in a vertical upward direction and entering the display panel (110 in Fig. 1), thereby preventing the occurrence of hot spots due to light incident in a vertical upward direction, thereby improving image quality deterioration caused by hot spots.

We will examine the optical pattern (227) in more detail later.

This second optical unit (220) can realize a more uniform light diffusion distribution through the optical pattern (227) and the first and second three-dimensional pattern layers (221, 223).

The third optical unit (230) is a composite optical sheet and includes a diffusion section (231) and first and second light collecting sections (233, 235). The first light collecting section (233) includes a first support layer (233a) and a first lens layer (233b) for collecting light on the upper surface of the first support layer (233a), and the second light collecting section (235) located on the upper surface of the first light collecting section (233) includes a second support layer (235a) and a second lens layer (235b) for collecting light on the upper surface of the second support layer (235a).

And, the diffusion part (231) is composed of a third support layer (231a) and first and second diffusion layers (231b, 231c) located on both sides of the third support layer (231a).

Looking at these layers in more detail here, the first and second support layers (233a, 235a) of the first and second light collecting members (233, 235) are made of light-transmittable polycarbonate series, polysulfone series, polyacrylate series, polystyrene series, polyvinyl chloride series, polyvinyl alcohol series, polynorbornene series, polyester series, etc.

And, the first and second lens layers (233b, 235b) formed on the first and second support layers (233a, 235a), respectively, are made of transparent acrylic resin, and are arranged in a belt shape along one longitudinal direction of the third optical unit (230), so that a plurality of first and second prism mountains (233c, 235c) in a form of repeated mountains and valleys are arranged in a row and protrude from the first and second support layers (233a, 235a), respectively.

Due to these first and second prisms (233c, 235c), the third optical unit (230) focuses light onto the display panel (110 in FIG. 1) positioned above the third optical unit (230), thereby achieving a brightness-enhancing effect.

Meanwhile, the first and second lens layers (233b, 235b) may be formed of, in addition to the first and second prism mountains (233c, 235c), a prism having a polygonal cross-section, a micro lens pattern, a lenticular lens, an emboss pattern, or a combination thereof.

In addition, although the heights of the first and second prism mountains (233c, 235c) are the same in the drawing, the heights of the adjacent first and second prism mountains (233c, 235c) may be different from each other. The heights of the first and second prism mountains (233c, 235c) may be 10 ㎛ to 40 ㎛, specifically, 10 ㎛ to 30 ㎛.

In addition, the pitches of the first and second prism mountains (233c, 235c) may also be different from each other, and the pitch corresponding to the bottom of the first and second prism mountains (233c, 235c) may be 10 µm to 60 µm, specifically 20 µm to 60 µm.

And, the vertex angle of the first and second prisms (233c, 235c) can be 80° to 100°, and within the above range, a brightness enhancement effect can be achieved.

Here, the cross sections of the first and second prism mountains (233c, 235c) of the first and second lens layers (233b, 235b) are shown to be identical in the drawing, so that the longitudinal directions of the first and second lens layers (233b, 235b) are shown to be in the same direction. However, the first and second lens layers (233b, 235b) that are arranged in a row and protrude along the longitudinal direction of the third optical unit (230) are arranged so that their longitudinal directions are perpendicular to each other, thereby preventing pitch moire from occurring between the first and second lens layers (233b, 235b) while also improving brightness.

That is, the first lens layer (233b) is arranged to protrude in a row in the X-axis direction defined in the drawing, and the second lens layer (235b) is arranged to protrude in a row in the Y-axis direction perpendicular to the X-axis direction defined in the drawing, so that the longitudinal directions of the first and second lens layers (233b, 235b) are orthogonal to each other.

At this time, a light diffusion adhesive (240) may be further positioned between the first light collecting unit (233) and the second light collecting unit (235), more precisely, between the first prism (233c) of the first lens layer (233b) and the second support layer (235a).

The light diffusing adhesive (240) enables the first and second light collecting members (233, 235) to be attached and fixed to each other, and also protects the vertex angle of the first prism (233c) of the first light collecting member (233).

In addition, a diffusion part (231) is positioned below the first and second light collecting parts (233, 235). That is, the diffusion part (231) is positioned at the lowest end of the third optical unit (230) to further diffuse the light emitted from the first and second optical units (210, 220) so that it has a uniform distribution over a wide range.

This diffusion part (231) is formed of a third support layer (231a), and first and second diffusion layers (231b, 231c) are positioned on both sides of the third support layer (231a). The third support layer (231a) is formed of a light-transmitting material such as polycarbonate, polysulfone, polyacrylate, polystyrene, polyvinyl chloride, polyvinyl alcohol, polynorbornene, or polyester.

Here, the first and second diffusion layers (231b, 231c) may be configured to include a light diffusion component such as a bead, or may be configured to form a micro-pattern on the lower surface of the first and second diffusion layers (231b, 231c) without including a bead.

Through this, the first and second diffusion layers (231b, 231c) diffuse the light by refracting and scattering the incident light, and play a role in emitting the non-uniform light passing through the first and second optical units (210, 220) as uniform light.

At this time, the beads are configured by being included in the binder resin, and the beads have the characteristic of being able to prevent light from being partially concentrated by dispersing light incident on the first and second diffusion layers (231b, 231c).

Here, the binder resin that can be used is one that has high transparency, excellent light transmittance, and easy viscosity control, such as acrylic, urethane, epoxy, vinyl, polyester, or polyamide resins.

At this time, it is desirable for the second diffusion layer (231c) to have a haze characteristic of 90% to 95% for the light emitted from the third support layer (231a), and for this purpose, the beads may have a size of 2 um to 15 um.

And, in order to diffuse the light incident on the third support layer (231a), the first diffusion layer (231b) may have beads with a size of 2 um to 5 um.

In addition, the first and second diffusion layers (231b, 231c) that do not include beads have a characteristic that the light scattering angle can be adjusted depending on the shape of the micro-pattern. The micro-pattern can be configured in various ways, such as an elliptical pattern and a polygon pattern. In addition, by using a hologram pattern, the light incident on the interference pattern can be refracted in an asymmetrical direction, thereby allowing the collected light to be diffused at a more inclined angle.

Through this, the first and second diffusion layers (231b, 231c) diffuse the light by refracting and scattering the incident light and play a role in emitting the non-uniform light passing through the first and second optical units (210, 220) as uniform light.

At this time, it is preferable that the beads contained in the binder resin of the second diffusion layer (231c) have various sizes and control the spreading toward the upper part of the third support layer (231a) so that the height of the second diffusion layer (231c) varies.

That is, in the first region (B) defined in the drawing, the spread of the bead (348a) is controlled so that the second diffusion layer (231c) has the first height (h1), and in the second region (C), the spread of the bead is controlled so that the second diffusion layer (231c) has the second height (h2) that is lower than the first height (h1).

The second diffusion layer (231c) of the first height (h1) located in the first region (B) comes into contact with the lower surface of the first support layer (233a) of the first light collecting unit (233) located above the second diffusion layer (231c), and the second diffusion layer (231c) of the second height (h2) located in the second region (C) is spaced apart from the lower surface of the first support layer (233a) of the first light collecting unit (233) by a certain distance to form an air gap (air gap: A).

The air gap (A) formed between the second diffusion layer (231c) and the first support layer (233a) serves to prevent the light collection function of the first and second light collection units (233, 235) of the third optical unit (230) from being impaired.

That is, the brightness of light differs depending on whether there is an air gap (A) between the diffusion unit (231) and the first and second light collectors (233, 235) and whether there is no air gap (A). In the case where there is an air gap (A) between the diffusion unit (231) and the first and second light collectors (233, 235), the light that is incident at 90 degrees to the first and second light collectors (233, 235) and is totally reflected is small, and the majority of the light is emitted in the direction of the display panel (110 in FIG. 1).

On the other hand, when there is no air gap (A) between the diffusion portion (231) and the first and second light collectors (233, 235), a large amount of light is incident at 90 degrees to the first and second light collectors (233, 235) and is totally reflected, and most of the light is not emitted toward the display panel (110 in FIG. 1) but is re-incident toward the diffusion portion (231).

Through this, it can be seen that by forming an air gap (A) between the diffusion part (231) and the first and second light collecting parts (233, 235), the amount of light can be increased, and thus the brightness can also be improved, compared to a configuration in which the air gap (A) is not formed between the diffusion part (231) and the first and second light collecting parts (233, 235) and are simply attached.

These first and second light-collecting parts (233, 235) and the diffusion part (231) are all joined together as one body. To this end, the second diffusion layer (231c) of the diffusion part (231) has a point-wise characteristic. Accordingly, the first light-collecting part (233) and the diffusion part (231) are joined together as one body through the adhesive characteristic of the second diffusion layer (231c) having the first height (h1) of the diffusion part (231).

Here, the third support layer (231a) of the diffusion unit (231) serves as a base supporting the entire third optical unit (230), and the first and second support layers (233a, 235a) serve to support only the first and second lens layers (233b, 235b) of the first and second light collecting units (233, 235), respectively. Therefore, the thickness of the first and second support layers (233a, 235a) can be formed thinner than the thickness of the third support layer (231a), thereby reducing the overall thickness of the third optical unit (230).

As described above, the display panel (110 of FIG. 1) according to the embodiment of the present invention comprises a first optical unit (210) formed of a dichroic layer (211) and a color conversion layer (213) above a light source (129a), a second optical unit (220) formed of a pattern layer (225) including first and second stereoscopic pattern layers (221, 223) and an optical pattern (227) above the first optical unit (210), and a third optical unit (230) formed of a composite optical sheet including first and second light collecting units (233, 235) and a diffusion unit (231) above the second optical unit (220), thereby providing a surface light source having high brightness and high color reproducibility and improved visibility from the backlight unit (120) to the display panel (110 of FIG. 1). It can be provided.

Through this, even if only one light source (129a) made of an LED or micro LED is turned on, halo mura can be prevented from occurring, and even if a reflector (125) is positioned around the light source (129a) to prevent halo mura, lattice mura can be prevented from occurring.

In addition, the display device (100 of FIG. 1) according to an embodiment of the present invention can be lightweight and thin and have a narrow bezel, and can prevent the occurrence of frame blur even when implementing a narrow bezel, thereby preventing the occurrence of a problem of deterioration in the image quality of the display device (100 of FIG. 1).

In addition, since a thick diffuser plate can be omitted on top of the light source (129a), a light weight and thin body can be realized, and there is also the effect of reducing process costs and facilitating assembly.

Meanwhile, in the explanation so far, it has been explained as an example that the light source (129a) emits blue light, but the light source (129a) may emit light of a different color in addition to blue light, and in this case, the color conversion layer (213) may include various minerals corresponding to the color of the light emitted from the light source (129a) in order to convert the color of the light emitted from the light source (129a) into white light.

For example, when green light is emitted from a light source (129a), the light material of the color conversion layer (213) may be a material having a property of absorbing green light and emitting red light, or absorbing green light and emitting blue light.

Meanwhile, it is desirable to form the optical pattern (227) of the second optical unit (220) to have a larger size than the light source (129a). This will be examined in more detail with reference to FIGS. 5 and 6.

FIG. 6 is a front view schematically illustrating the relationship between the size of a light source and an optical pattern according to an embodiment of the present invention, FIG. 7a is a photograph schematically illustrating an example of an optical pattern, and FIG. 7b is a photograph showing an appearance in which an optical pattern is applied.

And, Fig. 8 is a schematic diagram schematically illustrating the light propagation path passing through the second optical unit.

As illustrated in FIG. 6, the optical pattern (227) can be formed by printing using light-shielding ink so that light is not concentrated on the upper surface of the first base layer (221a) of the second optical unit (220). However, the optical pattern (227) does not have the function of completely blocking light, but rather, it is preferable to implement it so that the degree of light shielding or diffusion can be adjusted with a single optical pattern (227) so that it can perform both the functions of light shielding and diffusion for a portion of the light.

That is, the optical pattern (227) may be formed as a single layer structure (1 degree), but may also be implemented as a composite pattern overlapping printing structure. The overlapping printing structure refers to a structure that forms one pattern and implements it by printing another pattern shape on top of it.

For example, in implementing an optical pattern (227), a diffusion pattern formed using a light-shielding ink containing one or more materials selected from TiO2, CaCO3, BaSO4, Al2O3, and silicon (Si) on the lower surface of a polymer film in the direction of light emission can be implemented using an overlapping printing structure using a light-shielding ink containing Al or a mixture of Al and TiO2.

This overlapping printing structure can be formed by printing a diffusion pattern in white on the surface of a polymer film, and then forming a light-shielding pattern on top of it, or it can be formed in the opposite order as a double-layer structure (2 degrees). Of course, it is obvious that the formation design of this pattern can be modified in various ways by considering the efficiency and intensity of light, and the light-shielding rate.

Alternatively, it is also possible to form a triple-layer structure (3 degrees) in which a shading pattern, which is a metal pattern, is formed in the middle layer of the sequentially laminated structure, and a diffusion pattern is implemented on the upper and lower layers, respectively. In this triple-layer structure, it is possible to select and implement the materials described above, and as a preferable example, one of the diffusion patterns is implemented using TiO2 having an excellent refractive index, CaCO3 having excellent light stability and color sense is used together with TiO2 to implement another diffusion pattern, and Al having excellent hiding is used to implement a shading pattern, thereby ensuring the efficiency and uniformity of light.

In particular, CaCO3 has the function of implementing white light through the function of reducing exposure to yellow light, thereby enabling more stable and efficient light implementation. In addition to CaCO3, inorganic materials with large particle sizes and similar structures, such as BaSO4, Al2O3, and Silicon beads, can also be utilized.

As illustrated in FIG. 7a, the size of the pattern changes as it gets farther away from the emission direction of the light source (129a), or the optical pattern (227) can be formed by adjusting the pattern density so that the pattern density decreases as it gets farther away from the emission direction of the light source (129a).

As shown in Fig. 7b, these optical patterns (227) are arranged in multiple numbers at regular intervals corresponding to each light source (129a).

Here, it is preferable that the optical pattern (227) be formed to have a larger area than the light source (129a), and it is preferable that the diameter (d) of the optical pattern (227) be formed to be 5.3 to 5.6 times larger than the diameter (D) of the light source (129a).

Looking at Table 3 below, when D represents the diameter of the light source (129a), the diameter (d) of the optical pattern (227) can be formed to be 4.3 to 5.6 times larger than the diameter (D) of the light source (129a). Since the amount of change in brightness is minimal, the size of the optical pattern (227) can be designed by considering only the FOS evaluation by the grating Mura.

That is, when the diameter (d) of the optical pattern (227) is designed to be 5.3 to 5.6 compared to the diameter (D) of the light source (129a), the FOS evaluation by the grating Mura is measured well, so it is preferable to design the diameter (d) of the optical pattern (227) to be 5.3 to 5.6 compared to the diameter (D) of the light source (129a), and at this time, it is preferable to form the optical pattern (227) as a double-layered overlapping printing structure.

division Size of optical pattern D: 4.3 D: 4.6 D: 5 D: 5.3 D: 5.6 1 degree printing
(Printing thickness ≒ 10um) Brightness 696.8 693.2 685.2 685.1 683.2 Grid Mura river river river river river 2nd degree printing
(Printing thickness ≒ 20um) Brightness 668.6 665.5 659 659 654 Grid Mura river middle middle approximately approximately 3 degree printing
(Printing thickness ≒ 30um) Brightness 647 641.8 639 638 632.1 Grid Mura river middle middle middle middle

Here, referring to FIG. 8, when examining the path of light passing through the second optical unit (220), light emitted from the light source (129a) is first diffused in the process of passing through the first three-dimensional pattern layer (221) of the second optical unit (220), and some of the light emitted in the upper direction of the light source (129a) among the first diffused light is reflected by the optical pattern (227) so as to be dispersed in the lateral direction, and the remaining light passes through the optical pattern (227) so as to proceed upward. At this time, by forming the diameter (d) of the optical pattern (227) to be 5.3 to 5.6 times larger than the diameter (D) of the light source (129a), the light emitted from the light source (129a) is diffused in the process of passing through the first three-dimensional pattern layer (221), thereby enabling more light to be dispersed in the lateral direction of the light source (129a).

Accordingly, most of the light can be prevented from traveling in a vertical upward direction and entering the display panel (110 in Fig. 1), thereby preventing the occurrence of hot spots due to light incident in a vertical upward direction, thereby improving image quality deterioration caused by hot spots.

In addition, the light transmitted through the optical pattern (227) and the light dispersed in the lateral direction of the light source (129a) are secondarily diffused in the process of passing through the second three-dimensional pattern layer (223), so that the light passing through the second optical unit (220) is diffused more widely than the light emitted from the first optical unit (210 of FIG. 2) to have a uniform distribution over a wide range.

FIG. 9a is a schematic drawing illustrating a state in which backscattering occurs, and FIG. 9b is a schematic drawing illustrating a state in which backscattering does not occur in a display device according to an embodiment of the present invention.

FIG. 10a is a photograph showing a state in which dark spots occur due to backscattering, and FIG. 10b is a photograph showing a state in which dark spots are prevented in a display device according to an embodiment of the present invention.

And FIG. 11a is a graph showing the light transmission spectrum of a display device without a dichroic layer, and FIG. 11b is a graph showing the light transmission spectrum of a display device according to an embodiment of the present invention.

As illustrated in Fig. 9a, in the process of blue light (B) emitted from a light source (129a) being converted into white light in the color conversion layer (210) of the first optical unit (210), some of the red light (R) and green light (G) generated in the color conversion layer (210) are emitted downward toward the light source (129a).

This is defined as back scattering.

Such backscattering causes a dark spot in which the area where the light source (129a) is mounted appears relatively dark, as shown in FIG. 10a. In contrast, as shown in FIG. 9b, the display device (100 of FIG. 1) according to the embodiment of the present invention can further position the dichroic layer (211) between the light source (129a) of the backlight unit (120 of FIG. 2) and the color conversion layer (213), thereby preventing the red light and green light converted in the color conversion layer (213) from being emitted downward.

This prevents backscattering from occurring, minimizing light loss and achieving high brightness, thereby also preventing dark spots from occurring as shown in Fig. 10b.

In addition, referring to FIGS. 11a and 11b, it can be confirmed that the green light transmission spectrum of the display device (100 in FIG. 1) equipped with the dichroic layer (211) is higher than that of the display device not equipped with the dichroic layer (211).

Through this, it can be confirmed that the ditroic layer (211) prevents red light and green light from being emitted in the downward direction, thereby minimizing light loss.

division Sample 3 Sample 4 Review Results LCM Brightness (5P, Avg) 971.0
(100%) 1063.0
(110%) Color gamut (%) 98.8% 99.6%

The above (Table 4) is an experimental result measuring the luminance and color gamut of a display device (100 in FIG. 1) according to an embodiment of the present invention and a general display device, where Sample 3 represents a general display device and Sample 4 represents an experimental result measuring the luminance and color gamut of a display device (100 in FIG. 1) according to an embodiment of the present invention. Before explanation, LCM luminance represents an average value obtained by measuring the luminance of five arbitrary points after driving an image from the display device, and color gamut is a value expressed when the color space area according to the color standard of the DCI (digital cinema initiative), which is a digital cinema system standard, is assumed to be 100%.

A high color gamut means high color reproducibility.

Looking at the above (Table 4), we can see that the LCM brightness of Sample 4 is 10% higher than that of Sample 3, and the color gamut is also improved.

This means that the display device (100 in FIG. 1) according to the embodiment of the present invention has higher brightness and improved color reproducibility compared to general display devices.

Figures 12a and 12b are graphs showing the luminance distribution according to the viewing angle depending on the presence or absence of the first and second stereoscopic pattern layers of the second optical unit.

FIG. 12a shows a luminance distribution according to a viewing angle centered on one light source transmitting the second optical unit in a display device not equipped with the first and second stereoscopic pattern layers of the second optical unit, and FIG. 12b shows a luminance distribution according to a viewing angle centered on one light source (129a in FIG. 9b) transmitting the second optical unit (220 in FIG. 8) of a display device (100 in FIG. 1) according to an embodiment of the present invention.

Referring to Fig. 12a, it can be seen that when the first and second stereoscopic pattern layers are not provided, the brightness of the center corresponding to the light source is the highest, and the brightness is distributed relatively lower around it.

In contrast, referring to FIG. 12b, since the first and second stereoscopic pattern layers (221, 223 of FIG. 8) including the first and second inverted pyramid lenses (221c, 223c of FIG. 8) are provided in the second optical unit (220 of FIG. 8), it can be confirmed that the brightness is distributed higher around the light source (129a of FIG. 9b) than at the center corresponding to the light source.

Through this, it can be confirmed that the first and second stereoscopic pattern layers (221, 223 in FIG. 8) cause the light emitted from the light source (129a in FIG. 9b) to spread more widely.

In this way, the display device (100 of FIG. 1) according to the embodiment of the present invention can improve brightness and light uniformity by uniformly diffusing light emitted from a light source (129a of FIG. 9b) while passing through the second optical unit (220 of FIG. 8).

That is, the first and second stereoscopic pattern layers (221, 223 in FIG. 8) cause the light incident on the second optical unit (220 in FIG. 8) to be refracted and diffused in various ways by the first and second inverted pyramid lenses (221c, 223c in FIG. 8) of the first and second stereoscopic pattern layers (221, 223 in FIG. 8), thereby increasing the light collection efficiency of the light source for the display panel (110 in FIG. 1) and improving the brightness.

In addition, it also plays a role in improving the light uniformity so that light propagates as uniformly as possible toward the display panel (110 in Fig. 1) and minimizing the loss of light source due to wide diffusion.

FIG. 13a is a photograph showing a state in which grid mura occurs, FIG. 13b is a photograph showing a state in which grid mura does not occur in a display device according to an embodiment of the present invention, FIG. 14a is a photograph showing a state in which frame mura occurs, and FIG. 14b is a photograph showing a state in which frame mura is improved in a display device according to an embodiment of the present invention.

As illustrated in Fig. 13a, in a display device including a direct light type backlight unit, when a reflective layer is positioned between light sources, a grid mura occurs in which the reflective layer positioned between the light sources is directly visible in the display area of the display panel.

At this time, the grid Mura is evaluated as defective with an FOS rating of 3 to 5.

In contrast, looking at Fig. 13b, we can see that no lattice fog occurs.

That is, the display device (100 of FIG. 1) according to the embodiment of the present invention can prevent halo mura from occurring even when only one light source (129a of FIG. 9b) is turned on, and can also prevent lattice mura from occurring even when a reflector (125 of FIG. 9b) is positioned around the light source (129a of FIG. 9b).

In addition, referring to FIG. 14a, edge fog occurs due to a deviation of light supplied from the central portion where the light source (129a of FIG. 9b) is located and the edge region where the light source (129a of FIG. 9b) is not located. As in the display device (100 of FIG. 1) of the embodiment of the present invention, a first optical unit (210 of FIG. 9b) including a dichroic layer (211 of FIG. 9b) and a color conversion layer (213 of FIG. 9b) above the light source (129a of FIG. 9b), and a second optical unit (210 of FIG. 9b) including a pattern layer (225 of FIG. 8) including first and second stereoscopic pattern layers (221, 223 of FIG. 8) and an optical pattern (227 of FIG. 8) above the first optical unit (210 of FIG. 9b) By positioning the third optical unit (230 of FIG. 2) composed of a composite optical sheet including the first and second light collecting portions (233, 235 of FIG. 2) and the diffusion portion (231 of FIG. 2) above the second optical unit (220 of FIG. 8), a surface light source having high brightness and high color reproducibility and also improved visibility can be provided to the display panel (110 of FIG. 1) from the backlight unit (120 of FIG. 2).

Through this, it is possible to prevent halo mura from occurring even when only one light source (129a in FIG. 9b) consisting of an LED or micro LED (uLED) is turned on, and also to prevent lattice mura from occurring even when a reflector (125 in FIG. 9b) is positioned around the light source (129a in FIG. 9b).

In addition, the display device (100 of FIG. 1) according to an embodiment of the present invention can be lightweight and thin and have a narrow bezel, and can prevent the occurrence of frame blur even when the narrow bezel is implemented, thereby preventing the occurrence of a problem of deterioration in the image quality of the display device (100 of FIG. 1).

The present invention is not limited to the above embodiments, and may be implemented by making various changes without departing from the spirit of the present invention.

120 : Backlight unit
123 : Resin layer
125 : Reflector (125a : Through hole)
129: Light source unit (129a: Light source, 129b: PCB)
150 : Cover bottom (151 : Lower surface)
210: 1st optical unit (211: dichroic layer, 213: color conversion layer)
220: 2nd optical unit (221: 1st stereoscopic pattern layer (221a: 1st base layer, 221b: 1st stereoscopic lens layer, 221c: 1st inverted pyramid lens), 223: 2nd stereoscopic pattern layer (223a: 2nd base layer, 223b: 2nd stereoscopic lens layer, 223c: 2nd inverted pyramid lens), 225: pattern layer (227: optical pattern))
230: 3rd optical unit (231: diffusion unit (331a: 3rd support layer, 231b: 1st diffusion layer, 231c: 2nd diffusion layer), 233: 1st light collecting unit (233a: 1st support layer, 233b: 1st lens layer, 233c: 1st prism mountain), 235: 2nd light collecting unit (235a: 2nd support layer, 235b: 2nd lens layer, 235c: 2nd prism mountain)
240 : Light-diffusing adhesive

Claims (11)

A plurality of light sources mounted on a PCB;
A resin layer covering the plurality of light sources on the PCB;
A first optical unit positioned above the resin layer and including a dichroic layer and a color conversion layer;
A second optical unit positioned above the first optical unit and including an optical pattern positioned respectively corresponding to the plurality of light sources and a first three-dimensional pattern layer including a plurality of first inverted pyramid lenses;
A third optical unit positioned above the second optical unit and including a diffusion unit and a first light collecting unit;
A display panel positioned above the third optical unit
Including,
The above light source emits blue light,
The above dichroic layer reflects light other than the blue light,
The above dichroic layer is located between the resin layer and the color conversion layer,
The above color conversion layer converts the blue light into white light.
Display device.
delete delete In the first paragraph,
The first stereoscopic pattern layer includes a first base layer and a first stereoscopic lens layer in which a plurality of first inverted pyramid lenses are arranged to protrude from the lower surface of the first base layer.
The above-mentioned plurality of first inverted pyramid lenses are formed by a lower surface formed in a square shape and four side surfaces each extending from an edge of the lower surface to form one corner.
A display device having a length of 20 to 40 um and an angle of 90 to 130 degrees between the edges.
In paragraph 4,
A display device having a second stereoscopic pattern layer positioned above the first stereoscopic pattern layer, the second base layer, and a second stereoscopic lens layer in which a plurality of second inverted pyramid lenses are protruded and arranged from the lower surface of the second base layer.
In paragraph 4,
The above optical pattern is a display device formed by a double-layer overlapping printing structure.
In paragraph 4,
A display device in which the diameter of the optical pattern is 4.3 to 5.6 times larger than the diameter of the light source.
In the first paragraph,
The above first light collecting unit comprises a first support layer and a first lens layer on top of the first support layer.
A display device in which the first lens layer is arranged in a band shape along the first longitudinal direction and the first prism mountains are arranged in a row and protrude.
In Article 8,
A second light collecting unit including a second support layer is positioned above the first light collecting unit, and a second lens layer is positioned above the second support layer.
A display device in which the second lens layer is arranged in a row of second prism mountains in a band shape along a second longitudinal direction perpendicular to the first longitudinal direction.
In the first paragraph,
A display device including a third support layer and first and second diffusion layers on both sides of the third support layer.
In the first paragraph,
A display device having a reflector including a through hole through which the light source passes, positioned on the PCB.