KR102587621B1 - Reflection sheet for backlight unit - Google Patents

Abstract

One example of the present invention relates to a reflective sheet for a backlight unit that reduces the temperature of the backlight unit by quickly dispersing heat generated from a light source. The reflective sheet for a backlight unit according to an example of the present invention has two or more unit reflective layers, and each unit reflective layer has a metal layer. The reflective sheet for a backlight unit according to an example of the present invention can prevent damage to the backlight unit due to heat generated from a light source and increase the number of light sources, thereby improving product competitiveness.

Description

Reflective sheet for backlight unit {REFLECTION SHEET FOR BACKLIGHT UNIT}

One example of the present invention relates to a reflective sheet for a backlight unit.

Recently, it has become common for electronic devices to display screens using liquid crystal displays. Since the liquid crystal display device displays images by controlling the amount of light coming from the outside, a separate light source, that is, a back light unit, is inevitably needed to irradiate light to the liquid crystal display device.

The backlight unit consists of a light source that emits light, a light source housing that surrounds the light source, a light guide plate that converts the light emitted from the light source into a surface light source, a reflective sheet placed on the back of the light guide plate to reflect the light emitted to the rear of the light guide plate, and a light guide plate that reflects the light emitted to the rear of the light guide plate. It includes a plurality of optical sheets stacked on one another.

The reflective sheet consists of a plate-shaped base film, a shielding layer formed on the back of the base film to block light from being emitted rearward, and a reflective layer laminated on the front of the base film to reflect light from the light guide plate. .

The reflective layer is formed by depositing silver (Ag) on the upper surface of the base film or applying a white film, and a plurality of beads made of an acrylic-based material may be arranged.

As the luminance required for displaying images increases, the number of light sources such as light emitting diodes (LEDs) mounted on the backlight unit increases. When the number of mounted light sources increases or the mounting interval, which is the distance (pitch) between the mounted light sources, decreases, heat generated from the light source unit increases.

In a backlight unit, the temperature of the light incident area where the light source is mounted increases the most. If the temperature of the backlight unit increases, wrinkles may appear on the reflective sheet or optical sheet adjacent to the light incident area, or heat may be transferred to the display panel, causing problems such as liquid crystal deterioration.

One example of the present invention is to provide a reflective sheet for a backlight unit that reduces the temperature of the backlight unit by quickly dispersing heat generated from a light source.

The reflective sheet for a backlight unit according to an example of the present invention has two or more unit reflective layers, and each unit reflective layer has a metal layer.

A reflective sheet for a backlight unit according to another example of the present invention includes a base layer, a metal layer disposed on top of the base layer, and a core layer disposed on top of the metal layer, and the thickness of the metal layer is 0.01 μm or more and 1 μm or less.

The reflective sheet for a backlight unit according to an example of the present invention reduces the temperature of the backlight unit by quickly dispersing heat generated from a light source. Accordingly, the reflective sheet for a backlight unit according to an example of the present invention can prevent damage to the backlight unit due to heat generated from the light source and increase the number of light sources, thereby improving product competitiveness.

Figure 1 is a cross-sectional view showing the principle by which a reflective sheet for a backlight unit according to an example of the present invention dissipates heat.
2 to 5 are cross-sectional views of reflective sheets for backlight units according to other examples of the present invention.
Figure 6 is a plan view showing the temperature distribution of a reflective sheet for a backlight unit according to an example of the present invention.
Figure 7 is a graph showing light reflectance according to wavelength of a reflective sheet for a backlight unit according to an example of the present invention.

The advantages and features of the present application and methods for achieving them will become clear by referring to examples described in detail below along with the accompanying drawings. However, the present application is not limited to the examples disclosed below and will be implemented in various different forms, and only the examples of the present application are intended to ensure that the disclosure of the present application is complete and are within the scope of common knowledge in the technical field to which this application pertains. It is provided to fully inform those who have the scope of the invention, and this application is only defined by the scope of the claims.

The shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining an example of the present application are illustrative, and the present application is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present application, if it is determined that a detailed description of related known technology may unnecessarily obscure the gist of the present application, the detailed description will be omitted.

When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as 'after', 'successfully after', 'after', 'before', etc., 'immediately' or 'directly' Unless used, non-consecutive cases may also be included.

Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present application.

“First horizontal axis direction”, “second horizontal axis direction” and “vertical axis direction” should not be interpreted as only geometric relationships in which the relationship between each other is vertical, and the scope in which the configuration of the present application can function functionally It can mean having a broader direction than within.

The term “at least one” should be understood to include all possible combinations from one or more related items. For example, “at least one of the first, second, and third items” means each of the first, second, or third items, as well as two of the first, second, and third items. It can mean a combination of all items that can be presented from more than one.

Each feature of the various examples of the present application can be combined or combined with each other partially or entirely, and various technological interconnections and operations are possible, and each example can be implemented independently of each other or together in a related relationship. .

Hereinafter, a preferred example of a display device and an electronic device including the same according to the present application will be described in detail with reference to the attached drawings. In adding reference numerals to components in each drawing, identical components may have the same reference numerals as much as possible even if they are shown in different drawings.

Figure 1 is a cross-sectional view showing the principle by which the reflective sheet 100 for a backlight unit according to an example of the present invention dissipates heat. The reflective sheet 100 for a backlight unit according to an example of the present invention is disposed adjacent to the light source receiving unit 10.

The light source storage unit 10 is a case that contains the light source 20. The light source receiving unit 10 may be formed in a shape corresponding to the shape of the light source. The reflective sheet 100 for a backlight unit according to an example of the present invention reflects light emitted from an edge type light source 20. The light source receiving unit 10 is disposed adjacent to one edge of the reflective sheet 100 for a backlight unit. The light source accommodating portion 10 has an open surface adjacent to the reflective sheet 100 for a backlight unit in order to direct light emitted from the light source 20 toward the reflective sheet 100 for a backlight unit. The light source storage unit 10 may be made of reinforced plastic or metal material to stably accommodate the light source.

The light source 20 can be implemented with any type of light emitting means that emits light. The light source may be a light emitting diode (LED), a fluorescent lamp, or an ultraviolet LED. The light source 20 converts power energy input from a power source into light energy and emits light. According to thermodynamic principles, electric power energy cannot be completely converted into light energy, and part of the electric power energy is converted into heat energy. Therefore, the light source 20 emits heat (H). Heat emitted from the light source 20 is transferred to the light incident portion I of the reflective sheet 100 for a backlight unit.

The reflective sheet 100 for a backlight unit according to an example of the present invention includes a base layer 110, a metal layer 120, and a core layer 130.

The base layer 110 is disposed at the bottom of the reflective sheet 100 for a backlight unit. The base layer 110 serves as a base layer or base layer. The metal layer 120 is disposed on top of the base layer 110. The core layer 130 is disposed on top of the metal layer 120. The core layer 130 serves as a reflective layer that reflects light upward.

The reflective sheet 100 for a backlight unit according to an example of the present invention uses the metal layer 120 to quickly transfer the heat (H) transferred to the light incident part (I) to the light incident part (O), I) Reduce the temperature. The metal layer 120 is made of a metal with excellent thermal conductivity. The metal layer 120 is continuously disposed from the light entering portion (I) to the light entering portion (O). When the temperature of the light entering portion (I) is higher than that of the light receiving portion (O), the metal layer 120 attempts to reduce the temperature of the light entering portion (I) until the temperature becomes the same as the temperature of the light entering portion (O). Using this principle, the reflective sheet 100 for a backlight unit according to an example of the present invention can reduce the temperature of the light incident portion (I).

The base layer 110 according to an example of the present invention is an insulating layer. The base layer 110 may be formed of soft plastic, PET, tape treated with an insulating coating, etc. If the base layer 110 is an insulating layer, there is no need for separate insulating treatment, and the thickness of the reflective sheet 100 for the backlight unit can be reduced.

The metal layer 120 according to an example of the present invention may be made of Ag. The electrical conductivity of Ag is 6.3×10 ⁷ S/m. Ag is one of the metals with the best electrical conductivity. The electrical or thermal conductivity of a metal is due to the free electrons in the metal. Therefore, metals with good electrical conductivity also have good thermal conductivity. Ag is also one of the metals with the highest thermal conductivity. When such Ag is used as the metal layer 120, heat from the light entering portion (I) can be most quickly transferred to the light entering portion (O). Therefore, the temperature of the light incident portion (I) can be reduced most quickly.

Alternatively, the metal layer 120 according to an example of the present invention may be made of ITO. ITO is a layer widely used as a transparent conductive layer in the semiconductor, display, and electronic device manufacturing processes. Additionally, the deposition process is easy. Therefore, when the metal layer 120 according to an example of the present invention is deposited with ITO, the metal layer 120 can be easily formed and the manufacturing cost is reduced.

The light reflectance of the core layer 130 according to an example of the present invention is 95.0% or more and 99.9% or less. The core layer 130 is a layer that performs a reflective role in the reflective sheet 100 for a backlight unit according to an example of the present invention. If the light reflectance of the core layer 130 is lower than 95%, the light reflectance of the reflective sheet 100 for the backlight unit is lowered below the minimum reflectance standardized in quality assurance related to the backlight unit, and therefore cannot be used in the backlight unit. Accordingly, the light reflectance of the core layer 130 must be 95.0% or more and 99.9% or less in order for the reflective sheet 100 for the backlight unit to serve to reflect light emitted from the light source 20.

Figure 2 is a cross-sectional view of a reflective sheet 100 for a backlight unit according to another example of the present invention.

The reflective sheet 100 for a backlight unit according to another example of the present invention includes a base layer 110, a metal layer 120, a core layer 130, and a matte layer (Matte) 140.

The base layer 110 of the reflective sheet 100 for a backlight unit according to another example of the present invention is a black layer. The black layer forms the upper surface as a black light absorption layer. Accordingly, it is possible to prevent light emitted from the light source from leaking downward. Additionally, the black layer has higher thermal conductivity compared to layers of other colors. Accordingly, the speed at which heat transferred to one side of the base layer 110 adjacent to the light source is emitted to the other side of the base layer 110 can be increased.

The metal layer 120 of the reflective sheet 100 for a backlight unit according to another example of the present invention has a first thickness H1. The first thickness (H1) is 0.01 μm or more and 1 μm or less.

The metal layer 120 is manufactured through a deposition or coating process. In a deposition or coating process, the metal layer 120 can be manufactured to be 1㎛ or less. When manufactured to be thicker than 1㎛, the thickness of the reflective sheet 100 for the backlight unit increases due to the thickness of the metal layer 120, and as a result, the thickness of the backlight unit itself becomes thicker and its weight also increases.

However, if the thickness of the metal layer 120 is too thin, the amount of metal is small, and the metal layer 120 cannot quickly dissipate the heat of the light incident portion I. Accordingly, heat dissipation of the reflective sheet 100 for a backlight unit may be disadvantageous. In particular, when the thickness of the metal layer 120 is thinner than 0.01㎛, the degree of decrease in heat dissipation effect becomes steep. Accordingly, the metal layer 120 must have a thickness of 0.01 μm or more.

In addition, the reflective sheet 100 for a backlight unit according to another example of the present invention may further include a mat layer 140 disposed on the core layer 130.

The mat layer 140 is disposed on top of the core layer 130 and forms the uppermost layer of the reflective sheet 100 for a backlight unit. The mat layer 140 protects the lower layers from external shock. Additionally, the mat layer 140 prevents foreign substances such as external moisture and oxygen from penetrating into lower layers. The mat layer 140 may be formed using an acrylic material. However, the material is not limited to this, and the mat layer 140 is made of a material with low reactivity with external oxygen and moisture.

Since the mat layer 140 is a selectively disposed layer, it may be omitted. The mat layer 140 serves to protect the core layer 130 disposed on the top. However, if the thickness of the mat layer 140 increases more than necessary, the light reflectance of the core layer 130 decreases. Therefore, it is desirable to design the thickness of the mat layer 140 to be 8 μm or less.

Figure 3 is a cross-sectional view of a reflective sheet 100 for a backlight unit according to another example of the present invention. The reflective sheet 100 for a backlight unit according to another example of the present invention includes a base layer 110, a metal layer 120, and a core layer 130. Since the base layer 110 and the core layer 130 of the reflective sheet 100 for a backlight unit according to another example of the present invention are the same as those described in connection with FIGS. 1 and 2, detailed description thereof will be omitted. do.

The metal layer 120 of the reflective sheet 100 for a backlight unit according to another example of the present invention includes a plurality of sub-metal layers 121, 123, and 125.

The plurality of sub-metal layers 121, 123, and 125 are formed using the same material in the same process as the single metal layer 120. Each of the sub-metal layers 121, 123, and 125 disperses heat collected in the light entering portion (I) toward the light entering portion (O). When the sub-metal layers 121, 123, and 125 are gathered together, the thickness of the metal layer 120 may become thicker than necessary. Accordingly, each of the sub-metal layers 121, 123, and 125 is formed to be thinner than the single metal layer 120. The thickness of each sub-metal layer 121, 123, and 125 may be set according to the number of sub-metal layers 121, 123, and 125. For example, when three sub-metal layers 121, 123, and 125 are disposed in the metal layer 120 as shown in FIG. 3, the thickness of each sub-metal layer 121, 123, and 125 is 0.2 ㎛ or more and 0.3 ㎛. It may be below.

Each of the sub-metal layers 121, 123, and 125 of the reflective sheet 100 for a backlight unit according to another example of the present invention is connected to metal materials 122 and 124.

Metal materials 122 and 124 are disposed between sub-metal layers 121, 123, and 125. The metal materials 122 and 124 serve to fix the sub-metal layers 121, 123, and 125 so that they do not move. The metal materials 122 and 124 may be formed of the same material as the sub metal layers 121, 123, and 125. A filler 150 is disposed in a gap or empty space where the metal materials 122 and 124 are not disposed. The filler 150 can be implemented with any type of material that can fill space.

When connecting the sub metal layers 121, 123, and 125 using metal materials 122 and 124, compared to connecting the sub metal layers 121, 123, and 125 using a filler 150 or an adhesive layer. The bonding strength of the metal layers 121, 123, and 125 increases. Accordingly, it is possible to prevent some of the sub-metal layers 121, 123, and 125 from escaping to the outside of the metal layer 120.

When the sub-metal layers 121, 123, and 125 are connected using the metal materials 122 and 124, heat transfer between the sub-metal layers 121, 123, and 125 is facilitated by the metal materials 122 and 124. do. When heat transfer between the sub-metal layers 121, 123, and 125 is smooth, the problem of heat concentrating on any one sub-metal layer can be prevented. Even when only the temperature of the light incident portion I of one sub-metal layer increases, all of the sub-metal layers 121, 123, and 125 can help reduce the temperature of that portion. Accordingly, heat can be released faster than when each sub-metal layer 121, 123, and 125 releases heat independently.

Figure 4 is a cross-sectional view of a reflective sheet 100 for a backlight unit according to another example of the present invention. The reflective sheet 100 for a backlight unit according to another example of the present invention includes a base layer 110, a metal layer 120, and a core layer 130.

The thickness of the metal layer 120 of the reflective sheet 100 for a backlight unit according to another example of the present invention increases in the direction from the light incident part (I), where light is incident, to the light incident part (O). The light entering portion thickness (HO), which is the thickness of the metal layer 120 in the entering light portion (O), is thicker than the light entering portion thickness (HI), which is the thickness of the metal layer 120 in the light entering portion (I).

FIG. 4 illustrates a case where the upper part of the metal layer 120 has an upward inclined surface when moving from the light entering part (I) to the receiving part (O). In addition, when going from the light entering part (I) to the light entering part (O), the lower part of the metal layer 120 has a downward inclined surface. Accordingly, the case of having a tapered shape where the thickness increases in the direction from the light entering part (I) to the receiving part (O) is exemplified. However, it is not limited to this, and can be implemented in all types of forms where the thickness increases in the direction from the light entrance part (I) to the light entrance part (O). Accordingly, the thickness of the metal layer 120 may increase uniformly, but may also increase unevenly.

Even if the thickness of the metal layer 120 increases, the total thickness of the reflective sheet 100 for the backlight unit remains constant. In order to keep the total thickness of the reflective sheet 100 for the backlight unit constant, the base layer 110 and the core layer 130 increase in thickness of the metal layer 120 as it goes from the light entering part (I) to the light entering part (O). The thickness decreases to the same extent as the increase. The degree to which the thickness of the metal layer 120 increases can be set in various ways depending on the ratio of the length and thickness of the reflective sheet 100 for a backlight unit.

When the thickness of the metal layer 120 increases, the heat transfer rate becomes faster. Therefore, the heat transfer speed becomes faster toward the receiving light portion O, allowing heat to be better dissipated to the outside. Accordingly, the heat of the light incident part (I) can be quickly dispersed, and the temperature of the light incident part (I) can be reduced more quickly.

Figure 5 is a cross-sectional view of a reflective sheet for a backlight unit according to another example of the present invention.

A reflective sheet for a backlight unit according to another example of the present invention has two or more unit reflective layers (100, 200). Each of the unit reflective layers 100 and 200 has metal layers 120 and 220.

Each unit reflective layer (100, 200) is sequentially stacked. Each unit reflective layer 100, 200 performs the same function as the reflective sheet 100 for a backlight unit according to an example of the present invention. Each unit reflection layer (100, 200) reflects light emitted from a light source to uniformly supply light into the electronic device combined with the backlight unit.

In addition, when the metal layers 120 and 220 are disposed inside each unit reflective layer (100, 200), heat is transferred from the light incident portion (I) to the light receiving portion (O) in each unit reflective layer (100, 200). can perform its role. Accordingly, each unit reflective layer 100 lowers the temperature of the light incident portion (I), thereby speeding up the temperature decrease of the light incident portion (I).

Each unit reflective layer (100, 200) further includes base layers (110, 210). At this time, the metal layers 120 and 220 are disposed on top of the base layers 110 and 210.

The base layers 110 and 210 are disposed below the metal layers 120 and 220 and serve as a base layer or support layer. The base layer 110, the lowest layer among the unit reflective layers 100 and 200, may only play a supporting role. The base layers 110 and 210 may be formed using PET, reinforced plastic, or an insulator.

An adhesive surface capable of adhering to lower layers is formed on the lower surface of the upper base layer 210, excluding the lowest base layer 110. The adhesive surface prevents the upper layer from separating from the lower layer. Figure 5 illustrates a case where the core layer 130 is formed in the lower layer. However, it is not limited to this, and a structure in which the adhesive surface is directly bonded to the metal layer 120 of the lower layer can also be implemented.

When the base layers (110, 210) support the metal layers (120, 220) at the lower part of the metal layers (120, 220), the metal layers (120, 220) are not disposed thicker than necessary and are placed on the base layers (110, 210). It can be deposited thinly by coating on. Additionally, when the metal layers 120 and 220 are disposed on the base layers 110 and 210, they become stronger against external shocks than when the metal layers 120 and 220 are present alone. Additionally, when the metal layers 120 and 220 are disposed on each of the base layers 110 and 210, as the number of unit reflective layers 100 and 200 increases, the temperature reduction effect of the light incident portion I increases.

The metal layers 120 and 220 may be individually formed depending on the arranged position or using a material that matches the desired characteristics.

The metal layer 220 disposed at the top of the metal layers 120 and 220 is an Ag coating layer, and the metal layer 120 disposed at the bottom of the metal layers 120 and 200 is an Al coating layer. Both the Ag coating layer and the Al coating layer have excellent light reflectance. Accordingly, the metal layers 120 and 220 may increase the light reflectance of the reflective sheet for a backlight unit according to an example of the present invention. In addition, both the Ag coating layer and the Al coating layer have excellent electrical and thermal conductivity. Therefore, when using the Ag coating layer and the Al coating layer, the heat from the light entering portion (I) can be quickly transferred to the light entering portion (O) using the metal layers (120, 220).

Among these, the light reflectance, electrical conductivity, and thermal conductivity of the Ag coating layer are slightly better than those of the Al coating layer. On the other hand, the Al coating layer has the advantage of lower manufacturing costs compared to the Ag coating layer. The metal layer 220 disposed on the upper portion has a greater influence on the light reflectance of the reflective sheet for a backlight unit according to an example of the present invention. Therefore, by using an Ag coating layer with excellent light reflectance and heat dissipation performance on the upper part, and using an Al coating layer with low manufacturing cost on the lower part, it is possible to minimize the increase in manufacturing cost while providing excellent performance.

The first thickness H1, which is the thickness of the lower metal layer 120, and the second thickness H2, which is the thickness of the upper metal layer 220, are 0.01 μm or more and 1 μm or less.

The metal layers 120 and 220 are manufactured through a deposition or coating process. In a deposition or coating process, the metal layers 120 and 220 may be manufactured to be 1㎛ or less. When manufactured to be thicker than 1㎛, the thickness of the reflective sheet 100 for the backlight unit increases due to the thickness of the metal layers 120 and 220, and as a result, the thickness of the backlight unit itself becomes thicker and its weight also increases.

However, if the thickness of the metal layers 120 and 220 is too thin, the amount of metal is small, and the metal layer 120 cannot quickly dissipate the heat of the light incident portion I. Accordingly, heat dissipation of the reflective sheet 100 for a backlight unit may be disadvantageous. In particular, when the thickness of the metal layers 120 and 220 is thinner than 0.01 ㎛, the degree of decrease in heat dissipation effect becomes steep. Accordingly, the metal layers 120 and 220 must have a thickness of 0.01 μm or more.

Additionally, an uppermost coating layer 230 may be further disposed on the uppermost unit reflective layer 200 among the unit reflective layers 100 and 200.

The uppermost coating layer 230 forms the uppermost layer of the reflective sheet for a backlight unit according to an example of the present invention. The top coating layer 230 may primarily reflect light incident from the top. The uppermost coating layer 230 may transmit light reflected from the lower part. The uppermost coating layer 230 may be formed of a semi-transparent film or a half-mirror.

The top coating layer 230 is not limited to a layer with an optical function and may function as a protective layer. The top coating layer 230 can prevent foreign substances such as oxygen and moisture from penetrating from the top of the reflective sheet for a backlight unit according to an example of the present invention, thereby preventing corrosion of the metal layers 120 and 220. The uppermost coating layer 230 may absorb physical shock applied to the lower metal layers 120 and 220 or the base layers 110 and 210. In this case, the top coating layer 230 may be formed of a flexible cushioning material.

Figure 6 is a plan view showing the temperature distribution of the reflective sheet 100 for a backlight unit according to an example of the present invention.

The metal layer 120 is formed on the entire surface of the reflective sheet 100 for a backlight unit. The light source 20 is disposed below the metal layer 120. The light source 20 is disposed adjacent to one edge of the metal layer 120. The light incident portion 30 is formed adjacent to the light source 20. The light incident portion 30 is formed from the light source 20 toward the central portion of the metal layer 120.

The temperature of the light source 20 may be defined as the first temperature (T1), and the temperature of the metal layer 120 may be defined as the second temperature (T2). At this time, since heat is generated from the light source 20, the first temperature (T1) is higher than the second temperature (T2). At this time, the temperature of the light incident portion 30 has a temperature decreased from the first temperature T1 by the reduction temperature ΔT.

In the existing reflective sheet 100 for a backlight unit, the metal layer 120 was not disposed, so the reduction temperature (△T) was small. That is, the temperature of the light source 20 and the temperature of the light incident portion 30 were almost the same. Accordingly, there was a problem in which the reflective sheet 100 for the backlight unit in the area corresponding to the light incident portion 30 was deformed or the temperature increased, causing an abnormality to occur on the screen.

The reflective sheet 100 for a backlight unit according to an example of the present invention has a large reduction temperature (ΔT) due to the metal layer 120 being disposed. The temperature of the light incident portion 30 decreases significantly compared to the temperature of the light source 20. Accordingly, it is possible to solve the problem of abnormalities occurring on the screen due to deformation of the reflective sheet 100 for the backlight unit in the area corresponding to the light incident portion 30 or an increase in temperature. When a plurality of metal layers 120 are deposited, the magnitude of the reduction temperature (△T) increases. For example, when two metal layers 120 are deposited, the reduction temperature (ΔT) is 7.0°C.

Figure 7 is a graph showing the light reflectance according to the wavelength of the reflective sheet 100 for a backlight unit according to an example of the present invention.

The first embodiment (Case 1) shows a reflective sheet according to an example of the present invention in which the metal layer 120 is deposited on the side opposite to the white surface. In the case of the first example (Case 1), the light reflectance was 90% at a wavelength of 400 nm and then increased to 100% at 470 nm. Afterwards, as the wavelength increases, the light reflectance gradually increases, and at 700 nm, the light reflectance is 107%. That is, it has a light reflectance of 100% or more in the visible light wavelength range.

The second embodiment (Case 2) shows a reflective sheet according to another example of the present invention in which the metal layer 120 is deposited on a white surface. In the case of the second example (Case 2), it had a low reflectance of 80% at a wavelength of 400 nm, but then rapidly increased to have the highest light reflectance approaching 105% at 425 nm. Afterwards, as the wavelength increases, the light reflectance gradually decreases, reaching 100% at 700 nm. That is, it has a light reflectance of 100% or more in the visible light wavelength range.

In the case of the third embodiment (Case 3), a conventional white reflective sheet is shown without the metal layer 120 disposed. In the case of the third example (Case 3), it had a low reflectance of 80% at a wavelength of 400 nm, but then rapidly increased to have the highest light reflectance approaching 105% at 425 nm. Afterwards, as the wavelength increases, the light reflectance gradually decreases, reaching 100% at 550 nm, and at wavelengths longer than 550 nm, the light reflectance is less than 100% but over 95%.

From these experimental results, it can be confirmed that depositing the metal layer 120 not only has a heat dissipation effect, but also improves the reflection performance of the reflective sheet 100 for a backlight unit by increasing light reflectance.

The reflective sheet for a backlight unit according to an example of the present invention reduces the temperature of the backlight unit by quickly dispersing heat generated from a light source. Accordingly, the reflective sheet for a backlight unit according to an example of the present invention can prevent damage to the backlight unit due to heat generated from the light source and increase the number of light sources, thereby improving product competitiveness.

The present application described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the technical field to which this application belongs that various substitutions, modifications, and changes are possible without departing from the technical details of the present application. It will be clear to those who have the knowledge of. Therefore, the scope of the present application is indicated by the claims described later, and the meaning and scope of the claims and all changes or modified forms derived from the equivalent concept should be interpreted as being included in the scope of the present application.

10: light source storage unit 20: light source
30: Light receiving area 100: Reflective sheet for backlight unit
100, 200: unit reflection layer 110, 210: base layer
120, 220: metal layer 121, 123, 125: sub-metal layer
122, 124: metallic material 130: core layer
140: Mat layer 150: Filler
230: Top coating layer

Claims (9)

It has two or more unit reflective layers,
Each of the unit reflective layers has a metal layer,
The metal layer includes a plurality of sub-metal layers,
A reflective sheet for a backlight unit, wherein each of the sub-metal layers is connected with a metal material. According to claim 1,
The unit reflective layer further includes a base layer,
The reflective sheet for a backlight unit, wherein the metal layer is disposed on top of the base layer. According to claim 1,
Among the metal layers, the metal layer disposed at the top is an Ag coating layer,
Among the metal layers, the metal layer disposed at the bottom is an Al coating layer,
A reflective sheet for a backlight unit, wherein the metal layer has a thickness of 0.01 ㎛ or more and 1 ㎛ or less. The method according to any one of claims 1 to 3,
A reflective sheet for a backlight unit, further comprising an uppermost coating layer disposed on the uppermost unit reflective layer among the unit reflective layers. delete According to claim 1,
A reflective sheet for a backlight unit, wherein the metal layer increases in thickness from the light entering part where light enters to the receiving part. base layer;
a metal layer disposed on top of the base layer; and
It includes a core layer disposed on top of the metal layer,
The metal layer includes a plurality of sub-metal layers,
Each of the sub-metal layers is connected with a metal material,
A reflective sheet for a backlight unit, wherein the metal layer has a thickness of 0.01 ㎛ or more and 1 ㎛ or less. According to claim 7,
The base layer is a black layer,
A reflective sheet for a backlight unit, further comprising a mat layer disposed on top of the core layer. According to claim 7,
The base layer is an insulating layer,
The metal layer is made of Ag or ITO,
A reflective sheet for a backlight unit, wherein the core layer has a light reflectance of 95.0% or more and 99.9% or less.

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