KR102355584B1 - Backlight Unit and Display Device having the same - Google Patents

Abstract

The present invention relates to a backlight unit and a display device including the same. In a fluorescent light source device including a blue LED and a phosphor tube, the light source housing and the light source housing supporting the phosphor tube are formed in a U-shape made of a thermally conductive material, and the light source part is disposed on the bottom surface of the upper support surface of the light source housing and the phosphor tube is disposed to contact at least one of the side surface and the bottom surface of the light source housing, thereby improving heat dissipation performance of heat generated from the phosphor tube.

Description

A backlight unit and a display device including the same

The present invention relates to a backlight unit and a display device including a phosphor tube, and more particularly, to a backlight unit and a display device capable of preventing deterioration due to heat of a phosphor included in the phosphor tube.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. Various display devices such as an organic light emitting diode display device (OLED) are being used.

Among these display devices, a liquid crystal display (LCD) includes an array substrate including a thin film transistor as a switching element for on/off control of each pixel region, a color filter and/or a black matrix, and the like. It consists of an upper substrate, a display panel including a liquid crystal material layer formed therebetween, a driving unit for controlling the thin film transistor, and a backlight unit (BLU) that provides light to the display panel. , a device that displays an image by adjusting the arrangement of the liquid crystal layers according to the electric field applied between the pixel (PXL) electrode and the common voltage (Vcom) electrode provided in the pixel area and thus the transmittance of light accordingly.

In the case of such a liquid crystal display device, a backlight unit for providing light to the display panel is included, and the backlight unit may be of an edge-type or a direct-type type depending on the arrangement of the light source and the type of light transmission. can be distinguished.

Among them, in the edge type backlight unit, a light source such as an LED and a light source module or light source device including a holder or a housing for fixing the light source and a light source driving circuit are disposed on one side of the display device, and the light is diffused to the entire panel area. It may include a light guide plate (LGP) for, a reflector plate for reflecting light in the direction of the display panel, and one or more optical sheets disposed on the light guide plate for the purpose of improving luminance, diffusion and protection of light, etc. have.

The light source device used in such an edge-type backlight unit includes a light source of an LED or a light source package including the same, a light source PCB in which a plurality of light source packages are mounted long and circuit elements for driving the light source PCB, and the light source PCB to support the light source PCB. It may include a light source housing for

Meanwhile, in the backlight unit, a phosphor tube may be used as a structure for emitting white light by using a blue LED emitting blue light, and converting blue light into red, green, etc., in addition to the case of using a white light LED.

The phosphor material or phosphor particles contained in such a phosphor tube is excited with blue light to emit red or green light, and these phosphor materials are usually vulnerable to heat, so that when more than a certain amount of heat is applied, discoloration or sufficient color conversion efficiency cannot be achieved. Often times.

However, since the conventional backlight unit including a phosphor tube has a structure in which heat generated inside the phosphor tube is hardly radiated to the outside, there is a problem in that the light conversion characteristic of the phosphor tube is deteriorated due to heat during operation of the display device.

Against this background, it is an object of the present invention to provide a backlight unit structure capable of minimizing deterioration of a phosphor material included in a phosphor tube as a light source device used in an edge-type backlight unit.

Another object of the present invention is to provide a backlight unit capable of improving heat dissipation performance of a phosphor tube by optimizing the structures of a light source unit, a phosphor tube, and a light source housing in a fluorescent light source device including a blue LED and a phosphor tube.

Another object of the present invention is, in a fluorescent light source device including a blue LED and a phosphor tube, the light source housing supporting the light source part and the phosphor tube is formed in a U-shape made of a thermally conductive material, and the light source part is located on the lower surface of the upper surface of the light source housing. It is to provide a backlight unit capable of improving heat dissipation performance of heat generated from the phosphor tube by disposing and disposing the phosphor tube in contact with at least one of the side portion and the bottom portion of the light source housing.

In order to achieve the above object, one embodiment of the present invention is made of a thermally conductive material, the light source housing including an upper surface portion, a side portion and a bottom portion; a light source unit disposed on the inner surface of the upper surface of the light source housing, the light source unit including a blue light source and a light source PCB for supporting the blue light source; a phosphor tube disposed in contact with the inner surfaces of the side surface and the bottom surface of the light source housing and including a phosphor for converting blue light from the blue light source into light of another frequency band; Provided is a backlight unit for a display device comprising a; a light guide plate that receives and diffuses the light from the phosphor tube.

In another embodiment of the present invention, a light source housing made of a thermally conductive material and including an upper surface portion, a side surface portion and a bottom surface portion, and disposed on the inner surface of the upper surface portion of the light source housing, a blue light source and a light source for supporting the blue light source A light source unit including a PCB, a phosphor tube disposed in contact with the inner surface of the side surface and the bottom surface of the light source housing, the phosphor tube including a phosphor that converts blue light from the blue light source into light of another frequency band; a backlight unit including a light guide plate for receiving and diffusing the light; a cover bottom surrounding the outside of the bottom and side surfaces of the light source housing; a guide panel surrounding the outer side of the cover bottom, the outer side of the upper surface of the light source housing, and a portion of the upper side of the light guide plate; It provides a display device comprising a; a display panel supported on the upper portion of the guide panel.

According to an embodiment of the present invention as will be described below, there is an effect that can minimize the deterioration due to heat of the phosphor tube in the light source device used in the edge type backlight unit.

More specifically, in a fluorescent light source device including a blue LED and a phosphor tube, the light source housing for supporting the light source part and the phosphor tube is formed in a U-shape made of a thermally conductive material, and the light source part is located on the lower surface of the upper support surface of the light source housing. By disposing and disposing the phosphor tube in contact with at least one of the side surface and the bottom surface of the light source housing, heat dissipation performance of heat generated from the phosphor tube may be improved.

In addition, by adding a gap compensating member to the phosphor tube for compensating the optical gap between the phosphor tube and the light source (package) and between the phosphor tube and the light guide plate, the light transmission efficiency can be improved.

In addition, since the light source housing supporting the light source unit and the phosphor tube is formed in a U-shape made of a thermally conductive material and provided with an inclined surface inside the side surface of the light source housing, it is possible to improve the efficiency of light entering the light guide plate.

1 illustrates a cross-section of a display device including a general edge-type backlight unit to which an embodiment of the present invention can be applied.
2 is a cross-sectional view of a display device including a backlight unit according to an embodiment of the present invention, and an enlarged perspective view of a light source housing, a phosphor tube, and a light source part included in the backlight unit.
3 shows heat dissipation characteristics of a phosphor tube when a backlight unit according to an embodiment of the present invention is used.
4 shows a coupling method between the phosphor tube and the light source housing according to the present embodiment.
5 shows an example in which a gap compensating member for compensating an optical gap around a phosphor tube is used.
6 shows an example of an optical pattern formed in the phosphor tube according to the present embodiment.
7 is a cross-sectional view and an enlarged perspective view of a backlight unit according to another embodiment of the present invention, and FIG. 8 is a cross-sectional view of a display device including the backlight unit according to the embodiment of FIG. 7 .
FIG. 9 shows various types of phosphor tubes used in the backlight unit according to the embodiment of FIG. 7 .
10 shows the luminance distribution at the edge of the display area of the display device when the structure according to the present embodiment is used.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It should be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component.

1 illustrates a cross-section of a display device including a general edge-type backlight unit to which an embodiment of the present invention can be applied.

As shown in FIG. 1 , a display device to which an embodiment of the present invention can be applied includes a display panel 160 such as a liquid crystal display panel and a backlight unit disposed below the display panel to irradiate light to the display panel, and supports the backlight unit and and a cover bottom 110 made of a metal or plastic material extending over the entire rear surface of the display device.

In such a liquid crystal display device, a backlight unit for providing light to the display panel is included, and the backlight unit may be classified into an edge-type or a direct-type depending on the arrangement of the light source and the light transmission type. can

As shown in Figure 1, the edge type backlight unit is mounted on the side of the light source unit and the light source unit 126, such as an LED, and a light source PCB 124 including a light source driving circuit as a holder for fixing the light source, A light guide plate 130 (Light Guide Plate; LGP) for diffusing the light from the light source to the entire panel area, a reflecting plate for reflecting light toward the display panel, and disposed on the light guide plate to improve luminance, light diffusion and protection, etc. It may include one or more optical sheets 140 and the like disposed for a purpose.

In such an edge-type backlight unit, after light from the light source is incident on the light guide plate inlet, it is totally reflected in the light guide plate, spreads to the front of the display device, and exits in the direction of the display panel.

In general, an LED chip may be used as the light source, and the light source may be a white LED outputting white light, but a blue LED having excellent light efficiency may be used.

When a blue LED is used as a light source, a light conversion member that converts blue light into white light is used in order to provide white light to the light guide plate. A phosphor tube 127 including a light-converting material or phosphor that converts blue light into another frequency band may be used.

The phosphor tube 127 is a tube-shaped structure formed of a material in which phosphor particles and transparent silicon (Si) are mixed, and is disposed between the light source 126 and the light guide plate 130 to transmit blue light from the light source to R, G , Y, etc., by converting it into light of a different color, finally functions to transmit white light to the light guide plate.

The phosphor tube 127 includes a phosphor material or phosphor particles, and the phosphor material includes a fluoride compound KSF (K ₂ SiF ₆ ) that is an Mn4+ activator phosphor, sulfide, quantum dot particles, or the like. used

These phosphor materials have the disadvantage of being vulnerable to heat.

_{In particular, the fluoride compound KSF (K 2} SiF ₆ ), which is an Mn4+ activator phosphor widely used as a phosphor material, is a non-rare-earth red phosphor with difficult synthesis process conditions, but high productivity due to rapid synthesis and low unit cost. Also, white LED with high luminous efficiency It has excellent performance as a phosphor for

However, such KSF phosphors have a disadvantage in that they are vulnerable to heat, and in particular, when used as a backlight unit of a display device, problems are likely to occur when used in high-power LEDs or AC LEDs due to a long afterglow time.

In fact, the KSF phosphor is discolored or the light conversion efficiency is lowered at about 90 degrees Celsius or higher.

The phosphor tube 127 not only receives heat generated from the light source 126, but the phosphor particles inside the phosphor tube are excited by blue light to generate heat during the light conversion process to emit light in a different frequency band. .

Accordingly, the phosphor tube 127 may be exposed to a fairly strong heat, which may cause denaturation or deterioration of the phosphor particles inside the phosphor tube.

In order to solve this problem, in a backlight unit using a phosphor tube, a heat dissipation characteristic of dissipating heat inside the phosphor tube to the outside is required.

On the other hand, as shown in FIG. 1, a typical backlight unit includes a light housing (L/H; 122) supporting the light source PCB 124, etc., and a tube fixing member 128 for supporting the phosphor tube 127. Included.

The light source housing 122 is formed of a thermally conductive material such as aluminum (AL), and functions to emit heat generated from the light source PCB 124 mounted thereon.

In addition, the tube fixing member 128 is a white reflector support made to fix the phosphor tube 127 to the upper surface of the light source (LED), and is made of a thermosetting resin or a thermoplastic resin.

In the structure shown in FIG. 1, the tube fixing member 128 contacts the edge of the phosphor tube 127 to support the phosphor tube. Since the tube support member 128 is made of a low thermal conductivity resin, the phosphor tube 127 ) and the contact portion of the tube support member 128 (area A in Fig. 1 (b)) through the heat is less likely to be emitted.

In addition, although the other side of the tube support member 128 is in contact with the light source housing 122 having excellent thermal conductivity (region B in FIG. 1B), due to the low thermal conductivity of the tube support member, It is a structure in which heat is difficult to dissipate.

Therefore, when the backlight unit is operated for a long time, the temperature inside the phosphor tube 127 rises, and accordingly, there is a problem in that the phosphor material included in the phosphor tube is deteriorated.

The embodiment of the present invention is focused on this point, and it is proposed to improve the heat dissipation characteristics of the phosphor tube by changing the shape of the light source housing and the arrangement relationship between the light source part and the phosphor.

2 is a cross-sectional view of a display device including a backlight unit according to an embodiment of the present invention, and an enlarged perspective view of a light source housing, a phosphor tube, and a light source part included in the backlight unit.

As shown in FIG. 2 , the backlight unit according to the embodiment of the present invention includes a U-shaped light source housing 210 , a light source unit 220 disposed inside the upper surface of the light source housing, and side and bottom portions of the light source housing. It may be configured to include a phosphor tube 230 disposed in contact with the inside, a light guide plate 240 , and the like.

In this specification, the upper, upper, or upper side all refer to the front side of the display device, that is, the direction toward the display panel, and the bottom or lower side refers to the rear side of the display device.

Also, the first side of the phosphor tube 230 refers to a side facing the light guide plate among both side surfaces, and the second side refers to the opposite side thereof.

As shown in (b) of FIG. 2 , the light source housing 210 according to the present embodiment is a plate-shaped member made of a thermally conductive material such as aluminum (AL), and is double refracted to have a U-shaped cross section as a whole.

Accordingly, the light source housing 210 includes an upper surface portion 212, a side portion 214, and a bottom surface portion 216, and as a material constituting the light source housing, 10th series aluminum having a heat transfer rate of about 220 W/mK, a heat transfer rate is It is preferable that the 50th series aluminum of about 138 W/mK, the 60th series aluminum of about 180 W/mK of heat transfer rate, etc. are used.

In addition, the light source housing 210 needs to condense or guide the blue light emitted from the light source or the white light emitted from the phosphor tube 230 toward the light guide plate 240 in addition to the above-described heat dissipation characteristics, so it is preferable to have a constant reflection characteristic.

To this end, the material constituting the light source housing itself has more than a certain light reflection characteristic, or a reflective layer such as a separate reflective film is added to the inner surface of the upper surface part 212, the side part 214, and the bottom surface part 216 of the light source housing. may be formed as

The light source unit 220 used in this embodiment includes a light source 224 that can be implemented as a blue LED chip or a blue LED package, and a light source PCB 222 for mounting the light source and circuit elements necessary for driving the light source. can be configured.

The light source PCB 222 is a printed circuit board that extends along one or more sides of a display device or a backlight unit, and may include a printed circuit board base, an insulating layer, a power wiring layer, and the like.

The light sources 224 are disposed on the light source PCB 222 at regular intervals, and are mounted directly on the light source PCB without a mold frame or lead frame by surface mount technology (SMT). -On-Board (COB) or Chip Scale Package (CSP) type of chip. Alternatively, the light source 224 may be formed of two electrode layers on a growth substrate layer and a light emitting layer disposed between the electrodes, and may be a chip called a flip-chip, but is not limited thereto. .

Meanwhile, the light source 224 used in this embodiment may be a blue LED emitting blue light having a wavelength of about 430 nm to 450 nm, and the emitted blue light is red (R), green (G) in a phosphor tube as will be described later. ), the light emitted from the phosphor tube 230 after being converted into light of a yellow (Y) frequency band can constitute white light.

The light source 224 used in this embodiment may be an individual chip such as a blue LED chip, but may also be a light source package including an LED chip, a mold structure, and a lead frame.

Meanwhile, according to the present embodiment, the light source unit 220 is disposed in contact with the inner side of the upper surface portion 212 of the light source housing 210 .

That is, in the structure shown in FIG. 1, the light source unit is disposed on the inner side of the L-shaped light source housing and consequently is disposed on the side surface of the phosphor tube, but in the embodiment of the present invention as shown in FIG. By being disposed, it is positioned on the upper part of the phosphor tube.

The phosphor tube 230 used in this embodiment includes phosphor particles or phosphor materials for converting blue light transmitted from a light source into light in other frequency bands such as R, G, and Y, and transparent silicon ( Si) material may be further included.

That is, the phosphor tube 230 is a light conversion member formed in a long bar or tube shape using a phosphor and a transparent silicon (Si) material. It is a concept including all types of light conversion members including phosphors disposed between the light source and the light guide plate.

The phosphor material included in the phosphor tube may include _{, but is not limited to, a fluoride compound KSF phosphor (K 2} SiF ₆ hereinafter referred to as KSF phosphor), which is an Mn4+ activator phosphor, but is not limited thereto. Quantum Dot particles or quantum dot particles A phosphor material comprising

The phosphor material or phosphor particles included in the phosphor tube 230 may include a yellow phosphor (Y), a red phosphor (R), a green phosphor (G), etc. that absorb blue light and then emit light in a frequency band of a different color. , The emission color can be selected by adjusting the mixing ratio of the phosphors of each color.

The yellow phosphor (Y) uses yttrium (Y) aluminum (Al) garnet YAG:Ce(T3Al5O12:Ce)-based phosphors doped with cerium (Ce) having a dominant wavelength of 530 to 570 nm, or silicate-based phosphors may be a material of

The red (R) phosphor is a YOX (Y2O3:EU)-based phosphor composed of a compound of yttrium oxide (Y2O3) and europium (EU) having a wavelength of 611 nm as the dominant wavelength, and the phosphor of green (G) has a wavelength of 544 nm It is a phosphoric acid (Po4), lanthanum (La), and terbium (Tb)-based phosphor, LAP (LaPo4:Ce,Tb)-based phosphor, and the blue (B) phosphor is barium (Ba) with a wavelength of 450nm. A BAM blue (BaMgAl10O17:EU)-based phosphor, which is a compound of magnesium (Mg) and aluminum oxide, and europium (EU), may be used.

The phosphor tube 230 may be formed by molding a material in which silicon (Si) and a phosphor material are mixed in a certain mold, or by dispensing or transfer molding. not limited

On the other hand, in the conventional structure shown in FIG. 1, the cross-section of the phosphor tube has a rectangular shape, but the length of the upper and lower sides is shorter than the length of the side, and thus has a longer rectangular shape overall.

On the other hand, in the phosphor tube 230 according to the present embodiment, as will be described below, in order to have excellent heat dissipation characteristics, the surface in contact with the inner side and bottom of the light source housing 210 having thermal conductivity should be wide. , for that, it is preferable that the length of the upper and lower sides is equal to or greater than the length of the side, as shown in FIG. 2 .

That is, the phosphor tube according to the present embodiment preferably has a longer cross-sectional shape or at least a square shape, so that the contact area with the light source housing is increased.

In addition, the light guide plate 240 included in the backlight unit according to the present embodiment may be formed of a rectangular transparent plastic sheet that is die-cut, extruded, or injection-molded from a plastic sheet, and the phosphor tube 230 . White light emitted from the light guide plate 240 is incident on the edge of the light guide plate 240, is totally reflected inside the light guide plate, and spreads across the rear surface of the display panel, and the light emitted through the flat top surface of the light guide plate functions as a backlight of the display panel.

Materials constituting the light guide plate 240 include polymethyl methacrylate (PMMA), methlystylene (MS) resin, polystyrene (PS), polypropylene (PP), and polyethylene terephthalate. :PET) and polycarbonate (PC) may be at least one light-transmitting material selected from, but is not limited thereto.

In addition, the backlight unit according to the present embodiment may further include a reflective plate 250 disposed on a lower surface of the light guide plate and an optical sheet unit 260 disposed on an upper surface of the light guide plate.

The reflection plate 250 is located on the rear surface of the light guide plate 240 , and reflects the light passing through the rear surface of the light guide plate toward the display panel 330 to improve the luminance of the light.

The optical sheet unit 260 disposed on the light guide plate 240 collects light so that a more uniform surface light source is incident on the display panel 330 , and one or more individual optical sheets may be combined.

The optical sheet unit 260 includes a light collecting sheet or prism sheet (PS) having a light collecting function, a diffusing sheet (DS) for diffusing light, and a reflective type called DBEF (dual brightness enhancement film). Various functional sheets such as a polarizing film may be combined and configured.

In the case of a liquid crystal display panel, the display panel 330 receiving light by the backlight unit according to the present exemplary embodiment includes pixels defined in a plurality of gate lines and data lines and their crossing regions, and in each pixel. It may be configured to include an array substrate including a thin film transistor as a switching element for controlling light transmittance, an upper substrate having a color filter and/or a black matrix, and a liquid crystal material layer formed therebetween.

Meanwhile, the display panel to which the backlight unit according to the present embodiment can be applied is not limited to the liquid crystal display panel, and may include other types of display devices requiring a backlight unit.

In addition, as a structure for supporting the backlight unit according to the present embodiment, a cover bottom (Cover Bottom; 310), which is a metal or plastic back cover that covers a portion of the rear surface and side surfaces of the display device, and the display panel are disposed from the bottom A guide panel 320 for supporting, and a case top (not shown) covering the outermost side of the display device and the upper edge of the display panel may be additionally provided.

The cover bottom 310 used in the display device according to the present embodiment is an L-shaped support structure surrounding the outside of the bottom surface 216 and the side surface 324 of the light source housing 210 .

The cover bottom is not limited to the term, and may be expressed in other terms such as a back cover, a chassis, and a frame.

On the other hand, the cover bottom according to the present embodiment is not limited in its material, but in that it has to function to discharge heat from the light source housing in contact with the thermally conductive light source housing to the outside, it has a certain level of thermal conductivity, such as metal. It would be preferable to be made of a material.

In addition, the guide panel 320 used in the display device according to the present embodiment is a plastic support structure for surrounding the cover bottom 310 and supporting the display panel 330 from the lower portion.

The guide panel 320 extends so as to surround the outside of the side surface of the cover bottom 310, the outside of the upper surface 212 of the light source housing 210, and a part of the upper side of the light guide plate 240, and the upper portion of the horizontal support of the guide panel is The display panel 330 is seated.

The guide panel 320 is generally formed of a plastic material, and may be expressed in other terms such as a mold frame, a middle cabinet, a plastic chassis, and a plastic frame.

Meanwhile, a light blocking member 340 may be additionally disposed between the guide panel 320 and the upper portion of the light guide plate.

The light blocking member 340 may be a black tape or the like, and functions to block the leaking light that is not incident on the light guide plate 240 among the light from the light source unit 220 or the phosphor tube 230 according to the present embodiment. . Due to the light blocking member 340 , it is possible to minimize light leakage at the edge of the display panel.

3 shows heat dissipation characteristics of a phosphor tube when a backlight unit according to an embodiment of the present invention is used.

As shown in FIG. 3 , in the backlight unit according to the present embodiment, the light source unit 220 is disposed inside the upper surface portion 212 of the light source housing, and the phosphor tube 230 is disposed on the side surface portion 214 and the bottom surface portion of the light source housing 210 . 216 is placed in contact.

As a result, different from the structure shown in FIG. 1 , the light source 220 is positioned above the phosphor tube 230 .

At this time, since the light source housing 210 is made of aluminum with excellent thermal conductivity, the heat (H) generated in the phosphor tube 230 is moved to the light source housing 210 in contact with the side and bottom surfaces of the phosphor tube, It can be easily emitted to the outside through the cover bottom 310 connected to the light source housing.

Accordingly, in the backlight unit according to the present embodiment, the heat dissipation characteristic of the phosphor tube 230 is improved, and as a result, thermal degradation or deterioration of the phosphor tube is minimized, thereby improving the lifespan and performance of the backlight unit.

On the other hand, the blue light (B) emitted from the light source 224 is incident on the phosphor tube 230 by being reflected directly or from the inner surface of the light source housing 210 , and after being converted into white light (W) inside the phosphor tube 230 . It is emitted and is incident on the light guide plate 240 .

4 shows a coupling method between the phosphor tube and the light source housing according to the present embodiment.

As shown in FIG. 4 , thermoelectricity is formed between the second side surface of the phosphor tube 230 and the inner surface of the side part 214 of the light source housing 210 , and the bottom surface of the phosphor tube 230 and the inner surface of the bottom surface 216 of the light source housing 210 . It is preferable that a conductive adhesive tape or a thermally conductive adhesive 270 is disposed.

The thermally conductive adhesive tape or thermally conductive adhesive 270 may be made of a polymer-based electrical conductive adhesive (ECA). This ECA material is a material in which metal particles are dispersed in a polymer binder, and the metal particles have electrical properties, The polymeric medium provides thermal conductivity.

That is, by using an adhesive member having thermal conductivity in the portion where the phosphor tube 230 and the light source housing 210 are in contact, heat generated from the phosphor tube is well transferred to the light source housing, thereby further improving the heat dissipation characteristics of the phosphor tube. can do it

5 shows an example in which a gap compensating member for compensating an optical gap around a phosphor tube is used.

As shown in FIG. 4 , in the backlight unit according to the present embodiment, a first optical gap OG1 of a predetermined distance exists between the light source 224 of the light source unit and the upper surface of the phosphor tube. A second optical gap OG2 having a predetermined distance is formed between the first side surface and the light guide plate 240 .

Such an optical gap is an air gap formed in a path through which light is transmitted, and may weaken light transmission characteristics.

Therefore, as shown in FIG. 5 , the first gap compensating member 232 disposed in the first optical gap OG1 between the upper surface of the phosphor tube and the light source, and the first side of the phosphor tube and the light incident surface of the light guide plate 240 . A second gap compensating member 234 disposed in the second optical gap OG2 may be included.

The first gap compensating member 232 and the second gap compensating member 234 may be configured in the form of a transparent film or a transparent tape having a thickness smaller than that of the first optical gap OG1 and the second optical gap OG2, , may be separately manufactured and attached to the upper surface and the side surface of the phosphor tube 230 , respectively.

The first gap compensating member 232 and the second gap compensating member 234 may be made of a light-transmitting resin material having a constant refractive index, and specifically, polymethyl methacrylate (PMMA), MS ( Materials such as methlystylene resin, polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), and polycarbonate (PC) may be used.

Since the first gap compensating member 232 and the second gap compensating member 234 are manufactured in the form of a tape and adhered to the phosphor tube 230, an optically clear adhesive (hereinafter referred to as 'OCA') film or It may be formed as an OCA adhesive layer.

It is preferable that the OCA film or OCA material that can be used as the material of the first gap compensating member 232 and the second gap compensating member 234 does not cause yellowing and haze under high temperature and high humidity, and the substrate or glass attached thereto It is desirable to ensure durability and reliability in which lifting, peeling, and bubbles do not occur on the same substrate surface.

In addition, it is preferable to ensure reworkability that can be detached again after being attached to the phosphor tube 230, and an adhesive having a hydroxyl group (-OH) as a crosslinking functional group may be used to secure re-peelability. , a pressure-sensitive adhesive having mainly acrylic acid, which has strong adhesion, as a crosslinking functional group, can be used as long as re-peelability is ensured.

As the OCA film or OCA material that can be used as the material of the first gap compensating member 232 and the second gap compensating member 234, an acrylic copolymer can be used, and can be prepared using a conventional solution polymerization method. may, but is not limited thereto.

On the other hand, since the first gap compensating member 232 serves to transmit the light from the light source 224 to the phosphor tube, it is preferable to form a material having the same refractive index as that of the material constituting the phosphor tube 230 . .

Similarly, since the second gap compensating member 234 serves to transmit the light from the phosphor tube 230 to the light guide plate 240 , the material constituting the phosphor tube 230 or the same material as the material of the light guide plate 240 . It is preferably formed of a material having a refractive index.

As described above, by arranging the materials of the first gap compensating member 232 and the second gap compensating member 234 in the optical gap OG around the phosphor tube, as shown in Fig. 5(a), air on the optical path By minimizing the air gap, light transmission characteristics may be secured, and as a result, the light efficiency of the backlight unit may be improved.

6 shows an example of an optical pattern formed in the phosphor tube according to the present embodiment.

As described above, the white light converted by the phosphor tube 230 should be transmitted to the light incident portion of the light guide plate 240 .

Meanwhile, in the conventional structure as shown in FIG. 1 , since the light source, the phosphor tube, and the light incident surface of the light guide plate are arranged on the same line, light emitted from the phosphor tube can be easily incident on the light guide plate.

However, in the backlight unit according to the present embodiment, since the light source 224, the phosphor tube 230, and the light incident surface of the light guide plate are arranged to have a predetermined angle, the light emitted from the phosphor tube 230 is guided or condensed to the light guide plate. There is a need.

For this purpose, as shown in FIG. 6 , it is preferable that one or more optical patterns are formed on the first side opposite to the light incident surface of the light guide plate in the phosphor tube 230 according to the present embodiment.

This optical pattern is a light collecting pattern for condensing the light emitted from the phosphor tube to the light incident surface of the light guide plate. The optical pattern is a concave pattern 236 formed entirely on the first surface of the phosphor tube, or an embossing pattern formed on the first surface of the phosphor tube. (236').

The concave pattern 236 or the embossed pattern 236' may be formed of a material different from the material constituting the phosphor tube 230, and may be made of a material having a larger refractive index than the material of the phosphor tube in order to secure a light collecting characteristic. It is preferably formed, but is not limited thereto, and may be formed as a void such as a cavity.

In addition, the shape of the optical pattern is also not limited to a concave pattern or an embossing pattern, and may be formed in a prism pattern or the like.

In addition, the optical pattern may be directly formed on the first surface of the phosphor tube, or may be formed by attaching a separate light collecting sheet or the like to the first surface of the phosphor tube.

In addition, as described above, when the second gap compensating member 234 is disposed in the second optical gap OG2 between the first side of the phosphor tube and the light incident face of the light guide plate 240, the second gap compensating member ( The optical pattern may be formed on one surface of 234 , and the second gap compensating member 234 itself may be manufactured in the form of a condensing film and attached to the first side of the phosphor tube.

As described above, by forming a predetermined optical pattern on the first side of the phosphor tube 230 , it is possible to increase the light transmission efficiency between the phosphor tube and the light incident surface of the light guide plate.

7 is a cross-sectional view and an enlarged perspective view of a backlight unit according to another embodiment of the present invention, and FIG. 8 is a cross-sectional view of a display device including the backlight unit according to the embodiment of FIG. 7 .

In the backlight unit of FIGS. 7 and 8 , the light source housing 710 is formed in a U-shape as a whole, but an inclined surface 718 is further formed on the entire or part of the inner surface of the side surface.

In addition, the phosphor tube 730 also has a side inclined portion 738 to be seated on the inclined surface 718 of the above-described light source housing. That is, unlike the previous embodiment, the cross-section of the phosphor tube 730 according to the embodiment of FIG. 7 may be a triangle.

In addition, a reflective member 718 ′ having a reflective characteristic may be additionally disposed on the inclined surface 718 of the light source housing 710 or the side inclined portion 738 of the phosphor tube 730 .

The reason why the inclined surface 718 is formed on the light source housing as shown in FIG. 7 is to reflect the path of the light emitted from the light source 224 in a direction perpendicular to the light incident surface of the light guide plate to increase light transmission efficiency.

As shown in (a) of FIG. 7 , the light emitted from the light source 224 is incident into the phosphor tube 730 , is reflected from the inclined surface 718 , and is directed toward the light incident surface of the light guide plate.

That is, in the backlight unit according to this embodiment, since the light source 224, the phosphor tube 730, and the light incident surface of the light guide plate are arranged to have a constant angle, there is no need to guide the light emitted from the phosphor tube 730 to the light guide plate. And for this, the inclined surface structure of the light source housing is used.

Because of these characteristics, the inclination angle θ between the inclined surface 718 and the light source housing bottom 716 is preferably 45 degrees.

In this case, the reflective member 718 ′ may be formed as a type reflective layer by directly sputtering and depositing a material such as Au or Ag having a reflective characteristic superior to that of aluminum on the inclined surface 718 of the light source housing.

Alternatively, the reflective member 718 ′ may be manufactured in the form of a separate reflective film and adhered to the inclined surface of the light source housing.

In this case, the reflective film may have a double-layer structure including a light-transmitting parent film layer and a reflective coating layer disposed on at least one surface of the parent film layer.

The parent film layer constituting the double-layered reflective member 718' is polymethyl methacrylate (PMMA), MS (methlystylene) resin, polystyrene: PS, polypropylene (PP), polyethylene It is formed of a light-transmitting material such as polyethylene terephthalate (PET) and polycarbonate (PC), glass, etc. It can be formed by coating on.

As described above, by forming the inclined surface on the side surface of the light source housing and arranging the reflective member in the region, the light from the light source is guided to the light guide plate, so that the light transmission efficiency and furthermore, the luminance of the entire backlight unit can be improved.

FIG. 9 shows various types of phosphor tubes used in the backlight unit according to the embodiment of FIG. 7 .

As shown, the inclined surface 718 formed in the light source housing is not formed over the entire light source housing side part 714, but is formed to extend from a certain point inside the light source housing side part to a certain point on the bottom surface part.

In this case, the cross-sectional shape of the phosphor tube 730 may be a right-angled triangular shape as shown in FIG. 7 , but is not limited thereto.

That is, as shown in (a) of FIG. 9 , the side inclined portion 738 ′ formed in the phosphor tube 730 may be a chamfered surface formed by chamfering. It may have a pentagonal shape.

In addition, as shown in FIG. 9(b), in the backlight unit according to the embodiment of FIG. 7, a first gap compensating member 732 is disposed in the first optical gap between the upper surface of the phosphor tube 730 and the light source. and a second gap compensating member 734 disposed in a second optical gap between the first side surface of the phosphor tube and the light incident surface of the light guide plate 240 .

Also, as shown in FIG. 9C , in the backlight unit according to the embodiment of FIG. 7 , an optical pattern 736 for light collection may be formed on the first side of the phosphor tube 730 .

The configuration and functions of the gap compensating members 732 and 734 and the optical pattern 736 are the same as those of the embodiment of FIG. 2 , and thus descriptions will be omitted to avoid duplication.

Table 1 below compares and measures the internal temperature of the phosphor tube 127 in the structure shown in FIG. 1 and the internal temperature of the phosphor tube 230 in the embodiment of the present invention as shown in FIG. 2 .

Light source drive current (mA) Phosphor tube temperature (˚C) of conventional structure (Fig. 1) Phosphor tube temperature (˚C) of this embodiment (Fig. 2) temperature decrease
(˚C) 100mA 57 53 -4 200mA 82 76 -6 300mA 106 96 -10 400mA 128 116 -12 500mA 149 135 -14

As shown in the above experimental results, when the structure according to the present embodiment is used, the temperature inside the phosphor tube is reduced by 4 to 14 degrees or more according to the size of the driving current of the light source, compared with the existing structure.

10 shows the luminance distribution at the edge of the display area of the display device when the structure according to the present embodiment is used.

The experiment of FIG. 10 shows the phosphor tube assembly (conventional) having the same structure as in FIG. 1, the phosphor tube assembly of the present invention (first embodiment) according to FIG. 5, and the phosphor tube assembly (first embodiment) of the present invention according to FIG. Example 2) was arranged on one side of the display device (FIG. 10(a)) and then driven with the same light source driving current to measure the luminance at the edge of the active area (A/A) of the display panel. will be.

As a result, as shown in (b) of FIG. 10, the change in luminance between the phosphor tube assemblies is reduced compared to the conventional structure, and in particular, in the embodiment of FIG. 7 (the second embodiment), compared to the conventional structure, It was found that the luminance was improved by about 6% or more.

As described above, in the case of using the structure of the embodiment of the present invention, while the temperature of the phosphor tube is reduced to minimize deterioration of the phosphor, there is little decrease in luminance or the effect of increasing the luminance according to the embodiment was confirmed.

According to the embodiment of the present invention as described above, in the fluorescent light source device including a blue LED and a phosphor tube, the light source housing supporting the light source part and the phosphor tube is formed in a U-shape made of a thermally conductive material, and the light source part is the light source housing It is possible to improve the heat dissipation performance of the heat generated by the phosphor tube by arranging it on the bottom of the upper support surface of the phosphor tube and placing the phosphor tube in contact with at least one of the side surface and the bottom surface of the light source housing.

In addition, by adding a gap compensating member to the phosphor tube for compensating the optical gap between the phosphor tube and the light source (package) and between the phosphor tube and the light guide plate, the light transmission efficiency can be improved.

In particular, the light source housing for supporting the light source unit and the phosphor tube is formed in a U-shape made of a thermally conductive material, and an inclined surface is provided inside the side surface of the light source housing to improve the efficiency of light entering the light guide plate, thereby realizing high brightness.

The above description and the accompanying drawings are merely illustrative of the technical spirit of the present invention, and those of ordinary skill in the art to which the present invention pertains can combine configurations within a range that does not depart from the essential characteristics of the present invention. , various modifications and variations such as separation, substitution and alteration will be possible. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

210, 710: light source housing 220: light source unit
222: light source PCB 224: light source
230: phosphor tube 240: light guide plate
212, 712: upper surface 214, 714: side part
216, 716: bottom part 718: inclined surface
340: light blocking member 232, 234: first and second gap compensating member
310: cover bottom 320: guide panel
330: display panel

Claims (13)

a light source housing made of a thermally conductive material, the light source housing including an upper surface part, a side part, and a bottom surface part;
a light source unit disposed on the inner surface of the upper surface of the light source housing, the light source unit including a blue light source and a light source PCB for supporting the blue light source;
a phosphor tube disposed in contact with the inner surface of the side surface and the bottom surface of the light source housing and including a phosphor for converting blue light from the blue light source into light of another frequency band;
a light guide plate receiving and diffusing the light from the phosphor tube;
A first gap compensation member disposed in a first optical gap between the upper surface of the phosphor tube and the blue light source, and a second gap compensation member disposed in a second optical gap between the first side of the phosphor tube and the light incident surface of the light guide plate A backlight unit for a display device including a member. delete According to claim 1,
a thermally conductive adhesive member is disposed between the second side surface of the phosphor tube and the inner surface of the side surface of the light source housing, and between the bottom surface of the phosphor tube and the inner surface of the bottom surface of the light source housing. According to claim 1,
A backlight unit for a display device having one or more optical patterns disposed on a first side surface of the phosphor tube. 5. The method of claim 4,
The optical pattern is at least one of a concave pattern, an embossing pattern, and a prism pattern. According to claim 1,
The side surface portion of the light source housing further includes an inclined surface, and the phosphor tube includes a side inclined portion contacting the inclined surface of the light source housing. 7. The method of claim 6,
A reflective member having a light reflection characteristic is disposed on at least one of an inclined surface of the light source housing and a side inclined portion of the phosphor tube. A light source housing made of a thermally conductive material, the light source housing including an upper surface portion, a side surface portion, and a bottom surface portion, and disposed on the inner surface of the upper surface portion of the light source housing, the light source portion comprising a blue light source and a light source PCB for supporting the blue light source; A phosphor tube disposed in contact with the inner surface of the side surface and the bottom surface of the light source housing, the phosphor tube including a phosphor that converts blue light from the blue light source into light of another frequency band, and a light guide plate that receives and diffuses the light from the phosphor tube a backlight unit comprising;
a cover bottom surrounding the outside of the bottom and side portions of the light source housing;
a guide panel surrounding the outer side of the cover bottom, the outer side of the upper surface of the light source housing, and a portion of the upper side of the light guide plate;
and a display panel supported on an upper portion of the guide panel,
A first gap compensation member disposed in a first optical gap between the upper surface of the phosphor tube and the blue light source, and a second gap compensation member disposed in a second optical gap between the first side of the phosphor tube and the light incident surface of the light guide plate A display device including a member. delete 9. The method of claim 8,
An optical pattern including at least one of a concave pattern, an embossing pattern, and a prism pattern is disposed on a first side surface of the phosphor tube. 9. The method of claim 8,
The side surface portion of the light source housing further includes an inclined surface, and the phosphor tube includes a side inclined portion contacting the inclined surface of the light source housing. 12. The method of claim 11,
A reflective member having a light reflection characteristic is disposed on at least one of an inclined surface of the light source housing and a side inclined portion of the phosphor tube. 9. The method of claim 8,
and a light blocking member disposed between the guide panel and an upper portion of the light guide plate.

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