KR20060094632A - Reflective polarizer film and back-light unit - Google Patents

Abstract

In the present invention, the DRPF reflective polarizing film is reinforced to form a reflective polarizing film.

By reinforcing the DRPF film main body to form the reflective polarizing film in this manner, the price is low, the luminance of the liquid crystal display device is sufficiently increased, and the reflective polarizing film is not deformed by heat, thereby increasing the competitiveness of the liquid crystal display device.

DRPF film, reflective polarizing film, heat resistant, scratch

Description

Reflective polarizer film and back-light unit

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a cross-sectional view showing the positional relationship of the film in the backlight unit according to the embodiment of the present invention.

3 is a view showing the optical principle of the reflective polarizing film.

4 is a cross-sectional view of a reflective polarizing film which is one embodiment according to the present invention.

5 is a cross-sectional view of another reflective polarizing film according to the present invention.

6 is a cross-sectional view of a reflective polarizing film which is another embodiment according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: bottom chassis 12: lamp holder

14: frame mold side 16: lamp

18: reflective sheet 20: backlight unit

21: reflective polarizing film 22: prism sheet

23: diffusion plate 30: mold frame

51, 52: polarizer 60: top chassis

70: liquid crystal display panel 72: thin film transistor substrate

74: color filter substrate 80: liquid crystal panel assembly

81, 83: TCP 85, 87: printed circuit board

100: liquid crystal display

210: DRPF film body 211: protective layer

212: adhesive layer

The present invention relates to a reflective polarizing film and a backlight unit including the same.

In general, a liquid crystal display (LCD) includes a thin film transistor array panel on which gate lines, data lines, thin film transistors, and pixel electrodes are formed, and a color filter display panel on which color filters and a common electrode are formed. It consists of a liquid crystal layer etc. which are filled between these thin-film transistor display panels and a color filter display panel.

In the liquid crystal display, the transmittance of light changes as the liquid crystal rotates due to an electric field formed between the pixel electrode and the common electrode, and an image is displayed according to the change of the transmittance. The electric field formed between the pixel electrode and the common electrode is controlled by the pixel electrode, and the voltage of the pixel electrode is controlled through a switching element called a thin film transistor. Here, the thin film transistor transmits or blocks the image signal transmitted along the data line to the pixel electrode by the scan signal transmitted along the gate line.

When the voltage is not applied to the pixel electrode and the common electrode, the liquid crystal layers are arranged in a predetermined direction by an alignment layer formed on the surfaces of the thin film transistor array panel and the color filter display panel, and when the voltage is applied, the liquid crystal rotates according to the direction of the electric field. do.

Since the liquid crystal is a light receiving element, a portion for separately providing light is required for the liquid crystal display. In order to provide light, a separate backlight unit is formed on the rear surface of the thin film transistor substrate. The backlight unit is provided with a lamp for providing light and a light guide plate and other films for evenly distributing the light over the entire area of the substrate.

The liquid crystal display device does not transmit all of the light provided from the backlight, so the luminance of the panel is very important. Various films have been developed and used to improve the brightness of the panel, and a representative example thereof is a reflective polarizing film.

There are various types of reflective polarizing films, but representative examples thereof include dual brightness enhancement film (DBEF) and diffusive reflective polarization film (DRPF).

A dual brightness enhancement film (DBEF) reflective polarizing film is a film having a laminated structure of several hundred layers by repeatedly forming an isotropic film and an anisotropic film. As light transmits and reflects hundreds of layers, the light transmitted through the film generally increases, thereby increasing the brightness of the liquid crystal display.

On the other hand, the reflective reflective polarization film (DRPF) reflective polarizing film is formed to form a material having a different refractive index from the film in the film, the light is reflected and refracted by the material is formed to increase the light passing through the film.

Among the various reflective polarizing films, DBEF (dual brightness enhancement film) has the highest brightness enhancement ratio, but it is difficult to use in low-cost liquid crystal display because the manufacturing process is complicated and the manufacturing cost is very high because hundreds of layers of laminated structure must be formed. have. In contrast, a diffusive reflective polarization film (DRPF) has an advantage of low cost due to a simple manufacturing process.

In particular, as the size of the liquid crystal display increases, the cost of the reflective polarizing film greatly increases, so that the price of the LCD TV increases. Thus, even if a liquid crystal display device becomes large, the reflective polarizing film which does not have a problem in terms of price or brightness improvement is needed.

On the other hand, a reflective reflective polarization film (DRPF) reflective polarizing film generally has a high coefficient of thermal expansion in itself, it is thin and has a disadvantage in that the reliability is not high because the film is likely to cry or scratch. In particular, in large liquid crystal display devices such as TVs where the backlight is directly formed by deformation due to heat, the DRPF reflective polarizing film cannot be used.

The technical problem to be achieved by the present invention is to provide a reflective polarizing film that is low in price and sufficiently increases the luminance of the liquid crystal display device and does not expand or deform the film.

In order to solve this problem, the present invention forms a reflective polarizing film by reinforcing the DRPF reflective polarizing film.

Specifically, the present invention relates to a reflective polarizing film including a protective layer formed on a top surface and a bottom surface of a diffusive reflective polarization film (DRPF) film body and a top surface of the diffusive reflective polarization film (DRPF) film body.

It is preferable that irregularities are formed on at least one outer surface of the protective layer,

The protective layer is polycarbonate (polycabonate), polycarbonate-based, poly sulfone-based, poly acrylate-based, polystyrene-based, polyvinyl fluoride-based, polyvinyl alcohol-based, poly norbornene-based, polyester-based (especially polyethylene It is preferably formed of a substance such as terephthalate (PET) or polyethylene naphthalate (PEN)),

The protective layer preferably has a thickness of 30% or more and 100% or less of the thickness of the diffuse reflective polarization film (DRPF) film body,

It relates to a reflective polarizing film comprising a protective reflective polarization film (DRPF) film body, a protective layer formed on one surface of the reflective reflective polarization film (DRPF) film body,

The protective layer is preferably formed on the side of the liquid crystal display panel of the surface of the reflective reflective polarization film (DRPF) film body,

It is preferable that irregularities are formed on the outer surface of the protective layer,

The protective layer preferably has a thickness of 30% or more and 100% or less of the thickness of the diffuse reflective polarization film (DRPF) film body,

Reflective polarization comprising an adhesive layer for adhering the two or more diffusive reflective polarization film (DRPF) film bodies between two or more diffusive reflective polarization film (DRPF) film bodies and the two or more diffusive reflective polarization film (DRPF) film bodies For the film,

The adhesive layer is preferably an acrylic ester,

A lamp for providing light to the liquid crystal display panel, a light guide plate for allowing the light emitted from the lamp to enter the liquid crystal display panel, and a reflective polarizing film positioned on the light guide plate, wherein the reflective polarizing film is a DRPF (diffusive reflective polarization). film) and a backlight unit including a protective layer formed on the top and bottom surfaces of the diffusive reflective polarization film (DRPF) film body, respectively.

A lamp for providing light to the liquid crystal display panel, a light guide plate for allowing the light emitted from the lamp to enter the liquid crystal display panel, and a reflective polarizing film positioned on the light guide plate, wherein the reflective polarizing film is a DRPF (diffusive reflective polarization). film), the backlight unit including a protective layer formed on one surface of the diffusive reflective polarization film (DRPF) film body,

A lamp for providing light to the liquid crystal display panel, a light guide plate for injecting the light emitted from the lamp to the liquid crystal display panel, and a reflective polarizing film positioned on the light guide plate, the reflective polarizing film is two or more DRPF ( The present invention relates to a backlight unit including a diffusive reflective polarization film (DRPF) film body and an adhesive layer for bonding the two or more diffusive reflective polarization film (DRPF) film bodies to each other between the two or more diffusive reflective polarization film (DRPF) film bodies.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

Now, a reflective polarizing film and a backlight unit according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

The liquid crystal display device 100 according to the first exemplary embodiment of the present invention illustrated in FIG. 1 includes a direct-type backlight unit 20 for supplying light and a liquid crystal display panel for displaying an image corresponding to light. Assembly 80. In addition, the top chassis 60, the mold frame 30 and the bottom chassis 10 are coupled to fix them. The direct backlight unit 20 shown in FIG. 1 is merely for illustrating the present invention, and the present invention is not limited to this structure. Accordingly, the present invention can also be applied to liquid crystal displays having other structures. The backlight unit 20 supplies light to the liquid crystal display panel assembly 80 and guides the light to improve brightness, and the liquid crystal display panel assembly 80 positioned on the backlight unit 20 displays an image. Control panel 70.

The liquid crystal display panel assembly 80 includes a liquid crystal display panel 70, a tape carrier package (TCP) 81, 83, and a printed circuit board (PCB) 85, 87. Here, the liquid crystal display panel 70 is injected between a TFT substrate 72 composed of a plurality of TFTs (thin film transistors), a color filter substrate 74 positioned on the TFT substrate 72, and the substrates. It is made of liquid crystal (not shown).

The TFT substrate 72 is a transparent glass substrate on which a matrix thin film transistor is formed. A data line is connected to a source terminal and a gate line is connected to a gate terminal. In the drain terminal, a pixel electrode made of transparent indium tin oxide (ITO) as a conductive material is formed.

When electrical signals are input from the printed circuit boards 85 and 87 to the data lines and gate lines of the liquid crystal display panel 70 described above, electrical signals are input to the source terminal and the gate terminal of the TFT, Depending on the input, the TFT is turned on or turned off so that an electrical signal necessary for pixel formation is output to the drain terminal.

On the other hand, a color filter substrate 74 is disposed thereon opposite the TFT substrate 72. The color filter substrate 74 is a substrate in which RGB pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process, and a common electrode made of ITO is coated on the entire surface thereof. When power is applied to the gate terminal and the source terminal of the TFT and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate. By this electric field, the arrangement angle of the liquid crystal injected between the TFT substrate 72 and the color filter substrate 74 is changed, and the light transmittance is changed according to the changed arrangement angle to obtain a desired pixel.

In order to control the alignment angle of the liquid crystal of the liquid crystal display panel 70 and the timing when the liquid crystals are arranged, a driving signal and a timing signal are applied to the gate line and the data line of the TFT, and the data driving signal is applied to the source side of the liquid crystal display panel 70. A data TCP 81 for determining when to apply the data is attached, and a gate TCP 83 is attached to the gate for determining the time for applying the gate driving signal.

The data PCB 85 and the gate PCB 87 for receiving a video signal from the outside of the liquid crystal display panel 70 and applying a driving signal to the data line and the gate line, respectively, are provided on the gate line side of the liquid crystal display panel 70. It is connected to the gate TCP 83 and the data TCP 81 on the data line side, respectively.

The data PCB 85 and the gate PCB 87 generate data signals, gate driving signals, which are signals for driving the liquid crystal display device 100, and a plurality of timing signals for applying these signals at appropriate times, respectively. The gate driving signal is applied to the gate line of the liquid crystal display panel 70 through the gate TCP 83, and the data signal is applied to the data line of the liquid crystal display panel 70 through the data TCP 81.

The backlight unit 20 is provided below the liquid crystal display panel assembly 80 to provide uniform light to the liquid crystal display panel assembly 80.

The backlight unit 20 is accommodated and fixed on the bottom chassis 10, and is provided on the bottom surface of the lamp 16 and the lamp 16, which are a plurality of backlights spaced apart by a predetermined distance on the bottom chassis 10. A reflective sheet 18 positioned to reflect light emitted from the lamp, a lamp holder 12 holding and fixing the lamp 16 at both ends of the plurality of lamps 16, and a frame mold side fixing the lamp holder 12 (frame mold side) 14 and reflective polarizing film 21, prism sheet 22 and diffuser plate for securing the luminance characteristics of the light from lamp 16 to provide light to liquid crystal display panel assembly 80 23 is provided.

Although not shown in FIG. 1, an inverter board, which is a power supply PCB, and a signal conversion PCB are installed on the bottom of the bottom chassis 10. The inverter board transforms an external power supply to a constant voltage level to provide the lamp 16, and the signal conversion PCB is connected to the aforementioned data PCB 85 and the gate PCB 87 to convert analog data signals into digital data signals. To the liquid crystal display panel 70.

On the liquid crystal display panel assembly 80, the data PCB 85 and the gate PCB 87 are bent out of the mold frame 30 while preventing the liquid crystal display panel assembly 80 from being separated from the bottom chassis 10. A top chassis 60 is provided. Although not shown in FIG. 1, a front case and a rear case are positioned at an upper portion of the top chassis 60 and a lower portion of the bottom chassis 10, respectively, to form a liquid crystal display device 100 by combining them.

2 is a cross-sectional view showing the positional relationship of the film in the backlight unit according to the embodiment of the present invention.

As shown in FIG. 2, the backlight unit 20 forms a reflective sheet 18 on the bottom surface of the bottom chassis 10, and forms a lamp 16 thereon. The diffusion plate 23-2 and the diffusion sheet 23-1 are formed on the lamp 16 so that the light incident from the lamp 16 is diffused to spread evenly over the entire area of the substrate. The prism sheet 22 is formed on the diffusion sheet 23-1, and the reflective polarizing film 21 is formed thereon. The prism sheet 22 and the reflective polarizing film 21 are both kinds of brightness enhancement films, and are films for enhancing the brightness of a display device.

It is also possible to form so as to have a different arrangement from that shown in FIG.

It is a figure which shows the optical principle of a reflective polarizing film.

As shown in FIG. 3, the reflective polarizing film 21 allows P waves to pass through and reflects S waves without passing through them. S-waves reflected from the reflective polarizing film 21 are reflected back from the reflective sheet 18 under the lamp 16 and are incident on the reflective polarizing film 21. At this time, some of the polarization direction is changed by the P wave to pass through the reflective polarizing film 21. By repeating the above process, the brightness of the display device is improved.

Hereinafter, the reflective polarizing film 21 of the present invention will be described. It is preferable that a reflective polarizing film is formed in the position shown in FIG.

4 is a cross-sectional view of a reflective polarizing film which is one embodiment according to the present invention.

As shown in FIG. 4, an embodiment according to the present invention is formed of a DRPF film body 210 and a protective layer 211 attached to upper and lower portions thereof.

The DRPF film main body 210 contains a large amount of a material having a different refractive index from the inside of the film, and light having different polarization directions is reflected due to a material having a different refractive index when light is transmitted. The reflected light is reflected by the reflective sheet 18 of the backlight unit 20 and then incident to the DRPF film body 210 again. At this time, some of the light incident after being reflected again is the polarization direction is changed, thereby transmitting through the DRPF film body 210. As a result, the amount of light provided to the liquid crystal display panel 70 is increased to increase the luminance of the liquid crystal display device 100. However, the DRPF film body 210 is weak to scratches, and particularly has a disadvantage of weak heat. Since the liquid crystal used in the liquid crystal display device 100 is a light receiving element, a portion for providing light is required, and light must be provided from the lamp 16 of the backlight unit 20. Since the lamp 16 provides heat and also emits heat, the films used in the backlight unit 20 must all have heat resistance.

In the embodiment of the present invention, the protective layer 211 is formed on the upper and lower portions to protect the DRPF film body 210 from heat resistance and scratches.

The protective layer 211 should be optically stable (i.e., should not degrade the brightness of the liquid crystal display), should be resistant to heat in terms of physical properties, have a suitable strength to resist external damage such as scratches, and the DRPF film It should be able to adhere well to the surface of the body 210. Representative materials having such characteristics are polycarbonate (polycabonate; hereinafter referred to as PC), polycarbonate-based, polysulfone-based, polyacrylate-based, polystyrene-based, polyvinyl fluoride-based, polyvinyl alcohol-based, poly-norbornene A substance such as a series and a polyester series (especially polyethylene terephthalate (PET) and polyethylene naphthalate (PEN)) is preferable.

The protective layer 211 preferably has a thickness of 30% or more and 100% or less of the thickness of the DRPF film body 210.

In addition, in order to enhance heat resistance of the reflective polarizing film 21 on which the protective layer 211 is formed, irregularities may be formed on the surface of the protective layer 211. The unevenness also has a function of dispersing light in various directions.

The protective layer 211 in which the unevenness is formed is preferably formed in the protective layer on the side of the liquid crystal display panel 70, and may also be formed in the protective layer 211 on the opposite side.

5 is a cross-sectional view of another reflective polarizing film according to the present invention.

5 illustrates an embodiment different from FIG. 4. 5 illustrates an embodiment in which the protective layer 211 is formed only on the surface of the liquid crystal display panel 70 side of the DRPF film body 210. Forming the protective layer 211 only on the surface of the liquid crystal display panel 70 side is to protect the protective layer 211 from scratches that may be applied from the liquid crystal display panel 70.

Here, the protective layer 211 preferably has a thickness of 30% or more and 100% or less of the thickness of the DRPF film body 210.

Unevenness may also be added to the protective layer 211 so that the reflective polarizing film 21 may be formed to have high heat resistance as a whole.

6 is a cross-sectional view of a reflective polarizing film which is another embodiment according to the present invention.

The reflective polarizing film 21 illustrated in FIG. 6 illustrates a reflective polarizing film 21 having a structure in which two DRPF film bodies 210 are attached using the adhesive layer 212, unlike FIGS. 4 and 5.

By attaching two weak DRPF film bodies 210 to heat, the heat resistance is enhanced. In this case, the material used for the adhesive layer 212 is also used as a material resistant to heat. In addition, the adhesive layer 212 may be optically stable so as not to lower the brightness of the liquid crystal display, and have good adhesiveness with the DRPF film body 210.

The material usable as the adhesive layer 212 mainly uses a polymer having the above characteristics, and typically, an acrylic ester is preferable.

The present invention is not limited to the embodiments described above, and may be any method of reinforcing the DRPF film body 210 in various ways. As shown in FIG. 5, the protective layer 212 may be formed on the lower side of the DRPF film body 211 (the opposite side of the liquid crystal display panel 70), and as illustrated in FIG. 6, three or more DRPF film bodies ( 211 may be formed by adhering the adhesive layer 213.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, by forming the reflective polarizing film by reinforcing the DRPF film body, the price is low, the luminance of the liquid crystal display device is sufficiently increased, and the reflective polarizing film is not deformed by heat, thereby increasing the competitiveness of the liquid crystal display device. .

Claims (13)

DRPF (diffusive reflective polarization film) film body, Reflective polarizing film comprising a protective layer formed on the upper and lower surfaces of the diffusive reflective polarization film (DRPF) film body, respectively. In claim 1, Reflective polarizing film is formed on the outer surface of at least one of the protective layer. In claim 1, The protective layer is polycarbonate (polycabonate), polycarbonate-based, poly sulfone-based, poly acrylate-based, polystyrene-based, polyvinyl fluoride-based, polyvinyl alcohol-based, poly norbornene-based, polyester-based (especially polyethylene Reflective polarizing film formed of materials, such as terephthalate (PET) and polyethylene naphthalate (PEN)). In claim 1, The protective layer has a reflective polarizing film having a thickness of 30% or more and 100% or less of the thickness of the reflective reflective polarization film (DRPF) film body. DRPF (diffusive reflective polarization film) film body, Reflective polarizing film comprising a protective layer formed on one surface of the reflective reflective polarization film (DRPF) film body. In claim 5, The protective layer is a reflective polarizing film formed on the side of the liquid crystal display panel of the surface of the reflective reflective polarization film (DRPF) film body. In claim 5, Reflective polarizing film is formed on the outer surface of the protective layer irregularities. In claim 5, The protective layer has a reflective polarizing film having a thickness of 30% or more and 100% or less of the thickness of the reflective reflective polarization film (DRPF) film body. Two or more diffusive reflective polarization film (DRPF) film bodies, And a bonding layer for adhering the two or more diffusive reflective polarization film (DRPF) film bodies to each other between the two or more diffusive reflective polarization film (DRPF) film bodies. In claim 9, The adhesive layer is a reflective polarizing film of acrylic ester. Lamps that provide light to the liquid crystal display panel, A light guide plate to allow the light emitted from the lamp to enter the liquid crystal display panel; It includes a reflective polarizing film positioned on the light guide plate, The reflective polarizing film may include a reflective reflective polarization film (DRPF) film body and a protective layer formed on each of the upper and lower surfaces of the diffusive reflective polarization film (DRPF) film body. Lamps that provide light to the liquid crystal display panel, A light guide plate to allow the light emitted from the lamp to enter the liquid crystal display panel; It includes a reflective polarizing film positioned on the light guide plate, The reflective polarizing film may include a reflective reflective polarization film (DRPF) film body and a protective layer formed on one surface of the diffusive reflective polarization film (DRPF) film body. Lamps that provide light to the liquid crystal display panel, A light guide plate to allow the light emitted from the lamp to enter the liquid crystal display panel; It includes a reflective polarizing film positioned on the light guide plate, The reflective polarizing film is an adhesive layer for bonding the two or more diffusive reflective polarization film (DRPF) film bodies to each other between the two or more diffusive reflective polarization film (DRPF) film bodies and the two or more diffusive reflective polarization film (DRPF) film bodies. Backlight unit comprising a.

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