JP2009265593A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device having a protection member capable of enhancing reliability against an external impact, and outdoor visibility. <P>SOLUTION: The liquid crystal (LC) display device comprises: a LC panel for displaying images; a backlight unit disposed below the LC panel, and providing light; a protection member provided on the LC panel, and composed of a tempered substrate for protecting the LC panel from an external impact, and a low-reflective layer formed on the tempered substrate and reducing the reflectivity of external light which enters from the outside; and an adhesive layer formed of a material having a refractive index similar to that of the LC panel and that of the tempered substrate of the protection member for adhering the protection member to the LC panel by being interposed therebetween. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device provided with a protective member that simultaneously improves reliability against external impact and deterioration of outdoor visibility due to external light.

  A CRT, which is one of the display devices that are widely used in general, has been mainly used for monitors such as televisions, measuring devices, information terminal devices, etc., but depending on the weight and size of the CRT itself, It was not possible to respond positively to downsizing and weight reduction.

  Due to such drawbacks, liquid crystal display devices having advantages such as small size, light weight, and low power consumption have been actively developed in place of CRT, and recently, the liquid crystal display device can sufficiently function as a flat panel display. The demand for laptop computers, desktop computers, large outdoor monitors of 30 inches or more, and wall-mounted televisions is gradually increasing.

  The liquid crystal display device is a light receiving device that displays an image by adjusting the amount of light from the outside. As a result, a backlight device including a separate light source for irradiating the LCD panel with light is required, but the backlight device usually has an edge type and a direct type depending on the position of the light source with respect to the display surface of the LCD panel. It is divided roughly into. Among them, the direct type backlight device is widely used for a large-sized liquid crystal display device of 30 inches or more because it has a high light utilization rate, is easy to handle, and has no limitation on the size of the display surface.

  However, when a plurality of CCFLs are driven in parallel using a single transformer, the direct type backlight device has a problem that only a part of the plurality of CCFLs is driven due to the discharge characteristics of the CCFL. That is, the CCFL has an infinite resistance value before discharging, but after the discharging, the resistance value decreases due to the plasma of the conductor generated inside the glass tube. As a result, when the CCFL is discharged, the resistance value decreases from the initial stage and the amount of current increases. Therefore, when a plurality of CCFLs are connected in parallel and driven in parallel, a current flows to the CCFL side having a small resistance value after the initial discharge, so that only a part of the plurality of CCFLs is driven and the rest is not driven. .

  Currently, as part of solving such problems, capacitors of the same capacity, that is, ballast capacitors, are attached to both electrodes of each CCFL to form the same equivalent circuit as an external electrode fluorescent lamp (EEFL). Accordingly, there has been proposed a lamp driving device for a liquid crystal display device that can drive a plurality of CCFLs in parallel using one transformer.

  Here, EEFL is turned on when AC power is supplied to the external electrodes, and discharge is performed in the discharge space inside the glass tube by the electric field generated by the high frequency voltage applied to the pair of external electrodes. The fluorescent substance applied to the inner peripheral surface of the glass tube emits light by the ultraviolet rays generated by the above, and generates visible light.

  FIG. 7 is a cross-sectional view showing a configuration of a general direct liquid crystal display device. As shown in FIG. 7, a general direct type liquid crystal display device includes a backlight device (no reference) that provides light, and a liquid crystal panel 20 that is provided above the backlight device to provide light. And polarizing plates (or polarizing films) 21 and 22 attached to the upper and lower surfaces of the liquid crystal panel 20, respectively. Here, the backlight device includes a plurality of lamps 48 serving as light sources.

  On the lower cover 41, a reflecting plate 42 for reflecting the light from the plurality of lamps 48 to the front surface is attached. Further, on both sides of the lower cover 41, balance PCBs 49a and 49b to which a plurality of lamps 48 are fastened are provided. Further, inverter PCBs 50a and 50b for applying an alternating voltage are connected to the balance PCBs 49a and 49b, respectively, which will be described later.

  On the upper side of the lamp 48, a diffusion plate 43 for uniformly dispersing the light provided from the lamp 48 and reflected by the reflection plate 42 toward the front surface, and the optical function of the light transmitted through the diffusion plate 43 are complemented. An optical sheet 44 including a prism sheet and / or a protective sheet is placed.

  Next, a main support (not shown) is provided to maintain an overall force balance of the liquid crystal display device. In consideration of the liquid crystal panel 20 placed on the upper side, the main support is formed with a predetermined pattern having a step on the upper side.

  The liquid crystal panel 20 placed on the main support is formed by a number of unit processes. That is, the liquid crystal panel 20 includes a thin film transistor array substrate 20a in which thin film transistors are arranged for each unit pixel, a color filter substrate 20b on which a color filter that expresses a color corresponding to the thin film transistor array substrate is formed, and a space between these two substrates. Liquid crystal injected into the liquid crystal.

  The polarizing plates 21 and 22 attached to the upper and lower surfaces of the liquid crystal panel 20 transmit only light that vibrates in the same direction as the polarization axis among the light provided from the backlight device, and vibrate in other directions. The light to be absorbed is reflected or reflected by using an appropriate medium, thereby serving as light that vibrates in a specific direction. Such polarizing plates 21 and 22 are essential components of a TN mode LCD.

  The upper cover (not shown) is attached to the lower cover 41 by a separate fastening means such as a hook so as to cover the edge region of the liquid crystal panel 20 to which the polarizing plates 21 and 22 are attached and the side surface of the main support. It is concluded.

  FIG. 8 is a perspective view showing a conventional backlight structure, and shows a balance PCB on a lower cover and an inverter PCB linked thereto. As shown in FIG. 8, the inverter PCBs 50a and 50b convert a DC voltage supplied from the outside into a high-voltage AC voltage. The AC high voltage is applied to the balance PCBs 49a and 49b through the output connectors of the inverter PCBs 50a and 50b under the control of the integrated circuit.

  Next, the high-voltage AC voltage applied to the balance PCBs 49a and 49b is supplied to the ballast capacitors 49a1 and 49b1 via the conductive wires and the high-voltage supply pattern (or wiring), and the plurality of lamps 48 The amount of current flowing into each tube is the same. The ballast current flows into the lamps 48 connected to the ballast capacitors 49a1 and 49b1, respectively.

  However, when such a liquid crystal display device is installed in a public place such as an airport or a bus terminal, the liquid crystal panel is damaged due to an external impact or the like, and the surface hardness attached to the outside by a malicious user is 3H or less. Scratches may occur in a thin polarizing plate. As a result, a separate cost for solving such a problem is generated, and this leads to a decrease in reliability of the product.

  In addition, the liquid crystal display device is usually placed in a high illuminance environment such as external sunlight or indoor lighting, but there is no separate interface treatment on the polarizing plate attached to the outside of the liquid crystal panel. The reflectance reflected by the polarizing plate reaches a maximum of 4%, and even when a separate interface treatment is applied, the minimum exceeds 1.5%, the contrast ratio decreases due to the surface reflection, and the fade phenomenon, etc. As a result, the outdoor visibility of the liquid crystal display device is greatly reduced.

  The present invention has been made to remedy such problems, and it is a first object of the present invention to provide a liquid crystal display device provided with a protective member that can protect the liquid crystal panel from external impacts and improve outdoor visibility. The purpose.

  However, in the liquid crystal display device provided with the protection member, a light leakage phenomenon occurs in which light provided from a backlight provided on the lower side of the liquid crystal panel leaks in an edge region of the protection member. obtain.

  Therefore, a second object of the present invention is to provide a liquid crystal display device in which a light leakage prevention part for preventing a light leakage phenomenon is further formed in at least one side edge region of the protective member.

  In order to achieve the above object, a liquid crystal display device according to the present invention includes a liquid crystal panel on which an image is displayed, a backlight device provided on the lower side of the liquid crystal panel to provide light, and a liquid crystal panel on the liquid crystal panel. A protective substrate comprising a reinforced substrate that protects the liquid crystal panel from external impact, a low reflection layer that is formed on the reinforced substrate and reduces the reflectance of external light incident from the outside, the liquid crystal panel, and the liquid crystal panel It is made of a material having the same refractive index as that of the reinforced substrate of the protective member, and includes an adhesive layer that is interposed between the liquid crystal panel and the protective member to adhere them.

  In addition, a light leakage prevention unit that is formed in at least one side edge region of the protection member and prevents light leakage from the backlight device is further included.

  The liquid crystal display device according to the present invention improves the reliability of the product by protecting the liquid crystal panel from external impacts and the like, and has no gap between the reinforced substrate of the protective member and the liquid crystal panel, and is the same as the reinforced substrate and the liquid crystal panel. By forming the pressure-sensitive adhesive layer with a material having a refractive index of 5 mm, there is an effect that the total visibility of light to the outside of the liquid crystal panel can be reduced and the outdoor visibility can be improved.

  Further, by preventing light leakage phenomenon that may occur in at least one side edge region of the liquid crystal panel provided with the protection member by the light provided from the backlight device provided on the lower side, the liquid crystal display device There is an effect that uniform luminance can be maintained.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing a fastening state of FIG. 1, and FIG. It is a figure which shows the refractive index of the protection member shown in FIG.

  As shown in FIGS. 1 to 3, the liquid crystal display device according to the first embodiment of the present invention includes a backlight device (no symbol) that provides light by an externally applied voltage, and the backlight device. A liquid crystal panel 150 provided on the upper side for displaying an image, a reinforcing substrate 160a provided on the liquid crystal panel 150 for protecting the liquid crystal panel 150 from external impact, and an external formed on the reinforcing substrate 160a and incident from the outside And a protective member 160 made of a low reflective layer 160b that reduces the light reflectance. The protective member 160 is made of a material having the same refractive index as that of the reinforced substrate 160a of the protective member 160, and the protective member 160 is provided on the liquid crystal panel 150. It further includes a pressure-sensitive adhesive layer 160c that closely adheres to each other.

  First, on both side walls (or separate fixing means) of the lower cover 100 made of iron, electrogalvanized steel sheet (EGI), etc., a lamp is applied by an AC high voltage applied from the external first and second inverters. Balance PCBs 101 and 103 for driving 120 are provided vertically.

  The balance PCBs 101 and 103 include connectors 101a and 103a to which an AC high voltage is applied from the external first and second inverters, and ballasts formed in a pattern so as to provide a stable current by the applied AC high voltage. Capacitors 101b and 103b are electrically conductive so that the ballast current can stably flow into the lamp 120, and are arranged at a predetermined angle (about 90 °) so that the plurality of lamps 120 can be easily arranged and fastened. The lamp sockets 101c and 103c are formed as follows.

  In addition, a reflector 105 is attached on the lower cover 100 corresponding to an intermediate region between the balance PCBs 101 and 103 provided vertically on both sides. Here, as the reflection plate 105, for example, a white polyester film or a film coated with metal (Ag, Al) or the like can be used, but the reflectance of visible light on the reflection plate 105 is about 90 to 97%, The thicker the coated film, the higher the reflectivity.

  Further, a plurality of lamps 120 are fastened to the lamp sockets 101c and 103c arranged and fixed on the balance PCBs 101 and 103 on both sides and bent upward. Here, the distance between the lamp 120 fastened to the lamp sockets 101c and 103c and the reflecting plate 105 located on the back surface of the lamp 120 is normally kept constant within about 5 mm. This is because when the distance between the lamp 120 and the reflector 105 exceeds 5 mm, it affects an optical sheet (not shown) that is fastened to the upper side later, and may cause a wrinkle phenomenon due to heat.

  Therefore, in order to adjust the distance between the lamp 120 and the reflector 105, the height of the balance PCBs 101 and 103 provided vertically on both sides of the lower cover 100 is adjusted, or the lamp sockets 101c and 103c described above are formed. By adjusting the predetermined angle, the above problem can be overcome.

  Among them, in the method of adjusting the distance between the lamp 120 and the reflecting plate 105 by adjusting a predetermined angle formed by the lamp sockets 101c and 103c itself, the lamp socket 101c, 103c can be freely bent into various shapes, but typically can be “L” shaped as shown, or “C” or “V” shaped. . Here, one end portion thereof is fixed on the balance PCBs 101 and 103, and the other end portion serves as a holder portion to which the lamp 120 is fastened.

  As described above, a plurality of lamps 120 are fastened to the “L” -shaped lamp sockets 101c and 103c fixed on the balance PCBs 101 and 103 on both sides at a constant interval. In the case of a large LCD TV, about 16 lamps are usually arranged for 32 inches and about 18 to 20 lamps are arranged for 40 inches for high brightness, but this is slightly different depending on the model. Here, the lamp 120 may be any one of CCFL (Cold Cathode Fluorescent Lamp), EEFL, and HCFL (Hot Cathode Fluorescent Lamp).

  Further, on the balance PCBs 101 and 103 including the lamp sockets 101c and 103c located on both sides, a predetermined fixing member for protecting the balance PCBs 101 and 103 from the outside, that is, a side support 130 is placed. Here, the side support 130 manufactured by press working is inclined at a predetermined (or constant) angle, and a semicircular lamp fixing portion for arranging and fixing the lamp 120 on a portion in contact with the lower cover 100. An inclined frame 130b having 130b1, a vertical frame 130a formed perpendicular to the inclined frame 130b at a predetermined interval, and an upper frame 130c extending horizontally from the upper portions of these two frames and formed horizontally. .

  In the present invention, the vertical frame 130 b of the side support 130 is fastened by being positioned on the outer walls of both side walls of the lower cover 100. Accordingly, it is preferable to form a hole in a partial region of the vertical frame 130a in order to project the connector 101a to which an AC high voltage is applied from the external first and second inverters.

  The optical member 140 is placed with both sides supported by the side support 130. Here, the optical member 140 includes a diffusion plate (not shown) for uniformly dispersing light directly emitted from the plurality of lamps 120 and light reflected by the reflection plate 105 over the entire surface of the liquid crystal panel 150, and the diffusion. An optical sheet (not labeled) that allows the light transmitted through the plate to have additional optical properties.

  A main support 145 is fastened to the upper side of the backlight device composed of the above-described components. The main support 145 is located above the backlight device and serves to maintain an overall balance of forces transmitted to the liquid crystal display device when an impact is applied from the outside. The main support 145 is formed with a pattern in which the inner side surface and the outer side surface form a step in consideration that the liquid crystal panel 150 is placed on the front surface (or the upper surface).

  The liquid crystal panel 150 placed on the main support 145 is formed by a number of unit processes. In other words, this is an array substrate in which thin film transistors are arranged as switching elements for each unit pixel, a color filter substrate on which a color filter expressing a color is formed correspondingly, and an injection between these two substrates. Liquid crystal.

  Further, polarizing plates 151 and 152 are respectively attached to the upper and lower surfaces of the liquid crystal panel 150. The polarizing plates 151 and 152 transmit only the light oscillating in the same direction as the polarization axis among the light provided from the backlight device, and the light oscillating in the other directions is absorbed or absorbed using an appropriate medium. By reflecting, it plays a role of making light oscillate in one specific direction.

  A protective member 160 is provided on the liquid crystal panel 150 to protect the liquid crystal panel 150 from external impacts and reduce the reflectance of light incident from the outside. More specifically, the protection member 160 includes a reinforced substrate 160a that protects the liquid crystal panel 150 from external impacts, and a low reflection layer 160b that is exposed to the outside and is exposed to external light is formed on the upper surface of the reinforced substrate 160a. An adhesive layer 160c that contacts the liquid crystal panel 150 or the polarizing plate 151 on the liquid crystal panel 150 is formed on the lower surface of the substrate 160a.

  Here, the reinforced substrate 160a is made of, for example, tempered glass having a thickness of about 3 mm in order to protect the internal liquid crystal panel 150 from an external impact. Tempered glass is a glass that has been strengthened by heating the molded plate glass to approximately 500 to 600 ° C., which is close to the softening temperature, and quenching it with compressed cooling air, thereby compressively deforming the surface portion of the glass and tensilely deforming the inside. is there. Compared to ordinary glass, the bending strength is 3 to 5 times, the impact resistance is 3 to 8 times stronger, and the heat resistance is also superior. However, the glass itself maintains the balance of force inside, and the whole is broken into small bean-sized pieces just by cutting one side slightly. There is a need to.

  The low reflection layer 160b formed on the upper surface of the reinforced substrate 160a and exposed to external light is surface-treated by low-reflection sputtering. That is, two materials having different refractive indexes are alternately formed on the reinforced substrate 160a to form five or six layers. For example, the first layer first exposed to sunlight or an external illumination lamp is formed of a material having a low refractive index, the second layer is formed of a material having a high refractive index, and the third layer is again formed of a low refractive index. The reflectance is reduced by a method in which light absorbed by entering from the outside gradually disappears by passing through each layer. However, the low reflection layer 160a does not necessarily have to be surface-treated by sputtering, and various surface treatment methods such as anti-reflection coating, anti-staining treatment, or anti-fingerprint treatment can be applied.

  Further, the adhesive layer 160c formed on the lower surface of the reinforced substrate 160a and in contact with the liquid crystal panel 150 is UV-bonded with an adhesive (paste) having a refractive index similar to that of the upper reinforced substrate 160a or the lower polarizing plate 151. It is formed by curing or heat curing. In this way, the light incident on the low reflection layer 160b and transmitted through the reinforced substrate 160a is continuously absorbed (or transmitted) by the adhesive layer 160c and the polarizing plate 151 having a refractive index similar to that of the reinforced substrate 160a. By doing so, the reduction of the total reflectance to the outside of the liquid crystal panel 150 is maximized.

  That is, when the light transmitted through the low reflection layer 160b hits a gap between the protective member 160 including the low reflection layer 160b and the liquid crystal panel 150, that is, air, the refractive index of the protective member 160, particularly the reinforced substrate 160a and the refractive index of air. Therefore, the light is reflected to the outside from the interface where the protective member 160 and the air in the gap are in contact with each other due to the different refractive index, and as a result, the total reflectance to the outside of the liquid crystal panel 150 increases.

  In consideration of such points, in the present invention, the adhesive layer 160c on the protective member 160 is formed of a material having a refractive index similar to that of the reinforced substrate 160a, and the lower liquid crystal panel 150 or the liquid crystal panel 150 is formed. It is formed so as to have a refractive index similar to that of the upper polarizing plate 151.

  Here, as an adhesive having a refractive index of about 1.3 to 1.8 similar to the reinforced substrate 160a or the polarizing plate 151, for example, an optical elastic resin manufactured by Sony, whose main component is an acrylic ultraviolet curable resin. “SVR (Super View Resin)” is suitable. However, the present invention is not limited to a specific pressure-sensitive adhesive, and is a substance that does not depart from the technical idea of the present invention, and if UV curing or thermal curing for process ease is possible, A variety of adhesives could be used. Of course, a substance formed by a separate manufacturing method is most preferable.

  Here, the pressure-sensitive adhesive may further include at least one additive such as a solvent, a plasticizer, and / or a surfactant, but increases the binding force with the polarizing plate 151 on the liquid crystal panel 150. In addition, if UV curing or heat curing is performed rapidly, the content can be changed.

  After such an adhesive is formed in a liquid state on the lower surface of the reinforced substrate 160a, the reinforced substrate 160a on which the adhesive is formed is attached on a polarizing plate 151 formed on one side surface of the liquid crystal panel 150. Thereafter, when the adhesive is cured by irradiating UV from the upper side of the reinforced substrate 160a or applying heat from the lower side of the liquid crystal panel 150, the protective member 160 coupled to the liquid crystal panel 150 is formed.

  On the other hand, after the pressure-sensitive adhesive is formed on the lower surface of the reinforced substrate 160 a, the polarizing plate 151 is attached on the polarizing plate 151 of the liquid crystal panel 150 when the polarizing plate 151 is attached instead of being adhered to the liquid crystal panel 150. If not, after forming an adhesive on the liquid crystal panel 150 and attaching the reinforced substrate 160a on the adhesive, UV is irradiated from the upper side of the reinforced substrate 160a, or heat is applied from the lower side of the liquid crystal panel 150. The protective member 160 coupled to the liquid crystal panel 150 can also be formed by curing the pressure-sensitive adhesive by adding.

  The upper cover 170 is fastened to the lower cover 100 so as to cover the four edges of the protective member 160 provided on the liquid crystal panel 150 and the side surface of the main support 140.

  Referring to FIG. 3, light incident on the protection member 160 from the outside reflects in advance at the interface because the refractive index n1 of air is different from the refractive index n2 of the low reflection layer 160b constituting the protection member 160. The light transmitted through the low reflection layer 160b is gradually extinguished in such a manner that it passes through a plurality of layers in which two different substances are alternately formed and is scattered to the outside, and is subsequently similar to the low reflection layer 160b. The light is continuously reflected on the reinforced substrate 160a and the adhesive layer 160c having the refractive indexes n3 and n4 and the polarizing plate 151 on the liquid crystal panel 150, so that no light is reflected at each interface. The total reflectivity of the light reflected to the outside or the outside of the protective member 160 is reduced.

Here, as the refractive index of the reinforced substrate 160a, the adhesive layer 160c, and the polarizing plate 151, for example,
Refractive index of the reinforced substrate 160a: n3 = 1.4 to 1.7,
Refractive index of polarizing plate 151: When n5 = 1.4 to 1.6,
Refractive index of the adhesive layer 160c: n4 = 1.3 to 1.8
The difference between the refractive indexes of these layers can be a value that does not increase by 0.2 or more.

  By doing in this way, not only the surface reflectance on the protective member 160 but also the interface reflectance generated between the respective media can be reduced, and the total reflectance can be reduced.

  Hereinafter, the simulation regarding the reflectance of the liquid crystal display device provided with the protective member according to the present invention will be described. First, the experimental conditions will be briefly introduced. The liquid crystal display device was 42 inches with 18 lamps, and the illuminance could be measured up to 4,000 lux.

  4A is a graph showing the contrast ratio of the liquid crystal display device shown in FIGS. 1 and 2, and FIG. 4B is a graph showing the color reproducibility of the liquid crystal display device shown in FIGS.

  First, as shown in FIG. 4A, a liquid crystal display device provided with a protective member according to the present invention, that is, a case where a low-reflection layer surface-treated by sputtering is formed on the upper surface of a reinforced substrate (AG + single surface ARS); It can be confirmed that the difference in contrast ratio (CR) is almost the same as that in the case where the low reflection layer surface-treated by sputtering is formed on all of the upper and lower surfaces of the reinforced substrate (AG + double-sided ARS).

  On the other hand, the liquid crystal display device when the polarizing plate is attached without performing a separate surface treatment (low reflection treatment) (AG Pol), and when the low reflection coating is applied to one surface of the polarizing plate (ARC Pol), Compared with the liquid crystal display device according to the present invention (AG + single-sided ARS, AG + double-sided ARS), it can be seen that the difference is very large (based on 4,000 lux).

  That is, as shown in FIG. 4A, when the contrast ratio (CR) of all liquid crystal display devices is 1,000: 1 in a dark room environment, the contrast ratio (CR) in an illuminance environment of 4,000 lux is The liquid crystal display device (AG + single-sided ARS, AG + double-sided ARS) according to the invention is about 600: 1, but a polarizing plate is attached without performing a separate surface treatment (low reflection treatment) (AG Pol), and polarization When the low reflection coating was applied to one side of the plate (ARC Pol), the liquid crystal display devices were about 100: 1 and 300: 1, respectively.

  The predicted value can be derived from such a measured value. For example, if the illuminance of the liquid crystal display device when exposed to sunlight completely outdoors corresponds to 1,000,000 lux, The illuminance of the liquid crystal display device when exposed to light is equivalent to about 10,000 lux, and the strongest indoor lighting is equivalent to about 5,000 lux, but the graph of FIG. 4A shows the contrast ratio at that time, respectively. Show.

  Based on the actual experimental result of 4,000 lux, it can be confirmed that the contrast ratio (CR) is inversely proportional to the higher illuminance.

  Next, color reproducibility under the same conditions as in FIG. 4A will be described with reference to FIG. 4B. As shown in FIG. 4B, when the color reproduction rate of all the liquid crystal display devices in a dark room environment is about 73.4%, the color reproduction rate under an illuminance environment of 4,000 lux is the liquid crystal display device according to the present invention. (AG + single-sided ARS, AG + double-sided ARS) is about 72.4%, but on the other side of the polarizing plate when a polarizing plate is attached without performing a separate surface treatment (low reflection treatment) (AG Pol) In the case of the low reflection coating (ARC Pol), the liquid crystal display devices were about 69.1% and 71%, respectively.

  As shown in the above experiment, when the liquid crystal display device according to the present invention includes a protective member on the upper side of the liquid crystal panel, the liquid crystal panel and the protective layer are formed with a low reflection layer on the upper surface of the protective member exposed to external light. By forming an adhesive layer having the same refractive index as that of the member, the light incident on and transmitted through the protective member is not reflected to the outside due to the different refractive indexes of the liquid crystal display device and the interface between the components. As a result, the total reflectance of the liquid crystal panel to the outside is greatly reduced, and the outdoor visibility is improved.

  On the other hand, the pressure-sensitive adhesive layer in the liquid crystal display device according to the present invention is not limited to one formed by UV curing or heat curing a liquid pressure-sensitive adhesive as described above, and the pressure-sensitive adhesive layer itself is a double-sided tape, sheet, or plate type. Can also be Here, the double-sided tape, sheet, or plate is formed of a material having the same refractive index as that of the reinforced substrate and the polarizing plate (a liquid crystal panel in the case where there is no polarizing plate), and has to be formed without gaps. It will not come off.

  On the other hand, the liquid crystal display device according to the first embodiment of the present invention can improve reliability against external impact and / or decrease in outdoor visibility due to external light by providing a protective member on the liquid crystal panel. Other problems can arise due to the relative increase in thickness. That is, light leakage may occur from the edge region of the liquid crystal panel provided with the protective member due to the internal light (or backlight light) provided from the backlight device provided on the lower side.

  Hereinafter, a liquid crystal display device according to a second embodiment of the present invention for solving such a problem will be described. FIG. 5 is a partial cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention compared with FIG. 2, and FIG. 6 is a perspective view showing the protective member of FIG.

  As shown in FIGS. 5 and 6, the liquid crystal display device according to the second embodiment of the present invention includes a backlight device (no symbol) that provides light by an externally applied voltage, and the backlight device. A liquid crystal panel 250 that is provided on the upper side and displays an image, a reinforcing substrate 260a that is provided on the liquid crystal panel 250 and protects the liquid crystal panel 250 from external impacts, and an external that is formed on the reinforcing substrate 260a and is incident from the outside And a protective member 260 made of a low reflective layer 260b that reduces the light reflectance. The protective member 260 is made of a material having the same refractive index as that of the reinforced substrate 260a of the protective member 260, and the protective member 260 is provided on the liquid crystal panel 250. Are formed in at least one side edge region on the low reflection layer 260b constituting the protective member 260, and the backing layer 260c. And a light leakage prevention unit 261 to prevent leakage of the provided light from the device.

  More specifically, the protection member 260 includes a reinforced substrate 260a that protects the liquid crystal panel 250 from external impacts, a low reflection layer 260b that is formed on the upper surface of the reinforced substrate 260a and exposed to the outside by being exposed to the outside, and the reinforced substrate 260a. The adhesive layer 260c formed on the lower surface of the liquid crystal panel 250 and in contact with the polarizing plate 251 on the liquid crystal panel 250, and at least one side edge region on the low reflective layer 260b, is formed from the lower backlight device. The light leakage prevention unit 261 prevents leakage of the provided light.

  The tempered substrate 260a is made of, for example, tempered glass having a thickness of about 2 to 5 mm in order to protect the internal liquid crystal panel 250 from an external impact. Tempered glass is a glass that has been strengthened by heating the molded plate glass to approximately 500 to 600 ° C., which is close to the softening temperature, and quenching it with compressed cooling air, thereby compressively deforming the surface portion of the glass and tensilely deforming the inside. is there. Compared to ordinary glass, the bending strength is 3 to 5 times, the impact resistance is 3 to 8 times stronger, and the heat resistance is also superior. However, the glass itself maintains the balance of force inside, and the whole is broken into small bean-sized pieces just by cutting one side slightly. There is a need to.

  The low reflection layer 260b formed on the upper surface of the reinforced substrate 260a and exposed to external light is surface-treated by sputtering. That is, two substances having different refractive indexes are alternately formed on the reinforced substrate 260a to form five or six layers. For example, the first layer first exposed to sunlight or an external illumination lamp is formed of a material having a low refractive index, the second layer is formed of a material having a high refractive index, and the third layer is again formed of a low refractive index. The reflectance is reduced by a method in which light that is incident and absorbed from the outside gradually disappears as it passes through each layer, for example, is formed of a material having s. However, the low-reflection layer 260a does not necessarily have to be surface-treated by sputtering, and various methods such as low-reflection coating, anti-contamination treatment, or anti-fingerprint treatment can be applied.

  The adhesive layer 260c formed on the lower surface of the reinforced substrate 260a and in contact with the liquid crystal panel 250 is UV-cured or thermally cured with an adhesive having a refractive index similar to that of the upper reinforced substrate 260a or the lower polarizing plate 251. It is formed by curing. In this manner, the light incident on the low reflection layer 260b and transmitted through the reinforced substrate 260a is continuously absorbed (or transmitted) by the adhesive layer 260c and the polarizing plate 251 having the same refractive index as the reinforced substrate 260a. By doing so, the reduction of the total reflectance to the outside of the liquid crystal panel 250 is maximized.

  That is, when the light transmitted through the low reflective layer 260b hits the air gap between the protective member 260 including the low reflective layer 260b and the liquid crystal panel 250, that is, air, the refractive index of the protective member 260, particularly the reinforced substrate 260a and the refractive index of air. Therefore, light is reflected from the interface where the protective member 260 and the air in the gap are in contact with each other due to the different refractive indexes, and as a result, the total reflectance to the outside of the liquid crystal panel 250 increases.

  In consideration of such points, in the present invention, the adhesive layer 260c on the protective member 260 is formed of a material having the same refractive index as that of the reinforced substrate 260a, and the lower liquid crystal panel 250 or the liquid crystal panel 250 is formed. The upper polarizing plate 251 is formed to have the same refractive index.

  Here, as an adhesive having a refractive index of about 1.4 to 1.6 similar to that of the reinforced substrate 260a or the polarizing plate 251, for example, an optical elastic resin manufactured by Sony having an acrylic ultraviolet curable resin as a main component is used. “SVR” or the like is suitable. However, the present invention is not limited to a specific pressure-sensitive adhesive, and is a substance that does not depart from the technical idea of the present invention, and if UV curing or thermal curing for process ease is possible, A variety of adhesives could be used. Of course, a substance formed by a separate manufacturing method is most preferable.

  Here, the pressure-sensitive adhesive may further include at least one additive such as a solvent, a plasticizer, and / or a surfactant, but increases the binding force with the polarizing plate 251 on the liquid crystal panel 250. In addition, if UV curing or heat curing is performed rapidly, the content can be changed.

  After such a pressure-sensitive adhesive is formed in a liquid state on the lower surface of the reinforced substrate 260 a, the reinforced substrate 260 a on which the pressure-sensitive adhesive is formed is attached on a polarizing plate 251 formed on one side surface of the liquid crystal panel 250. Thereafter, when the adhesive is cured by irradiating UV from the upper side of the reinforcing substrate 260a or applying heat from the lower side of the liquid crystal panel 250, the protective member 260 coupled to the liquid crystal panel 250 is formed.

  On the other hand, after the pressure-sensitive adhesive is formed on the lower surface of the reinforced substrate 260 a, the polarizing plate 251 is attached on the polarizing plate 251 of the liquid crystal panel 250 when the polarizing plate 251 is attached instead of being in close contact with the liquid crystal panel 250. If not, after forming an adhesive on the liquid crystal panel 250 and attaching the reinforced substrate 260a on the adhesive, UV is irradiated from the upper side of the reinforced substrate 260a, or heat is applied from the lower side of the liquid crystal panel 250. The protective member 260 bonded to the liquid crystal panel 250 can also be formed by curing the pressure-sensitive adhesive by adding.

  Further, at least one side edge region of the protection member 260 is provided with a light leakage prevention portion (or light leakage prevention member) 261 that prevents light leakage provided to the liquid crystal panel 250 provided below the protection member 260. ing. Here, the light leakage prevention unit 261 can be provided (or attached) as a separate sheet type, but sputtering or a coating method is applied as in the case of forming the black matrix (BM) of the color filter substrate. It is preferable to form a single layer formed of a resin-based BM formed by a photolithography process or an opaque metal chromium oxide (CrOx).

  In the present invention, since the lamp 220 that substantially serves as the light source of the backlight device is configured as a direct type, the light leakage prevention portion 261 is formed in the edge region of the four surfaces of the protection member 260 ( In the case of a sheet, the protective member 260 is provided in an edge type in which a lamp 220 serving as a light source of a backlight device is provided in one side edge region. The upper light leakage prevention unit 261 can be formed only in one side edge region corresponding to the lamp 220. That is, the formation position is not particularly limited.

  In addition, when the liquid crystal panel 250 is divided into a first region where an image is displayed and a second region which is a non-image region located on one side of the first region, the light leakage prevention unit 261 is arranged in the second region. As a result, the light leakage prevention member 261 is substantially formed from an area that is partially covered by contact with the upper cover 270 and an exposed area that is exposed to external light on the protection member 260. Become.

  In this case, in order to maintain the reflectance of the light leakage prevention unit 261 exposed to the external light to be the same as the total reflectance reflected to the first region of the liquid crystal panel 250, that is, the image region, the light leakage prevention unit 261 also includes: The reflective member is formed of a material having the same refractive index as that of the low reflective layer 260b, the reinforcing substrate 260a, and the adhesive layer 260c of the protective member 260 so that the reflectance is in the range of 0.5 to 1.5%.

  Except for this part, the remaining components of the liquid crystal display device according to the second embodiment of the present invention, such as the lamp 220 and the balance PCB 201 constituting the backlight device, are described in the first embodiment of the present invention described above. Since it is the same as the content of embodiment of this, it is used.

  The liquid crystal display device according to the second embodiment of the present invention can be variously modified. For example, referring to FIG. 5, in order to maximize the light leakage prevention effect of light provided from the backlight device provided on the lower side of the liquid crystal panel 250, the liquid crystal panel 250, that is, two substrates to be bonded together A second light leakage prevention portion can be further formed in the intermediate edge region so as to correspond to the light leakage prevention portion 261 described above.

  At this time, the formation width may be the same or may not be the same, but the boundary portion where the first region where the image is displayed and the second region located on at least one side of the first region (or The boundary line is preferably formed to coincide. This means that the first areas in which images are displayed are formed in ranges that are not shielded.

  Although not shown in the drawings, the present invention achieves only the purpose of reducing the total reflectance of the external light in the image area of the liquid crystal panel and preventing light leakage of the internal light below it. It can also be configured as a liquid crystal display device.

  For example, in the formation of the protective member, after the liquid crystal panel or polarizing plate forms an adhesive layer on the polarizing plate of the liquid crystal panel, a low reflective layer is formed again on the adhesive layer by coating or the like. A light leakage prevention portion for preventing leakage of light provided from the backlight device is formed in at least one side edge region.

  As a result, the protection member is in close contact with the liquid crystal panel without a gap and transmits light absorbed through the low reflection layer, reducing the reflectance of external light, and the liquid crystal panel and the low reflection layer. A light leakage layer that is formed in at least one side edge region of the low reflection layer and prevents leakage of light provided from the backlight device; and an adhesive layer formed of the same material having the same refractive index as the layer. It can also consist only of a prevention part.

  Although the present specification has described the present invention based on preferred embodiments, those who have ordinary knowledge in the art will be able to understand the concept of the present invention described in the appended claims. It will be understood that various changes and modifications can be made without departing from the scope of the invention.

1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention. It is a fragmentary sectional view which shows the fastening state of FIG. It is a figure which shows the refractive index of the protection member shown in FIG.1 and FIG.2. 3 is a graph showing a contrast ratio of the liquid crystal display device shown in FIGS. 1 and 2. It is a graph which shows the color reproducibility of the liquid crystal display device shown in FIG.1 and FIG.2. FIG. 3 is a partial cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention compared with FIG. 2. It is a perspective view which shows the protection member of FIG. It is sectional drawing which shows the structure of a general direct type | mold liquid crystal display device. It is a perspective view which shows the conventional backlight structure.

Claims (10)

A liquid crystal panel on which an image is displayed, including a polarizing plate attached to at least the upper surface;
A backlight device provided under the liquid crystal panel to provide light;
Provided on the polarizing plate, a reinforced substrate that protects the liquid crystal panel from external impact, and a protective member that is formed on the reinforced substrate and includes a low reflection layer that reduces the reflectance of external light incident from the outside,
A liquid crystal comprising a material having a refractive index similar to that of the reinforced substrate of the polarizing plate and the protective member, and including an adhesive layer interposed between the liquid crystal panel and the protective member and closely contacting them. Display device. The refractive index of the reinforced substrate is 1.4 to 1.7,
The refractive index of the adhesive layer is 1.3 to 1.8,
The refractive index of the polarizing plate is 1.4 to 1.6,
2. The liquid crystal display device according to claim 1, wherein the difference in refractive index between these layers can take a value within a range not to be increased by 0.2 or more. The liquid crystal display device according to claim 1, wherein the tempered substrate is tempered glass. The liquid crystal display device according to claim 1, wherein the low reflective layer is surface-treated by sputtering. 5. The liquid crystal display device according to claim 1, wherein the adhesive layer includes at least one additive of a solvent, a plasticizer, and a surfactant.   6. The light leakage prevention unit according to claim 1, further comprising a light leakage prevention unit that is formed in at least one side edge region of the protection member and prevents leakage of light provided from the backlight device. The liquid crystal display device according to item. The liquid crystal panel is divided into a first region where an image is displayed and a second region which is formed on at least one side of the first region and does not display an image.
The adhesive layer is provided so as to adhere to the liquid crystal panel without a gap, and is provided corresponding to the first region of the liquid crystal panel to reduce the reflectance of external light incident from the outside,
The liquid crystal display device according to claim 6, wherein the light leakage prevention unit is provided corresponding to a second region of the liquid crystal panel to prevent leakage of light provided from the backlight device. The liquid crystal display according to claim 6, wherein the adhesive layer is formed on a lower surface of the protective member, and the light leakage prevention portion is formed corresponding to a second region on the upper surface of the protective member. apparatus. The liquid crystal display device according to claim 1, wherein the adhesive layer is formed by UV curing or heat curing. 10. The liquid crystal display device according to claim 6, wherein the light leakage prevention portion is formed of at least one of a resin material and chromium oxide (CrOx).

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