KR100829240B1 - Light guide plate for pellicle type back light and manufacture method it - Google Patents

Abstract

The present invention forms a UV coating layer on the reflective surface, by limiting the shape, arrangement, number, etc. of the UV coating layer to an optimized form to improve the brightness of the light emitted through the thinner light guide plate, the surface light source formed by the light guide plate The present invention relates to a light guide plate for a thin film type backlight and a method of fabricating the same, which have a uniform light emission distribution in the entire surface of the film, and which can be realized at a lower cost.

To this end, the present invention, the light source is coupled to at least one side to receive the light supplied from the light source, one surface is formed as an emission surface of the light, the other surface is a light guide plate formed of the reflective surface of the light, the thin film type And a reflective layer made of UV resin cured by UV on the reflective surface, and a reflective pattern having a reflective pattern in which the amount of reflection of light supplied from the light source is changed according to the distance from the light source is formed on the reflective layer. Provides a light guide plate and a method for manufacturing the same.

Backlight, Light Guide Plate

Description

Light guide plate for thin film type backlight and manufacturing method thereof {Light guide plate for pellicle type back light and manufacture method it}

1 is a front view of a light guide plate according to the present invention.

2 is a side view of the light guide plate according to the present invention;

3 is a rear view of the light guide plate according to the present invention;

Figures 4a to 4g is a manufacturing process of the light guide plate according to the present invention.

5a to 5c is an exemplary view of a product to which the light guide plate according to the present invention is applied.

Figure 6 is a graph of the experimental results of the light guide plate according to the present invention.

Figure 7 is a side view of another embodiment 1 of the present invention.

Figure 8 is a side view of another embodiment 2 of the present invention.

9 is a side view of another third embodiment of the present invention;

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

10: Film for Carrier 11: exit face

12: reflective surface 20: light source

30,50: UV coating layer 31, 51: reflection pattern

32: turning 52: groove

The present invention relates to a light guide plate for a thin film type backlight and a manufacturing method thereof. In detail, the UV coating layer is formed on the reflective surface, and the shape, arrangement, number, etc. of the UV coating layer are optimized to improve the brightness of the light emitted through the UV coating layer which performs the thinner light guide plate function. The present invention relates to a light guide plate for a thin film type backlight and a method of manufacturing the same, having a uniform light emission distribution on the entire surface of a surface light source formed by the UV coating layer.

The backlight is applied to a liquid crystal display (LCD), a key pad of a mobile phone or various electronic devices, and the like to form a surface light source. An assembly type that supplies and diffuses light to form a surface light source to implement such lighting is called a backlight unit.

The liquid crystal display device is currently the largest market share in the domestic and overseas display market, and is being applied to various devices such as thin wall-mounted televisions, monitors of notebook computers, monitors of desktop computers, navigation devices, PDAs, mobile phones, and game machines. to be. In this case, in the liquid crystal display device, the liquid crystal is arranged in a specific form by external electric and electronic signals to form an image to be displayed. However, since the liquid crystal does not have its own light emitting function, the liquid crystal display may be rearward to observe the image. There is a need for a backlight unit which is a surface light emitting means that emits light at.

In addition, the key-pad of the mobile phone also displays letters, numbers, and the like on each function button. However, in order to easily recognize each function button of the key-pad at night or in a dark room, a backlight unit emitting from the back of the button is required. do.

The backlight unit includes a light guide plate formed in a generally rectangular plate shape for surface emission, and a light source for supplying light from one side or multiple sides of the light guide plate. Here, the light guide plate is formed of an emission surface for receiving the light supplied from at least one side to diffuse to the entire surface after the light is emitted to one side, the light emitting surface, the light emitting plate is emitted from the received light A reflective surface is formed which reflects the light emitted in a direction different from the surface and proceeds to the exit surface. In particular, a separate reflection sheet having excellent reflectance of light is attached to the reflective surface to obtain higher reflection efficiency.

At this time, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL) is applied as a light source for supplying light to the light guide plate, and a cold cathode fluorescent lamp and Compared to external electrode fluorescent lamps, light emitting diodes (LEDs) with excellent color, low power, and electrical response characteristics are used.

As a more advanced form of the above-described backlight unit, a form in which an element called an organic EL (Organic Electro Luminescence) or an organic light emitting diode (OLED) is applied is proposed. Here, the organic light emitting diode is a device which is manufactured using an organic compound and is self-emitted by a power supplied from the outside, and the display may be realized in the form of a device.

In particular, in the form for applying the organic light emitting diode as a backlight, a plurality of organic light emitting diode elements are arranged on the base substrate. At this time, the light guide plate is not applied.

In the configuration in which the light guide plate is applied in the configuration of implementing the backlight as described above, the light guide plate has a predetermined thickness to receive the light from the light source and to receive and reflect the light therein to emit light to the exit surface. This thickness is known to be manufactured to a value in excess of 0.4 mm to produce at least the LED minimized. In particular, when the weight of the light guide plate is increased to the thickness of the reflective sheet, it becomes a significant thickness, which makes it difficult to implement a thin film type backlight unit.

In the case of the backlight to which the OLED is applied, although the light guide plate is excluded, a considerably thin film type configuration can be realized, the manufacturing cost is very high because a large number of expensive OLEDs are arranged. In addition, the backlight to which the OLED is applied has a very difficult process of manufacturing a base substrate on which a pattern for electrically connecting a plurality of OLEDs is formed, and also has a problem of significantly low manufacturability.

The present invention has been invented to solve the above problems, to have a higher light emission uniformity over the entire area of the emission surface with improved brightness and light emitting thinner, and to be manufactured at a lower price It is an object to provide a light guide plate for a thin film type backlight.

Another object of the present invention is to provide a method for manufacturing a light guide plate for a thin film type backlight having the improved brightness and high light emission uniformity.

In order to achieve the above object, the present invention has the following configuration.

The present invention, the light source is coupled to at least one side of the light guide plate formed of the light emitting surface, the other surface is formed as the light emitting surface, in order to receive the light supplied from the light source and the surface light emission,

A coating layer made of UV resin cured by UV is formed on a carrier film, and a reflective pattern is formed on a reflective surface of the coating layer in which a reflection amount of light supplied from a light source is changed according to a distance from the light source. . The carrier film is the film that is removed after the final product finish.

The present invention to achieve the above another object, the step of doping the UV resin on the carrier film; Pressing the mold having a pattern corresponding to the reflective pattern to the UV resin side by using a press to disperse the UV resin on the carrier film and form a reflective pattern; Performing UV curing using a UV lamp on the back side of the mold in which the mold is pressurized with the UV resin; And removing the carrier film, which serves as a support in doping the UV resin.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention to which the above configuration is applied will be described in detail.

1 is a front view of a light guide plate according to the present invention, FIG. 2 is a side view of the light guide plate according to the present invention, and FIG. 3 is a rear view of the light guide plate according to the present invention. The light guide plate presented in the embodiment of the present invention is made by a UV coating layer to be described later, not a general light guide plate, it will be noted that refers to a UV coating layer (coating layer) having the form and function of the light guide plate.

Referring to the drawings, the light guide plate to which the light guide plate according to the present invention is applied is composed of a UV coating layer 30 in which a functional pattern is formed to perform a function of the light guide plate, and a light source 20 for supplying light from one side.

One surface of the UV coating layer 30 is an emission surface 11 for emitting the light supplied from the light source 20, the back surface of the light is supplied from the light source 20 does not proceed to the exit surface 11 Is formed as a reflecting surface 12 which reflects the light toward the exit surface 11 and proceeds to perform the function of the light guide plate as described above.

In particular, the UV coating layer 30 is a dot-shaped reflection for scattering the light received in the lateral direction of the reflective surface 12 to reflect the emission surface 11 to improve the reflection efficiency of the light The pattern 31 is formed on the reflecting surface 12. The dot-shaped reflection pattern 31 is formed by forming a projection 32 of the UV resin is formed at the tip of the tip to be a scattering pattern of the dot shape.

The protrusion 32 has a shape protruding from the reflective surface 12. In particular, the protrusions 32 may be uniformly distributed over the entire reflection surface 12, but preferably, as the distance from the light source 20 increases, the protrusion 32 gradually increases in size, or the size of the protrusions 32 itself. It is made up large. In addition, the UV coating layer 30 has also been proposed a configuration in which the light source 20 is installed on both sides, in this configuration the densities of the projections 32 toward the center side of the UV coating layer 30 (farther from the light source) It can be configured to have one distribution, larger size.

This increases the amount of reflected light received from the light source 20 as the distribution of the projections serving as the reflection pattern 31 is denser or larger, thereby increasing the amount of reflection of the projection surface 11 far from the light source 20. It is possible to improve the brightness of light emitted from the emission surface 11 close to the light source 20 and to maintain the uniformity of the light emission for the entire emission surface 11. Such a difference in distribution may be divided into several sections, and for the sake of simplicity, a state divided into five sections is illustrated.

The UV coating layer 30 is formed of a UV resin having high reflection efficiency, so that the UV coating layer 30 can be formed thinner than the light guide plate of the conventional injection type. The reflection efficiency of such a UV coating layer 30 is demonstrated through the experimental example to be described later.

The light source 20 may be cold cathode fluorescent lamp (CCFL), external electrode fluorescent lamp (EEFL) as described above, but low power, long service life, short response characteristics, etc. In consideration of this, the LED 21 is basically applied. In particular, the light source 20 is provided with a cover 22 on the outer surface of the LED 21 to prevent the light from leaking out when the light emitted from the LED 21 is emitted to the UV coating layer 30, LED The diffusion lens 23 is configured to be coupled between the LED 21 and the UV coating layer 30 to diffuse the light emitted from 21.

4A to 4G are manufacturing process diagrams of the light guide plate according to the present invention.

Referring to the drawings, in order to manufacture the light guide plate according to the present invention, the carrier film 10 is prepared as shown in FIG. 4A, and as shown in FIG. 4B, the UV resin R is formed on a surface of the carrier film 10 in a constant thickness. Doping

Here, the carrier film 10 may be made of styrene such as polymethylmethacrylate (PMMA), polycarbonate (PC), transparent polyolefin resin, transparent acrylonitrile butadiene styrene (ABS), and the like. Any plastic that can pass UV light can be used, such as plastic-based resins and glass-based resins. In addition, the carrier film 10 is configured to support the UV resin (R) when the UV coating layer 30 is produced by performing a function of a work substrate for manufacturing the light guide plate.

Thereafter, the UV resin R is pressurized as shown in FIG. 4C, in which a pattern corresponding to the reflective pattern 31 is formed in order to implement the reflective pattern 31 on the UV resin R. It is pressed by the metal mold | die K.

At this time, the UV resin (R) is composed of 60% to 70% by weight of the oligomer and 20% to 23% by weight of the monomer in 100% by weight, and 5% by weight of the photoinitiator to promote UV curing Produce by mixing% ~ 7% by weight.

Here, when the resin material is less than 93% by weight, it is difficult to obtain the desired reflection efficiency of light, and when it exceeds 95% by weight, the UV curing time is delayed or hardened to the desired hardness in some sections. In addition, even when the photoinitiator is less than 5% by weight, UV curing time is delayed or the resin material is not cured to the desired hardness in some sections, and when it exceeds 7% by weight, it is cured to a too high hardness and is broken by minor external force. Its brittleness is lowered.
In particular, the UV resin (R) is produced by combining a monomer and a UV curable acrylate oligomer having an intrinsic refractive index of 1.42-1.58 with respect to UV. In this case, the numerical value for the intrinsic refractive index is Optimized limitations to have good optical performance during and after UV curing.

The means for pressurizing the UV resin R is carried out by a press P as in FIG. 4D (representing a weight body that performs a press role in the figure). In particular, when the UV resin R is pressed by the mold K, it is natural that the pattern corresponding to the reflective pattern 31 is formed in the mold K so that the reflective pattern 31 is simultaneously formed.

At the same time, the UV resin (R) is a UV lamp (L) provided on one side of the UV resin (R) in contact with the carrier film 10, that is, the exit surface 11 side formed after the UV coating layer (30) Cured by).

At this time, the pressing force by the press (P) is set to 2.5kgf to 3.5kgf to perform the work for about 8 to 12 seconds.

Here, when the pressing force of the press (P) is less than 2.5kgf, it is difficult to form the reflective pattern 31 of the desired shape. When the pressing force exceeds 3.5kgf, the thickness of the UV resin R becomes excessively thin and the reflective pattern 31 ) Does not have the correct shape. In addition, when the pressurization time is less than 8 seconds, the UV resin (R) will not be completely cured, and if it exceeds 10 seconds, the UV resin (R) is excessively cured, resulting in weak brittleness as described above.

Thereafter, as shown in FIG. 4E, when the press P, the mold K, and the UV lamp L are removed, the UV coating layer having the reflective pattern 31 is formed on the carrier film 10. In this state, the carrier film 10 is removed, and then the cutting is performed in accordance with the section in which the reflective pattern 31 is formed, that is, the size of the actual backlight unit, which is already set, thereby completing the UV coating layer 30 as shown in FIGS. 4F and 4G. .

5A to 5C are exemplary views of products to which the light guide plate according to the present invention is applied.

The figure shows a front view, a rear view, and a side view of the UV coating layer 30 implemented as the light guide plate applied to the key pad 40 of the mobile phone, respectively. Since the key pad 40 is coupled to the light source 20 on one side thereof (upper side in FIG. 5C), the key pad 40 emits light in its entirety because it is made of a light guide plate, and a specific color body is applied to each key button 42. By combining the crystal crystals 43 formed on the back surface, the key-buttons 42 are configured to emit light of a desired color, respectively.

The key pad 40 as described above has the reflection pattern 31 described above on the reflection surface 12 formed on the back surface of the emission surface 11 on which the user is observed, with the UV coating layer 30 on which the curing is performed. Is a configuration in which a reflective layer (not shown in the magnification of the drawing) is formed.

Such a key pad 40 was conventionally used to emit light for each button mainly by OLED, and after applying it to the light guide plate configuration according to the present invention, the experiment was performed as described in the Experimental Example to be described later. The above improvement rate of luminance was shown.

Experimental Example

After assembling a 1.8-inch backlight unit using the light guide plate manufactured by the above method, the light guide plate was divided by each position of the light guide plate and luminance was measured to obtain the results as shown in Table 1 and FIG. 6.

The results of Table 1 and FIG. 6 show similar or somewhat improved values compared to the configuration of the conventional LGP. As a result, it can be seen that the light guide plate according to the present invention obtains the desired luminance efficiency by the UV coating layer 30 in which hardening of the thickness is greatly reduced compared to the conventional light guide plate.

In the backlight unit to which the light guide plate according to the present invention is applied, a functional sheet such as a prism sheet, a diffusion sheet, and the like may be formed on the exit surface 11 of the UV coating layer 30 which is cured. In this case, the prism sheet performs a function of condensing light emitted through the exit surface, and the diffusion sheet is configured to perform a function of scattering and diffusing light to obtain more improved luminance efficiency.

In addition, although not shown as a general matter, the UV coating layer 30, which has been cured, becomes a light guide plate so that the outer surface of the UV coating layer 30 may be combined with the light source 20 and the product by means of a frame or the like. do.

<Other Example 1>

Figure 7 is a side view of another embodiment 1 of the present invention.

Referring to the drawings, another embodiment 1 suggests a configuration in which the reflective patterns 51 are formed by arranging a plurality of grooves 52 recessed into the reflective layer 50. At this time, the groove 52 is formed so that the recessed end of the inner tip is formed in a point-shaped pattern. In addition, the arrangement of the grooves 52 has a denser distribution as it moves away from the light source 20 like the protrusion 32 of the original embodiment, so that the luminance of light emitted by the distance from the light source 20 is low. It prevents losing and maintains uniformity of light output.

To this end, in the above-described manufacturing method, it is natural that the pattern of the metal mold K for forming the reflective layer 50 also corresponds to the reflective pattern 51 formed of the groove 52.

<Other Example 2>

8 is a side view of another embodiment 2 of the present invention.

Referring to the drawings, another embodiment 2 shows a state in which the reflective surface 12 of the cured UV coating layer 50 is formed as the inclined surface 60. The inclined surface 60 is formed so that the end of the light source 20 side of the cured UV coating layer 50 is wide and the opposite end thereof is narrowed so that the light emitted from the light source 20 is reflected through the exit surface 11. By shortening the emitted distance is configured to maintain the improved brightness and uniformity of light emission.

In particular, the reflective surface 12 may be applied to the reflective patterns 31 of the first and other embodiments to maintain higher luminance and more precise light emission uniformity.

<Other Example 3>

8 is a side view of another embodiment 2 of the present invention.

Referring to the drawings, another embodiment 3 presents a configuration in which a UV prism layer 33 is formed to focus light emitted from the exit surface 11 of the cured UV coating layer 30.

The UV prism layer 33 may be formed by pressing a prism mold having a prism shape by a press as in the above-described process of forming the reflective pattern 31. The UV prism layer 33 is first formed on the carrier film 10 before the reflective pattern 31 is formed and then the reflective pattern 31 is formed, or the reflective pattern 31 is first formed as described above. It can be formed after one.

As described above, the present invention is composed of a thinner thickness and at the same time improved brightness and uniformity of light emission is maintained throughout the entire area of the emission surface to contribute to the miniaturization and quality improvement of various products using the same You get

The present invention has the effect of preempting the price competition of the product by reducing the unit cost and processing time compared to the backlight unit implemented by conventional injection molding or thermocompression molding.

In addition, compared to the light guide plate manufactured by conventional injection molding or thermocompression molding, it is possible to give flexible characteristics, thereby preventing cracks.

Claims (14)

In one embodiment, the light source 20 is coupled to one side to receive light supplied from the light source, so that one surface is formed as an emission surface 11 of light, and the other surface is formed as a reflective surface 12 of light.  UV resin (R) mixed with oligomers, monomers, and photoinitiators is formed in a thin plate form to form a UV coating layer 30, the UV coating layer 30 is a reflection amount of light supplied from the light source 20 A light guide plate for a thin film type backlight, characterized in that a reflective pattern 31 is formed which is changed according to the distance from the 20. The method of claim 1, wherein the reflective pattern 31 Light guide plate for a thin film type backlight, characterized in that formed as the distance from the light source 20 has a denser distribution of the pattern. The method of claim 1, wherein the UV coating layer 30 A light guide plate for a thin film type backlight, characterized in that formed to a thickness of 0.2mm ~ 0.4mm or less. The method of claim 1, wherein the reflective pattern 31 Light guide plate for a thin film type backlight, characterized in that the projection (32) protruding from the reflection surface (12). The method of claim 1, wherein the reflective pattern 51 A light guide plate for a thin film type backlight, characterized in that the groove 52 is recessed toward the reflection surface (12) side. The method according to any one of claims 1 to 5, The light guide plate for a thin film type backlight which has the inclined surface 60 narrowed toward the opposite side end from the light source 20 couple | bonded. Doping the UV resin (R) onto the carrier film (10); The doped UV resin R is dispersed on the carrier film 10 to form a thin UV coating layer, and a mold having a pattern corresponding to the reflective pattern 31 is formed to form the reflective pattern 31 on the UV coating layer ( Pressurizing K) to the UV resin R side using a press P; In the state in which the mold K presses the UV resin R, UV curing is performed using the UV lamp L on the back side of the back surface doped with the UV resin R, and the carrier film 10 is peeled off. Method of manufacturing a light guide plate for a thin film type backlight comprising the step of forming a coating layer (30). The method of claim 7, wherein the carrier film 10 A method of manufacturing a thin film type light guide plate, characterized in that produced by selecting any one of a transparent material PMMA, PC, transparent polyolefin resin, transparent polystyrene resin and glass-based material for UV transmission. The method of claim 7, wherein the UV coating layer 30 A method of manufacturing a light guide plate for a thin film type backlight, characterized in that to form a UV prism layer 32 for condensing the light exiting the exit surface (11) to which light is emitted. 10. The method of claim 9 wherein the UV prism layer 32 A method of manufacturing a light guide plate for a thin film type backlight, characterized in that the pressing of the prism mold before or after the formation of the reflective pattern (31) by pressing. The method of claim 7, wherein the UV resin (R) is 60% to 70% by weight of the oligomer, 20% to 23% by weight of the monomer, and 5% to 7% by weight of the photoinitiator for promoting UV curing. Manufacturing method of light guide plate for thin film type backlight. The method of claim 7, wherein Pressing by the press (P) is a method of manufacturing a light guide plate for a thin film type backlight, characterized in that performed for 8 to 12 seconds at a pressing force of 2.5kgf to 3.5kgf. The method according to any one of claims 7 to 12, A plurality of key-buttons 42 are formed on the UV coating layer 30, and the crystal-crystal 43 having a specific color is combined with the key-button 45 to the key pad 40 of the mobile phone. Method of manufacturing a light guide plate for a thin film type backlight, characterized in that to be applied. The method of claim 7 or 11, wherein the UV resin (R) is A method of manufacturing a light guide plate for a thin film type backlight, which is produced by mixing a UV curable acrylate oligomer and a monomer having an intrinsic refractive index of 1.42-1.58.

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