KR20080010173A - Light guide plate and method of pellicle type back-light - Google Patents

Abstract

A thin film type light guide plate and a method for manufacturing the same are provided to reduce thickness and to improve brightness and light exit uniformity, thereby reducing the size of a light guide plate and improving the quality of the light guide plate. A light guide plate(10) is combined with a light source(20) for receiving a light supplied from the light source and emitting the light. One side of the light guide plate is formed as a light exit plane(11) and the other side of the light guide plate is formed as a light reflecting plane(12). A reflecting layer(30) is formed on the light reflecting plane, made of UV(Ultraviolet rays) resin hardened by UV. Reflecting patterns(31) are formed at the reflecting layer, changing a reflection amount of the light supplied from the light source in accordance with a distance with the light source.

Description

Light guide plate for thin film type backlight and its manufacturing method {Light guide plate and method of pellicle type back-light}

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.

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

10: thin film 11: exit surface

12: reflective surface 20: light source

30, 50: reflection 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, by forming a UV coating layer on the reflective surface, limiting the shape, arrangement, number, etc. of the UV coating layer to an optimized form to improve the brightness of 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.

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 case of the liquid crystal display, the liquid crystal is arranged in a specific form by an external electric and electronic signal 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 viewed from the rear in order to visually observe the image. There is a need for a backlight unit which is surface emitting means for emitting light.

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 fabrication.

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,

It is formed of a thin film, a reflective layer of UV resin cured by UV is formed on the reflective surface, and the reflective layer is formed by forming 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.

In order to achieve the above another object, the present invention comprises the steps of doping the UV resin on the reflective surface of the thin film; Pressing the mold having a pattern corresponding to the reflective pattern to the UV resin side to disperse the UV resin on the thin film and forming a reflective pattern; and to press the mold to press the UV resin; And performing UV curing using a UV lamp on the doped back side.

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.

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 thin film type film 10 for performing a function of the light guide plate and a light source 20 for supplying light from one side of the film 10.

The thin film 10 is one surface is an emission surface 11 for emitting the light supplied from the light source 20, the back surface is supplied from the light source 20 to the light that does not proceed to the exit surface (11) It is formed of the reflecting surface 12 which reflects and advances to the exit surface 11 side.

Such a thin film 10 is formed of a light guide plate formed with a reflective layer 30 formed by UV resin to improve the reflection efficiency of light on the reflective surface 12. A reflective pattern 31 having a dot shape is formed on the reflective layer 30 to scatter the light received from the side surface and reflect the light to the exit surface 11. 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, a configuration in which the light source 20 is provided on both sides of the thin film 10 is also proposed, and in such a structure, the closer the projection 32 is toward the center side of the thin film 10 (the farther from the light source), the closer the distribution is. It can be configured to have a 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. The luminance of light emitted from the emission surface 11 close to the light source 20 may be improved, and the light emission uniformity of the entire emission surface 11 of the thin film 10 may be maintained in an excellent state. 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 thin film 10 may be formed thinner than the configuration in which the light guide plate and the reflective sheet are combined by the reflective layer 30 formed of UV resin having high reflection efficiency. The reflection efficiency of such a thin film 10 is demonstrated through an experimental example to be described later.

 In particular, the thin film 10 has a high light transmittance, and thus, polymethylmethacrylate (PMMA), polycarbonate (PC), transparent polyolefin-based resin, and transparent acrylonitrile butadiene styrene, which are applied as materials of a light guide plate. It is made of styrene resin such as (Acrylonitrile Butadiene Styrene copolymer; ABS).

CCFL and EEFL may be applied to the light source 20 as described above, but the LED 21 is basically applied in view of low power, long service life, and short response characteristics. 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 flowing out when the light emitted from the LED 21 is emitted to the thin film 10, the LED ( The diffusion lens 23 is configured to be coupled between the LED 21 and the thin film 10 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 fabricate the light guide plate according to the present invention, as shown in FIG. 4a, a previously prepared thin film 10 is prepared, and as shown in FIG. 4b, a UV resin is formed on the reflective surface 12 of the thin film 10. (R) is doped to a constant thickness.

Thereafter, the UV resin R is pressurized as shown in FIG. 4C, wherein the UV resin R is formed of a reflective layer 30, and the reflective pattern 31 is implemented on the reflective layer 30. For this purpose, the pattern corresponding to the reflective pattern 31 is pressed by the formed mold K.

At this time, the thickness of the thin film 10 is applied to the already produced 0.4mm or less, UV resin (R) is 100% by weight of the oligomer 60% to 70% by weight, monomer 23% to ~ It consists of 35% by weight, and is prepared by mixing 5% to 7% by weight of the photoinitiator to promote UV curing.

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.

The means for pressurizing the UV resin R is performed by a press as in FIG. 4D (in the drawings, a weight body representatively performing a press role). 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 cured by the UV lamp (L) provided on the exit surface 11 side of the thin film (10).

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, and when the pressure exceeds 3.5kgf, the thickness of the reflective layer 30 is excessively thin and the reflective pattern 31 You will not have this right shape. In addition, when the pressing time is less than 8 seconds, the UV resin (R) is not fully cured, when exceeding 10 seconds, the UV resin (R) is excessively cured, and brittleness is weakened as described above.

Thereafter, as shown in FIG. 4E, when the press P, the mold K, and the UV lamp L are removed, the reflective layer 30 having the reflective pattern 31 is formed on the thin film 10. In this state, if the cutting pattern is cut in accordance with the section in which the reflective pattern 31 is formed, that is, the size of the actual backlight unit, the light guide plate of FIGS. 4F and 4G is completed.

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 back view, and a side view, respectively, with the light guide plate applied to the key pad 40 of the cellular phone. 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 maintains its shape by pressing or injecting the thin film 10, and is described above on the reflective surface 12 formed on the rear surface of the emission surface 11 on which the user is observed. It is a configuration in which a reflective layer (not shown in the magnification of the drawing) on which the reflective pattern 31 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 brightness was measured by dividing the light unit by each position of the light guide plate 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, the light guide plate according to the present invention was found to obtain the desired luminance efficiency by the thin film type film 10 of the thickness significantly 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 emission surface 11 of the thin film 10. 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 in general, the thin film 10 has a configuration that can be combined with the light source 20 and the product by means of a frame or the like when the thin film 10 is configured as a backlight unit.

<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 thin film 10 is formed as the inclined surface 60. The inclined surface 60 is formed such that the light source 20 side end portion of the thin film 10 is wide and the opposite end portion is narrowed so that the light emitted from the light source 20 is emitted through the exit surface 11 after reflection. By shortening it is configured to maintain the brightness enhancement and light emission uniformity in an excellent state.

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.

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

According to the present invention, a backlight unit using a light guide plate, which can be manufactured at a very low unit cost, is implemented as compared to a backlight unit implemented by an OLED.

Claims (8)

At least one side of the light source 20 is coupled to receive light supplied from the light source to one side of the light emitting surface 11 is formed in the light emitting surface 11, the other surface is formed in the light guide plate 12 of the light , It is formed of a thin film 10, a reflective layer 30 made of UV resin cured by UV is formed on the reflective surface 12, the reflective 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, The thin film type light guide plate for thin film type backlights characterized by being formed in thickness below 0.4 mm. 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 of claim 1, wherein the thin film 10 A light guide plate for a thin film type backlight, which is formed by selecting any one of PMMA, PC, transparent polyolefin resin, and transparent polystyrene resin. The method according to any one of claims 1 to 6, 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 reflective surface 12 of the thin film type 10; In order to disperse the UV resin R on the thin film 10 and to form the reflective pattern 31, a mold K having a pattern corresponding to the reflective pattern 31 is formed by using a press P. Pressurizing to the R) side; Thin film type backlight comprising the step of performing the UV curing using the UV lamp (L) at the back side doped with the UV resin (R) in the state in which the mold (K) pressurized the UV resin (R) Manufacturing method of light guide plate.

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