KR20090069147A - Lgp patterning by micro-lens ink-jetting using plasma previous treatment - Google Patents

Abstract

Light guide plate patterning of a micro lens inkjet type using plasma preprocessing is provided to make an optical device thin. An optical medium forms micro lens dot or line patterns by applying a micro lens inkjet patterning process to one side or both sides of an optical device. A plasma preprocessing process is applied before the micro lens inkjet patterning process. A light guide plate(50) efficiently propagates light to the whole of a display screen uniformly by light scattering within a printed dot pattern. The optical device is formed of the light guide plate, a light diffusing plate, glass or a film.

Description

LGP PATTERNING BY MICRO-LENS INK-JETTING USING PLASMA PREVIOUS TREATMENT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to patterning of a light guide plate (LGP), which is a key component of a light emitting device for a backlight, and more particularly, to a dot or line patterning process in a manufacturing process of an optical substrate such as a light guide plate.

Generally, a light emitting device for a backlight is known. In such a backlight light emitting device, a light source is introduced from an end face of the light guide plate, scattered and diffused in the light guide plate, and is emitted from the light emitting surface toward the liquid crystal panel.

FIG. 1 is an exploded perspective view illustrating a conventional backlight light emitting device. As shown in FIG. 1, a backlight light emitting device includes a protective sheet 10, two prisms 20 and 30 divided into upper and lower portions, and a diffusion sheet 40. , The light guide plate 50, the reflective sheet 60, the mold frame 70, and the lamp assembly 80.

Here, the backlight refers to the light emitting part of the liquid crystal display (LCD) excluding the panel and other circuit components. In addition, the light guide panel (LGP) serves to uniformly transmit the light emitted through the light source to the entire display screen.

In such a light emitting device, an optical substrate such as a light guide plate is conventionally patterned using an infrared curing ink in a silk screen printing process using a semi-automatic silk print machine, and the flow of such a process is schematically shown in FIG. 2.

As shown in Fig. 2, the conventional silk screen printing process is performed by putting a bare LGP, printing (filming), printing (silk screen printing) using a silk screen machine in a semi-automatic manner, and drying the same. Pack it.

This process, that is, the optical substrate manufactured by silkscreen printing using an infrared curing ink has various problems in processability, reproducibility, reliability and productivity, and thus it is not necessary to manufacture an optical substrate such as a light guide plate in other ways. have. On the other hand, the problem with the conventional patterning process and the comparison of the superiority of the patterning process according to the present invention will be described in detail in the embodiments to be described later.

Therefore, in view of the above-mentioned problems, the present invention substitutes the microlens inkjet patterning process instead of the conventional semi-automatic silkscreen printing process, and applies the infrared curable ink used in the conventional process to the microlens inkjet patterning process. By replacing with UV curable ink, it is possible to reduce the thickness of optical materials (for example, light guide plate, diffusion sheet, glass, film), and plasma that can maximize processability, reproducibility, reliability and productivity by improving efficiency by automation. A light guide plate patterning method using a micro lens inkjet method using pretreatment is provided.

The optical medium according to the present invention forms a hemispherical microlens dot or line pattern by applying a microlens inkjet patterning process on one or both surfaces of an optical substrate, and the optical substrate may be made of a light guide plate, a diffusion sheet, glass, or a film. have.

The plasma pretreatment process may be applied before the microlens inkjet patterning process so that the hemispherical microlens dot or line pattern formed on the optical substrate maintains the contact angle with the surface of the substrate and the adhesion is enhanced.

The plasma pretreatment process may be a surface treatment process using atmospheric low temperature plasma.

The microlens inkjet patterning is formed by directly injecting ink onto the surface of the optical substrate in an inkjet head of an inkjet printer, and the surface of the optical substrate may be printed with ultraviolet curing ink for uniform light emission.

The microlens inkjet patterning process may be applicable to the size of a pattern of 100 microns or less.

In addition, the optical medium may apply microlens inkjet patterning to an optical substrate such as a backlight, a keypad, or a light panel.

As described above, the present invention is applied to the microlens inkjet patterning process instead of the conventional semi-automatic silkscreen printing process, and the infrared curable ink used in the conventional process is UV curable in the microlens inkjet patterning process. By replacing with ink, it is possible to reduce the thickness of optical materials (for example, light guide plate, diffusion sheet, glass, film) and to maximize the workability, reproducibility, reliability and productivity by improving efficiency by automation. .

The foregoing objects, features, and advantages will become more apparent from the following examples taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart of a process by microlens inkjet patterning of an optical substrate according to the present invention, and FIG. 4 is a function and configuration diagram of an optical substrate pattern according to the present invention.

3 and 4, the optical medium according to an embodiment of the present invention is a micro-lens inkjet (MLI; Micro-Lens) on one or both surfaces of an optical substrate (shown in FIG. Ink-Jetting) patterning process is applied to form hemispherical micro lens dots or line patterns. Here, a plasma pretreatment process is applied before the microlens inkjet patterning process so that the hemispherical microlens dot or line pattern formed on the optical substrate maintains the contact angle with the surface of the substrate and the adhesion is enhanced. In addition, the optical substrate may be made of a light guide plate, a diffusion sheet, a glass or a film.

In the light guide plate which is an example of an optical substrate, the patterning of the light guide plate is made by marking a dot or line pattern by various printing methods in order to induce light scattering on the back surface of the acrylic resin of the bare LGP. Say.

As shown in FIG. 4, the light guide plate 50 uniformly propagates light uniformly throughout the display screen by light scattering 300 in a printed dot pattern.

As shown in FIG. 3, the non-printed LGP is subjected to plasma pretreatment and then microlens inkjet patterned with UV curable ink using an inkjet printer.

5 is a view showing a micro lens formed of UV curable ink after plasma pretreatment on the substrate according to the present invention, Figure 6 is a view comparing the micro lens formed on the surface of the substrate according to the present invention. As can be seen from this, it can be seen that microlenses are not formed on the surface of the non-printed substrate, and microlenses are formed on the surface of the plasma pretreated substrate.

In addition, the plasma pretreatment process is a surface treatment process using an atmospheric pressure low temperature plasma, and in the microlens inkjet patterning process, the surface of the optical substrate is printed with ultraviolet curing ink for uniform light emission. The microlens inkjet patterning process may be applicable to the size of a pattern of 100 microns or less.

Specifically, the plasma is a collection of particles made up of ion nuclei and free electrons formed by increasing the temperature by continuously applying heat to a gaseous substance. Heat is applied to the lowest energy solids in a material and becomes liquid when the temperature rises, and when heat energy is applied again, it causes a transition to gas. Subsequently, when the gas receives more energy, ionized particles are produced that are different from the state transitions, and the total charges of the cations and the anions are about the same. This state is an electrically neutral plasma state. Therefore, plasma pretreatment is a surface treatment operation for smoothly forming a lens of a dot or line pattern using plasma.

The purpose of the surface treatment work using the plasma pretreatment is to maintain an environmentally friendly working environment by maintaining the contact angle of the lens by the first surface tension, improving the adhesion with the second ink, and eliminating the chemical reaction by the third surface activation. .

The advantage of plasma under atmospheric pressure is that it is suitable for continuous in-line processes because it is not limited by the first substrate size or material. Second, chemical reactions occur only on the surface, thus preventing losses due to substrate changes in the light guide plate. Third, because it uses nitrogen (N ₂ ), air, etc., it is environmentally friendly. Fourth, work is possible even at low temperature (40 ° C. or less). Therefore, the plasma pretreatment applied to this process is a surface treatment operation using atmospheric low temperature plasma.

In addition, the optical medium is characterized in that the microlens inkjet patterning process is applied to the dot or line pattern of various forms on one side or both sides of the optical substrate such as a backlight, keypad and light panel.

Hereinafter, the content according to an embodiment of the present invention in more detail.

As shown in Fig. 3, the configuration of the microlens inkjet patterning process is based on the conveyor system, and is primarily a pattern generator by optical simulation in S / W, and pretreatment in a second plasma equipment. Process and tertiary patterning process in an inkjet printer.

That is, after the plasma light-treatment of the non-printed light guide plate is carried out using a micro-lens inkjet patterning operation using an inkjet printer.

Micro lens inkjet patterning improves optical properties (uniformity / brightness / visibility, etc.) by printing for uniform light emission on the surface of optical materials (light guide plate, diffuser plate, glass and film, etc.) that enter the backlight for TFT LCD. Do it. In addition, microlens inkjets are directly formed by the ink jetted from the inkjet head, eliminating the need for plate making / filming, such as molding (mold and injection) operations or silkscreens, and typically reducing development time, typically four weeks or more. (For example, a microlens inkjet patterning process is enough for about 1 day).

In order to obtain good patterning in such an optical substrate, the following requirements must be met.

In order to obtain a good print, the conditions of the squeegee and the plate making conditions must be changed so that the optimum ink can be transferred to the print. The ink on the squeegee is rotated when the ink is placed on the plate and printed with squeegee. At this time, if the ink agitation is not properly generated, the problem of the ink is missing, so that a clear print can not be obtained, the ink agitation is necessary. In addition, the amount of squeegee to be imprinted with the to-be-printed plate after transferring the ink to the to-be-printed material is called delamination. In the screening machine, the amount of delamination is generally sequentially shifted to take account of this. The height between the engraving and the printed object is called the offset, which is generally important to get a good print.

Accordingly, in the microlens inkjet patterning process according to the exemplary embodiment of the present invention, an ultraviolet (UV) curing ink is used instead of a conventional infrared (IR) curing ink.

The infrared curable ink used in the present invention is an ink whose drying is accelerated by irradiation of infrared rays. The ink layer is heated in infrared to promote penetration into the substrate (substrate), and the oxidative polymerization is promoted by heating the substrate (substrate) after printing.

Ink materials include rosin-based resins with high infrared absorption, dry oils with many double bonds with rapid oxidation polymerization, and low molecular (low molecular) solvents with low boiling point and high penetration rate on paper.

On the other hand, infrared rays can be seen that the temperature rises by placing a high-sensitivity thermometer outside the red portion of the solar spectrum through the spectrometer. This is called infrared rays, also called heat wire in that it has a thermal action. The near-infrared wavelength range is most suitable for practical use, and is a light source currently used for printing (examples include a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED)). Most are near infrared. Infrared curable inks are also referred to as "IR INK".

However, the disadvantage of such an infrared curable ink is that the first plate making needs to be replaced frequently. It contains an organic solvent component, so evaporation is severe and viscosity changes. Therefore, there is a need to replace the plate making after every 3,000 prints. Second, since the size of the pattern does not apply to less than 150 microns, there is a problem that the pattern is not suitable for the notebook because it is visible.

However, as described above, the present invention substitutes the silkscreen printing process using a semi-automatic silkprint machine, which has been used previously, with an inkjet microlens inkjet patterning process using plasma pretreatment, and is used in the silkscreen printing process. By replacing the infrared curable ink with the ultraviolet curable ink in the microlens inkjet patterning process, the optical material can be thinned, and the efficiency of the automation can be improved to maximize the processability, reproducibility, reliability, and productivity.

The advantage of using UV-curable ink by substituting such micro lens inkjet patterning process is that the size of the first pattern can be applied to 100 microns or less, so it can be used not only for notebooks but also for monitors, TVs, and light panels. It is also suitable for a light guide plate and a pattern for high brightness film.

Second, the microlens inkjet patterning process is more precise than the semi-automatic silkscreen printing process using a silkprint machine, which is absolutely advantageous in processability, reproducibility, reliability, and mass production.

Hereinafter, the characteristics of the ultraviolet (UV) curable ink used in the present invention will be described.

UV curable inks are inks that undergo a photochemical reaction with the energy of ultraviolet rays to cure from a liquid to a solid state. As environmental problems increase day by day, low-pollution inks are required, and in the effort to reduce organic solvents that are a problem for the environment and worker's health when using solvent-based inks, the selection of UV curable inks becomes inevitable, and compared with conventional inks. Therefore, many advantages such as instant drying, low temperature and high speed productivity, energy saving, solvent-free, and pollution-free are highly appreciated and used in a wide range of applications.

Advantages of UV curable ink include improved workability according to short curing time, 100% solids without volatile organic solvents, and pollution prevention. Continuous work is possible because there is no dryness of the board during the work, there is no smell with printed materials, strong resistance to friction, heat, solvent, chemicals, etc., and there is no fear of backing and blocking, and special ink such as heat and peeling Can be made.

In addition, the characteristics of the ultraviolet curable ink and the solvent ink (that is, the infrared curing ink) are as follows.

UV curing ink is solvent-free ink of 100% solid content, but infrared curing ink is solvent ink which needs stirring tank.

Table 1 below compares the characteristics of the ultraviolet curable ink and the solvent type ink (ie, infrared curing ink).

division UV Curing Ink Solvent ink Item Volatility none have Curing time short Relatively long Heat shock none Limited by heat treatment Plate dry none have working time fast slow Properties Great usually Skin irritation small Big

The following Table 2 compares the composition of the ultraviolet curable ink and the solvent ink. The solvent ink adjusts the viscosity according to the solvent, while the ultraviolet curable ink has ultraviolet rays such as oligomers (low polymers) and monomers (monomers) of low viscosity. Since the viscosity is adjusted by the reactive diluent, it is a 100% nonvolatile component.

U V Ink Kinds Solvent type ink High viscosity oligomer Vehicle Thermoplastic resin Low Viscosity Oligomers, Monomers Various solvents Photopolymerization initiator catalyst none Pigment coloring agent Pigment Antifoaming Agent Supplements Antifoaming Agent Polymerization inhibitor Other none

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is an exploded perspective view showing a general light emitting device for a backlight.

2 is a flowchart of a process by silkscreen printing of a conventional optical substrate.

3 is a flowchart of a process by microlens inkjet patterning of an optical substrate according to the present invention.

4 is a function and configuration diagram of an optical substrate pattern according to the present invention.

5 is a view showing a micro lens formed of UV curable ink after plasma pretreatment on the substrate according to the present invention.

6 is a view comparing microlenses formed on the surface of a substrate according to the present invention.

* Description of the symbols for the main parts of the drawings *

50: light guide plate 100: light source

200: print pattern 300: light scattering in the print pattern

Claims (8)

Microlens dot or line pattern is formed by applying microlens inkjet patterning process to one or both sides of the optical substrate Optical media. The method of claim 1, The optical substrate is made of any one of a light guide plate, a diffusion sheet, glass, or a film. Optical media. The method of claim 1, Plasma pretreatment is applied before the microlens inkjet patterning process so that the microlens dot or line pattern formed on the optical substrate maintains the contact angle with the surface of the substrate and the adhesion is enhanced. Optical media. The method of claim 3, The plasma pretreatment process is a surface treatment process using atmospheric low temperature plasma Optical media. The method of claim 1, The micro lens inkjet patterning is a process formed by directly injecting ink onto the surface of the optical substrate in an inkjet head of an inkjet printer. Optical media. The method of claim 5, The surface of the optical substrate is printed with ultraviolet curing ink in the micro lens inkjet patterning for uniform light emission Optical media. The method of claim 1, The microlens inkjet patterning process is applicable to pattern sizes of 100 microns or less Optical media. The method of claim 1, The optical medium is a microlens inkjet patterning to any one of the optical substrate of the backlight, keypad or light panel Optical media.

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