KR101051823B1 - Laser generator for light guide plate processing - Google Patents

Abstract

The present invention relates to a laser generating apparatus for light guide plate processing, and more particularly, to a laser generating apparatus used for processing a light guide plate using a laser, using a cooling device to generate a laser optimized for processing, and a square wave laser pulse of a processing level or higher. By generating uniformly, the workability is improved and the laser generating apparatus for light guide plate processing which can prevent unnecessary thermal deformation.

The laser generating apparatus for light guide plate processing of the present invention includes a laser light source for continuously generating a laser to process an optical pattern on the light guide plate, a shutter unit for converting the laser continuously generated from the laser light source into a pulsed laser, and the laser. A cooling unit for maintaining the light source at a predetermined temperature, and a control unit for controlling the operation of the shutter unit in response to the optical pattern.

According to the laser generating apparatus for light guide plate processing of the present invention, it is possible to generate a high quality laser by maintaining the temperature of the laser light source within a predetermined temperature range, and to generate a high processing speed by generating a laser pulse having a uniform energy above the processing level. Even in mass production, it is possible to prevent unnecessary thermal deformation, and the dot size constituting the optical pattern is uniformly processed.

Laser processing equipment, light guide plate, optical pattern

Description

Laser generating apparatus for light guide plate processing

The present invention relates to a laser generating device used in a light guide plate processing apparatus using a laser to an apparatus for generating a laser irradiated for processing on a light guide plate in a device for processing an optical pattern using a laser on the light guide plate used in the backlight unit. It is about.

BACKGROUND ART Liquid crystal displays (LCDs), which are recently attracting attention as display devices, inject liquid crystals between substrates on which electrodes for controlling each pixel are formed, and form an electric field between the substrates to display image information. The state is changed and the desired image information is displayed using the transmittance difference accordingly.

Unlike a plasma display pannel (PDP), an LCD, such as a liquid crystal itself, does not emit light, but only light passes. Therefore, a light source device must be separately provided to display image information.

A light source device provided in an LCD or the like is commonly referred to as a backlight unit, and includes a light source such as a cathode ray tube for generating light, an LED, a fluorescent lamp, and a light guide plate and a prism sheet for evenly dispersing light generated from the light source.

In a backlight unit used in an LCD or the like, the light source is generally located at the end of the LCD, and several sheets including the light guide plate are required to evenly distribute the light generated at the end.

The double light guide plate is usually made of an acrylic resin to form a constant optical pattern in an intaglio or embossed on one side. The optical pattern plays a role that the light generated from the light source comes out of the light guide plate during propagation by total reflection, that is, the incident angle of the light propagated at a specific position is less than the critical angle so that the light generated from the light source provided on one side is transferred to the entire LCD. Serve evenly.

Conventionally, injection molding and the like have been used to form the optical pattern on the light guide plate. However, as the thickness of products adopting LCD and the like has become thinner and larger in size, there has been a limitation in manufacturing the light guide plate on which the optical pattern is formed. Due to this problem, devices that process optical patterns directly on the light guide plate using laser have emerged, but the output of the laser irradiated for processing on the light guide plate is not constant, so that the uniformity of the optical pattern is reduced and the laser below the processing level is irradiated to the light guide plate. As a result, there has been a problem that the defect rate due to thermal deformation after processing is high.

In addition, in order to meet mass production, fast processing is required, but if the processing is fast, not only the defect rate is high but also the processing speed is limited, and the overall manufacturing time of the light guide plate is much longer than that of injection molding, resulting in high manufacturing cost and low economic efficiency. There is this.

The present invention is to solve the above problems, an object of the present invention to generate a laser pulse of a uniform square wave above the processing level to improve the light guide plate processing quality and generate a laser capable of processing a high quality light guide plate at an economical processing speed The present invention provides a laser generating apparatus for light guide plate processing.

In order to achieve the above object, the laser generating apparatus for light guide plate processing of the present invention includes a laser light source for continuously generating a laser to process an optical pattern on the light guide plate, and a laser continuously generated from the laser light source as a pulse type laser. A shutter unit for converting, a cooling unit for maintaining the laser light source at a predetermined temperature, and a control unit for controlling the operation of the shutter unit in response to the optical pattern.

In addition, the laser light source is characterized in that the laser light source for generating a laser having a wavelength substantially 1.7㎛ or more.

In addition, the laser light source is characterized in that the carbon dioxide laser.

In addition, the shutter unit includes an acoustic optical modulator (AOM).

In addition, the cooling unit adjusts the temperature of the laser light source within the range of ± 0.1 ℃ of the predetermined temperature.

In addition, the cooling unit is to adjust the temperature through at least two or more steps in order to adjust within the range of ± 0.1 ℃ of the predetermined temperature, characterized in that the width of the temperature control narrows as each step passes.

In addition, the cooling unit is a water-cooled cooling unit using a cooling water, and comprises a temperature sensor for sensing the temperature of the cooling water in the main cooling unit and the auxiliary cooling unit in order to maintain a constant temperature of the cooling water, the auxiliary cooling unit is It is provided at the inlet or outlet of the main cooling unit, characterized in that for heating or cooling the cooling water flowing in or out of the main cooling unit based on the temperature of the cooling water detected by the temperature sensor.

In addition, the control unit controls the operation of the shutter unit to adjust the opening and closing period of the shutter unit corresponding to the optical pattern to be processed.

The present invention having the above configuration has the effect of uniformly generating a laser optimized for light guide plate processing.

In addition, by generating a laser continuously and generating a laser pulse of a predetermined period according to the optical pattern by using a shutter device, there is an effect that can be processed quickly and uniformly light guide plate.

In addition, by using the step-by-step cooling unit to maintain a constant temperature of the laser light source has the effect of generating a uniform and high-quality laser.

Hereinafter, a laser generating apparatus for processing a light guide plate according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a laser generating apparatus for light guide plate processing according to an embodiment of the present invention. Laser generation apparatus for light guide plate processing according to an embodiment of the present invention is the laser light source 100 and the laser light source 100 for continuously generating a laser for processing the optical pattern (A) on the light guide plate of the laser pulse Of the shutter unit 200 corresponding to the optical unit A to be processed on the cooling unit 300 and the light guide plate 1 which maintain the temperature of the shutter unit 200 and the laser light source 100 at a predetermined temperature. It comprises a control unit 400 for controlling the operation.

The laser light source 100 is a light source for generating a laser for processing the optical pattern A on the light guide plate 1. The laser generated by the laser generator is irradiated to the light guide plate 1 to correspond to the optical pattern. And all shapes that form an optical pattern such as a rectangle).

There are various types of laser light source 100 depending on the principle of its generation or the material used for amplification of the laser, and the characteristics of the laser generated according to this also vary. FIG. 2 is a graph of reflectance versus wavelength of a laser of an acrylic resin used as the light guide plate 1, and it can be seen that only a specific wavelength laser has excellent absorption rate for the acrylic resin. Therefore, in order to process the optical pattern on the light guide plate 1, the energy of the laser must be transferred to the acrylic and for this purpose, the laser must be absorbed into the acrylic. Therefore, it is suitable to process the optical pattern uniformly and efficiently by using the light of the wavelength range which is excellent in the absorption rate.

Especially, CO2 laser is a gas laser using transition between vibration levels of carbon dioxide, and it is suitable for processing light guide plate using laser because it has high absorbency to acrylic resin used as material of light guide plate and can be easily oscillated using RF signal. Laser light source. However, in order to form an optical pattern, a laser having a pulse shape corresponding to the pattern needs to be irradiated to the light guide plate 1, so that an RF signal is applied to a carbon dioxide laser light source to generate a laser pulse corresponding to the optical pattern. The period of the RF signal is adjusted according to the optical pattern to be processed.

The dots forming the optical pattern have to be uniform in size in order to distribute the light evenly throughout the LCD, and the dot forming the optical pattern is not processed unless the energy of the laser becomes more than a predetermined size. 3A and 3B are graphs showing the energy of the laser and the laser pulse generated in the conventional laser generator and the laser generator according to the present invention. As described above, the energy of the laser irradiated to the light guide plate 1 is at a predetermined level (processing). Level) is higher than the dot processing. However, in the case of the laser generated by the conventional laser generator, it can be seen that the energy of the generated laser increases exponentially when the generation signal is applied to the laser light source, and decreases exponentially when the laser stop signal is applied. Therefore, the energy graph shown in FIG. 3A is shown, and in the case of ① and ③ sections, energy having a processing level or less cannot be processed so that the dots forming the light guide plate 1 optical pattern cannot be processed. ② Only the sections form dots on the light guide plate 1. The laser beam irradiated in the sections 1 and 3 is absorbed by the light guide plate 1 to cause thermal deformation of the light guide plate 1. Such thermal deformation causes plastic deformation of the light guide plate 1, which causes a failure rate. On the contrary, as shown in FIG. 3B, the laser generating apparatus of the present invention generates uniform laser pulses at or above the processing level and all have energy above the processing level. It is formed uniformly.

In addition, as the thickness of the light guide plate becomes thinner, the dot size of the optical pattern formed on the light guide plate becomes smaller. To form such a small dot, the width of the laser pulse must be small. In addition, in order to achieve a high-speed processing that is suitable for mass production, not only a laser pulse having a uniform size and sufficient energy for processing a light guide plate should be generated, but also a short cycle of each pulse.

However, the carbon dioxide laser has a waveform in which the energy of the laser generated when the laser is generated or stopped by the RF signal increases exponentially and decreases exponentially as shown in FIG. 3A. Therefore, when a laser pulse is generated by a certain period of RF signal, the energy waveform of the laser does not have the shape of a square wave but is exponentially increased and then exponentially decreased. The RF signal period is shortened to process at speeds that are acceptable. As the RF signal cycle becomes shorter, the laser oscillated by the CO2 laser shows a waveform in which the energy decreases even before reaching the processing energy level (because the section ② is not formed). Lasers below the processing level continue to be transmitted to the light guide plate, causing thermal deformation of the light guide plate. In addition, as laser oscillation and interruption are repeated at short intervals, there is a problem that the size of the processed dot is not constant because the energy of the oscillated laser is not constant.

The present invention is to control the laser light source 100 to generate a laser continuously and to provide a shutter unit 200 to block or pass through the laser output continuously to generate a pulse of uniform size for each pulse, Not only does the laser pulse above the processing level energy be generated, but there is an effect that the waveform of the laser pulse can be a square wave. That is, instead of turning on / off the carbon dioxide laser to generate the laser pulse, the carbon dioxide laser is controlled to be blocked / passed using the shutter unit 200 while continuing to generate a laser pulse suitable for processing. This enables the generation of laser pulses with high quality and uniform energy even at high processing speeds to meet mass productivity. For example, with a CO2 laser, the minimum on / off time is 150μs, but if the processing speed is 4m / s, dots below 0.6mm cannot be processed. However, the shutter unit 200 can be turned on / off by about 1 μs, which is much shorter than the on / off time of the laser, so that the laser pulse can be generated even when processing at a processing speed suitable for mass production.

Accordingly, as the dot of the optical pattern processed on the light guide plate 1 is uniformly formed and only the laser of the processing level or more is irradiated, the optical pattern can be processed while minimizing the thermal deformation of the light guide plate 1 and is also suitable for mass production. There is an effect that can supply a high quality laser suitable for processing even at the processing speed.

As described above, the shutter unit 200 is a device for generating a laser pulse by blocking and passing the laser generated continuously. The shutter unit 200 may be used as long as the device can block or pass the laser for a very short time. However, it is preferable to use an AOM (Acoustic Optical Modulator) in which the refractive index is changed by the RF signal for ease of control of the shutter unit 200. In AOM, the internal refractive index is changed by the RF signal, and accordingly, the refractive angle of the laser is changed. By using the difference in refractive index, the laser beam irradiated to the light guide plate 1 can be transmitted or blocked.

Since the laser light source 100 oscillates the laser at a predetermined temperature or more, a lot of heat is generated. In addition, since the laser light source 100 is sensitive to temperature, if the temperature is not constant, the output of the laser is not constant, and thus the size of the processed dot is not uniformly formed. Therefore, in order to maintain a constant output of energy, the cooling unit 300 of the present invention maintains a constant temperature of the laser light source 100. As described above, the light guide plate becomes thinner and thinner in accordance with the recent slimming trend, and thus, the size of the dot forming the optical pattern must be formed very small. In addition, since the size of the dot must be uniform for uniform light distribution, it is very important to keep the uniformity of the laser output constant. However, a typical cooling unit has a deviation of about several degrees Celsius, which is not enough to uniformly form small dots. At approximately room temperature, the output fluctuations of the laser light source are typically formed in the range of 3% of the output (100W ± 3W for CO2 laser), but in order to form very small dots (approximately 40μm to 300μm), The temperature is preferably maintained within the range of ± 0.1 ℃ at a predetermined temperature.

However, in the case of the cooling unit 300, water cooling or air cooling may be used as long as the temperature deviation can be matched, but water cooling is more efficient in terms of maintaining temperature accuracy.

It is very difficult to maintain the above temperature at a time or the cooling unit that maintains the above temperature is very expensive, so the present invention controls the temperature through two or more steps. That is, in order to maintain the laser light source 100 at a predetermined temperature, the temperature is maintained in a range of ± 0.2 ° C. in one step of temperature control and the temperature adjusted in the first step is detected and the difference is adjusted in two steps. If the temperature is adjusted through three or more steps, step 3 detects the temperature adjusted in step 2 and adjusts the difference in step 3. The cooling unit 300 maintains the temperature using the cooling water, but the water does not change easily because the heat is large. The reality is that it is difficult to control the temperature at once and it is more difficult to match the accuracy. Therefore, by providing a plurality of cooling unit and through this step by adjusting the temperature of the cooling water it is possible to adjust the temperature to the desired precision.

In an embodiment of the present invention, as shown in FIG. 4, the temperature of the laser light source 100 is controlled by using the cooling unit 300 in two stages, that is, the main cooling unit 332 and the auxiliary cooling unit 334. For example, in order to maintain the constant, in order to maintain the temperature of the laser light source 100 with an accuracy of 8 ± 0.1 ° C, if the temperature deviation in the specification of the main cooling part 332 is 0.2 ° C, the main cooling part ( 332) is set to 7.7 ° C. In this case, even if considering the temperature deviation in the specification does not exceed 8 ℃, the holding temperature of the laser light source 100, the temperature sensor 338 is provided at the outlet of the main cooling unit 332 and exit from the main cooling unit 332 Compared with the temperature of the cooling water and the target holding temperature of 8 ℃ and the difference is supplemented by the auxiliary cooling unit 334. The auxiliary cooling unit 334 is not a large temperature control capacity, but it is preferable to use a cooling device that can adjust the temperature more precisely. In an example for explanation, the auxiliary cooling unit 334 has only a function of heating, but a function of cooling on the contrary. May be performed or both heating and cooling may be performed. By changing the set temperature of the main cooling unit 332 according to the function of the auxiliary cooling unit 334 it is possible to maintain the temperature of the laser light source 100 with a precision of ± 0.1 ℃. Cooling water having a precision of ± 0.1 ° C. through the main cooling unit 332 and the auxiliary cooling unit 334 of the cooling unit 300 is supplied to the cooling chamber 336 surrounding the laser light source 100, thereby providing a laser light source. The temperature of 100 is kept constant and circulated through the main cooling unit 332 and the auxiliary cooling unit 334. Cooling of the light source in the cooling chamber 336 uses the principle of forming a flow path through which cooling water flows between the electrode plates of the laser light source 100, cooling the electrode or providing a heat sink, and allowing the cooling water to flow through the heat sink. It can be cooled while moving around the various devices provided in the laser light source (100).

The control unit 400 controls the operation of the shutter unit 200 to generate a laser pulse corresponding to the optical pattern A to be processed in the light guide plate 1. The light guide plate 1 has a different optical pattern for obtaining uniform luminance according to its size, thickness, and the like, and the dot size is changed corresponding to each optical pattern, so the period of blocking / transmission of the shutter unit 200 is changed. . FIG. 5 is a diagram illustrating laser pulses generated in response to an optical pattern in the laser generating apparatus for light guiding plate processing according to the present invention. As shown in FIG. 5, the present invention may generate a laser pulse corresponding to the optical pattern A at a uniform energy level by using the shutter unit 200 and the cooling unit 300. It is possible to generate a laser capable of processing the optical pattern of.

1 is a schematic block diagram of a laser generating apparatus for light guide plate processing according to an embodiment of the present invention;

FIG. 2 is a graph showing absorbance versus wavelength of a laser of an acrylic light guide plate; FIG.

3A is an energy graph of a laser generated in a conventional laser generating apparatus for light guide plate processing,

3b is an energy graph of the laser pulse generated in the laser generating apparatus for light guide plate processing according to the present invention;

Figure 4 is a schematic block diagram of a cooling unit included in the laser generating apparatus for light guide plate processing of the present invention,

5 is a view showing a laser pulse generated corresponding to the optical pattern in the laser generating apparatus for light guide plate processing of the present invention.

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

Laser light source: 100 Shutter unit: 200

Cooling unit: 300 Main cooling part: 332

Secondary cooling part: 334 Cooling chamber: 336

Temperature sensor: 338

Claims (8)

A laser light source for continuously generating a laser to process an optical pattern on the light guide plate; A shutter unit for converting the laser generated continuously from the laser light source into a pulsed laser; A cooling unit for maintaining the laser light source at a predetermined temperature; A control unit for controlling the operation of the shutter unit in response to the optical pattern, And the cooling unit adjusts the temperature of the laser light source within a range of ± 0.1 ° C. of the predetermined temperature. In claim 1, And the laser light source is a laser light source for generating a laser having a wavelength substantially 1.7 μm or more. In claim 2, The laser light source for processing the light guide plate, characterized in that the laser light source is a carbon dioxide laser. In claim 1, The shutter unit is a laser generating apparatus for light guide plate processing, characterized in that it comprises an acoustic optical modulator (AOM). delete In claim 1, The cooling unit is to control the temperature through at least two or more steps in order to adjust within the range of ± 0.1 ℃ of the predetermined temperature, the width of the temperature control laser processing apparatus characterized in that the narrower the width of each step. In claim 1, The cooling unit is a water-cooled cooling unit using the cooling water, In order to maintain a constant temperature of the cooling water is made comprising a temperature sensor for sensing the temperature of the cooling water in the main cooling unit and the auxiliary cooling unit, The auxiliary cooling unit is provided at an inlet or an outlet of the main cooling unit, and generates or cools the light guide plate by heating or cooling the cooling water flowing in or out of the main cooling unit based on the temperature of the cooling water detected by the temperature sensor. Device. In claim 1, And the control unit controls the operation of the shutter unit to adjust the opening and closing period of the shutter unit corresponding to the optical pattern to be processed.

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