JP2007175773A - Laser cutting machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser cutting machine which enhances cutting quality of a substrate. <P>SOLUTION: The laser cutting machine is used for cutting a brittle substrate, and comprises a pre-cutting system 78 for forming a pre-cutting plane line on the substrate, a laser beam system for generating a laser beam which heats and thermally expands the substrate along the pre-cutting plane line, and a cooling system 79 for cooling the thermally expanded substrate. The laser beam system has a hollow body 7 which generates the laser beam, and an optical path distance adjusting system 75. The optical path distance adjusting system is placed in an optical path where the substrate is irradiated with the laser beam and is used to adjust the optical path distance. The laser cutting machine can meet different cutting requirements by placing the optical path distance adjusting system in the optical path of the laser beam to adjust the size of a light spot where the substrate is irradiated with the laser beam. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser cutting device, and more particularly to a laser cutting device used for cutting a brittle material such as a glass face plate of a liquid crystal display device.

  With the development of display technology, the liquid crystal display device has been widely applied in the consumption area, replacing the conventional cathode ray tube display device due to its own properties.

  A liquid crystal display device generally includes two glass substrates, a liquid crystal accommodated between the two glass substrates, and a plurality of circuits. The liquid crystal displays by changing the alignment method under the influence of an electric field. In order to manufacture liquid crystal face plates with different dimensions, it is necessary to satisfy the demand for liquid crystal face plates with different dimensions by cutting large liquid crystal face plates.

  Conventionally, when a glass substrate is cut with a laser cutting device, a cutting line is previously formed on the glass substrate surface with a wheel cutter or a diamond cutter, and then the substrate surface is heated with a laser beam and the substrate surface is cooled with a cooling liquid. . Since stress changes due to a rapid temperature difference in the substrate, a crack generated from a pre-cut line formed on the surface of the substrate extends and penetrates the substrate cross section, whereby the substrate is completely separated.

  FIG. 1 is a schematic view showing a configuration of a conventional laser cutting apparatus. The laser cutting device includes a carbon dioxide laser light unit 1 that generates carbon dioxide laser light, a reflecting mirror 2, a focus lens assembly 3, a wheel cutter 4, and a cooling system 5. When the substrate 6 is cut along the cutting direction A, the wheel cutter 4 cuts the surface of the substrate 6 to form a cutting line having a predetermined depth in advance. The carbon dioxide laser light applied to the surface of the substrate 6 through the reflecting mirror 2 and the focus lens assembly 3 heats the substrate along the cutting line in advance, and then the cooling system 5 heats the cutting line in advance. The substrate is cooled along. By cooling immediately after heating, a temperature difference occurs in the glass face plate. The stress generated inside the glass face plate due to this temperature difference completely separates the substrates. The substrate 6 is sucked onto the mounting table by a metal vacuum chuck.

  According to FIG. 1, in a traditional laser cutting device, the optical path configuration system of laser light is a fixed optical path, and after the laser light is emitted from the laser light unit 1 and incident on the reflecting mirror 2 through a predetermined distance L1, It can be seen that the substrate 6 is irradiated after being reflected by the focus lens 3 through a predetermined distance L2.

  However, in the optical path configuration system described above, the optical elements are simple because L1 and L2 are configured at a predetermined distance. However, when the dimensions of the substrate 6 change, the optical path configuration system changes the laser beam according to the change in the substrate 6. The size and shape of the points cannot be adjusted in a timely manner, and the requirements for cutting characteristics cannot be satisfied.

  The traditional wheel cutter 4 is largely driven directly by atmospheric pressure, and when the substrate 6 is cut using the wheel cutter 4, the cutting depth is not uniform due to the influence of the flatness of the substrate. Since the gas is compressible and lags behind the start of control, the wheel cutter 4 driven by atmospheric pressure is less sensitive to the flatness of the substrate surface. Therefore, the cutting depth cannot be made uniform.

  Further, the suction force with which the traditional metal vacuum chuck sucks the substrate is not uniform depending on the position of the vacuum source, so that the substrate is easily deformed. Therefore, the cutting depth of the substrate is made uniform. In addition, traditional metal vacuum chucks cannot quickly remove the coolant remaining in the cutting process.

  An object of the present invention is to provide a laser cutting apparatus that improves the cutting quality of a substrate.

  The laser cutting device of the present invention includes a pre-cutting system that forms a pre-cut line on a substrate, a laser light system that generates laser light that heats and heat-expands the substrate along the pre-cut line, and the thermal expansion. A laser cutting device used for cutting a brittle substrate, the laser beam system comprising: a laser cavity that generates the laser beam; an optical path distance adjustment system; The optical path distance adjustment system is disposed in an optical path that the laser beam irradiates the substrate, and is used to adjust the optical path distance.

  Compared with the prior art, the laser cutting apparatus according to the present invention has different cutting requirements by arranging an optical path distance adjusting system for adjusting the size of the light spot irradiated to the substrate by the laser light in the laser optical path. Can be satisfied.

  2 and 3, the laser cutting apparatus of the present invention is used for cutting a brittle substrate. The apparatus includes a cutting system 78, a laser light system, and a cooling system 79 in advance. The laser light system includes a laser cavity 7 for generating laser light, a first reflecting mirror 71, a light blocker 72, a second reflecting mirror 73, a collimator 74, and an optical path distance adjusting system 75. And a third reflecting mirror 76 and a focus lens assembly 77. In the present embodiment, after the carbon dioxide laser light generated from the laser cavity 7 is reflected by the first reflecting mirror 71, it is generated by the reflection of the second reflecting mirror 73 and the action of the collimator 74 through the light breaker 72. The parallel light beams are incident on the substrate through the focus lens assembly 77 by reflection of the optical path distance adjustment system 75 and the third reflecting mirror 76. A porous material vacuum chuck 80 sucks the substrate and attaches the substrate to the mounting table. Further, since the vacuum chuck 80 made of a porous material is adopted, when cooling by the cooling system 79, the remaining cooling liquid can be effectively removed, and the cutting quality is improved.

  In an embodiment of the present invention, the cooling system 79 is a single liquid, a mixture of a single gas and a single liquid, or a mixture of one or more gases and liquids. For example, air, pure water, cooling oil, liquid nitrogen or liquid helium.

  2 and 3, a cooling system 79, a laser beam system, and a pre-cutting system 78 are arranged in this order along the cutting direction. When the substrate is cut, first, a pre-cut line is formed on the substrate by the pre-cut system 78, and then the focus lens assembly 77 causes the energy of the laser light along the pre-cut line in a non-focus lens manner to the substrate surface. When the substrate is irradiated to thermally expand the substrate, a compressive stress is generated inside the substrate.

  After the pre-cut line of the substrate is heated with the laser light, a mist-like cooling liquid is rapidly sprayed onto the substrate along the pre-cut line heated using the cooling system 79. Accordingly, the temperature of the substrate surface rapidly decreases, and the inside of the substrate contracts to generate tensile stress.

  Since the substrate generates a sudden change in stress in a short time, a crack is formed along the pre-cut line formed from the laser beam. Since the crack extends along the cut surface, the substrate is completely separated. Thereby, the cutting of the substrate is realized.

  Although there are many factors that cause the substrates to be separated, the stress is mainly generated inside the glass. The stress is expressed by the following formula.

  Here, σ is the magnitude of the stress generated inside the glass faceplate, α is the thermal expansion coefficient inside the glass faceplate, E is the longitudinal elastic modulus of the glass faceplate, T1 is the temperature of the glass faceplate heated by the laser cutting device, T2 Is the temperature of the glass faceplate after cooling.

  From Equations 1 and 2, it can be seen that the magnitude of the stress inside the glass face plate is directly proportional to the thermal expansion coefficient of the material, the longitudinal elastic modulus, and the temperature difference formed on the glass face plate by the laser and the cooling system. . The maximum value of T1 is not greater than the vaporization temperature of the glass face plate.

  If the stress that the laser heating device and the cooling system form on the substrate is greater than the fracture toughness of the substrate material, a crack is formed on the substrate surface. The cracks exhibit different growth forms on the surface of the glass, for example, the substrate completely separates depending on the manufacturing method.

  The size of the light spot where the laser beam from the laser cutting device irradiates the substrate greatly affects the characteristics of laser cutting. The size of the light spot at the time of cutting is determined by the angle between the outgoing light beams of the laser light, the diameter of the light spot at the outgoing end of the laser light, and the length of the optical path, and is expressed by the following formula.

  Here, D is the diameter of the light beam through which the laser beam has passed through the optical path distance L, d is the diameter of the light spot at the laser beam emission end, θ is the angle between the laser beam emission beams, and L is the optical path distance. . The unit of θ is Rad. Accordingly, the cutting requirement can be satisfied by adjusting the size of the optical path distance L and changing the size of the light spot of the laser beam.

  Referring to FIGS. 2, 3, and 4, in this embodiment, the optical path distance adjustment system 75 includes a fourth reflecting mirror 751, a fifth reflecting mirror 752, a sixth reflecting mirror 753, and a seventh reflecting mirror 754. And including. The laser light passes through the fourth reflecting mirror 751, the fifth reflecting mirror 752, the sixth reflecting mirror 753, and the seventh reflecting mirror 754, and then exits from the optical path distance adjustment system 75. A fourth reflecting mirror 751, a fifth reflecting mirror 752, a sixth reflecting mirror 753, and a seventh reflecting mirror 754 are movably installed.

  Referring to FIG. 2, the laser light has an optical path distance L1 from the emitting end of the laser cavity body 7 to the first reflecting mirror 71, and an optical path distance from the first reflecting mirror 71 to the second reflecting mirror 73 is L2. Yes, the optical path distance from the second reflecting mirror 73 to the fourth reflecting mirror 751 is L3, the optical path distance from the fourth reflecting mirror 751 to the fifth reflecting mirror 752 is L4, and the fifth reflecting mirror 752 to the sixth reflecting mirror 752 The optical path distance from the reflecting mirror 753 is L5, the optical path distance from the sixth reflecting mirror 753 to the seventh reflecting mirror 754 is also L4, and the optical path distance from the seventh reflecting mirror 754 to the third reflecting mirror 76 is L6. The optical path distance from the third reflecting mirror 76 to the focus lens assembly 77 is L7. The optical path distance at which the laser light starts to be emitted from the laser cavity 7 and enters the focus lens assembly 77 is L. That is, L = L1 + L2 + L3 + 2 * L4 + L5 + L6 + L7.

  Referring to FIG. 3, the optical path distance adjustment system 75 simultaneously adjusts the distance between the fourth reflecting mirror 751 and the fifth reflecting mirror 752 and the distance between the sixth reflecting mirror 753 and the seventh reflecting mirror 754. That is, the optical path distance L4 between the fourth reflecting mirror 751 and the fifth reflecting mirror 752 and the optical path distance L4 between the sixth reflecting 753 and the seventh reflecting mirror 754 are adjusted to the optical path distance L4 ′. At this time, the laser beam starts to be emitted from the laser cavity 7 and the optical path distance incident on the focus lens assembly 77 is L ′. That is, L ′ = L1 + L2 + L3 + 2 * L4 ′ + L5 + L6 + L7.

  In the present embodiment, in order to increase the optical path distance, L4 ′ is provided to be larger than L4. Of course, the optical path distance may be reduced as required.

  Since L4 ′ is larger than L4, the optical path distance L ′ becomes larger than the optical path distance L. The fourth reflecting mirror 751 and the fifth reflecting mirror 752 simultaneously adjust the distance to the seventh reflecting mirror 754 and the sixth reflecting mirror 753, that is, the optical path distance L5 between the fourth reflecting mirror 751 and the seventh reflecting mirror 754, and The optical path distance L5 between the fifth reflection 752 and the sixth reflecting mirror 753 is adjusted to the optical path distance L5 ′. The optical path distance at which the laser light starts to be emitted from the laser cavity body 7 and enters the focus lens assembly 77 is L ′. That is, L ′ = L1 + L2 + L3 + 2 * L4 ′ + L5 ′ + L6 + L7.

  3 indicates that the diameter D ′ of the light beam shown in FIG. 3 is larger than the diameter D of the light beam shown in FIG. By changing the optical path distance by the optical path distance adjustment system 75, the size of the light spot irradiated on the substrate can be changed. In this way, different cutting requirements can be satisfied.

  In addition, referring to FIGS. 2, 3, 5, and 6, since it takes time from the state where the laser light is closed to the state where it is excited and stably output, the laser light is stable. In order to output the light, a light breaker 72 is installed in the optical path of the laser light. As shown in FIG. 5, the laser light is blocked by the light breaker 72 and not incident on the second reflecting mirror 73 when the light breaker 72 is closed. As shown in FIG. 6, the laser beam can pass in a state where the light breaker 72 is opened. The light blocker 72 is a switch for passing or blocking the laser beam, and controls whether the laser beam is output to the surface of the workpiece. In the manufacturing process, it is possible to control the output of the laser light by controlling only the opening / closing of the light breaker 72 without controlling the laser cavity body 7.

  Referring to FIG. 7, in the present embodiment, the pre-cutting system 78 is a cutting unit and, of course, a laser system. The cutting unit includes a motor 781 and a brake 782. The motor 781 and the brake 782 cooperate to move the cutting unit along the X, Y, and Z axes. The cutting unit further includes a voice-coil motor 783 installed on the brake 782 and a cutting cutter head 784 attached to the voice coil motor 783. The voice coil motor 783 is used as a power transmission tool for the cutting cutter head 784, and since there is no mechanical back clearance, controlling the output is precise and fast. Therefore, the sensitivity to the flatness of the substrate is good, and the uniformity of the precut depth of the cutting cutter head 784 can be well controlled.

It is the schematic which shows the structure of the laser cutting device of a prior art. It is the schematic which shows the structure of the laser cutting device of embodiment of this invention. It is the schematic which shows the structure of the laser cutting device which the optical path distance of FIG. 2 increases. It is a three-dimensional view of the optical path distance adjustment system of the laser cutting device of embodiment of this invention. It is a three-dimensional figure in the state where the optical circuit breaker of the laser cutting device of an embodiment of the present invention closes. It is a three-dimensional view in the state where the optical circuit breaker of the laser cutting device of the embodiment of the present invention is opened. It is a three-dimensional view of the cutting module of the laser cutting device of the embodiment of the present invention. It is a three-dimensional view of the vacuum chuck of the laser cutting device of the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam unit 2 Reflecting mirror 3 Focus lens assembly 4 Wheel cutter 5 Cooling system 6 Substrate 7 Laser cavity body 71 First reflecting mirror 72 Optical blocker 73 Second reflecting mirror 74 Collimator 75 Optical path distance adjustment system 751 4th reflection Mirror 752 fifth reflecting mirror 753 sixth reflecting mirror 754 seventh reflecting mirror 76 third reflecting mirror 77 focus lens assembly 78 pre-cutting system 781 motor 782 brake 783 voice coil motor 784 cutting cutter head 79 cooling system 80 of porous material Vacuum chuck

Claims (11)

A pre-cutting system for forming a pre-cut line on the substrate;
A laser beam system for generating a laser beam for heating and thermally expanding the substrate along the pre-cut line;
A laser cutting device utilized for cutting a brittle substrate, comprising: a cooling system for cooling the thermally expanded substrate;
The laser light system is
A laser cavity for generating the laser beam;
An optical path distance adjustment system, and
The optical path distance adjustment system is disposed in an optical path where the laser beam irradiates the substrate,
A laser cutting device used for adjusting the optical path distance.   The laser cutting device according to claim 1, wherein the optical path distance adjustment system includes two pairs of reflecting mirrors facing each other.   The laser cutting apparatus according to claim 2, wherein the two pairs of reflecting mirrors are installed so as to be movable.   The laser cutting apparatus according to claim 1, wherein the laser light system further includes a focus lens assembly that collects a focus of the laser light and irradiates the substrate with the focus. The laser cutting apparatus according to claim 4, wherein the laser beam system further includes an optical blocker that is installed in the laser cavity body and controls passage or blocking of the laser beam.   The laser cutting apparatus according to claim 4, wherein the laser light system further includes a collimator that converts the laser light into parallel light beams that can pass through a focus lens assembly. A pre-cutting system for forming a pre-cut line on the substrate;
A laser beam system for generating a laser beam for heating and thermally expanding the substrate along the pre-cut line;
A laser cutting device utilized for cutting a brittle substrate, comprising: a cooling system for cooling the thermally expanded substrate;
The laser light system is
A laser cutting apparatus comprising: a laser cavity that generates the laser light; and a light interrupter that is installed in the laser cavity and controls passage or blocking of the laser light.   The laser cutting apparatus according to claim 7, wherein the laser beam system further includes a focus lens assembly that collects a focus of the laser beam and irradiates the substrate with the focus.   The laser cutting device according to claim 1, wherein the substrate is attached to a mounting table by suction through a vacuum chuck made of a porous material.   The laser cutting apparatus according to claim 1, wherein the pre-cutting system is a cutting unit that can move along the Z-axis. The cutting unit is
A voice coil motor,
The laser cutting apparatus according to claim 10, further comprising: a cutting cutter head that is attached to the voice coil motor, cuts the substrate, and previously forms a cutting line.

Images