Patent Publication Number: US-2012024829-A1

Title: Laser machining device

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to laser machining technology and, particularly, to a laser machining device. 
     2. Description of Related Art 
     Laser machining devices are preferred for use in dot-pattern-formation on a bottom surface of a light guide plate. Generally, the laser machining device includes a laser source and a laser head. Laser beams emitted from the laser source reach the laser head and then are projected onto a bottom surface of a substrate to form a dot. The laser head is driven to move relative to the substrate to form dots in different positions on the bottom surface by a driving member. Therefore, a light guide plate or a light guide plate insertion is formed. The light guide plate insertion is then used in a molding die to form a light guide plate. 
     However, during the dot-pattern-formation process, the length of the light path from the laser source to the laser head changes with movement of the laser head. Intensity of the laser beam projection onto the bottom surface decreases with the length of the light path. Therefore, the intensity of the laser beam projecting on different positions on the bottom surface is not uniform. This results different sizes and depths of dots formed. 
     Therefore, it is desirable to provide a laser machining device and a method for manufacturing a light guide plate which can overcome or at least alleviate the limitations described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a laser machining device for forming dots on a substrate, according to a first exemplary embodiment. 
         FIG. 2  is a planar view of the substrate of  FIG. 1  with the dots formed. 
         FIG. 3  is a schematic view of a laser machining device for forming dots on a substrate, according to a second exemplary embodiment. 
         FIG. 4  is a flowchart of a method for manufacturing a light guide plate, according to a third exemplary embodiment. 
         FIG. 5  is a flowchart of a method for manufacturing a light guide plate, according to a fourth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-2 , a laser machining device  20 , according to a first exemplary embodiment, is used to form a dot pattern including a number of dots  50  on a substrate  10 . 
     The substrate  10  includes a surface  102  opposite to the laser machining device  20 . The surface  102  is substantially rectangular and includes two first sides  104  and two second sides  106 . The first sides  104  are substantially parallel to each other. The second sides  106  are substantially parallel to each other. The first sides  104  are substantially perpendicular to the second sides  106 . The dots  50  are formed on the surface  102 . 
     The laser machining device  20  includes a first laser source  202 , a first filter element  204 , a first light condensing element  206 , a first light reflection element  208 , a second light reflection element  210 , a second laser source  212 , a second filter element  214 , a second light condensing element  216 , a third light reflection element  218 , a fourth light reflection element  220 , a third light condensing element  222 , a fourth light condensing element  224 , and a light-combining assembly  226 . In particular, the first laser source  202 , the first filter element  204 , the first light condensing element  206 , the first light reflection element  208 , the second light reflection element  210 , and the third light condensing element  222  cooperatively form a first laser source module  201 . The second laser source  212 , the second filter element  214 , the second light condensing element  216 , the third light reflection element  218 , the fourth light reflection element  220 , and the fourth light condensing element  224  cooperatively form a second laser source module  211 . 
     The first laser source  202  is configured for emitting a first laser beam. The first filter element  204  is positioned between the first laser source  202  and the first light condensing element  206 . The first filter element  204  is configured for filtering a weak portion of the first laser beam. The first light condensing element  206  is positioned between the first filter element  204  and the first light reflection element  208 . The first light condensing element  206  is configured for condensing the first laser beam. The first light reflection element  208  is configured for reflecting the first laser beam condensed by the first light condensing element  206  toward the second light reflection element  210 . The second light reflection element  210  is configured for reflecting the first laser beam reflected by the first light reflection element  208  toward the third light condensing element  222 . The third light condensing element  222  is positioned between the second light reflection element  210  and the light-combining assembly  226 . The first laser beam emitted from the first laser source  202  passes through the first filter element  204 , the first light condensing element  206  and then is reflected by the first light reflection element  208  and the second light reflection element  210  toward the third light condensing element  222 , and finally reaches the light-combining assembly  226  to form a first light path. 
     The second laser source  212  is configured for emitting a second laser beam. The second laser source  212  is fixed relative to the first laser source  202 . The second filter element  214  is positioned between the second laser source  212  and the second light condensing element  216 . The second filter element  214  is configured for filtering a weak portion of the second laser beam. The second light condensing element  216  is positioned between the second filter element  214  and the third light reflection element  218 . The second light condensing element  216  is configured for condensing the second laser beam. The third light reflection element  218  is configured for reflecting the second laser beam condensed by the second light condensing element  216  toward the fourth light reflection element  220 . The fourth light reflection element  220  is configured for reflecting the second laser beam reflected by the third light reflection element  218  toward the fourth light condensing element  224 . The fourth light condensing element  224  is positioned between the fourth light reflection element  220  and the light-combining assembly  226 . The second laser beam emitted from the second laser source  212  passes through the second filter element  214 , the second light condensing element  216  and then is reflected by the third light reflection element  218  and the fourth light reflection element  220  toward the fourth light condensing element  224 , and finally reaches the light-combining assembly  226  to form a second light path. 
     The light-combining assembly  226  is moveable between the first laser source  202  and the second laser source  212 . In this embodiment, the light-combining assembly  226  is driven to move along a direction perpendicular to the reflected first laser beam and the reflected second laser beam by a driving member. A sum of the length of the first light path and the length of the second light path is maintained constant. The light-combining assembly  226  includes a reflection unit  2262  and a condensing unit  2264 . The reflection unit  2262  has a triangular section and includes a first reflection surface  2266  and a second reflection surface  2268  connecting to the first reflection surface  2266 . The first reflection surface  2266  is symmetrical to the second reflection surface  2268 . In this embodiment, the first laser beam reaches the first reflection surface  2266 , and the second laser beam reaches the second reflection surface  2268 . An angle of incidence of the first laser beam on the first reflection surface  2266  is equal to that of the second laser beam on the second reflection surface  2268 . The first reflection surface  2266  and the second reflection surface  2268  are configured for respectively reflecting the first and second laser beams in a manner that the reflected first and second laser beams are parallel to each other. The condensing unit  2264  is a light converging lens. In this embodiment, the focus of the light converging lens focuses on the surface  102  of the substrate  10 . 
     In this embodiment, the first light reflection element  208 , the second light reflection element  210 , the third light reflection element  218 , and the fourth light reflection element  220  are reflection lenses. 
     When the laser machining device  20  forms dots  50  on the surface  102 , the first laser beam and the second laser beam are reflected by the first reflection surface  2266  and the second reflection surface  2268  toward the condensing unit  2264  to form a third laser beam. The third laser beam focuses on a point on the surface  102  to form a dot  50 . The first laser source  202  and the second laser source  212  are re-activated after the light-combining assembly  226  moves to a subsequent position along the first side  104  (positive direction on an X axis shown in  FIG. 2 ) so that a subsequent dot  50  is formed on the surface  102 . As this action is repeated, a first line of dots  50  is formed on the surface  102 . The laser machining device  20  then moves along the second side  106  (positive direction on a Y axis shown in  FIG. 2 ). The first laser source  202  and the second laser source  212  are re-activated after the light-combining assembly  226  moves to a subsequent position along the negative direction of the first side  104  (negative direction on the X axis shown in  FIG. 2 ) so that a subsequent dot  50  is formed on the surface  102 . As this action is repeated, a second line of dots  50  is formed on the surface  102 . Operations are repeated until the dot pattern is complete on the surface  102 . 
     During the dot-formation process, when the light-combining assembly  226  moves to increase the length of the first light path and the intensity of the first laser beam decreases accordingly, the length of the second light path decreases to increase the intensity of the second laser beam. When the light-combining assembly  226  moves to decrease the length of the first light path and the intensity of the first laser beam increases accordingly, the length of the second light path increases to decrease the intensity of the second laser beam. Therefore, the total intensity of the first laser beam and the second laser beam will be substantially maintained constant. As a result, the intensity of the third laser beam focused on different positions on the surface  102  is substantially maintained constant. The sizes and depths of the dots  50  are approximately consistent. 
     In other embodiments, the substrate  10  may be round or triangular. The first filter element  204 , the second filter element  214 , the third light condensing element  222 , and the fourth light condensing element  224  may be omitted. 
     It is to be understood that in alternative embodiments, the laser machining device  20  can include only a first laser source  202 , a second laser source  212 , and a light-combining assembly  226 . The light-combining assembly  226  is moveably positioned between the first laser source  202  and the second laser source  212 . The first laser beam emitted from the first laser source  202  directly reaches the light-combining assembly  226 . The second laser beam emitted from the second laser source  212  directly reaches the light-combining assembly  226 . 
     Referring to  FIG. 3 , a laser machining device  40 , according to a second exemplary embodiment, is used to form a dot pattern including a number of dots (not shown) on a substrate  30 . 
     The differences between the laser machining device  40  of this embodiment and the laser machining device  20  of the first embodiment are: the light-combining assembly  426  includes a first reflection unit  4262 , a second reflection unit  4264 , and a condensing unit  4266 . The first reflection unit  4262  includes a first reflection surface  4263 . The second reflection unit  4264  includes a second reflection surface  4265 . The first reflection surface  4263  inclines relative to the second reflection surface  4265 . The first reflection surface  4263  is symmetrical to the second reflection surface  4265 . The condensing unit  4266  is a light converging lens focused on a surface  302  of the substrate  30 . The first laser beam and the second laser beam are reflected by the first reflection surface  4263  and the second reflection surface  4265  in a manner that the reflected first and second laser beams are parallel to each other toward the condensing unit  4266  to form a third laser beam. The third laser beam focuses on a point of the surface  302  to form a dot. 
     The advantages of the laser machining device  40  of the second exemplary embodiment are similar to those of the laser machining device  20  of the first exemplary embodiment. 
     Referring to  FIGS. 1-2  and  4 , a method for manufacturing a light guide plate (not shown) according to a third exemplary embodiment can be implemented by, for example, the laser machining device  20  and includes the following steps. In step S 102 : a substrate  10  is provided. The substrate  10  includes a surface  102 . The material of the substrate  10  may be acryl resin or material. 
     In step S 104 : a laser machining device  20  is provided, dots  50  are processed on the surface  102  of the substrate  10  using the laser machining device  20  to form a light guide plate insertion (not shown). In particular, the first laser beam and the second laser beam are reflected by the first reflection surface  2266  and the second reflection surface  2268  toward the condensing unit  2264  to form a third laser beam. The third laser beam focuses on a point on the surface  102  to form a dot  50 . The first laser source  202  and the second laser source  212  are re-activated after the light-combining assembly  226  moves to a subsequent position along the first side  104  (positive direction on an X axis shown in  FIG. 2 ) so that a subsequent dot  50  is formed on the surface  102 . The action is repeated, a first line of dots  50  can be formed on the surface  102 . The laser machining device  20  then moves along the second side  106  (positive direction on a Y axis shown in  FIG. 2 ). The first laser source  202  and the second laser source  212  are re-activated after the light-combining assembly  226  moves to a subsequent position along the negative direction of the first side  104  (negative direction of the X axis shown in  FIG. 2 ) so that a subsequent dot  50  is formed on the surface  102 . The action is repeated, a second line of dots  50  can be formed on the surface  102 . Operations are repeated until the dot pattern is formed on the surface  102 . 
     In step S 106 : a light guide plate (not shown) is molded using a molding die (not shown) with the light guide plate insertion (not shown). 
     In other embodiments, the method for manufacturing a light guide plate (not shown) can be implemented by the laser machining device  40 . In addition, the substrate  10  may be a light guide plate workpiece. After dot pattern is formed on the surface  102 , the ultimate product of the light guide plate is formed. Therefore, the step S 106  can be omitted. This simplifies the making method of the light guide plate and makes the cost down. 
     Referring to  FIG. 5 , a method for manufacturing a light guide plate (not shown) according to a fourth exemplary embodiment can be implemented by, for example, the laser machining device  20  and includes the following steps. In step S 202 : a substrate  10  is provided. The substrate  10  includes a surface  102 . The material of the substrate  10  may be acryl resin or material. 
     In step S 204 : a tinsel (not shown) is provided. The tinsel has a predetermined thickness. 
     In step S 206 : the tinsel is attached on the surface  102  of the substrate  10 . 
     In step S 208 : a laser machining device  20  is provided, the tinsel is penetrated by laser beam emitted from the laser machining device  20  and dots  50  are processed on the surface  102  of the substrate  10  using the laser machining device  20 . 
     In step  210 : the tinsel is removed from the substrate  10  to form a light guide plate insertion (not shown). 
     In step S 212 : a light guide plate (not shown) is molded using a molding die (not shown) with the light guide plate insertion (not shown). 
     The advantages of the method for manufacturing a light guide plate of the fourth exemplary are similar to those of the method for manufacturing a light guide plate of the third exemplary embodiment. Further, the tinsel with predetermined thickness can block the intensity of the edge of the laser beam. Therefore, the shape of the dots  50  will be more exact. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments. The disclosure is illustrative only, and changes may be made in details, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.