WO2010044497A1

WO2010044497A1 - Laser switching apparatus

Info

Publication number: WO2010044497A1
Application number: PCT/KR2008/006095
Authority: WO
Inventors: Deukil Park; Choongyop Rhew; Kiyong Baek; Daisoung Park
Original assignee: Ls Tech Co., Ltd.
Priority date: 2008-10-16
Filing date: 2008-10-16
Publication date: 2010-04-22

Abstract

A laser switching apparatus is provided. The apparatus includes one or more laser systems for outputting laser beams, a high speed rotary slit unit having a difference of an aperture ratio depending on a position and having one or more slits, and mirror units installed at front/rear ends of the high speed rotary slit unit. Continuous laser beams coming from the one or more laser systems pass through the high speed rotary slit unit via the mirror unit and then, are converted into a discontinuous laser pulse beam. As the continuous laser beams pass through a slit having a difference of an aperture ratio depending on a position by a movement of the mirror unit, a pulse length of the discontinuous laser pulse beam changes.

Description

LASER SWITCHING APPARATUS

Technical Field

[1] The present invention relates to a switching apparatus of a laser device for light guide panel pattern formation used for backlight of a Liquid Crystal Display (LCD), a keypad, a telephone, a surface light source for lighting, etc. More particularly, the present invention relates to a laser switching apparatus for simultaneously processing a plurality of patterns on a Light Guide Panel (LGP), by converting a continuous laser beam into a pulse beam by a mechanical construction, also generating a multiple laser beam by changing and each controlling a length of a pulse, and then concentrating the generated plurality of laser beams on a processed surface of the LGP by multiple focus. Background Art

[2] In general, an LGP is a panel for providing a path uniformly scattering and diffusing a scanned light from a light source. The LGP is applied to a light-receiving type flat display device such as a Liquid Crystal Display (LCD) or a surface light source device used for a lighting signboard, etc.

[3] The surface light source device using the LGP generally uses a scheme of arranging a light source such as a Cold Cathode Fluorescent Lamp (CCFL) or a Light Emitting Diode (LED). This surface light source device has been disclosed in Korean Patent Application Numbers. 1994-33115, 2001-25870, 2001-53844, 2002-26023, 2002-28919, 2003-03466, 2004-73443, 2005-12556, 2006-32631, and 2006-135207, etc.

[4] FIG. 1 is a cross section schematically illustrating a conventional surface light source device.

[5] Referring to FIG. 1, the conventional surface light source device 10 includes an LGP

11, a reflector sheet 12 installed below the LGP 11, a light source 13 installed at a sidewall of the LGP 11, and a cover member 14 covering the light source 13. As the light source 13, a CCFL, an LED, etc. can be used. A plurality of light guide pattern units 15 printed with ink including bead shaped titanium oxide (TiO₂) and glass or acryl, etc. are formed on the LGP 11 to scatter and diffuse light incident on one surface of transparent acrylic resin. In the above-constructed surface light source device 10, light irradiated from the light source 13 is incident into the LGP 11, the incident light is guided through the LGP 11 as indicated by arrows, and then the light is reflected at a relatively uniform luminance from each portion by the reflector sheet 12 and the light guide pattern units 15.

[6] However, the light guide pattern unit 15 formed in a printing method have the following problems.

[7] A manufacturing and printing process of ink for forming the light guide pattern unit

15 is very complex, and an error rate in which a portion of a printed part is dropped out or stained, etc. is high. A yield of the light guide pattern unit 15 according to this is at a low percentage of about 80% to 90%. Because it is impossible to recycle the LGP 11 of a printing scheme after removing a printing pattern, there is a disadvantage that recycling is impossible and pollution is caused, thus not being environment-friendly. Particularly, because the light guide pattern unit 15 is of a scheme using light reflection of a printed ink material itself, a phenomenon of light absorption of the ink material itself inevitably takes place. This light absorption phenomenon deteriorates the light efficiency of the surface light source device.

[8] As a solution to the problem, there is a method of processing a light guide pattern unit using a laser. In the case of using a laser, constant process according to a desired size is possible with no influence of a thickness deviation of material, and an additional device such as a mold, a mask, etc. is not required. Also, because the pattern is not coated with a separate material, recycling is possible and thus, it is environment- friendly. However, there is a disadvantage that, because all patterns should be molded by a laser process one by one at one time, a process time is so lengthened, thus causing a problem of deteriorating productivity. Also, a laser pattern is switched one by one. At this time, there is a disadvantage that, because of an oscillation characteristic of a laser system, upon pulse driving, an output of a laser is not constant as time goes by. Also, if a laser beam is separated and divided into several beams, a beam splitter is used and the thus separated beams each require as a switching device an expensive modulator device such as an Acousto-Optic Modulator (AOM). However, this modulator also has a disadvantage that its own heat loss is generated, a laser beam transmission rate is low at about 80%, and a price is very high. Thus, it is not suitable as a switching device. Disclosure of Invention Technical Problem

[9] Accordingly, the present invention is directed to a laser switching apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

[10] An object of the present invention is to provide a laser switching apparatus for light guide panel pattern formation, for simultaneously processing a plurality of patterns on a Light Guide Panel (LGP).

[11] Another object of the present invention is to provide a laser switching apparatus for

LGP pattern formation, being very usefully available and being able to maximize light efficiency if a delta structure pattern of arranging patterns in zigzags is installed at the time of light guide pattern design. Technical Solution

[12] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a laser switching apparatus for Light Guide Panel (LGP) pattern formation. The apparatus includes one or more laser systems for outputting laser beams, a high speed rotary slit unit having a difference of an aperture ratio depending on a position and having one or more slits, and mirror units installed at front/rear ends of the high speed rotary slit unit. Continuous laser beams coming from the one or more laser systems pass through the high speed rotary slit unit via the mirror unit and then, are converted into a discontinuous laser pulse beam. As the continuous laser beams coming from the one or more laser systems pass through a slit having a difference of an aperture ratio depending on a position by a movement of the mirror unit, a pulse length of the discontinuous laser pulse beam passing through the high speed rotary slit unit changes.

[13] According to a second exemplary embodiment of the present invention, a laser switching apparatus for Light Guide Panel (LGP) pattern formation is provided. The apparatus includes one or more laser systems for outputting laser beams, a high speed rotary slit unit having a difference of an aperture ratio depending on a position and having one or more slits, and mirror units installed at front/rear ends of the high speed rotary slit unit. Continuous laser beams coming from the one or more laser systems pass through the high speed rotary slit unit via the mirror unit and then, are converted into a discontinuous laser pulse beam. The continuous laser beams coming from the one or more laser systems each are incident with a constant arrangement of angles between respective slits of the high speed rotary slit unit and pass. As the continuous laser beams coming from the one or more laser systems pass through a slit having a difference of an aperture ratio depending on a position by a movement of the mirror unit, a pulse length of the discontinuous laser pulse beam passing through the high speed rotary slit unit changes.

[14] Preferably, the laser switching apparatus is characterized by further including a mirror unit position control device for controlling a position of the mirror unit such that the pulse length of the laser beam forming a light guide pattern is variable depending on a process position on an LGP.

[15] Preferably, the laser switching apparatus is characterized by further including one or more beam splitters for splitting the laser beams coming from the one or more laser systems into two or more laser beams.

[16] Preferably, the laser switching apparatus is characterized in that, when being incident on the high speed rotary slit unit, the continuous laser beams coming from the one or more laser systems each are incident at a distance with half of an angle between slits when viewing from a rotation surface.

[17] Preferably, the laser switching apparatus is characterized by further including the high speed rotary slit unit more than one.

Advantageous Effects

[18] As described above, according to the present invention, a plurality of patterns can be simultaneously processed on a Light guide panel (LGP) by converting a continuous laser beam into a pulse beam by a mechanical construction, also generating a multiple laser beam by changing and each controlling a length of a pulse, and then concentrating the generated plurality of laser beams on a processed surface of the LGP by multiple focus.

[19] Also, according to the present invention, by giving synchronization to a specific position of a slit and synchronization-controlling each of laser beams, if a delta structure pattern of arranging a pattern in zigzags is formed at the time of light guide pattern design, it is very usefully available and can maximize light efficiency. Brief Description of Drawings

[20] FIG. 1 is a cross section schematically illustrating a conventional surface light source device;

[21] FIG. 2 is an exploded perspective diagram illustrating a surface light source device applying a Light Guide Panel (LGP) according to an exemplary embodiment of the present invention;

[22] FIG. 3 is a construction diagram of a laser switching apparatus for light guide pattern formation according to an exemplary embodiment of the present invention;

[23] FIG. 4 is a diagram illustrating a high speed rotary slit unit 320 and a process of obtaining a discontinuous laser pulse beam using the high speed rotary slit unit 320 according to an exemplary embodiment of the present invention;

[24] FIG. 5 is a diagram illustrating a process of obtaining a discontinuous laser pulse beam depending on a position on a high speed rotary slit unit 320 through a movement of a mirror unit within optic units 310 and 330 according to an exemplary embodiment of the present invention;

[25] FIG. 6 is a conceptual diagram of synchronization of a laser beam incident on a high speed rotary slit unit 320 according to an exemplary embodiment of the present invention;

[26] FIG. 7 is a diagram illustrating a shape of a light guide pattern unit according to an exemplary embodiment of the present invention; and

[27] FIG. 8 is a diagram illustrating a case in which two high speed rotary slit units 320 are provided according to an exemplary embodiment of the present invention. Best Mode for Carrying out the Invention

[28] Hereinafter, most preferable exemplary embodiments for a laser switching apparatus according to the present invention will be described in detail with reference to accompanying drawings. However, the present invention is not limited to exemplary embodiments disclosed below but can be realized in different various forms. The present exemplary embodiment is provided to merely make the disclosure of the present invention perfect and make the scope of the invention perfectly known to those skilled in the art.

[29] FIG. 2 is an exploded perspective diagram illustrating a surface light source device applying a Light Guide Panel (LGP) according to an exemplary embodiment of the present invention.

[30] Referring to FIG. 2, the LGP 210 is prepared for the surface light source device 200.

A light guide pattern unit 250 is formed at a bottom surface of the LGP 210. A reflector sheet 220 being able to reflect incident light to the top is installed at a bottom of the LGP 210. At least one or more light sources 240 scanning light to the LGP 210 are installed at a sidewall of the LGP 210.

[31] A diffuser sheet 230 scattering and diffusing light is further installed at a top of the

LGP 210. Light emitted from the light source 240 is incident on a side surface of the LGP 210 and the light incident into the LGP 210 is guided and moved within the LGP 210 by the total reflection effect. Among the guided light, light reaching a light guide pattern is emitted outside the LGP 210 by an incident angle exceeding the total reflection threshold angle. The light emitted from the light guide pattern has a principle of going through the reflector sheet 220, again passing through the LGP 210, then passing through the diffuser sheet 230 on an LGP top surface, and being radiated to the front surface. At this time, the light guide pattern unit 250 is arranged such that a portion close to the light source 240 is formed at low density and a portion far from the light source 240 is formed at high density, thus achieving a uniform surface light source.

[32] FIG. 3 is a construction diagram of a laser switching apparatus for light guide pattern formation for forming a light guide pattern unit on an LGP according to an exemplary embodiment of the present invention. The laser switching apparatus includes a laser system 300, a first optic unit 310, a high speed rotary slit unit 320, and a second optic unit 330. The first optic unit 310 includes a mirror unit, a mirror unit position control device for controlling a position of the mirror unit, and a beam splitter for splitting a laser beam into a plurality of laser beams inside. The second optic unit 330 includes a mirror unit and a mirror unit position control device for controlling a position of the mirror unit inside. [33] First, a continuous laser beam coming from the laser system 300 passes through the first optic unit 310, which is comprised of the mirror unit, the mirror unit position control device, and the beam splitter, and is split into a plurality of laser beams. Preferably, the beam splitter can be provided one or more. The thus split laser beam passes through the high speed rotary slit unit 320. The high speed rotary slit unit 320 and a process of obtaining a discontinuous laser pulse beam using the high speed rotary slit unit 320 are described in detail with reference to FIG. 4 below.

[34] FIG. 4 is a diagram illustrating the high speed rotary slit unit 320 and a process of obtaining a discontinuous laser pulse beam using the high speed rotary slit unit 320 according to an exemplary embodiment of the present invention.

[35] Referring to FIG. 4, the high speed rotary slit unit 320, as illustrated, has a saw- toothed rotary knife like shape 400, and has a difference of an aperture ratio depending on a position on the high speed rotary slit unit 320. At this time, although not having a starlike shape as in FIG. 4, the saw-toothed shape can use any shape irrespectively if it is a shape being capable of having a difference of an aperture ratio depending on a position.

[36] This high speed rotary slit unit 320 performs high speed rotation. At this time, if a continuous laser beam is dashed against a rotary knife, a laser beam of a portion crashed into a saw tooth is blocked and a laser beam of a portion crashed into a slit opened between saw teeth passes through and thus, a laser beam of a pulse form is formed.

[37] FIG. 5 is a diagram illustrating a process of obtaining a discontinuous laser pulse beam depending on a position on the high speed rotary slit unit 320 through a movement of mirror units within optic units 310 and 330 according to an exemplary embodiment of the present invention, (a) is a diagram illustrating centering on only the mirror units and the high speed rotary slit unit 320 among the optic units 310 and 330. The left side of (b) is viewed from a side surface of the high speed rotary slit unit 320. The right side of (b) is a diagram viewed from a front surface of the high speed rotary slit unit 320.

[38] Referring to FIG. 5, as illustrated in (a), if the mirror units within the optic units 310 and 330 move in an up/down direction 500, as illustrated in (b), widths (Ll) and (L2) of opened slits change depending on positions (Pl) and (P2) on the high speed rotary slit unit 320. As a result, time (Tl), (T2) passing through the high speed rotary slit unit 320 also change and pulse widths of two laser beams split through the beam splitter change. In this manner, the pulse width of the laser beam can be controlled and thus, a length of a light guide pattern processed in an LGP can be simultaneously easily controlled.

[39] Meantime, FIG. 6 is a conceptual diagram of synchronization of a laser beam incident on the high speed rotary slit unit 320 according to an exemplary embodiment of the present invention, (a) is a diagram illustrating centering on only the mirror units and the high speed rotary slit unit 320 among the optic units 310 and 330. The left side of (b) is viewed from a side surface of the high speed rotary slit unit 320. The right side of (b) is a diagram viewed from a front surface of the high speed rotary slit unit 320.

[40] Referring to FIG. 6, if synchronization is given to a specific position of a slit, laser beams each can be synchronization controlled. In a detailed description of this, as illustrated in (a), laser beams are incident on four points of Pl, P2, P3, and P4. Among the laser beams incident on the four points of Pl, P2, P3, and P4, cases of Pl and P3 are in phase and P2 and P4 are out of phase and thus, it is of a structure in which laser beams cannot be simultaneously output. Accordingly, lasers of Pl and P2 can obtain an effect in which laser beams always appear out of phase on the LGP.

[41] It is to be capable of obtaining an effect in which a laser beam does not appear in phase.

[42] This effect has an advantage of, when a delta structure pattern of FIG. 7 in which patterns are arranged in zigzags is installed at the time of light guide pattern design, it is very usefully available and can maximize light efficiency. The light guide pattern unit is formed throughout the whole region of the LGP such that light guided from the light source to the LGP can be effectively diffused and scattered. That is, the light guide pattern unit can be of a dot type formed of a groove of a predetermined depth, a dotted line type formed of a discontinuous groove of a predetermined depth, or a straight line type formed of a continuous groove.

[43] Also, the light guide pattern unit shall be able to gradually increase in size or gradually decrease in pitch between light guide patterns to enhance light diffusion and a scattering rate as it is distant away from the light source. Also, the light guide pattern unit may gradually increase in depth to enhance light diffusion and a scattering rate as it is distant away from the light source.

[44] Meantime, FIG. 8 illustrates a case in which two high speed rotary slit units 320 are provided according to an exemplary embodiment of the present invention.

[45] Referring to FIG. 8, the high speed rotary slit unit 320 can be installed one or more.

In this case, because arrangement of the mirror units within the optic units 310 and 330 can be more smoothly made, there is an advantage of less spatial limitation.

[46] On the other hand, although not illustrated in FIG. 8, if one or more high speed rotary slit unit 320 are provided, each high speed rotary slit unit 320 should be synchronized for rotation and thus, it is possible to perform a synchronization control using a precision numerical control method or perform a synchronization control using a coaxial motor. [47] As described above, a plurality of patterns can be simultaneously processed on an

LGP by converting a continuous laser beam into a pulse beam by a mechanical construction, also generating a multiple laser beam by changing and each controlling a length of a pulse, and then concentrating the generated plurality of laser beams on a processed surface of the LGP by multi focus.

[48] While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

Claims

[1] A laser switching apparatus for Light Guide Panel (LGP) pattern formation, the apparatus comprising: one or more laser systems for outputting laser beams; a high speed rotary slit unit having a difference of an aperture ratio depending on a position and having one or more slits; and mirror units installed at front/rear ends of the high speed rotary slit unit, wherein continuous laser beams coming from the one or more laser systems pass through the high speed rotary slit unit via the mirror unit and then, are converted into a discontinuous laser pulse beam, and wherein, as the continuous laser beams coming from the one or more laser systems pass through a slit having a difference of an aperture ratio depending on a position by a movement of the mirror unit, a pulse length of the discontinuous laser pulse beam passing through the high speed rotary slit unit changes.

[2] A laser switching apparatus for Light Guide Panel (LGP) pattern formation, the apparatus comprising: one or more laser systems for outputting laser beams; a high speed rotary slit unit having a difference of an aperture ratio depending on a position and having one or more slits; and mirror units installed at front/rear ends of the high speed rotary slit unit, wherein continuous laser beams coming from the one or more laser systems pass through the high speed rotary slit unit via the mirror unit and then, are converted into a discontinuous laser pulse beam, wherein the continuous laser beams coming from the one or more laser systems each are incident with a constant arrangement of angles between respective slits of the high speed rotary slit unit and pass, and wherein, as the continuous laser beams coming from the one or more laser systems pass through a slit having a difference of an aperture ratio depending on a position by a movement of the mirror unit, a pulse length of the discontinuous laser pulse beam passing through the high speed rotary slit unit changes.

[3] The apparatus of claim 1 or 2, further comprising a mirror unit position control device for controlling a position of the mirror unit such that the pulse length of the laser beam forming a light guide pattern is variable depending on a process position on an LGP.

[4] The apparatus of claim 1 or 2, further comprising one or more beam splitters for splitting the laser beams coming from the one or more laser systems into two or more laser beams.

[5] The apparatus of claim 2, wherein, when being incident on the high speed rotary slit unit, the continuous laser beams coming from the one or more laser systems each are incident at a distance with half of an angle between slits when viewing from a rotation surface.

[6] The apparatus of claim 1 or 2, further comprising the high speed rotary slit unit more than one.