WO2008075885A1 - Apparatus and method for blacking liquid crystal using laser - Google Patents

Apparatus and method for blacking liquid crystal using laser Download PDF

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Publication number
WO2008075885A1
WO2008075885A1 PCT/KR2007/006643 KR2007006643W WO2008075885A1 WO 2008075885 A1 WO2008075885 A1 WO 2008075885A1 KR 2007006643 W KR2007006643 W KR 2007006643W WO 2008075885 A1 WO2008075885 A1 WO 2008075885A1
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WO
WIPO (PCT)
Prior art keywords
laser beam
laser
wavelength
liquid crystal
crystal panel
Prior art date
Application number
PCT/KR2007/006643
Other languages
French (fr)
Inventor
Il Ho Kim
Original Assignee
Cowin Dst Co., Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cowin Dst Co., Ltd filed Critical Cowin Dst Co., Ltd
Priority to JP2009542643A priority Critical patent/JP5235896B2/en
Priority to CN2007800472509A priority patent/CN101617262B/en
Publication of WO2008075885A1 publication Critical patent/WO2008075885A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1306—Details
    • G02F1/1309—Repairing; Testing
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1303—Apparatus specially adapted to the manufacture of LCDs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/50—Protective arrangements
    • G02F2201/506—Repairing, e.g. with redundant arrangement against defective part
    • G02F2201/508—Pseudo repairing, e.g. a defective part is brought into a condition in which it does not disturb the functioning of the device

Definitions

  • the present invention relates, in general, to the repair of defects in a liquid crystal panel and, more particularly, to a blacking apparatus and method, which eliminate light leakage caused by impurities present in liquid crystal cells .
  • a Liquid Crystal Display has recently attracted attention as a next generation and advanced display device, which has low power consumption, has excellent portability, is technology-intensive, and has high added value.
  • LCD Liquid Crystal Display
  • an active matrix-type LCD provided with switching devices capable of switching voltages to be applied to respective pixels, has attracted the most attention because of the high resolution and excellent moving image realization ability thereof.
  • a liquid crystal panel is manufactured such that a color filter substrate, which is an upper plate, and a Thin Film Transistor (TFT) array substrate, which is a lower plate, are laminated to be arranged opposite each other, and a liquid crystal layer having dielectric anisotropy is formed therebetween, and is driven such that voltages are applied to corresponding pixels by switching TFTs, attached to hundreds of thousands of pixels, through address lines required for pixel selection.
  • TFT Thin Film Transistor
  • TFT array substrate process a color filter substrate process, a liquid crystal cell process, etc. must be performed.
  • the TFT array substrate process is a process for forming gate lines, data lines, TFTs, and pixel electrodes on a glass substrate by repeating deposition, photolithography, and etching .
  • the color filter substrate process is a process for forming an Indium Tin Oxide (ITO) layer for a common electrode after manufacturing an RGB color filter layer, in which color filters are arranged in a predetermined sequence on a glass substrate, in which a black matrix is formed, and are configured to realize colors .
  • ITO Indium Tin Oxide
  • the liquid crystal cell process is a process for laminating the TFT array substrate and the color filter array substrate to maintain a certain gap between the substrates and injecting liquid crystal into the gap, thus forming a liquid crystal layer.
  • a test pattern is displayed on the screen of the liquid crystal panel, and the existence of defective pixels is detected, and thus operation of repairing the defective pixels is performed when the defective pixels are detected.
  • Defects in the liquid crystal panel can be classified as point defects, line defects, and display non-uniformity defects.
  • Point defects occur due to defects in TFT devices, pixel electrodes, and color filter lines.
  • Line defects occur due to an open in lines, a short between lines, the breakage of TFTs attributable to static electricity, and failures of connection to driving circuits .
  • Display non-uniformity may occur due to non-uniformity in cell thickness and liquid crystal alignment, distribution of TFTs in a specific place, and the relatively high time constant of lines .
  • Japanese Patent Laid-Open Publication No. 2006-72229 discloses technology for obstructing the arrangement characteristics of liquid crystal by radiating a laser beam onto an alignment layer and by damaging the alignment layer, thus decreasing the transmissivity of light to liquid crystals and eliminating light leakage.
  • a technology is problematic in that arrangement, characteristics cannot be perfectly eliminated, and a lot of time is required for a manufacturing process .
  • Korean Patent Laid-Open publication No. 2006- 65134 discloses technology for allowing a laser to radiate a laser beam onto the upper plate of a liquid crystal panel and hazing a required region to be opaque, thus eliminating light leakage.
  • a laser neodymium Yttrium Aluminum Garnet
  • YAG YAG
  • a diode a CO 2 laser, etc.
  • a laser having a nanosecond pulse width which is typically used, is employed.
  • a laser beam is radiated onto a substrate to be repaired, it may damage other regions of the substrate due to thermal diffusion, thus causing a liquid crystal panel itself to be defective.
  • an organic layer is hazed, since the area of a laser beam to be radiated for hazing processing is smaller than that of the organic layer, the time required for hazing processing increases, and, in addition, it is difficult to apply such a method to an industrial production line in which products are manufactured.
  • an object of the present invention is to provide a blacking apparatus and method, which can efficiently eliminate light leakage occurring in an LCD.
  • Another object of the present invention is to provide a blacking apparatus and method, which can decrease energy loss in laser beams by selectively using a laser beam having a wavelength region in which the absorption spectrum of a film is wide at the time of blacking.
  • a further object of the present invention is to provide a blacking apparatus and method, which can adjust the intensity of a laser beam and the radiation area of the laser beam, thus improving a blacking speed and adjusting a blacking thickness .
  • Yet another object of the present invention is to provide a blacking apparatus and method, which can use a scope (block shot) method or a scan method as a laser beam radiation method, thus improving a blacking speed and adjusting a blacking thickness .
  • the present invention provides an apparatus for blacking a liquid crystal panel, comprising a laser oscillation unit including a plurality of laser oscillators, beam adjustment means for adjusting intensity of a laser beam emitted from each laser oscillator, beam formation means for converting a profile of the laser beam, and a half mirror having characteristics of selectively transmitting or reflecting the laser beam; a beam delivery unit for switching a direction of the laser beam radiated from the laser oscillation unit; and a scan unit for adjusting the direction of the laser beam so that the laser beam is radiated onto a region desired to be blacked in the liquid crystal panel.
  • FIG. 1 is a diagram showing the construction of a blacking apparatus according to the present invention
  • FIG. 2 is a sectional view showing a liquid crystal panel in which impurities are adsorbed
  • FIG. 3 is a graph showing the transmission and reflection versus wavelength curves of a half mirror 110 for selectively transmitting or reflecting a laser beam in a laser oscillation unit;
  • FIG. 4 is a graph showing the transmission and reflection versus wavelength curves of a half mirror 111 for selectively transmitting or reflecting a laser beam in a laser oscillation unit;
  • FIG. 5 is an enlarged view of a scan lens 135 and an illumination light source 136;
  • FIG. 6 is a graph showing the reflection versus wavelength curves of the direction switching mirror of a beam delivery unit, and the X-axis Galvano mirror and the Y-axis Galvano mirror of an XY-axis movable scanner;
  • FIG. 7 is a graph showing the transmissivity of a film for respective wavelengths
  • FIG. 8 is a graph showing the transmissivity of a polarizing film for respective wavelengths
  • FIG. 9 is a graph showing the profile (shape) of a laser beam according to the implementation of the present invention,-
  • FIG. 10 is a view showing a process for processing blacking while controlling a focal distance according to the thickness of a film desired to be blacked;
  • FIG. 11 is a flowchart showing a blacking process
  • FIGS . 12 to 14 are schematic diagrams showing a blacking method according to the present invention.
  • FIG. 15 is a diagram showing the construction of a blacking apparatus according to another embodiment of the present invention .
  • second half mirror 120 beam delivery unit
  • Galvano mirror 135 scan lens
  • FIG. 1 is a diagram showing the construction of a blacking apparatus according to the present invention.
  • the blacking apparatus includes a laser oscillation unit 100, a beam delivery unit 120 for adjusting the traveling path of a laser beam radiated from the laser oscillation unit, and a scan unit 130 for adjusting the laser beam passed through the beam delivery unit 120 so that the laser beam can be radiated onto a target, such as a liquid crystal panel.
  • the laser oscillation unit 100 includes a plurality of laser oscillators 101, 102, and 103, laser beam adjustment means 104, 105, and 106 for adjusting the intensity, angle, or polarization of each laser beam, beam formation means 107, 108 and 109 for converting the profile of the laser beam into a flat top form, first and second half mirrors 110 and 111 for transmitting or reflecting the laser beam generated by the laser oscillator 101, 102 or 103, and a laser controller.
  • the laser oscillator 101, 102, or 103 can be implemented using a laser diode, a laser diode module, or a Diode Pumped Solid State (DPSS) laser light source. Further, the laser oscillators 101, 102, and 103 are preferably implemented using a red wavelength laser, a green wavelength laser, and a near infrared wavelength laser, respectively. According to the circumstances, instead of the near infrared wavelength laser, a blue wavelength laser can be used.
  • DPSS Diode Pumped Solid State
  • Each of the beam formation means 107, 108, and 109 includes a beam shaper for expanding a region that can be processed by a laser beam, and flattening the shape of the beam, and a beam slit for adjusting the size of a laser beam to be radiated according to the size of a region desired to be blacked, that is, a processing region.
  • the beam delivery unit 120 includes direction switching mirrors 121 and 122 for adjusting the traveling path of a laser beam. In this embodiment, two direction switching mirrors 121 and 122 are shown, but the number and locations of direction switching mirrors 121 and 122 can be variously changed according to the location of the laser oscillation unit 100 and the target 140.
  • FIG. 6 illustrates graphs showing the coating specifications of the direction switching mirrors 121 and 122 of the beam delivery unit.
  • FIG. 6 (a) shows that the mirrors are designed to reflect all wavelengths belonging to the entire region ranging from 350nm to llOOnm
  • FIG. 6 (b) shows that the mirrors are designed to reflect wavelengths only in specific regions in consideration of the wavelength of a radiated laser beam.
  • the scan unit 130 includes a Z-axis movable scanner 131 for varying the focal position of a laser beam, a CCD camera 133 for monitoring the laser beam radiated onto the target 140 in real time, a connection device 132 for connecting the Z- axis movable scanner 131 with the CCD camera 133, an XY-axis movable scanner 134 having an X-axis Galvano mirror 134-1 and a Y-axis Galvano mirror 134-2 for switching the direction of the laser beam, a scan lens 135 for condensing the laser beam, the direction of which has been switched by the movable scanner 134, and an illumination light source 136 for obtaining a more clear image.
  • the X-axis Galvano mirror 134-1 and the Y-axis Galvano mirror 134-2 are also coated to satisfy the beam delivery unit and the graph characteristics of FIG. 6.
  • the scan lens 135 functions to form an image through the radiation of the laser beam onto the liquid crystal panel so as to allow the CCD camera 133 to observe the image while condensing the laser beam.
  • FIG. 2 is a sectional view of a liquid crystal panel in which impurities are adsorbed.
  • the liquid crystal panel includes a first substrate 240, which includes an Indium Tin Oxide (ITO) layer 210, a color filter 220 made of organic material, a black matrix 230, an alignment layer (not shown) , a polarizing film 280, a protective film (not shown) , and a reflection prevention film (not shown) , and a second substrate 260 (b) , which includes a liquid crystal layer 250, a TFT layer (not shown) , an alignment layer (not shown) , a polarizing film (not shown) , etc .
  • ITO Indium Tin Oxide
  • impurities 270 including dust, organic material, and metal, are adsorbed.
  • the impurities 270 are adsorbed near the color filter 220, corresponding pixels are formed as defective pixels having bad luminance, which emit light having much higher brightness than the brightness of normal pixels at the time of driving the panel, that is, pixels causing so- called light leakage. Accordingly, such a panel is classified as a defective panel during a panel inspection process.
  • the pixels of the liquid crystal panel, in which impurities are adsorbed are processed to be blacked, and are prevented from being recognized by human beings, and thus the liquid crystal panel can be marketed.
  • the liquid crystal panel 140 is moved to the blacking apparatus through the driving control unit 150.
  • the driving control unit 150 of the present invention includes a panel stage (not shown) for loading or unloading the liquid crystal panel 140 by moving or rotating the liquid crystal panel 140 along the X, Y or Z axis and for moving the location of the defective pixel to a laser radiation location, a gantry stage (not shown) for enabling a laser beam to be radiated onto the location of the defective panel after the panel has been loaded, and a controller (not shown) for controlling the operation of the gantry stage and the panel stage.
  • the location of the defective pixel having bad luminance is detected by the scan unit 130.
  • the image captured by the CCD camera 133 is checked by the scan unit 130, and the accurate processing location is determined. This is monitored in real time by the CCD camera 133.
  • the laser oscillation unit 100 is operated.
  • the wavelength and intensity of a laser to be used vary according to the type of film to be blacked, and are selected by previously calculated software, and thus the selected laser emits a laser beam.
  • the laser oscillation unit 100 includes a red wavelength laser 101, a near infrared wavelength laser 102, and a green wavelength laser 103 so as to independently implement three types of wavelengths. Respective lasers 101, 102, and 103 are controlled by a laser-only controller 112. Instead of the near infrared wavelength laser, a blue wavelength laser can be used. Further, the laser oscillation unit 100 can use an ultraviolet wavelength laser or a near ultraviolet wavelength laser. Since the ultraviolet or near ultraviolet wavelength is absorbed in all regions regard Less of the R, G and B colors of the film of the liquid crystal panel, it can be selected regardless of the color of the film to be blacked.
  • a laser oscillator corresponding to the location of the defective pixel and having a wavelength region that is absorbed in the film to be blacked is selected.
  • a laser beam emitted from the selected laser oscillator is implemented such that the angle, intensity or polarization thereof is adjusted through the beam adjustment unit 104, 105, or 106, and such that the size thereof is adjusted to be suitable for the size of the location to be blacked at the same time that the profile thereof is converted into a flat form through the beam formation means 107, 108, or 109.
  • respective laser beams are combined into a single beam by two half mirrors 110 and 111.
  • the size of the laser beam can be adjusted while the energy distribution of the beam is made uniform. Accordingly, it is possible to black the region desired to be blacked by radiating a laser beam using a scan method, and it is also possible to black the region by increasing the size of a laser beam and by radiating the laser beam using a block shot method (a method of radiating a laser beam onto the region to be blacked at one time) .
  • the first half mirror 110 transmits a beam emitted from the red wavelength laser 101, and reflects a beam emitted from the near infrared wavelength laser 102
  • the second half mirror 111 transmits beams emitted from both the red wavelength laser 101 and the near infrared wavelength laser 102, and reflects a beam emitted from the green wavelength laser 103.
  • FIG. 3 is a graph showing the transmission and reflection versus wavelength curves of the first half mirror
  • FIG. 4 is a graph showing the transmission and reflection versus wavelength curves of the second half mirror
  • first half mirror 110 and the second half mirror 111 transmit or reflect laser beams having different wavelengths, they must be designed to be coated according to the wavelength characteristics of respective lasers.
  • the transmission and reflection characteristics of the first half mirror and the second half mirror can be variously changed according to the locations of laser oscillators and the characteristics of the half mirrors .
  • the beam adjustment means 104, 105, or 106 adjusts the emitted laser beam to a state suitable for blacking.
  • the laser beam may also damage components other than the film to be blacked, and thus the liquid crystal panel itself can be discarded as a completely defective panel .
  • the laser beam adjusted to a suitable state passes through the beam formation means 107, 108 or 109 and then passes through the half mirror 110 or 111.
  • the direction of the passed beam is switched by the beam delivery unit 120, and then the beam is incident on the Z-axis movable scanner 131.
  • the laser beam, condensed by the Z-axis movable scanner 131 and the scan lens 135, is radiated onto the liquid crystal panel 140.
  • a laser beam having a desired size and profile is moved by the XY-axis movable scanner 134, and thus the film is blacked.
  • a process for blacking the film constituting the liquid crystal panel 140 can be monitored in real time in such a way that a processed image viewed by the scan lens 135 is reflected from the image half mirror 132-1 in the camera connection device 132, and is transmitted to the CCD camera 133.
  • a relay lens (not shown) for enabling the magnification or reduction of an image as needed, or a cutoff filter (not shown) for cutting off a predetermined wavelength region so as to realize a clear image, can be inserted.
  • FIG. 5 is an enlarged view of the scan lens 135 and the illumination light source 136.
  • the illumination light source 136 includes a plurality of Lighting Emitting Diodes (LEDs) 137.
  • LEDs Lighting Emitting Diodes
  • a laser having a wavelength in which the absorption spectrum of the pixel is widest is used. Since the laser oscillators having the above construction can selectively emit respective laser beams for eliminating portions of respective pixels, pixels can be efficiently blacked.
  • the laser oscillation unit 100 preferably uses the red wavelength laser 101, the green wavelength laser 103, and the near infrared wavelength laser 102 at the time of attaching the polarizing film 280, and preferably uses the red wavelength laser 101, the green wavelength laser 103, and the blue wavelength laser 102-1 during a process performed before the polarizing film 280 is attached. That is, the blue wavelength laser 102-1 can be used instead of the near infrared wavelength laser depending on whether the polarizing film has been attached.
  • blacking is processed after the polarizing film 280 has been attached to the liquid crystal panel is more general, and blacking also be applied to a finished product . If processing is possible even after the polarizing film 280 has been attached, processing is naturally possible when no polarizing film 280 is present. However, as the wavelength is short, the absorbance of light into the material increases, and thus it is more efficient to use the blue wavelength laser 102-1 instead of the near infrared wavelength laser 102 when no polarizing film 280 is present.
  • FIG. 7 is a graph showing the transmissivity of the color filter of the liquid crystal panel .
  • FIG. 8 is a graph showing the transmissivity of a polarizing film for respective wavelengths.
  • a laser having a wavelength in which the absorption spectrum of the pixel is widest is used. Since the laser oscillators having the above construction can selectively emit respective laser beams for eliminating portions of respective pixels, pixels can be efficiently blacked. For example, when it is desired to black the blue (B) region of the color filter of the liquid crystal panel, the red wavelength laser is used, when it is desired to black the red (R) region, the green wavelength laser is used, and when it is desired to black the green (G) region, the near infrared wavelength laser is used, and thus blacking is performed.
  • light when it is desired to black the blue region of the color filter, light can be emitted using a laser having a wavelength above a yellow wavelength (equal to or greater than the yellow wavelength) or a wavelength below a near ultraviolet wavelength.
  • a laser having a wavelength above a yellow wavelength equal to or greater than the yellow wavelength
  • a wavelength below a near ultraviolet wavelength When it is desired to black the red region, light is emitted using a laser having a wavelength below a green wavelength or a wavelength above a near infrared wavelength.
  • light is emitted using a laser having a wavelength below a blue wavelength or a wavelength above a yellow wavelength.
  • the molecular connection of the organic material constituting the film is cut, so that the organic material is ablated while emitting radicals, clusters, electrons and photons, as well as plasma, including neutral atoms, molecules, and positive and negative ions, and thus blacking is performed.
  • FIG. 9 is a view showing the profile of a laser beam according to the implementation of the present invention.
  • a laser beam initially radiated from a laser oscillator has a Gaussian shape, in which energy is concentrated into a center portion.
  • a laser beam passes through the beam formation means 107, 108, or 109 (beam shaper or homogenizer) , it is converted into a beam having a flat top profile, in which the intensity of the laser beam is made uniform within a predetermined range and the size of the laser beam is increased.
  • the radiation area of the laser beam is also changed together with the profile of the beam.
  • the profile of the beam can be converted into a rectangular flat top shape 300 or a circular flat top shape 301.
  • the size and intensity of a laser beam to be radiated can be changed using the beam formation means and the beam adjustment means.
  • the blacking speed is increased by converting the size of a laser beam into a uniform size, so that the laser beam can be applied to a production line in which products are manufactured.
  • the laser beam converted into the rectangular flat top profile 300 or circular flat top profile 301 having a suitable intensity, can black portions of R, G, or B pixels, corresponding to a desired thickness, in a plurality of films constituting the liquid crystal panel using the Z-axis movable scanner.
  • FIG. 10 is a view schematically showing the Depth of Focus (DOF) of a laser beam designed to eliminate a portion of a film corresponding to a desired thickness and to black the film according to the thickness of the film to be blacked. That is, FIG. 10 illustrates a process for performing blacking by eliminating a portion of the film corresponding to a desired thickness and adjusting the focal distance.
  • DOE Depth of Focus
  • the pixel is blacked using the XY-axis movable scanner 134.
  • a blacking level is checked using the CCD camera. When the blacking level is insufficient, a relevant portion of the pixel is eliminated using the XY-axis movable scanner 134 after the location of the Z-axis movable scanner 131 is moved, and DOF is made identical to the portion corresponding to 20% of the thickness of the pixel to be blacked.
  • a desired blacking level is satisfied after repeated elimination is performed two to four times, blacking is terminated, and preparation for subsequent processing is conducted.
  • FIG. 11 is a flowchart showing a process for processing blacking while moving a focal distance according to the above procedure .
  • an initial laser beam is radiated at step SlO, blacking is performed only up to 10% at step S20, a blacking level is checked at step S30, whether the blacking level reaches a satisfactory level is determined at step S40, the process is terminated if the blacking is performed to a satisfactory level at step S60; otherwise, the focal distance is moved at step S50, and thus a blacking process is performed again by radiating a laser beam.
  • the DOF of the laser beam is calculated using the focal distance between the Z-axis movable scanner 131 and the scan lens 135, and the diameter of an incident beam within a range which does not exceed i ⁇ m.
  • Equation 5 can be derived from Equation 3 and Equation 4.
  • NA Numerical Aperture
  • a scan lens 135 having a large diameter is used, and a suitable optical system is designed to form a beam meeting the scan lens .
  • blacked thickness preferably corresponds to 20 to 40% of the thickness of the color filter so as to prevent the occurrence of light leakage within the range of the viewing angle of the liquid crystal panel, and, at a maximum thereof, does not exceed 90% of the thickness of the color filter.
  • blacking thickness can be adjusted according to the output energy of the laser.
  • FIGS. 12 to 14 illustrate a blacking method according to the present invention.
  • a scan method (FIG. 12) , a multi- block shot method (FIG. 13) , or a block shot method (FIG. 14) can be used.
  • the scan method is a method of radiating a laser beam onto a blacking region using a method of scanning the laser beam.
  • the block shot method is a method of radiating a laser beam onto a blacking region at one time, and is also called a scope method.
  • the multi-block shot method is a combination of the scan method and the block shot method, in which a laser beam is continuously radiated, like the scan method, while the laser beam is radiated using the block shot method.
  • the area of a single pixel is more than tens of thousands of ⁇ m 2 .
  • the size of a laser beam is changed to the size of a pixel by the beam formation means, and thus it corresponds to the area of the pixel of the liquid crystal panel, the entire area of a single pixel can be blacked through the radiation of a laser beam at one time (block shot) (refer to FIG. 14) .
  • the area of a single pixel is hundreds of thousands of ⁇ m 2 , and thus it is impossible to black the entire area of the film, corresponding to the area of the pixel, through the radiation of a laser beam at one time. Therefore, in this case, it is preferable to use a scan method (FIG. 12) or a multi-block shot method (FIG. 13) of radiating a laser beam while moving the laser beam in a ⁇ zi.qT.a.q form over the entire surface of the film.
  • FIG. 15 is a diagram showing the construction of a blacking apparatus according to another embodiment of the present invention.
  • the blacking apparatus includes a laser oscillation unit 100 including a plurality of laser oscillators, beam adjustment means for adjusting the intensity of a laser beam emitted from each laser oscillator, beam formation means for converting the profile of the laser beam, and half mirrors having characteristics of selectively transmitting or reflecting the laser beam; and an optical unit 400 for controlling the profile of the laser beam radiated from the laser oscillation unit 100, and focusing the laser beam for image capturing.
  • a repeated description of parts similar to those of FIG. 1 is omitted.
  • the optical means 400 includes a direction switching mirror 401 for leading each laser beam emitted from the laser oscillation unit 100 to a liquid crystal panel 140 to be blacked.
  • a direction switching mirror 401 for leading each laser beam emitted from the laser oscillation unit 100 to a liquid crystal panel 140 to be blacked.
  • a single direction switching mirror 401 is illustrated, but the number and locations of direction switching mirrors 401 can be variously changed according to the location of the laser oscillation unit 100 and the target 140. Since the direction switching mirror 401 must reflect laser beams having all wavelengths generated by the laser oscillation unit 100, it must be designed to be used in a wide wavelength region. Mirror coating specifications identical to those of FIG. 6 can be applied to the mirror 401.
  • the optical unit includes a focus sensor 415 and a focus lens 419 for automatically controlling the focus of a laser beam on a film desired to be blacked among a plurality of films, a slit 413 for adjusting the size of the laser beam, a slit illumination element 412 for checking the size and location of the slit, a slit half mirror 411 for reflecting light emitted from the slit illumination element 412, two half mirrors 414 and 417 for checking a defective pixel having bad luminance, a CCD camera 416, and a light source 418.
  • a focus sensor 415 and a focus lens 419 for automatically controlling the focus of a laser beam on a film desired to be blacked among a plurality of films
  • a slit 413 for adjusting the size of the laser beam
  • a slit illumination element 412 for checking the size and location of the slit
  • a slit half mirror 411 for reflecting light emitted from the slit illumination element 412
  • the focus of a laser beam is controlled to black a specific film among the plurality of films using the focus sensor and the focus lens.
  • the focus sensor 415 senses light that is radiated from the light source 418 onto the specific film among the plurality of films, is reflected from the film, and is incident on the focus sensor 415 through the splitter 414.
  • the focus sensor 415 vertically controls the focus lens 419, and transmits a clear image obtained through the focus lens to the CCD camera 416 in real time.
  • the laser oscillator 101, 102, or 103, suitable for blacking is operated according to the type of film.
  • the emitted laser beam is adjusted to a state suitable for blacking by the beam adjustment means 104, 105, or 106.
  • the size of the laser beam is adjusted while the laser beam passes through the slit 413.
  • the laser beam is radiated onto the liquid crystal panel 140 through the focus lens 419. The process for blacking the film constituting the liquid crystal panel 140 can be monitored in real time through the CCD camera 416.
  • the present invention is advantageous in that the wavelengths of laser beams are selectively used, thus reducing the output loss of a laser and increasing overall processing efficiency. Further, according to the present invention, a blacking speed can be increased using an XY-axis movable scanner, and a focal distance can be adjusted using a Z-axis movable scanner, so that films having various thicknesses can be blacked.
  • the profile and size of a beam to be radiated is changed using a beam formation means, so that the beam can be radiated using a scan method or a block shot method, thus improving a processing speed.

Abstract

The present invention relates to a blacking apparatus and method, which eliminate light leakage caused by impurities present in liquid crystal cells. The apparatus for blacking a liquid crystal panel according to the present invention includes a laser oscillation unit (100), a beam delivery unit (120), and a scan unit (130). The laser oscillation unit includes a plurality of laser oscillators, beam adjustment means for adjusting intensity of a laser beam emitted from each laser oscillator, beam formation means for converting a profile of the laser beam, and a half mirror having characteristics for selectively transmitting or reflecting the laser beam. The beam delivery unit switches a direction of the laser beam. The scan unit adjusts a direction of the laser beam so that the laser beam is radiated onto a region of the liquid crystal panel desired to be blacked.

Description

[DESCRIPTION]
[invention Title]
APPARATUS AMD METHOD FOR BLACKING LIQUID CRYSTAL USING LASER
[Technical Field]
The present invention relates, in general, to the repair of defects in a liquid crystal panel and, more particularly, to a blacking apparatus and method, which eliminate light leakage caused by impurities present in liquid crystal cells .
[Background Art]
A Liquid Crystal Display (LCD) has recently attracted attention as a next generation and advanced display device, which has low power consumption, has excellent portability, is technology-intensive, and has high added value. Of the types of LCD, an active matrix-type LCD, provided with switching devices capable of switching voltages to be applied to respective pixels, has attracted the most attention because of the high resolution and excellent moving image realization ability thereof. A liquid crystal panel is manufactured such that a color filter substrate, which is an upper plate, and a Thin Film Transistor (TFT) array substrate, which is a lower plate, are laminated to be arranged opposite each other, and a liquid crystal layer having dielectric anisotropy is formed therebetween, and is driven such that voltages are applied to corresponding pixels by switching TFTs, attached to hundreds of thousands of pixels, through address lines required for pixel selection. In order to manufacture such a liquid crystal panel, a
TFT array substrate process, a color filter substrate process, a liquid crystal cell process, etc. must be performed.
The TFT array substrate process is a process for forming gate lines, data lines, TFTs, and pixel electrodes on a glass substrate by repeating deposition, photolithography, and etching .
The color filter substrate process is a process for forming an Indium Tin Oxide (ITO) layer for a common electrode after manufacturing an RGB color filter layer, in which color filters are arranged in a predetermined sequence on a glass substrate, in which a black matrix is formed, and are configured to realize colors .
Further, the liquid crystal cell process is a process for laminating the TFT array substrate and the color filter array substrate to maintain a certain gap between the substrates and injecting liquid crystal into the gap, thus forming a liquid crystal layer.
During a process for inspecting such an LCD, a test pattern is displayed on the screen of the liquid crystal panel, and the existence of defective pixels is detected, and thus operation of repairing the defective pixels is performed when the defective pixels are detected. Defects in the liquid crystal panel can be classified as point defects, line defects, and display non-uniformity defects. Point defects occur due to defects in TFT devices, pixel electrodes, and color filter lines. Line defects occur due to an open in lines, a short between lines, the breakage of TFTs attributable to static electricity, and failures of connection to driving circuits . Display non-uniformity may occur due to non-uniformity in cell thickness and liquid crystal alignment, distribution of TFTs in a specific place, and the relatively high time constant of lines .
Typically, point defects and line defects, among these defects, are due to wiring failures. In the prior art, when an open line is detected, disconnected portions of the open line are merely connected, and when a shorted line is detected, corresponding lines are merely disconnected.
In addition to such defects, there is light leakage, in which a specific pixel emits very bright light . Such light leakage caused by a specific pixel can be easily visually observed due to the visual characteristics of a human being, and a panel in which light leakage is detected is classified as a defective panel. However, since such light leakage is not related to the electrical open or short of lines, it cannot be repaired using only technology for processing lines, as in the case of the prior art . During a process for manufacturing a liquid crystal panel, impurities, including dust, organic material, metal, etc., are adsorbed. When such impurities are adsorbed near a color filter, a corresponding pixel is formed as a defective pixel having bad luminance, which emits light having much higher brightness than the brightness of other normal pixels at the time of driving the panel, that is, a pixel causing so- called light leakage, and thus such a panel is classified as a defective panel during a panel inspection process. In order to eliminate impurities, research into a method using a laser has been conducted.
Japanese Patent Laid-Open Publication No. 2006-72229 discloses technology for obstructing the arrangement characteristics of liquid crystal by radiating a laser beam onto an alignment layer and by damaging the alignment layer, thus decreasing the transmissivity of light to liquid crystals and eliminating light leakage. However, such a technology is problematic in that arrangement, characteristics cannot be perfectly eliminated, and a lot of time is required for a manufacturing process .
Further, Korean Patent Laid-Open publication No. 2006- 65134 discloses technology for allowing a laser to radiate a laser beam onto the upper plate of a liquid crystal panel and hazing a required region to be opaque, thus eliminating light leakage. For such a laser, neodymium Yttrium Aluminum Garnet
(YAG), a diode, a CO2 laser, etc., are used. However, in this method, a laser having a nanosecond pulse width, which is typically used, is employed. When a laser beam is radiated onto a substrate to be repaired, it may damage other regions of the substrate due to thermal diffusion, thus causing a liquid crystal panel itself to be defective. In particular, when an organic layer is hazed, since the area of a laser beam to be radiated for hazing processing is smaller than that of the organic layer, the time required for hazing processing increases, and, in addition, it is difficult to apply such a method to an industrial production line in which products are manufactured.
[Disclosure] [Technical Problem] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a blacking apparatus and method, which can efficiently eliminate light leakage occurring in an LCD. Another object of the present invention is to provide a blacking apparatus and method, which can decrease energy loss in laser beams by selectively using a laser beam having a wavelength region in which the absorption spectrum of a film is wide at the time of blacking. A further object of the present invention is to provide a blacking apparatus and method, which can adjust the intensity of a laser beam and the radiation area of the laser beam, thus improving a blacking speed and adjusting a blacking thickness . Yet another object of the present invention is to provide a blacking apparatus and method, which can use a scope (block shot) method or a scan method as a laser beam radiation method, thus improving a blacking speed and adjusting a blacking thickness .
[Technical Solution] In order to accomplish the above objects, the present invention provides an apparatus for blacking a liquid crystal panel, comprising a laser oscillation unit including a plurality of laser oscillators, beam adjustment means for adjusting intensity of a laser beam emitted from each laser oscillator, beam formation means for converting a profile of the laser beam, and a half mirror having characteristics of selectively transmitting or reflecting the laser beam; a beam delivery unit for switching a direction of the laser beam radiated from the laser oscillation unit; and a scan unit for adjusting the direction of the laser beam so that the laser beam is radiated onto a region desired to be blacked in the liquid crystal panel.
[Description of Drawings]
FIG. 1 is a diagram showing the construction of a blacking apparatus according to the present invention;
FIG. 2 is a sectional view showing a liquid crystal panel in which impurities are adsorbed;
FIG. 3 is a graph showing the transmission and reflection versus wavelength curves of a half mirror 110 for selectively transmitting or reflecting a laser beam in a laser oscillation unit;
FIG. 4 is a graph showing the transmission and reflection versus wavelength curves of a half mirror 111 for selectively transmitting or reflecting a laser beam in a laser oscillation unit;
FIG. 5 is an enlarged view of a scan lens 135 and an illumination light source 136;
FIG. 6 is a graph showing the reflection versus wavelength curves of the direction switching mirror of a beam delivery unit, and the X-axis Galvano mirror and the Y-axis Galvano mirror of an XY-axis movable scanner;
FIG. 7 is a graph showing the transmissivity of a film for respective wavelengths;
FIG. 8 is a graph showing the transmissivity of a polarizing film for respective wavelengths;
FIG. 9 is a graph showing the profile (shape) of a laser beam according to the implementation of the present invention,-
FIG. 10 is a view showing a process for processing blacking while controlling a focal distance according to the thickness of a film desired to be blacked;
FIG. 11 is a flowchart showing a blacking process;
FIGS . 12 to 14 are schematic diagrams showing a blacking method according to the present invention; and
FIG. 15 is a diagram showing the construction of a blacking apparatus according to another embodiment of the present invention . description of reference characters of important parts> 100: laser oscillation unit
101: red wavelength laser
102 : near infrared wavelength laser
102-1: blue wavelength laser 103 : green wavelength laser
104, 105, 106: beam adjustment means
107, 108, 109: beam formation means
110: first half mirror
111 : second half mirror 120: beam delivery unit
121, 122: direction switching mirror
130: scan unit
131: Z-axis movable scanner
132 : camera connection device 133: CCD camera
132-1: image half mirror
134: XY-axis movable scanner
134-1: X-axis Galvano mirror
134-2: Y-axis Galvano mirror 135: scan lens
136: illumination light source
140: processing target
150: driving control unit
[Best Mode] Hereinafter, embodiments of the present invention wille described in detail with reference to the attached drawings .
FIG. 1 is a diagram showing the construction of a blacking apparatus according to the present invention. The blacking apparatus includes a laser oscillation unit 100, a beam delivery unit 120 for adjusting the traveling path of a laser beam radiated from the laser oscillation unit, and a scan unit 130 for adjusting the laser beam passed through the beam delivery unit 120 so that the laser beam can be radiated onto a target, such as a liquid crystal panel. The laser oscillation unit 100 includes a plurality of laser oscillators 101, 102, and 103, laser beam adjustment means 104, 105, and 106 for adjusting the intensity, angle, or polarization of each laser beam, beam formation means 107, 108 and 109 for converting the profile of the laser beam into a flat top form, first and second half mirrors 110 and 111 for transmitting or reflecting the laser beam generated by the laser oscillator 101, 102 or 103, and a laser controller.
The laser oscillator 101, 102, or 103 can be implemented using a laser diode, a laser diode module, or a Diode Pumped Solid State (DPSS) laser light source. Further, the laser oscillators 101, 102, and 103 are preferably implemented using a red wavelength laser, a green wavelength laser, and a near infrared wavelength laser, respectively. According to the circumstances, instead of the near infrared wavelength laser, a blue wavelength laser can be used.
Each of the beam formation means 107, 108, and 109 includes a beam shaper for expanding a region that can be processed by a laser beam, and flattening the shape of the beam, and a beam slit for adjusting the size of a laser beam to be radiated according to the size of a region desired to be blacked, that is, a processing region. The beam delivery unit 120 includes direction switching mirrors 121 and 122 for adjusting the traveling path of a laser beam. In this embodiment, two direction switching mirrors 121 and 122 are shown, but the number and locations of direction switching mirrors 121 and 122 can be variously changed according to the location of the laser oscillation unit 100 and the target 140. Since the beam delivery unit 120 must reflect laser beams having all wavelengths generated by the laser oscillation unit 100, it must be designed to be used in a wide wavelength region. FIG. 6 illustrates graphs showing the coating specifications of the direction switching mirrors 121 and 122 of the beam delivery unit. FIG. 6 (a) shows that the mirrors are designed to reflect all wavelengths belonging to the entire region ranging from 350nm to llOOnm, and FIG. 6 (b) shows that the mirrors are designed to reflect wavelengths only in specific regions in consideration of the wavelength of a radiated laser beam.
The scan unit 130 includes a Z-axis movable scanner 131 for varying the focal position of a laser beam, a CCD camera 133 for monitoring the laser beam radiated onto the target 140 in real time, a connection device 132 for connecting the Z- axis movable scanner 131 with the CCD camera 133, an XY-axis movable scanner 134 having an X-axis Galvano mirror 134-1 and a Y-axis Galvano mirror 134-2 for switching the direction of the laser beam, a scan lens 135 for condensing the laser beam, the direction of which has been switched by the movable scanner 134, and an illumination light source 136 for obtaining a more clear image. The X-axis Galvano mirror 134-1 and the Y-axis Galvano mirror 134-2 are also coated to satisfy the beam delivery unit and the graph characteristics of FIG. 6. The scan lens 135 functions to form an image through the radiation of the laser beam onto the liquid crystal panel so as to allow the CCD camera 133 to observe the image while condensing the laser beam.
FIG. 2 is a sectional view of a liquid crystal panel in which impurities are adsorbed. The liquid crystal panel includes a first substrate 240, which includes an Indium Tin Oxide (ITO) layer 210, a color filter 220 made of organic material, a black matrix 230, an alignment layer (not shown) , a polarizing film 280, a protective film (not shown) , and a reflection prevention film (not shown) , and a second substrate 260 (b) , which includes a liquid crystal layer 250, a TFT layer (not shown) , an alignment layer (not shown) , a polarizing film (not shown) , etc .
During a process for manufacturing the liquid crystal panel, impurities 270, including dust, organic material, and metal, are adsorbed. When the impurities 270 are adsorbed near the color filter 220, corresponding pixels are formed as defective pixels having bad luminance, which emit light having much higher brightness than the brightness of normal pixels at the time of driving the panel, that is, pixels causing so- called light leakage. Accordingly, such a panel is classified as a defective panel during a panel inspection process. However, through the above-described blacking apparatus, the pixels of the liquid crystal panel, in which impurities are adsorbed, are processed to be blacked, and are prevented from being recognized by human beings, and thus the liquid crystal panel can be marketed.
Hereinafter, a process for eliminating light leakage from a liquid crystal panel, that is, a blacking process, using the blacking apparatus having the above construction is described.
First, when a defective pixel having bad luminance, which causes light leakage, is detected in the liquid crystal panel 140 using inspection equipment, the liquid crystal panel 140 is moved to the blacking apparatus through the driving control unit 150.
The driving control unit 150 of the present invention includes a panel stage (not shown) for loading or unloading the liquid crystal panel 140 by moving or rotating the liquid crystal panel 140 along the X, Y or Z axis and for moving the location of the defective pixel to a laser radiation location, a gantry stage (not shown) for enabling a laser beam to be radiated onto the location of the defective panel after the panel has been loaded, and a controller (not shown) for controlling the operation of the gantry stage and the panel stage. In the liquid crystal panel 140 moved to the blacking apparatus by the control unit 150, the location of the defective pixel having bad luminance is detected by the scan unit 130.
When the location of the defective pixel having bad luminance is detected, the image captured by the CCD camera 133 is checked by the scan unit 130, and the accurate processing location is determined. This is monitored in real time by the CCD camera 133. When the location of the defective pixel, having bad luminance, and the film to be blacked are determined through the CCD camera 133, the laser oscillation unit 100 is operated.
The wavelength and intensity of a laser to be used vary according to the type of film to be blacked, and are selected by previously calculated software, and thus the selected laser emits a laser beam.
The laser oscillation unit 100 includes a red wavelength laser 101, a near infrared wavelength laser 102, and a green wavelength laser 103 so as to independently implement three types of wavelengths. Respective lasers 101, 102, and 103 are controlled by a laser-only controller 112. Instead of the near infrared wavelength laser, a blue wavelength laser can be used. Further, the laser oscillation unit 100 can use an ultraviolet wavelength laser or a near ultraviolet wavelength laser. Since the ultraviolet or near ultraviolet wavelength is absorbed in all regions regard Less of the R, G and B colors of the film of the liquid crystal panel, it can be selected regardless of the color of the film to be blacked. Hereinafter, a description will be made on the basis of the laser oscillation unit 100 provided with the red wavelength laser 101, the near infrared wavelength laser 102, and the green wavelength laser 103. A laser oscillator, corresponding to the location of the defective pixel and having a wavelength region that is absorbed in the film to be blacked is selected. A laser beam emitted from the selected laser oscillator is implemented such that the angle, intensity or polarization thereof is adjusted through the beam adjustment unit 104, 105, or 106, and such that the size thereof is adjusted to be suitable for the size of the location to be blacked at the same time that the profile thereof is converted into a flat form through the beam formation means 107, 108, or 109. Further, respective laser beams are combined into a single beam by two half mirrors 110 and 111. Through the above method, the size of the laser beam can be adjusted while the energy distribution of the beam is made uniform. Accordingly, it is possible to black the region desired to be blacked by radiating a laser beam using a scan method, and it is also possible to black the region by increasing the size of a laser beam and by radiating the laser beam using a block shot method (a method of radiating a laser beam onto the region to be blacked at one time) .
The first half mirror 110 transmits a beam emitted from the red wavelength laser 101, and reflects a beam emitted from the near infrared wavelength laser 102, and the second half mirror 111 transmits beams emitted from both the red wavelength laser 101 and the near infrared wavelength laser 102, and reflects a beam emitted from the green wavelength laser 103.
FIG. 3 is a graph showing the transmission and reflection versus wavelength curves of the first half mirror
110, and FIG. 4 is a graph showing the transmission and reflection versus wavelength curves of the second half mirror
111.
That is, since the first half mirror 110 and the second half mirror 111 transmit or reflect laser beams having different wavelengths, they must be designed to be coated according to the wavelength characteristics of respective lasers. The transmission and reflection characteristics of the first half mirror and the second half mirror can be variously changed according to the locations of laser oscillators and the characteristics of the half mirrors .
As described above, the beam adjustment means 104, 105, or 106 adjusts the emitted laser beam to a state suitable for blacking. When the intensity of an emitted laser beam is excessively high, the laser beam may also damage components other than the film to be blacked, and thus the liquid crystal panel itself can be discarded as a completely defective panel . The laser beam adjusted to a suitable state passes through the beam formation means 107, 108 or 109 and then passes through the half mirror 110 or 111. The direction of the passed beam is switched by the beam delivery unit 120, and then the beam is incident on the Z-axis movable scanner 131. The laser beam, condensed by the Z-axis movable scanner 131 and the scan lens 135, is radiated onto the liquid crystal panel 140. At the same time that the laser beam is radiated, a laser beam having a desired size and profile is moved by the XY-axis movable scanner 134, and thus the film is blacked.
A process for blacking the film constituting the liquid crystal panel 140 can be monitored in real time in such a way that a processed image viewed by the scan lens 135 is reflected from the image half mirror 132-1 in the camera connection device 132, and is transmitted to the CCD camera 133. In this case, in the camera connection unit 132, a relay lens (not shown) for enabling the magnification or reduction of an image as needed, or a cutoff filter (not shown) for cutting off a predetermined wavelength region so as to realize a clear image, can be inserted.
FIG. 5 is an enlarged view of the scan lens 135 and the illumination light source 136.
As shown in the drawing, the outer circumference of the scan lens 135 is enclosed by the illumination light source 136. The illumination light source 136 includes a plurality of Lighting Emitting Diodes (LEDs) 137. When light passes through the scan lens 135, and the image on the processing surface is transmitted to the CCD camera 133, the illumination light source 136 condenses the light at a size slightly larger than a processing region, thus functioning to compensate for an insufficient amount of light.
For example, in order to black one pixel of R, G, and B pixels of the color filter of the liquid crystal panel, a laser having a wavelength in which the absorption spectrum of the pixel is widest is used. Since the laser oscillators having the above construction can selectively emit respective laser beams for eliminating portions of respective pixels, pixels can be efficiently blacked.
Depending on whether a polarizing film 280 is placed on the surface of a color filter glass 260 (a) to be processed, the laser oscillation unit 100 preferably uses the red wavelength laser 101, the green wavelength laser 103, and the near infrared wavelength laser 102 at the time of attaching the polarizing film 280, and preferably uses the red wavelength laser 101, the green wavelength laser 103, and the blue wavelength laser 102-1 during a process performed before the polarizing film 280 is attached. That is, the blue wavelength laser 102-1 can be used instead of the near infrared wavelength laser depending on whether the polarizing film has been attached.
The case where blacking is processed after the polarizing film 280 has been attached to the liquid crystal panel is more general, and blacking also be applied to a finished product . If processing is possible even after the polarizing film 280 has been attached, processing is naturally possible when no polarizing film 280 is present. However, as the wavelength is short, the absorbance of light into the material increases, and thus it is more efficient to use the blue wavelength laser 102-1 instead of the near infrared wavelength laser 102 when no polarizing film 280 is present.
FIG. 7 is a graph showing the transmissivity of the color filter of the liquid crystal panel .
In order to black one of RGB pixels, the graph must be referred to. For example, if the green wavelength laser is used to black a region having a wavelength of 530nm, that is, a green wavelength region, transmission occurs, the beam from the green wavelength laser is transmitted, and thus blacking does not occur. FIG. 8 is a graph showing the transmissivity of a polarizing film for respective wavelengths.
It can be seen that, in a visible light region, 50% or less transmissivity is exhibited, and in an ultraviolet (UV) light region, no light is transmitted, and that transmissivity gradually increases toward the near infrared light region. Therefore, in order to black one of R, G, and B of the panel to which the polarizing film is attached, it is preferable to use the near infrared region laser.
For example, in order to black one of R, G, and B pixels of the color filter of the liquid crystal panel, a laser having a wavelength in which the absorption spectrum of the pixel is widest is used. Since the laser oscillators having the above construction can selectively emit respective laser beams for eliminating portions of respective pixels, pixels can be efficiently blacked. For example, when it is desired to black the blue (B) region of the color filter of the liquid crystal panel, the red wavelength laser is used, when it is desired to black the red (R) region, the green wavelength laser is used, and when it is desired to black the green (G) region, the near infrared wavelength laser is used, and thus blacking is performed. According to the circumstances, when it is desired to black the blue region of the color filter, light can be emitted using a laser having a wavelength above a yellow wavelength (equal to or greater than the yellow wavelength) or a wavelength below a near ultraviolet wavelength. When it is desired to black the red region, light is emitted using a laser having a wavelength below a green wavelength or a wavelength above a near infrared wavelength. When it is desired to black the green region, light is emitted using a laser having a wavelength below a blue wavelength or a wavelength above a yellow wavelength.
When a laser beam is radiated onto the film, the molecular connection of the organic material constituting the film is cut, so that the organic material is ablated while emitting radicals, clusters, electrons and photons, as well as plasma, including neutral atoms, molecules, and positive and negative ions, and thus blacking is performed.
The term 'ablation' means a phenomenon in which organic material becomes molecules or ions, as the connections between molecules constituting the organic material are dissociated. However, for this disassociation, there is a need to absorb energy having an energy level equal to or greater than that of the organic material . FIG. 9 is a view showing the profile of a laser beam according to the implementation of the present invention.
A laser beam initially radiated from a laser oscillator has a Gaussian shape, in which energy is concentrated into a center portion. As such a laser beam passes through the beam formation means 107, 108, or 109 (beam shaper or homogenizer) , it is converted into a beam having a flat top profile, in which the intensity of the laser beam is made uniform within a predetermined range and the size of the laser beam is increased. In this case, the radiation area of the laser beam is also changed together with the profile of the beam. At this time, the profile of the beam can be converted into a rectangular flat top shape 300 or a circular flat top shape 301. According to an embodiment of the present invention, the size and intensity of a laser beam to be radiated can be changed using the beam formation means and the beam adjustment means. As the radiation area of a laser beam is small, the time required to black all pixels increases . The blacking speed is increased by converting the size of a laser beam into a uniform size, so that the laser beam can be applied to a production line in which products are manufactured. The laser beam, converted into the rectangular flat top profile 300 or circular flat top profile 301 having a suitable intensity, can black portions of R, G, or B pixels, corresponding to a desired thickness, in a plurality of films constituting the liquid crystal panel using the Z-axis movable scanner. FIG. 10 is a view schematically showing the Depth of Focus (DOF) of a laser beam designed to eliminate a portion of a film corresponding to a desired thickness and to black the film according to the thickness of the film to be blacked. That is, FIG. 10 illustrates a process for performing blacking by eliminating a portion of the film corresponding to a desired thickness and adjusting the focal distance.
After DOF is caused to be identical to a portion corresponding to 10% of the thickness of a pixel to be blacked using the Z-axis movable scanner 131, the pixel is blacked using the XY-axis movable scanner 134. A blacking level is checked using the CCD camera. When the blacking level is insufficient, a relevant portion of the pixel is eliminated using the XY-axis movable scanner 134 after the location of the Z-axis movable scanner 131 is moved, and DOF is made identical to the portion corresponding to 20% of the thickness of the pixel to be blacked. When a desired blacking level is satisfied after repeated elimination is performed two to four times, blacking is terminated, and preparation for subsequent processing is conducted.
FIG. 11 is a flowchart showing a process for processing blacking while moving a focal distance according to the above procedure .
As shown in the drawing, an initial laser beam is radiated at step SlO, blacking is performed only up to 10% at step S20, a blacking level is checked at step S30, whether the blacking level reaches a satisfactory level is determined at step S40, the process is terminated if the blacking is performed to a satisfactory level at step S60; otherwise, the focal distance is moved at step S50, and thus a blacking process is performed again by radiating a laser beam. The DOF of the laser beam is calculated using the focal distance between the Z-axis movable scanner 131 and the scan lens 135, and the diameter of an incident beam within a range which does not exceed iμm.
[Equation 1] DOF = λl2(NA)2 [Equation 2] NA = nsinθ [Equation 3] f/#=\/2(NA) [Equation 4] f/#=efl/φ
The following Equation 5 can be derived from Equation 3 and Equation 4.
[Equation 5] NA =φ/2(efl)
In the above equations, a Numerical Aperture (NA) denotes an effective numeral aperture, λ (Lambda) denotes the wavelength of a laser, and efl denotes a focal distance.
As the diameter of an incident beam is large, and the wavelength of a laser is short, DOF decreases. It can be seen that, when the focal distance efl of the lens is short, NA increases , and DOF decreases . In the present invention, in order to realize DOF below IfM, a scan lens 135 having a large diameter is used, and a suitable optical system is designed to form a beam meeting the scan lens . In the case of the color filter 220 used in LCD, blacked thickness preferably corresponds to 20 to 40% of the thickness of the color filter so as to prevent the occurrence of light leakage within the range of the viewing angle of the liquid crystal panel, and, at a maximum thereof, does not exceed 90% of the thickness of the color filter. When blacking is performed at less than 20% of the thickness of the color filter, blacking itself may not block light leakage by 100%. When excessive blacking is performed at more than 90% of the thickness of the color filter, blacking may damage layers stacked below the color filter. Further, in order to black a film at a suitable thickness, laser energy plays an important role. That is, blacking thickness can be adjusted according to the output energy of the laser.
FIGS. 12 to 14 illustrate a blacking method according to the present invention.
When the film of a pixel in which light leakage occurred is blacked using a laser, the beam size of which is adjusted by the beam formation means, a scan method (FIG. 12) , a multi- block shot method (FIG. 13) , or a block shot method (FIG. 14) can be used. The scan method is a method of radiating a laser beam onto a blacking region using a method of scanning the laser beam. The block shot method is a method of radiating a laser beam onto a blacking region at one time, and is also called a scope method. The multi-block shot method is a combination of the scan method and the block shot method, in which a laser beam is continuously radiated, like the scan method, while the laser beam is radiated using the block shot method.
For example, in a liquid crystal panel having a size similar to that of a computer monitor, the area of a single pixel is more than tens of thousands of μm2. When the size of a laser beam is changed to the size of a pixel by the beam formation means, and thus it corresponds to the area of the pixel of the liquid crystal panel, the entire area of a single pixel can be blacked through the radiation of a laser beam at one time (block shot) (refer to FIG. 14) . As another example, in the case of a liquid crystal panel for a 30-inch large- scale TV, the area of a single pixel is hundreds of thousands of μm2 , and thus it is impossible to black the entire area of the film, corresponding to the area of the pixel, through the radiation of a laser beam at one time. Therefore, in this case, it is preferable to use a scan method (FIG. 12) or a multi-block shot method (FIG. 13) of radiating a laser beam while moving the laser beam in a ■zi.qT.a.q form over the entire surface of the film.
FIG. 15 is a diagram showing the construction of a blacking apparatus according to another embodiment of the present invention.
The blacking apparatus includes a laser oscillation unit 100 including a plurality of laser oscillators, beam adjustment means for adjusting the intensity of a laser beam emitted from each laser oscillator, beam formation means for converting the profile of the laser beam, and half mirrors having characteristics of selectively transmitting or reflecting the laser beam; and an optical unit 400 for controlling the profile of the laser beam radiated from the laser oscillation unit 100, and focusing the laser beam for image capturing. A repeated description of parts similar to those of FIG. 1 is omitted.
The optical means 400 includes a direction switching mirror 401 for leading each laser beam emitted from the laser oscillation unit 100 to a liquid crystal panel 140 to be blacked. In this embodiment, a single direction switching mirror 401 is illustrated, but the number and locations of direction switching mirrors 401 can be variously changed according to the location of the laser oscillation unit 100 and the target 140. Since the direction switching mirror 401 must reflect laser beams having all wavelengths generated by the laser oscillation unit 100, it must be designed to be used in a wide wavelength region. Mirror coating specifications identical to those of FIG. 6 can be applied to the mirror 401.
Further, the optical unit includes a focus sensor 415 and a focus lens 419 for automatically controlling the focus of a laser beam on a film desired to be blacked among a plurality of films, a slit 413 for adjusting the size of the laser beam, a slit illumination element 412 for checking the size and location of the slit, a slit half mirror 411 for reflecting light emitted from the slit illumination element 412, two half mirrors 414 and 417 for checking a defective pixel having bad luminance, a CCD camera 416, and a light source 418.
When the location of a defective pixel having bad luminance is detected, the focus of a laser beam is controlled to black a specific film among the plurality of films using the focus sensor and the focus lens. The focus sensor 415 senses light that is radiated from the light source 418 onto the specific film among the plurality of films, is reflected from the film, and is incident on the focus sensor 415 through the splitter 414. When an image is not focused, the focus sensor 415 vertically controls the focus lens 419, and transmits a clear image obtained through the focus lens to the CCD camera 416 in real time. When the location of the defective pixel having bad luminance and the film to be blacked are determined through the CCD camera 416, the laser oscillator 101, 102, or 103, suitable for blacking, is operated according to the type of film. The emitted laser beam is adjusted to a state suitable for blacking by the beam adjustment means 104, 105, or 106. After the laser beam adjusted to the suitable state passes through the beam formation means 107, 108, or 109, the size of the laser beam is adjusted while the laser beam passes through the slit 413. The laser beam is radiated onto the liquid crystal panel 140 through the focus lens 419. The process for blacking the film constituting the liquid crystal panel 140 can be monitored in real time through the CCD camera 416.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that the present invention is not limited to the embodiments, and that various modifications and variations are possible, without departing from the scope and spirit of the invention.
[industrial Applicability]
The present invention is advantageous in that the wavelengths of laser beams are selectively used, thus reducing the output loss of a laser and increasing overall processing efficiency. Further, according to the present invention, a blacking speed can be increased using an XY-axis movable scanner, and a focal distance can be adjusted using a Z-axis movable scanner, so that films having various thicknesses can be blacked.
In addition, according to the present invention, the profile and size of a beam to be radiated is changed using a beam formation means, so that the beam can be radiated using a scan method or a block shot method, thus improving a processing speed.

Claims

[CLAIMS]
[Claim l]
An apparatus for blacking a liquid crystal panel, comprising: a laser oscillation unit including a plurality of laser oscillators, beam adjustment means for adjusting intensity of a laser beam emitted from each laser oscillator, beam formation means for converting a profile of the laser beam, and a half mirror having characteristics of selectively transmitting or reflecting the laser beam,- a beam delivery unit for switching a direction of the laser beam radiated from the laser oscillation unit; and a scan unit for adjusting the direction of the laser beam so that the laser beam is radiated onto a region desired to be blacked in the liquid crystal panel .
[Claim 2]
The apparatus according to claim 1, wherein the laser oscillation unit includes laser oscillators for emitting a laser beam having a red wavelength, a laser beam having a green wavelength, and a laser beam having a near infrared wavelength.
[Claim 3]
The apparatus according to claim 2, wherein the laser oscillation unit emits a laser beam having a blue wavelength instead of the laser beam having the near infrared wavelength. [Claim 4]
The apparatus according to claim 1, wherein the laser oscillation unit emits a laser beam having an ultraviolet (UV) wavelength or a near ultraviolet (NUV) wavelength.
[Claim 5]
The apparatus according to claim 1, wherein the laser oscillation unit selectively emits a laser beam having a wavelength region in which an absorption spectrum of a color filter desired to be blacked is wide .
[Claim 6]
The apparatus according to claim 1, wherein the laser oscillation unit is configured to emit a laser beam having a wavelength above a yellow wavelength or a wavelength below a near ultraviolet wavelength when a blue (B) region of a color filter of the liquid crystal panel is desired to be blacked, to emit a laser beam having wavelength below a green wavelength or a wavelength above a near infrared wavelength when a red (R) region of the color filter is desired to be blacked, and to emit a laser beam having a wavelength below a blue wavelength or a wavelength above the yellow wavelength when a green (G) region of the color filter is desired to be blacked.
[Claim 7] The apparatus according to claim 1, wherein the laser oscillation unit emits a laser beam having a wavelength above a near infrared wavelength when a polarizing film is attached to the color filter of the liquid crystal panel.
[Claim 8]
The apparatus according to claim 1, wherein each of the laser oscillators is one of a laser diode, a laser diode module, and a Diode Pumped Solid State (DPSS) laser.
[Claim 9] The apparatus according to claim 1, wherein each of the laser oscillators is a continuous wave laser or a pulse laser.
[Claim 10]
The apparatus according to claim 1, wherein the beam adjustment means adjusts an angle and a polarizing state of the laser beam together with the intensity of the laser beam.
[Claim ll]
The apparatus according to claim 1, wherein the beam formation means comprises a beam shaper for converting a laser beam having a Gaussian distribution into a rectangular flat top form or a circular flat top form, and a beam slit for adjusting a size of the laser beam.
[Claim 12] The apparatus according to claim 1, wherein the half mirror comprises a first half mirror for transmitting a laser beam having a red wavelength and reflecting a laser beam having a near infrared wavelength, and a second half mirror for transmitting a laser beam having a red wavelength and reflecting a laser beam having a green wavelength.
[Claim 13]
The apparatus according to claim 1, wherein the beam delivery unit comprises a reflective mirror for reflecting a laser beam that is emitted from the laser oscillation unit and that has wavelengths belonging to a region ranging from 350nm to l,100nm.
[Claim 14]
The apparatus according to claim 13, wherein the reflective mirror is designed to reflect only a wavelength region of the laser beam radiated from the laser oscillation unit .
[Claim 15]
The apparatus according to claim 1, wherein the scan unit comprises a Z-axis movable scanner for adjusting a focal distance of the laser beam and an XY-axis movable scanner for vertically or horizontally adjusting the direction of the laser beam. [Claim 16]
The apparatus according to claim 15, wherein the scan unit further comprises a Charge Coupled Device (CCD) camera for monitoring whether the laser beam is accurately radiated onto a desired location of the liquid crystal panel, a camera connection device disposed between the Z-axis movable scanner and the XY-axis movable scanner and configured to transmit an image to the CCD camera, and a scan lens for condensing the laser beam so as to radiate the laser beam, passed through the scanners, onto the liquid crystal panel and forming an image radiated onto the liquid crystal panel .
[Claim 17]
The apparatus according to claim 15, wherein the XY-axis movable scanner comprises an X-axis Galvano mirror and a Y- axis Galvano mirror for converting the direction of the laser beam, the Galvano mirrors reflecting a laser beam that is emitted from the laser oscillation unit and has wavelengths ranging from 350nm to l,100nm.
[Claim 18] The apparatus according to claim 16, wherein the scan lens is implemented using a telecentric lens for forming a perpendicular beam at all locations .
[Claim 19]
The apparatus according to claim 16, wherein the CCD camera determines a location of a processing target and realizes a processing image in real time.
[Claim 2θ]
The apparatus according to claim 16, wherein the camera connection device comprises an image half mirror, a ratio of transmissivity to reflexibility of which is 50:50 in a visible light region.
[Claim 21]
The apparatus according to claim 1, further comprising: a panel stage for loading or unloading the liquid crystal panel, and moving or rotating the liquid crystal panel along an x, y or z axis; a gantry stage for moving the laser beam along the x, y or z axis so that the laser beam can be radiated onto a defective pixel of the liquid crystal panel; and a controller for controlling operation of both the gantry stage and the panel stage .
[Claim 22]
An apparatus for blacking a liquid crystal panel, the apparatus including a laser oscillation unit and an optical unit for processing a shape of a laser beam radiated from the laser oscillation unit and condensing the laser beam for realtime image capturing, wherein: the laser oscillation unit comprises a plurality of laser oscillators, beam adjustment means for adjusting intensity of a laser beam emitted from each laser oscillator, beam formation means for converting a profile of the laser beam, and a half mirror having characteristics of selectively transmitting or reflecting the laser beam, and the laser oscillators selectively radiate laser beams according to an absorption spectrum of a region to be blacked.
[Claim 23]
A method of blacking a liquid crystal panel, comprising the steps of: emitting a laser beam corresponding to a wavelength in which an absorption spectrum of a region desired to be blacked is wide,- adjusting intensity of the Laser beam,- converting a profile of the laser beam; adjusting a focal distance of the laser beam; and radiating the laser beam, thus blacking the region.
[Claim 24]
The method according to claim 23, wherein the step of emitting the laser beam is performed to emit any one of a laser beam having a red wavelength, a laser beam having a blue wavelength, a laser beam having a near infrared wavelength, a laser beam having an ultraviolet wavelength, and a laser beam having a near ultraviolet wavelength. [Claim 25]
The method according to claim 23, wherein the step of emitting the laser beam is performed to emit a laser beam having a red wavelength when a blue (B) region of a color filter of the liquid crystal panel is desired to be blacked, to emit a laser beam having a green wavelength when a red (R) region of the color filter is desired to be blacked, and to emit a laser beam having a near infrared wavelength when a green (G) region of the color filter is desired to be blacked.
[Claim 26]
The method according to claim 23, wherein the step of adjusting the intensity of the laser beam is performed to adjust an angle and polarizing state of the laser beam together with the intensity of the laser beam.
[Claim 27]
The method according to claim 23, wherein the step of converting the profile of the laser beam is performed to convert the profile of the laser beam into a flat top form and to adjust a size of the laser beam.
[Claim 28]
The method according to claim 23, wherein the step of adjusting the intensity of the laser beam is performed such that sizes of respective laser beams are identical to each other, and thus sizes of focuses on a processing region are identical to each other.
[Claim 29]
The method according to claim 23 , wherein the step of adjusting the intensity of the laser beam and the step of adjusting the focal distance are performed to adjust the intensity and focal distance of the laser beam so that a portion of a film corresponding to 20% to 90% of a thickness of the film is blacked.
[Claim 3θ] The method according to claim 23, wherein the step of radiating the laser beam is performed to sequentially radiate the laser beam while adjusting a focal distance of the laser beam.
[Claim 3l] The method according to claim 23, wherein the step of radiating the laser beam is performed using any one of a scan method, a block scan method, and a block shot method.
PCT/KR2007/006643 2006-12-19 2007-12-18 Apparatus and method for blacking liquid crystal using laser WO2008075885A1 (en)

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JP2010513979A (en) 2010-04-30
TW200827821A (en) 2008-07-01

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