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WO2004088399A1 - Lcd cell edge inspection apparatus and method thereof - Google Patents

Lcd cell edge inspection apparatus and method thereof Download PDF

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Publication number
WO2004088399A1
WO2004088399A1 PCT/KR2004/000748 KR2004000748W WO2004088399A1 WO 2004088399 A1 WO2004088399 A1 WO 2004088399A1 KR 2004000748 W KR2004000748 W KR 2004000748W WO 2004088399 A1 WO2004088399 A1 WO 2004088399A1
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WO
WIPO (PCT)
Prior art keywords
lcd cell
edge
signal
align
vision controller
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/KR2004/000748
Other languages
French (fr)
Inventor
Sun Yeol Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HITS CO Ltd
Original Assignee
HITS 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
Priority claimed from KR1020030020296A external-priority patent/KR100418356B1/en
Priority claimed from KR1020030020297A external-priority patent/KR100418357B1/en
Application filed by HITS CO Ltd filed Critical HITS CO Ltd
Publication of WO2004088399A1 publication Critical patent/WO2004088399A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects
    • 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
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N2021/9513—Liquid crystal panels

Definitions

  • the present invention relates to an LCD (liquid crystal display) panel
  • a TFT (thin film transistor) substrate and a color filter substrate are manufactured, they are combined
  • respective unit panels represent LCD cells.
  • the grinding process is executed on
  • ground edges are inspected when the four edges of the LCD cell are ground.
  • the above-described method has a demerit for an operator
  • FIG. 1 shows a flowchart for inspecting edges of an LCD cell
  • FIG. 2 shows a device for inspecting edges of an LCD cell according
  • FIGs. 3 to 5 show a perspective view of the LCD cell shown in FIG.
  • FIG. 6 shows a magnified plane view of the LCD cell shown in FIG.
  • FIG. 7 shows a device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention.
  • FIGs. 8 to 1 1 show a side view and a plane view of the LCD cell according to a second preferred embodiment of the present invention
  • FIG. 12 shows a modified device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention.
  • FIG. 13 shows a flowchart for inspecting edges of an LCD cell
  • a method for inspecting an edge of an LCD cell by using a line scan camera comprises: inputting a predetermined reference value for determining a defect state of the LCD cell to a vision controller, and establishing an initial position of the line scan camera; allowing the vision controller to generate an align control signal and transmit it to a PLC controller, and allowing the PLC controller to drive an inspection table according to the transmitted align control signal and align the LCD cell moved to the inspection table, when the reference value is input to the vision controller and the initial position of the line scan camera is established; allowing the vision controller to use an align mark formed on the LCD cell and determine whether the alignment is correct, when the LCD cell moved to the inspection table is aligned; allowing the vision controller to drive the line scan camera, photograph the edge of the LCD cell, and obtain an edge image, when the LCD cell is correctly aligned; allowing the vision controller to use the obtained edge image, inspect whether a case in which a difference between an actual distance value of from the edge of the LCD cell to a reference line and the
  • a device for inspecting an edge of an LCD cell comprises: a camera illumination generator for receiving a camera illumination control signal and generating a camera illumination driving signal for driving the illumination used for photographing the LCD cell; a bottom illumination generator for receiving a bottom illumination control signal to generate a bottom illumination driving signal for generating the illumination used for photographing the edge of the LCD cell, and generating the illumination through a measuring illuminator; a first camera for receiving the camera illumination driving signal, a first photographing signal, and a second photographing signal respectively, photographing the align mark formed on the LCD cell when the first photographing signal is received, and photographing the edge of the LCD cell, generating a first align mark image signal and an edge image signal, and outputting them when the second photographing signal is received; a second camera for receiving the camera illumination driving signal and first photographing signal respectively, photographing the align marks formed on the LCD cell, generating a second align mark image signal, and outputting it when the second photographing signal is received; a second camera for receiving the camera illumination driving signal and first photographing signal respectively
  • a method for inspecting an edge of an LCD cell comprises: establishing initial positions of a first camera and a second camera, and allowing a vision controller to receive information on the LCD cell from a PLC controller; determining whether a measure signal for measuring the LCD cell is provided to the vision controller from the PLC controller in a measuring standby state when the information on the LCD cell is input to the vision controller; allowing the vision controller to transmit a signal for moving the LCD cell to the PLC controller in order to move the ground LCD cell to an inspection table when the measure signal is provided to the vision controller; photographing an edge of the LCD cell to calculate a ground amount, and transmitting the calculated ground amount to the PLC controller or transmitting the photographed edge image signal to a display of the vision controller when the signal for moving the LCD cell is transmitted and the LCD cell is moved to the inspection table; allowing the vision controller to determine whether a predetermined number of predefined test points are measured when the edge image signal of
  • FIG. 1 shows a flowchart of a method for inspecting edges of an LCD cell according to a first preferred embodiment of the present invention
  • FIG. 2 shows a device for inspecting edges of an LCD cell according to a first preferred embodiment of the present invention.
  • the method for inspecting edges of an LCD cell comprises: inputting a predetermined reference value for determining whether defects are generated on the edges of the LCD cell 10 to a vision controller 70, and establishing an initial position of a line scan camera 40 in step S10; allowing the vision controller 70 to generate an align control signal and transmit it to a PLC (programmable logic controller) controller 60, and allowing the PLC controller 60 to drive an inspection table 61 according to the transmitted align control signal and align the LCD cell 10 moved to the inspection table 61 in step S20 when the predetermined reference value is input to the vision controller 70 and the initial position of the line scan camera 40 is established; allowing the vision controller 70 to determine whether the alignment is correct by using an align mark 11d formed on the LCD cell 10 in step S30 when the LCD cell 10 moved to the inspection table 61 is aligned; allowing the vision controller 70 to drive the line scan camera 40 to photograph edges of the LCD cell 10 and obtain an edge image in step S40 when the LCD cell 10 is correctly aligned; allowing the vision
  • the device for inspecting the edges of the LCD cell comprises a bottom illuminator 20, a first bottom illuminator 30, a line scan camera 40, a first line scan camera 50, a PLC controller 60, and a vision controller 70.
  • the bottom illuminator 20 and the first bottom illuminator 30 are provided to respectively face the line scan camera 40 and the first line scan camera 50, and they generate light when photographing the edges of the LCD cell 10 installed in the inspection table 61 with the line scan camera 40 and the first line scan camera 50.
  • the PLC controller 60 shifts or rotates the LCD cell 10 installed in the inspection table 61 in the directions of the X axis, the Y axis, and the rotation axis of the inspection table 61 in order to arrange the LCD cell 10.
  • the configuration of the inspection table 61 is briefly described since a general table which can be driven in the directions of the X axis, the Y axis, and the rotation axis is generally known.
  • the vision controller 70 for transmitting and receiving information to/from the PLC controller 60 which drives the inspection table 60, and for controlling the bottom illuminator 20, the first bottom illuminator 30, the line scan camera 40, and the first line scan camera 50 comprises a PC (personal computer) 71 , an I/O (input/output) unit 72, a grabber 73, a display 74, and a keyboard 75.
  • the grabber 73 obtains the edge images from the first and second line scan cameras 40 and 50 respectively, and transmits them to the PC 71.
  • the I/O unit 72 manages inputs and outputs.
  • the keyboard 75 is used for the operator to input information and initial setting values to the vision controller 70.
  • the display 74 displays obtained results of the edge images and other results to the operator.
  • the edge image displayed on the display 74 of the vision controller 70 is generated by photographing the edges of the LCD cell 10.
  • the TFT substrate 11 and the color filter substrate 12 are manufactured as shown in FIG. 3, they are adhered to face with each other as shown in FIG. 4, and they are separated into the LCD cells 10 through the scribing and breaking process as shown in FIG. 5.
  • the edge inspection method for inspecting the defect phenomenon generated on the edges of the separated LCD cells 10 uses one bottom illuminator 20 and one line scan camera 40, differing from the inspection device shown in FIG. 2. Noting this point, as shown in FIGs. 1 and 2, the edge inspection method according to the first preferred embodiment inputs a predetermined reference value for determining whether the edge of the LCD cell 10 has a defect, to the vision controller 70, and establishes the initial position of the line scan camera 40 in step S10.
  • the vision controller 70 When the predetermined reference value is input to the vision controller 70, and the initial position of the line scan camera 40 is established, the vision controller 70 generates an align control signal, and transmits it to the PLC controller 60, and the PLC controller 60 drives an inspection table 61 according to the transmitted align control signal to align the moved LCD cells 10 in step S20.
  • the vision controller 70 uses the align mark 11d formed on the LCD cells 10 to determine whether they are correctly aligned in step S30.
  • the vision controller 70 photographs the image of the cross-type align mark 11d, checks whether the photographed image corresponds to the normal align mark 11d to calculate a compensated amount according to a rotated amount of the inspection table 61 , and uses an extended central line 11 b which is passed through a plurality of align marks 11d to calculate a compensated amount for moving in the directions of the X axis and the Y axis of the inspection table 61.
  • the compensated amount is transmitted to the PLC controller
  • the PLC controller 60 drives the inspection table 61 according to the
  • the vision controller 70 photographs one align mark 11d, moves along a straight line, photographs another facing align mark 11d, and aligns them
  • the first line scan camera 50 are provided, they are fixed on the straight line,
  • the vision controller 70 obtains a plurality of align marks 1 1d and aligns
  • the vision controller 70 drives the line scan camera 40 to photograph the edge of the LCD cell 10 to obtain an edge image in step S40.
  • the vision controller 70 drives the bottom illuminator 20 to generate illumination light, and drives the line scan camera to photograph the edge of the LCD cell 10. In this instance, the photographing speed on the edge of the LCD cell 10 can be improved in the
  • the vision controller 70 uses a reference value to determine whether a defect has occurred in the obtained edge image in step S50.
  • the vision controller 70 uses the edge image to calculate the edge image.
  • step S51 In order
  • the vision controller 70 uses the obtained edge image to inspect whether a case in which a difference between the actual distance value p of from the edge of the LCD cell 10 to a reference line and the reference value m is greater than a predetermined first distance value has been generated. When it is found that "(p-m) > first
  • the damaged pattern phenomenon d has been generated on the pattern of the LCD cell 10. That is, it is determined that the pattern damage d has been generated when an error allowance range is established to be the first distance value and damage which exceeds the error allowance range is generated.
  • the vision controller 70 uses the edge image to determine whether burrs ("a" and "b” in FIG. 6) have been generated on the edges of the LCD cell 10 in step S52.
  • the burr "a" represents
  • the vision controller 70 uses the obtained edge image to inspect whether a case that a difference between the actual distance values n and k of from the edge of the LCD cell 10 to the reference line and the reference value m is greater than a predetermined second distance value has been generated. When it is found that "
  • burrs "a” and "b” have been generated when an error allowance range is established to be the second distance value and damage which exceeds the error allowance range is generated.
  • the reference value m for determining the defect state of the pattern damage d and the burrs "a" and "b” in the previous steps S51 and S52 is calculated by using the distance m to the edge of the normal LCD cell 20, that is, the distance between the extended central line 11b of the two align marks 11d formed on the LCD cell 10 and the reference line 11c which is provided in parallel with the extended central line 11b and at a predetermined distance from the edge of the LCD cell 10.
  • the vision controller 70 determines it to be pattern damage d, and when a difference between the distances n and k and the reference value m is greater than a predetermined second distance value, the vision controller 70 determines that the burrs "a" and "b" have been generated.
  • the vision controller 70 uses the edge image to check whether a breakage phenomenon (the reference numeral c shown in FIG. 6) is generated on the edge of the LCD cell 10 and whether a predetermined brightness value is greater than a reference value, and thereby determine whether the breakage phenomenon c has been generated in step S53.
  • a breakage phenomenon the reference numeral c shown in FIG. 6
  • the brightness reference value for determining the defect state of the breakage phenomenon c is established by using the brightness of the normal edge image obtained by using the line scan camera 40, and the vision controller 70 determines that the breakage phenomenon c has been generated on the edge of the LCD cell 10 when the difference between the established brightness reference value and the measured edge image is greater than a predetermined brightness value.
  • the vision controller 70 When no defect is shown to be generated on the edge image of the LCD cell 10 through the above-described process, the vision controller 70 generates goodness information of the edge of the LCD cell 10 and outputs it in step S60, and when a defect is shown to be generated on the edge image, the vision controller 70 generates badness information of the edge of the LCD cell 10 and outputs it in step S70. That is, the vision controller 70 displays goodness information and badness information to the display 74 or transmits the same to the PLC controller 60 in the respective cases to be ready for the subsequent inspection process.
  • All the defects which can be generated on the edges can be easily inspected by establishing a predetermined reference line on the edge of the LCD cell, using a line scan camera to sequentially photograph the edge, and processing them as images as described above.
  • FIGs. 7 to 13 a device for inspecting edges of an LCD panel according to a second preferred embodiment of the present invention will be described.
  • FIG. 7 shows a device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention
  • FIGs. 8 to 11 show a side view and a plane view of the LCD cell according to a second preferred embodiment of the present invention.
  • the device for inspecting edges of an LCD cell comprises a PLC controller 110, a camera illumination generator 120, a bottom illumination generator 130, a first camera CAM1 , a second camera CAM2, and a vision controller 150.
  • the camera illumination generator 120 receives a camera illumination control signal and generates a camera illumination driving signal for driving illumination for photographing the LCD cell.
  • the bottom illumination generator 130 receives a bottom illumination control signal, generates a bottom illumination driving signal for generating illumination for photographing the edge of the LCD cell 160, and generates the illumination through a bottom illuminator 131.
  • the LCD cell 160 includes a TFT substrate 161 and a color filter substrate 162 as shown in FIG. 9.
  • the first camera CAM1 receives the camera illumination driving signal output by the camera illumination generator 120, generates illumination according to the camera illumination driving signal, and when receiving a first photographing signal according to the photographing signal and a second photographing signal respectively output by the vision controller 150, the first camera CAM1 photographs an align mark (shown as A in FIG. 8) formed on the LCD cell 160, photographs the edge of the LCD cell 160 when receiving the second photographing signal, generates a first align mark image signal and an edge image signal, and outputs them.
  • an align mark shown as A in FIG. 8
  • the first camera CAM1 photographs an align mark A for aligning the LCE cell 160
  • the second camera CAM2 concurrently photographs an align mark A.
  • the second camera CAM2 photographs an align mark A which faces the align mark A photographed by the first camera CAM1 on the straight line as shown in FIG. 8.
  • the second camera CAM2 receives the camera illumination control signal from the camera illumination generator 120, generates illumination according to the received camera illumination control signal, receives the first photographing signal from the vision controller 150, photographs the align mark A formed on the LCD cell, generates a second align mark image signal, and outputs it.
  • the first and second cameras CAM1 and CAM2 photograph two align marks A which face with each other on the straight line.
  • the first camera CAM1 photographs the align mark A provided on the top right of the drawing
  • the second camera CAM2 photographs the align mark A provided on the top left thereof
  • the LCD cell 160 is aligned through the vision controller 150.
  • the vision controller 150 receives a measure signal from the PLC controller 110, generates a camera illumination control signal, a bottom illumination control signal, a first photographing signal, and a second photographing signal for photographing the LCD cell 160 at intervals of a predetermined time, and outputs them.
  • the intervals of predetermined times represent the time intervals for moving the LCD cell 160 according to photographing times of predefined test points.
  • the vision controller 150 When the vision controller 150 generates the camera illumination control signal, the bottom illumination control signal, the first photographing signal, and the second photographing signal, and receives the first and second align mark image signals and the edge image signal from the first and second cameras CAM1 and CAM2, the vision controller 150 controls an inspection table 140 through the PLC controller 110 in order to modify the aligned states of the LCD cell 160 according to the received first and second align mark image signals, and photographs a predetermined number of test points.
  • the inspection table 140 is moved on the X axis and the Y axis and is rotated on the ⁇ axis (the X axis, the Y axis, and the ⁇ axis are not illustrated), and no detailed configuration of the inspection table 140 is described.
  • the vision controller 150 comprises a PC (personal computer) 151 , an I/O (input/output) unit 152, a grabber 153, a display 154, and a keyboard 155.
  • the grabber 153 captures images, and the keyboard 155 is used to allow the operator to input desired information to the PC 151.
  • the vision controller 150 uses the align mark A registered during the measurement preparation process and the first and second align mark image signals photographed by the two first and second cameras CAM1 and CAM2, and modifies the aligned states of the LCD cell 160, or accurately calculates a rotation angle and distances of the X axis and the Y axis to be rotated and moved and transmits the calculated data to the PLC controller 110 in order for the first camera CAM1 to photograph the edge of the LCD cell 160 depending on the number of the test points.
  • the PLC controller 110 rotates and moves the inspection table 140 according to the transmitted rotation angle, and the distances of the X axis and the Y axis to be moved.
  • FIG. 11 shows the edge of the LCD cell 160, and the first camera CAM1 photographs the edge of the TFT substrate 161 of the LCD cell 160 according to control by the vision controller 150.
  • the bottom illumination generator 130 controls the brightness of the edge illuminator 131 through the vision controller 150.
  • the edge image signal shown in FIG. 11 is generated by the first camera CAiWil .
  • a plurality of patterns 161a and tab pads 161b are formed on the edge image signal shown in FIG. 11 , and they are established to be adjacent to the web pad 161b as indicated by a dotted region B when establishing a test point.
  • FIG. 12 shows another configuration of a device for inspecting the edge of the LCD cell 160.
  • the device further comprises a third camera CAM3 for photographing the ground edge of the LCD panel 160.
  • the third camera CAM3 comprises a lens 171 , a first half mirror 172, a photographer 173, and a second half mirror 174.
  • the third camera CAM3 photographs the bottom edge of the TFT substrate 161 according to the second photographing signal output by the vision controller 150, and allows the first camera CAM1 to photograph the top edge.
  • the initial positions of the first and second cameras CAM1 and CAM2 are established, and information on the LCD cell 160 is provided to the vision controller 150 from the PLC controller 110 in step S110.
  • the initial positions distances between the align marks (A shown in FIG. 8) formed on the LCD cell 160 and information on the actual measured distances of the align marks A are respectively input, initial positions of the first and second cameras CAM1 and CAM2 are established, the pixel distance displayed on the display 154 is calculated, and the distances "m” and "n” shown in FIGs. 10 and 11 for indicating ground amounts are calculated.
  • the distance of the pixels of the display 154 of the vision controller 150 is calculated in order to calculate the distances "m” and "n” shown in FIGs. 10 and 11.
  • the align marks A formed on the LCD cell 160 are magnified by a predetermined multiple, a length thereof in one direction is measured, the align marks A are displayed on the display 154 of the vision controller 150 with the same size as that of the measured align mark, the number of pixels in the same direction of the measured align marks A of the displayed align marks is determined, and the pixel distance is found by dividing the length of the measured align marks A by the number of pixels.
  • the distances "m” and "n” shown in FIGs. 10 and 11 are calculated by using the pixel distance.
  • the PLC controller 110 drives a grinder (not illustrated) in the process for manufacturing the LCD cell 160, and controls a device (not illustrated) for moving the LCD cell 160 to the inspection table 140 from the grinder, and accordingly, the PLC controller 110 notifies the vision controller 150 of a fact that the ground LCD cell 160 has been moved to the inspection table 140 by transmitting the measure signal to the vision controller 150.
  • a signal for moving the LCD cell is transmitted to the PLC controller 110 in step S130 in order to move the ground LCD cell 160 to the inspection table 140.
  • the LCD cell 160 is moved thereto by using a device (not illustrated) for moving the LCD cell 160 to the inspection table 140 from the grinder (not illustrated) according to control by the PLC controller 110.
  • the edge of the LCD cell 160 is photographed to calculate a ground amount, and the calculated ground amount is transmitted to the PLC controller 110 or the photographed edge image signal is transmitted to the display 154 of the vision controller 150 in step S140.
  • the grinding task is more accurately performed by automatically measuring the ground amount of the LCD cell 160 and automatically comparing grinding process conditions with the ground amount while the grinding process conditions are previously input to the vision device 110.
  • the vision controller 150 determines whether the number of the predefined test points has been measured in step S150. When having determined that the number of the predefined test points has been measured, the vision controller 150 determines whether to consecutively measure the edge of the subsequent LCD cell 160 in step S160. When the measure signal is not received in the previous step S120 for the vision controller 150 to determine whether the measure signal has been received from the PLC controller 110 in order to automatically measure the ground amount to accurately inspect the ground state of the LCD cell 160 and improve the speed of inspecting the tasks, the vision controller 150 determines whether an align signal is received from the PLC controller 110 in step S190.
  • the vision controller 150 uses the first and second cameras CAM1 and CAM2 to detect the align marks A formed on the edge of the LCD cell 160 in step S200.
  • step S210 When the vision controller 150 determines whether the align mark A corresponds to a predetermined reference align line and finds that they do not correspond to each other in the previous step S200 for detecting the align mark formed on the edge of the LCD cell 160, an error signal is generated in step S210. That is, it is determined whether the align marks A formed on the LCD cell 160 correspond to the reference align line previously stored in the vision controller 150 and displayed on the display 154. When no error is generated in the previous step S210 for determining whether the align marks correspond to the reference align line and generating an error signal, the vision controller 150 calculates an align modified amount for modifying the align error of the LCD cell 160 and transmits it to the PLC controller 110 in step S220. In this instance, the vision controller 150 uses the align marks (A shown in FIG.
  • the PLC controller 110 uses the transmitted align modified amount to drive the inspection table 140 and automatically align the LCD cell 160 in the rotation directions of the X axis, the Y axis, and the ⁇ axis.
  • the vision controller 150 calculates the grind modified amount for modifying the edge grinding amount of the LCD cell 160, transmits it to the PLC controller 110, and performs a measuring standby state in step S180 to inspect the edge of the ground LCD cell 160.
  • the measuring standby state represents a state for the vision controller 150 to check whether a measure signal has been generated and an align signal has been generated by the PLC controller 110.
  • the inspection task speed can be improved by automatically measuring the ground amount to further accurately inspect the defect state of grinding and aligning the LCD cell moved to the inspection table automatically in the directions of the X axis, the Y axis, and the ⁇ axis.

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Abstract

A method for inspecting an edge of an LCD cell by using a line scan camera comprises: inputting a reference value for determining whether defects are generated on the edge of the LCD cell to a vision controller, and establishing an initial position of the line scan camera; generating an align control signal, transmitting it to a PLC (programmable logic controller) controller, driving an inspection table according to the align control signal, and aligning the LCD cell moved to the inspection table; determining whether the alignment is correct by using an align mark formed on the LCD cell; driving the line scan camera to photograph edges of the LCD cell, and obtaining an edge image; determining whether a defect is generated on the obtained edge image by using the reference value; and generating goodness information on the edges of the LCD cell and outputting the goodness information.

Description

LCD Cell Edge Inspection Apparatus and Method Thereof
BACKGROUND OF THE INVENTION
The present invention relates to an LCD (liquid crystal display) panel
edge inspection device and method. More specifically, the present invention
relates to an LCD panel edge inspection device and method using a line scan
camera.
In order to manufacture LCD cells, a TFT (thin film transistor) substrate and a color filter substrate are manufactured, they are combined
through an assembly process, and they are separated into respective unit panels through a scribing and breaking process. In this instance, the
respective unit panels represent LCD cells.
When the LCD cells are separated, burrs, depressions, and phenomena of disconnected patterns can be generated on the broken edges of the unit panels through the scribing and breaking process. In particular, since the occurrence of burrs on the edges thereof causes a serious defect
on the LCD cell manufacturing devices, it is needed to inspect the edges of the LCD cells after the scribing and breaking process for the LCD cells.
A conventional technique for inspecting the edges of the LCD cells is
a method for mechanically providing a means with a sensor on a side thereof to the edges of the LCD cells and measuring the burrs generated on the
edges. However, this method has difficulties in measuring the burrs when the
defects on the edges are formed within a predetermined reference line, and
in failing to sense the burrs when the pattern is damaged. Also, a process for grinding the edges is executed after the scribing
and breaking process for the LCD cells. The grinding process is executed on
the four edges, that is, top, bottom, right, and left of the LCD cell, and the
ground edges are inspected when the four edges of the LCD cell are ground.
A conventional technique for inspecting the ground states of the LCD
cell is a method for providing the ground LCD cell on an inspection table, and processing a predetermined number of predefined test points as images by
using a vision device, and accordingly inspecting the ground states of the LCD cell. However, the above-described method has a demerit for an operator
to manually arrange the LCD cells one by one and inspect them when the ground LCD cells are transferred to the inspection table, and it has a problem of reducing inspection speed since the ground states are not accurately inspected. It is an advantage of the present invention to provide a method for
inspecting edges of LCD cells for inspecting defects which may occur on the edges of the LCD cells.
It is another advantage of the present invention to provide a device and method for automatically inspecting the ground states of the LCD cells.
It is still another advantage of the present invention to provide a
device and method for improving the speed for inspecting the ground states
of the LCD cells. BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate an embodiment of the invention,
and, together with the description, serve to explain the principles of the
invention:
FIG. 1 shows a flowchart for inspecting edges of an LCD cell
according to a first preferred embodiment of the present invention;
FIG. 2 shows a device for inspecting edges of an LCD cell according
to a first preferred embodiment of the present invention; FIGs. 3 to 5 show a perspective view of the LCD cell shown in FIG.
2;
FIG. 6 shows a magnified plane view of the LCD cell shown in FIG.
2;
FIG. 7 shows a device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention;
FIGs. 8 to 1 1 show a side view and a plane view of the LCD cell according to a second preferred embodiment of the present invention;
FIG. 12 shows a modified device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention; and
FIG. 13 shows a flowchart for inspecting edges of an LCD cell
according to a second preferred embodiment of the present invention. DISCLOSURE
In one aspect of the present invention, a method for inspecting an edge of an LCD cell by using a line scan camera, comprises: inputting a predetermined reference value for determining a defect state of the LCD cell to a vision controller, and establishing an initial position of the line scan camera; allowing the vision controller to generate an align control signal and transmit it to a PLC controller, and allowing the PLC controller to drive an inspection table according to the transmitted align control signal and align the LCD cell moved to the inspection table, when the reference value is input to the vision controller and the initial position of the line scan camera is established; allowing the vision controller to use an align mark formed on the LCD cell and determine whether the alignment is correct, when the LCD cell moved to the inspection table is aligned; allowing the vision controller to drive the line scan camera, photograph the edge of the LCD cell, and obtain an edge image, when the LCD cell is correctly aligned; allowing the vision controller to use the obtained edge image, inspect whether a case in which a difference between an actual distance value of from the edge of the LCD cell to a reference line and the reference value is greater than a predetermined first distance value, and determine whether pattern damage of the LCD cell is generated, when the edge image of the LCD cell is obtained; allowing the vision controller to use the edge image, inspect whether a case in which a difference between an actual distance value of from the edge of the LCD cell to a reference line and the reference value is greater than a predetermined second distance value, and determine whether a burr is generated when no pattern damage of the LCD cell is determined to be generated; allowing the vision controller to use the edge image, inspect whether a value generated by comparing the edge image with a predetermined brightness value is greater than a brightness reference value, and determine whether pattern breakage is generated, when no burr is found on the edge of the LCD cell; and allowing the vision controller to generate goodness information on the edge of the LCD cell and output it, when no defect is generated on the edge image.
In another aspect of the present invention, in a device for inspecting a ground state of an edge of an LCD cell, a device for inspecting an edge of an LCD cell comprises: a camera illumination generator for receiving a camera illumination control signal and generating a camera illumination driving signal for driving the illumination used for photographing the LCD cell; a bottom illumination generator for receiving a bottom illumination control signal to generate a bottom illumination driving signal for generating the illumination used for photographing the edge of the LCD cell, and generating the illumination through a measuring illuminator; a first camera for receiving the camera illumination driving signal, a first photographing signal, and a second photographing signal respectively, photographing the align mark formed on the LCD cell when the first photographing signal is received, and photographing the edge of the LCD cell, generating a first align mark image signal and an edge image signal, and outputting them when the second photographing signal is received; a second camera for receiving the camera illumination driving signal and first photographing signal respectively, photographing the align marks formed on the LCD cell, generating a second align mark image signal, and outputting it; and a vision controller for receiving a measure signal from a PLC controller, generating a camera illumination control signal, a bottom illumination control signal, a first photographing signal, and a second photographing signal for photographing the LCD cell at intervals of predetermined times, outputting them, receiving the first align mark image signal, the second align mark image signal, and the edge image signal respectively to modify an aligned state of the LCD cell, and controlling an inspection table through the PLC controller in order to photograph a predetermined number of test points.
In still another aspect of the present invention, in a method for inspecting a ground state of an edge of an LCD cell, a method for inspecting an edge of an LCD cell comprises: establishing initial positions of a first camera and a second camera, and allowing a vision controller to receive information on the LCD cell from a PLC controller; determining whether a measure signal for measuring the LCD cell is provided to the vision controller from the PLC controller in a measuring standby state when the information on the LCD cell is input to the vision controller; allowing the vision controller to transmit a signal for moving the LCD cell to the PLC controller in order to move the ground LCD cell to an inspection table when the measure signal is provided to the vision controller; photographing an edge of the LCD cell to calculate a ground amount, and transmitting the calculated ground amount to the PLC controller or transmitting the photographed edge image signal to a display of the vision controller when the signal for moving the LCD cell is transmitted and the LCD cell is moved to the inspection table; allowing the vision controller to determine whether a predetermined number of predefined test points are measured when the edge image signal of the LCD cell is photographed; and allowing the vision controller to determine whether to consecutively measure the edge of a subsequent LCD cell, and measure the edge of the subsequent LCD cell when the vision controller determines that the predetermined number of predefined test points are measured, wherein the ground amount is calculated by magnifying the align marks formed on the LCD cell by a predetermined multiple, measuring a length in one direction, displaying the align marks on the display of the vision controller with the same size as that of the measured align mark, calculating the pixel number of the displayed align marks, and using the pixel distance calculated by dividing the pixel number by the length of the measured align mark.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following detailed description, only the preferred embodiment of the invention has been shown and described, simply by way of illustration of the best mode contemplated by the inventor(s) of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive. <First preferred embodiment
A first preferred embodiment of the present invention will be described in detail with reference to drawings.
FIG. 1 shows a flowchart of a method for inspecting edges of an LCD cell according to a first preferred embodiment of the present invention, and FIG. 2 shows a device for inspecting edges of an LCD cell according to a first preferred embodiment of the present invention.
As shown in FIGs. 1 and 2, the method for inspecting edges of an LCD cell comprises: inputting a predetermined reference value for determining whether defects are generated on the edges of the LCD cell 10 to a vision controller 70, and establishing an initial position of a line scan camera 40 in step S10; allowing the vision controller 70 to generate an align control signal and transmit it to a PLC (programmable logic controller) controller 60, and allowing the PLC controller 60 to drive an inspection table 61 according to the transmitted align control signal and align the LCD cell 10 moved to the inspection table 61 in step S20 when the predetermined reference value is input to the vision controller 70 and the initial position of the line scan camera 40 is established; allowing the vision controller 70 to determine whether the alignment is correct by using an align mark 11d formed on the LCD cell 10 in step S30 when the LCD cell 10 moved to the inspection table 61 is aligned; allowing the vision controller 70 to drive the line scan camera 40 to photograph edges of the LCD cell 10 and obtain an edge image in step S40 when the LCD cell 10 is correctly aligned; allowing the vision controller 70 to determine whether a defect is generated on the obtained edge image by using the reference value in step S50 when the edge image of the LCD cell 10 is obtained; and allowing the vision controller 70 to generate goodness information on the edges of the LCD cell 10 and output the goodness information in step S60 when no defect is generated on the edge image.
The configuration of the device for inspecting the edges of the LCD cell according to the first preferred embodiment of the present invention will now be described in further detail. As shown in FIG. 2, the device for inspecting the edges of the LCD cell comprises a bottom illuminator 20, a first bottom illuminator 30, a line scan camera 40, a first line scan camera 50, a PLC controller 60, and a vision controller 70.
The bottom illuminator 20 and the first bottom illuminator 30 are provided to respectively face the line scan camera 40 and the first line scan camera 50, and they generate light when photographing the edges of the LCD cell 10 installed in the inspection table 61 with the line scan camera 40 and the first line scan camera 50.
The PLC controller 60 shifts or rotates the LCD cell 10 installed in the inspection table 61 in the directions of the X axis, the Y axis, and the rotation axis of the inspection table 61 in order to arrange the LCD cell 10. The configuration of the inspection table 61 is briefly described since a general table which can be driven in the directions of the X axis, the Y axis, and the rotation axis is generally known.
The vision controller 70 for transmitting and receiving information to/from the PLC controller 60 which drives the inspection table 60, and for controlling the bottom illuminator 20, the first bottom illuminator 30, the line scan camera 40, and the first line scan camera 50 comprises a PC (personal computer) 71 , an I/O (input/output) unit 72, a grabber 73, a display 74, and a keyboard 75. The grabber 73 obtains the edge images from the first and second line scan cameras 40 and 50 respectively, and transmits them to the PC 71. The I/O unit 72 manages inputs and outputs. The keyboard 75 is used for the operator to input information and initial setting values to the vision controller 70. The display 74 displays obtained results of the edge images and other results to the operator.
The edge image displayed on the display 74 of the vision controller 70 is generated by photographing the edges of the LCD cell 10. When the TFT substrate 11 and the color filter substrate 12 are manufactured as shown in FIG. 3, they are adhered to face with each other as shown in FIG. 4, and they are separated into the LCD cells 10 through the scribing and breaking process as shown in FIG. 5.
The edge inspection method for inspecting the defect phenomenon generated on the edges of the separated LCD cells 10 uses one bottom illuminator 20 and one line scan camera 40, differing from the inspection device shown in FIG. 2. Noting this point, as shown in FIGs. 1 and 2, the edge inspection method according to the first preferred embodiment inputs a predetermined reference value for determining whether the edge of the LCD cell 10 has a defect, to the vision controller 70, and establishes the initial position of the line scan camera 40 in step S10.
When the predetermined reference value is input to the vision controller 70, and the initial position of the line scan camera 40 is established, the vision controller 70 generates an align control signal, and transmits it to the PLC controller 60, and the PLC controller 60 drives an inspection table 61 according to the transmitted align control signal to align the moved LCD cells 10 in step S20. When the LCD cells 10 moved to the inspection table 61 are aligned, the vision controller 70 uses the align mark 11d formed on the LCD cells 10 to determine whether they are correctly aligned in step S30. That is, the vision controller 70 photographs the image of the cross-type align mark 11d, checks whether the photographed image corresponds to the normal align mark 11d to calculate a compensated amount according to a rotated amount of the inspection table 61 , and uses an extended central line 11 b which is passed through a plurality of align marks 11d to calculate a compensated amount for moving in the directions of the X axis and the Y axis of the inspection table 61. When the compensated amount is transmitted to the PLC controller
60, the PLC controller 60 drives the inspection table 61 according to the
transmitted compensated amount to align the LCD cells 10. In this instance,
the vision controller 70 photographs one align mark 11d, moves along a straight line, photographs another facing align mark 11d, and aligns them
when one line scan camera 40 is used. When the line scan camera 40 and
the first line scan camera 50 are provided, they are fixed on the straight line,
and the vision controller 70 obtains a plurality of align marks 1 1d and aligns
them.
When having determined that the LCD cell 10 is correctly aligned,
the vision controller 70 drives the line scan camera 40 to photograph the edge of the LCD cell 10 to obtain an edge image in step S40. When
photographing the edge of the LCD cell 10, the vision controller 70 drives the bottom illuminator 20 to generate illumination light, and drives the line scan camera to photograph the edge of the LCD cell 10. In this instance, the photographing speed on the edge of the LCD cell 10 can be improved in the
case of concurrently using the line scan camera 40 and the first line scan camera 50 compared to the case of only using the line scan camera 40. When having obtained the edge image of the LCD cell 10, the vision controller 70 uses a reference value to determine whether a defect has occurred in the obtained edge image in step S50. The step S50 for using a
reference value to determine whether a defect has occurred in the obtained
edge image will now be described in detail. When having obtained the edge image, the vision controller 70 uses
the edge image to determine whether the pattern on the LCD cell 10 is
damaged (given as the reference numeral "d" of FIG. 6) in step S51. In order
to determine whether the pattern is damaged, the vision controller 70 uses the obtained edge image to inspect whether a case in which a difference between the actual distance value p of from the edge of the LCD cell 10 to a reference line and the reference value m is greater than a predetermined first distance value has been generated. When it is found that "(p-m) > first
distance value" according to the inspection result, it is determined that the damaged pattern phenomenon d has been generated on the pattern of the LCD cell 10. That is, it is determined that the pattern damage d has been generated when an error allowance range is established to be the first distance value and damage which exceeds the error allowance range is generated.
When it is determined that no pattern damage phenomenon on the LCD cell 10 is generated, the vision controller 70 uses the edge image to determine whether burrs ("a" and "b" in FIG. 6) have been generated on the edges of the LCD cell 10 in step S52. In this instance, the burr "a" represents
a concave defect and the burr "b" represents a convex defect, with reference to the edge. In order to determine generation of the burr, the vision controller 70 uses the obtained edge image to inspect whether a case that a difference between the actual distance values n and k of from the edge of the LCD cell 10 to the reference line and the reference value m is greater than a predetermined second distance value has been generated. When it is found that "|(n,k)-m| > second distance value" according to the inspection result, it
is determined that the burrs have been generated on the pattern of the LCD cell 10. That is, it is determined that burrs "a" and "b" have been generated when an error allowance range is established to be the second distance value and damage which exceeds the error allowance range is generated.
The reference value m for determining the defect state of the pattern damage d and the burrs "a" and "b" in the previous steps S51 and S52 is calculated by using the distance m to the edge of the normal LCD cell 20, that is, the distance between the extended central line 11b of the two align marks 11d formed on the LCD cell 10 and the reference line 11c which is provided in parallel with the extended central line 11b and at a predetermined distance from the edge of the LCD cell 10. Therefore, when a difference between the distance p and the reference value m is greater than a predetermined first distance value for determining the pattern damage d in the previous step S51 , the vision controller 70 determines it to be pattern damage d, and when a difference between the distances n and k and the reference value m is greater than a predetermined second distance value, the vision controller 70 determines that the burrs "a" and "b" have been generated.
When the case in which the burrs "a" and "b" are generated at greater or less than the reference value m and the second distance value on the edge of the LCD cell 10 is not generated, the vision controller 70 uses the edge image to check whether a breakage phenomenon (the reference numeral c shown in FIG. 6) is generated on the edge of the LCD cell 10 and whether a predetermined brightness value is greater than a reference value, and thereby determine whether the breakage phenomenon c has been generated in step S53. In this instance, the brightness reference value for determining the defect state of the breakage phenomenon c is established by using the brightness of the normal edge image obtained by using the line scan camera 40, and the vision controller 70 determines that the breakage phenomenon c has been generated on the edge of the LCD cell 10 when the difference between the established brightness reference value and the measured edge image is greater than a predetermined brightness value.
When no defect is shown to be generated on the edge image of the LCD cell 10 through the above-described process, the vision controller 70 generates goodness information of the edge of the LCD cell 10 and outputs it in step S60, and when a defect is shown to be generated on the edge image, the vision controller 70 generates badness information of the edge of the LCD cell 10 and outputs it in step S70. That is, the vision controller 70 displays goodness information and badness information to the display 74 or transmits the same to the PLC controller 60 in the respective cases to be ready for the subsequent inspection process.
All the defects which can be generated on the edges can be easily inspected by establishing a predetermined reference line on the edge of the LCD cell, using a line scan camera to sequentially photograph the edge, and processing them as images as described above.
<Second preferred embodiment
Referring to FIGs. 7 to 13, a device for inspecting edges of an LCD panel according to a second preferred embodiment of the present invention will be described.
FIG. 7 shows a device for inspecting edges of an LCD cell according to a second preferred embodiment of the present invention, and FIGs. 8 to 11 show a side view and a plane view of the LCD cell according to a second preferred embodiment of the present invention.
As shown in FIG. 7, the device for inspecting edges of an LCD cell comprises a PLC controller 110, a camera illumination generator 120, a bottom illumination generator 130, a first camera CAM1 , a second camera CAM2, and a vision controller 150. The camera illumination generator 120 receives a camera illumination control signal and generates a camera illumination driving signal for driving illumination for photographing the LCD cell. The bottom illumination generator 130 receives a bottom illumination control signal, generates a bottom illumination driving signal for generating illumination for photographing the edge of the LCD cell 160, and generates the illumination through a bottom illuminator 131. The LCD cell 160 includes a TFT substrate 161 and a color filter substrate 162 as shown in FIG. 9.
The first camera CAM1 receives the camera illumination driving signal output by the camera illumination generator 120, generates illumination according to the camera illumination driving signal, and when receiving a first photographing signal according to the photographing signal and a second photographing signal respectively output by the vision controller 150, the first camera CAM1 photographs an align mark (shown as A in FIG. 8) formed on the LCD cell 160, photographs the edge of the LCD cell 160 when receiving the second photographing signal, generates a first align mark image signal and an edge image signal, and outputs them.
The first camera CAM1 photographs an align mark A for aligning the LCE cell 160, and the second camera CAM2 concurrently photographs an align mark A. The second camera CAM2 photographs an align mark A which faces the align mark A photographed by the first camera CAM1 on the straight line as shown in FIG. 8.
In order to photograph the align mark A for aligning the LCD cell 160, the second camera CAM2 receives the camera illumination control signal from the camera illumination generator 120, generates illumination according to the received camera illumination control signal, receives the first photographing signal from the vision controller 150, photographs the align mark A formed on the LCD cell, generates a second align mark image signal, and outputs it.
In the case of photographing the first and second align mark image signals, the first and second cameras CAM1 and CAM2 photograph two align marks A which face with each other on the straight line. For example, the first camera CAM1 photographs the align mark A provided on the top right of the drawing, and the second camera CAM2 photographs the align mark A provided on the top left thereof, and the LCD cell 160 is aligned through the vision controller 150.
In order to receive first and second align mark image signals and edge image signals generated by the first and second cameras CAM1 and CAM2, the vision controller 150 receives a measure signal from the PLC controller 110, generates a camera illumination control signal, a bottom illumination control signal, a first photographing signal, and a second photographing signal for photographing the LCD cell 160 at intervals of a predetermined time, and outputs them. In this instance, the intervals of predetermined times represent the time intervals for moving the LCD cell 160 according to photographing times of predefined test points.
When the vision controller 150 generates the camera illumination control signal, the bottom illumination control signal, the first photographing signal, and the second photographing signal, and receives the first and second align mark image signals and the edge image signal from the first and second cameras CAM1 and CAM2, the vision controller 150 controls an inspection table 140 through the PLC controller 110 in order to modify the aligned states of the LCD cell 160 according to the received first and second align mark image signals, and photographs a predetermined number of test points. In this instance, the inspection table 140 is moved on the X axis and the Y axis and is rotated on the θ axis (the X axis, the Y axis, and the θ axis are not illustrated), and no detailed configuration of the inspection table 140 is described.
In order to control the PLC controller 110 and obtain the edge image signal of the LCD cell 160, the vision controller 150 comprises a PC (personal computer) 151 , an I/O (input/output) unit 152, a grabber 153, a display 154, and a keyboard 155. The grabber 153 captures images, and the keyboard 155 is used to allow the operator to input desired information to the PC 151.
When the LCD cell 160 to be ground is provided to the inspection table 140 on a measuring area side, the vision controller 150 uses the align mark A registered during the measurement preparation process and the first and second align mark image signals photographed by the two first and second cameras CAM1 and CAM2, and modifies the aligned states of the LCD cell 160, or accurately calculates a rotation angle and distances of the X axis and the Y axis to be rotated and moved and transmits the calculated data to the PLC controller 110 in order for the first camera CAM1 to photograph the edge of the LCD cell 160 depending on the number of the test points. The PLC controller 110 rotates and moves the inspection table 140 according to the transmitted rotation angle, and the distances of the X axis and the Y axis to be moved. The edge image signal of the LCD cell 160 photographed by the first and second cameras CAM1 and CAM2 as shown in FIG. 10 are displayed on the display 154 of the vision controller 150 as shown in FIG. 11. FIG. 11 shows the edge of the LCD cell 160, and the first camera CAM1 photographs the edge of the TFT substrate 161 of the LCD cell 160 according to control by the vision controller 150.
When the top side and the bottom side of the TFT substrate 161 are ground and slanted to be a trapezoidal format by a grinder (not illustrated) driven according to control by the PLC controller 110, the ground top edge distance "m" and the bottom edge distance "n" are photographed
concurrently, and a distance between the photographed top edge distance "m" and the bottom edge distance "n" is calculated to display it through the display 154 of the vision controller 150 or transmit it to the PLC controller 110 and is used for grinding data of the subsequent LCD cell 160. In order to concurrently measure the top edge and the bottom edge, the bottom illumination generator 130 controls the brightness of the edge illuminator 131 through the vision controller 150.
When the edge of the TFT substrate 161 is photographed while the brightness of the edge illuminator 131 driven by the edge illumination generator 130 is controlled to be a predetermined level of brightness, the edge image signal shown in FIG. 11 is generated by the first camera CAiWil . A plurality of patterns 161a and tab pads 161b are formed on the edge image signal shown in FIG. 11 , and they are established to be adjacent to the web pad 161b as indicated by a dotted region B when establishing a test point.
FIG. 12 shows another configuration of a device for inspecting the edge of the LCD cell 160. As shown, the device further comprises a third camera CAM3 for photographing the ground edge of the LCD panel 160. The third camera CAM3 comprises a lens 171 , a first half mirror 172, a photographer 173, and a second half mirror 174. The third camera CAM3 photographs the bottom edge of the TFT substrate 161 according to the second photographing signal output by the vision controller 150, and allows the first camera CAM1 to photograph the top edge. An inspecting method of an edge inspecting device of the LCD cell 160 will now be described in detail with reference to FIG. 13.
As shown, the initial positions of the first and second cameras CAM1 and CAM2 are established, and information on the LCD cell 160 is provided to the vision controller 150 from the PLC controller 110 in step S110. In this instance, as to the initial positions, distances between the align marks (A shown in FIG. 8) formed on the LCD cell 160 and information on the actual measured distances of the align marks A are respectively input, initial positions of the first and second cameras CAM1 and CAM2 are established, the pixel distance displayed on the display 154 is calculated, and the distances "m" and "n" shown in FIGs. 10 and 11 for indicating ground amounts are calculated.
The distance of the pixels of the display 154 of the vision controller 150 is calculated in order to calculate the distances "m" and "n" shown in FIGs. 10 and 11. To achieve them, the align marks A formed on the LCD cell 160 are magnified by a predetermined multiple, a length thereof in one direction is measured, the align marks A are displayed on the display 154 of the vision controller 150 with the same size as that of the measured align mark, the number of pixels in the same direction of the measured align marks A of the displayed align marks is determined, and the pixel distance is found by dividing the length of the measured align marks A by the number of pixels. When the pixel distance is calculated, the distances "m" and "n" shown in FIGs. 10 and 11 are calculated by using the pixel distance. When the pixel distance of the display 154 is calculated and information on the LCD cell is input from the PLC controller 110, it is determined in a measuring standby state whether a measure signal for measuring the LCD cell is provided from the vision controller 150 in step S120. In this instance, the PLC controller 110 drives a grinder (not illustrated) in the process for manufacturing the LCD cell 160, and controls a device (not illustrated) for moving the LCD cell 160 to the inspection table 140 from the grinder, and accordingly, the PLC controller 110 notifies the vision controller 150 of a fact that the ground LCD cell 160 has been moved to the inspection table 140 by transmitting the measure signal to the vision controller 150.
When the vision controller 150 receives the measure signal, a signal for moving the LCD cell is transmitted to the PLC controller 110 in step S130 in order to move the ground LCD cell 160 to the inspection table 140. The LCD cell 160 is moved thereto by using a device (not illustrated) for moving the LCD cell 160 to the inspection table 140 from the grinder (not illustrated) according to control by the PLC controller 110.
When the signal for moving the LCD cell 160 is transmitted to move the LCD cell 160 to the inspection table 140, the edge of the LCD cell 160 is photographed to calculate a ground amount, and the calculated ground amount is transmitted to the PLC controller 110 or the photographed edge image signal is transmitted to the display 154 of the vision controller 150 in step S140. The grinding task is more accurately performed by automatically measuring the ground amount of the LCD cell 160 and automatically comparing grinding process conditions with the ground amount while the grinding process conditions are previously input to the vision device 110.
When the ground amount is calculated and the edge image signal of one test point of the LCD cell 160 is photographed, the vision controller 150 determines whether the number of the predefined test points has been measured in step S150. When having determined that the number of the predefined test points has been measured, the vision controller 150 determines whether to consecutively measure the edge of the subsequent LCD cell 160 in step S160. When the measure signal is not received in the previous step S120 for the vision controller 150 to determine whether the measure signal has been received from the PLC controller 110 in order to automatically measure the ground amount to accurately inspect the ground state of the LCD cell 160 and improve the speed of inspecting the tasks, the vision controller 150 determines whether an align signal is received from the PLC controller 110 in step S190. When receiving the align signal from the PLC controller 110 in the step S190 for the vision controller 150 to determine whether the align signal is received from the PLC controller 110, the vision controller 150 uses the first and second cameras CAM1 and CAM2 to detect the align marks A formed on the edge of the LCD cell 160 in step S200.
When the vision controller 150 determines whether the align mark A corresponds to a predetermined reference align line and finds that they do not correspond to each other in the previous step S200 for detecting the align mark formed on the edge of the LCD cell 160, an error signal is generated in step S210. That is, it is determined whether the align marks A formed on the LCD cell 160 correspond to the reference align line previously stored in the vision controller 150 and displayed on the display 154. When no error is generated in the previous step S210 for determining whether the align marks correspond to the reference align line and generating an error signal, the vision controller 150 calculates an align modified amount for modifying the align error of the LCD cell 160 and transmits it to the PLC controller 110 in step S220. In this instance, the vision controller 150 uses the align marks (A shown in FIG. 8) formed on the LCD cell 160 to calculate the align modified amount for moving the LCD cell 160 in the rotation directions of the X axis, the Y axis, and the θ axis and performing alignment and transmit it to the PLC controller 110, and the PLC controller 110 uses the transmitted align modified amount to drive the inspection table 140 and automatically align the LCD cell 160 in the rotation directions of the X axis, the Y axis, and the θ axis.
When the subsequent LCD cell 160 is not measured in step S160 for determining whether to measure the subsequent LCD cell 160, and modification of the ground amount is selected in step S170 for determining whether to modify the ground amount of the LCD cell 160, the vision controller 150 calculates the grind modified amount for modifying the edge grinding amount of the LCD cell 160, transmits it to the PLC controller 110, and performs a measuring standby state in step S180 to inspect the edge of the ground LCD cell 160. The measuring standby state represents a state for the vision controller 150 to check whether a measure signal has been generated and an align signal has been generated by the PLC controller 110.
The inspection task speed can be improved by automatically measuring the ground amount to further accurately inspect the defect state of grinding and aligning the LCD cell moved to the inspection table automatically in the directions of the X axis, the Y axis, and the θ axis.
While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Figs, grinded

Claims

WHAT IS CLAIMED IS:
1. A method for inspecting an edge of an LCD cell by using a line scan camera, comprising: inputting a predetermined reference value for determining a defect state of the LCD cell to a vision controller, and establishing an initial position of the line scan camera; allowing the vision controller to generate an align control signal and transmit it to a PLC controller, and allowing the PLC controller to drive an inspection table according to the transmitted align control signal and align the LCD cell moved to the inspection table, when the reference value is input to the vision controller and the initial position of the line scan camera is established; allowing the vision controller to use an align mark formed on the LCD cell and determine whether the alignment is correct, when the LCD cell moved to the inspection table is aligned; allowing the vision controller to drive the line scan camera, photograph the edge of the LCD cell, and obtain an edge image, when the LCD cell is correctly aligned; allowing the vision controller to use the obtained edge image, inspect whether a case in which a difference between an actual distance value of from the edge of the LCD cell to a reference line and the reference value is greater than a predetermined first distance value, and determine whether pattern damage of the LCD cell is generated, when the edge image of the LCD cell is obtained; allowing the vision controller to use the edge image, inspect whether a case in which a difference between an actual distance value of from the edge of the LCD cell to a reference line and the reference value is greater than a predetermined second distance value, and determine whether a burr is generated when no pattern damage of the LCD cell is determined to be generated; allowing the vision controller to use the edge image, inspect whether a value generated by comparing the edge image with a predetermined brightness value is greater than a brightness reference value, and determine whether pattern breakage is generated, when no burr is found on the edge of the LCD cell; and allowing the vision controller to generate goodness information on the edge of the LCD cell and output it, when no defect is generated on the edge image.
2. The method of claim 1 , wherein the reference value for determining generation of the pattern damage and the burr is calculated by using a distance of from the edge of the LCD cell to a reference line, and the reference line is established on a position at a predetermined distance from the edge of the LCD cell and in parallel to an extended central line with reference to the extended central line which connects two align marks formed on the LCD cell.
3. The method of claim 1 , wherein the brightness reference value for determining generation of the pattern breakage is established with reference to the brightness of a normal edge image obtained by using the line scan camera.
4. The method of claim 1 , wherein the step for determining whether a defect is generated on the edge image further comprises allowing the vision controller to generate badness information of the edge of the LCD cell and output it when a defect is generated on the edge image.
5. In a device for inspecting a ground state of an edge of an LCD cell, a device for inspecting an edge of an LCD cell comprising: a camera illumination generator for receiving a camera illumination control signal and generating a camera illumination driving signal for driving the illumination used for photographing the LCD cell; a bottom illumination generator for receiving a bottom illumination control signal to generate a bottom illumination driving signal for generating the illumination used for photographing the edge of the LCD cell, and generating the illumination through a measuring illuminator; a first camera for receiving the camera illumination driving signal, a first photographing signal, and a second photographing signal respectively, photographing the align mark formed on the LCD cell when the first photographing signal is received, and photographing the edge of the LCD cell, generating a first align mark image signal and an edge image signal, and outputting them when the second photographing signal is received; a second camera for receiving the camera illumination driving signal and first photographing signal respectively, photographing the align marks formed on the LCD cell, generating a second align mark image signal, and outputting it; and a vision controller for receiving a measure signal from a PLC controller, generating a camera illumination control signal, a bottom illumination control signal, a first photographing signal, and a second photographing signal for photographing the LCD cell at intervals of predetermined times, outputting them, receiving the first align mark image signal, the second align mark image signal, and the edge image signal respectively to modify an aligned state of the LCD cell, and controlling an inspection fable through the PLC controller in order to photograph a predetermined number of test points.
6. The device of claim 5, wherein the bottom illumination generator is installed to face the first camera for photographing the edge of the LCD cell, generating an edge image signal, and outputting it.
7. The device of claim 5, wherein the vision controller further comprises a third camera for receiving the camera illumination driving signal
and the second photographing signal respectively, and photographing the bottom of the edge of the LCD cell.
8. In a method for inspecting a ground state of an edge of an LCD
cell, a method for inspecting an edge of an LCD cell comprising:
establishing initial positions of a first camera and a second camera,
and allowing a vision controller to receive information on the LCD cell from a PLC controller; determining whether a measure signal for measuring the LCD cell is provided to the vision controller from the PLC controller in a measuring standby state when the information on the LCD cell is input to the vision controller; allowing the vision controller to transmit a signal for moving the LCD cell to the PLC controller in order to move the ground LCD cell to an inspection table when the measure signal is provided to the vision controller; photographing an edge of the LCD cell to calculate a ground amount, and transmitting the calculated ground amount to the PLC controller or transmitting the photographed edge image signal to a display of the vision controller when the signal for moving the LCD cell is transmitted and the LCD cell is moved to the inspection table; allowing the vision controller to determine whether a predetermined number of predefined test points are measured when the edge image signal of the LCD cell is photographed; and allowing the vision controller to determine whether to consecutively measure the edge of a subsequent LCD cell, and measure the edge of the subsequent LCD cell when the vision controller determines that the predetermined number of predefined test points are measured, wherein the ground amount is calculated by magnifying the align marks formed on the LCD cell by a predetermined multiple, measuring a length in one direction, displaying the align marks on the display of the vision controller by the same size as the that of the measured align mark, calculating the pixel number of the displayed align marks, and using the pixel distance calculated by dividing the pixel number by the length of the measured align mark.
9. The method of claim 8, further comprising: allowing the vision controller to determine whether ground amount modification of the edge of the LCD cell is selected when measurement of the subsequent LCD cell is not selected in the step for determining whether to measure the subsequent LCD cell; and allowing the vision controller to calculate a ground modified amount and transmit it to the PLC controller in order to modify the ground amount of the edge of the LCD cell when modification of the ground amount is selected in the step for determining whether modification of the ground amount of the edge of the LCD cell is selected.
10. The method of claim 8, further comprising: allowing the vision controller to determine whether an align signal is received from the PLC controller when no measure signal is received in the step for determining whether the measure signal is received; allowing the vision controller to use a first camera and a second camera to detect align marks formed on the edge of the LCD cell when the align signal is received from the PLC controller in the step for the vision controller to determine whether the align signal is received from the PLC controller; allowing the vision controller to determine whether the align marks correspond to a predetermined reference align line in the step for detecting the align marks formed on the edge of the LCD cell, and generate an error signal when they do not correspond to each other; and allowing the vision controller to calculate an align modified amount for modifying an align error of the LCD cell, transmit it to the PLC controller, and entering a measuring standby state when no error is generated.
PCT/KR2004/000748 2003-03-31 2004-03-31 Lcd cell edge inspection apparatus and method thereof Ceased WO2004088399A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2003-0020297 2003-03-31
KR1020030020296A KR100418356B1 (en) 2003-03-31 2003-03-31 LCD Cell Edge Inspection System
KR10-2003-0020296 2003-03-31
KR1020030020297A KR100418357B1 (en) 2003-03-31 2003-03-31 LCD Cell Automatic Aligner&Grinding Inspection System

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