WO2002039130A1 - Method and apparatus for testing flat panel video displays - Google Patents

Method and apparatus for testing flat panel video displays Download PDF

Info

Publication number
WO2002039130A1
WO2002039130A1 PCT/GB2001/004932 GB0104932W WO0239130A1 WO 2002039130 A1 WO2002039130 A1 WO 2002039130A1 GB 0104932 W GB0104932 W GB 0104932W WO 0239130 A1 WO0239130 A1 WO 0239130A1
Authority
WO
WIPO (PCT)
Prior art keywords
display
test signal
input electrodes
peripheral circuitry
flat panel
Prior art date
Application number
PCT/GB2001/004932
Other languages
French (fr)
Inventor
Wallace Troup Miller
Michael Wallace
Kenneth Davidson
Original Assignee
Display Products Technology Limited
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 Display Products Technology Limited filed Critical Display Products Technology Limited
Priority to AU2002212519A priority Critical patent/AU2002212519A1/en
Publication of WO2002039130A1 publication Critical patent/WO2002039130A1/en

Links

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/006—Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays
    • 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

Definitions

  • the present invention relates to methods and apparatus for testing flat panel video display devices, particularly liquid crystal displays (LCDs), such as are employed in laptop computers, flat panel video monitors etc. More specifically, the invention relates to the testing of display inputs and pixel addressing electrodes in diagnosing the causes of dead lines/blocks in the display.
  • LCDs liquid crystal displays
  • a common problem occurring with liquid crystal displays is that of "dead” lines or blocks; i.e specific areas of the screen where the liquid crystals do not respond to the applied electric field. Such lines or blocks are referred to hereinafter simply as “dead lines".
  • the presence of a dead line results in a horizontal or vertical line that cannot be refreshed by new data input to the display.
  • a dead line is a permanent feature and is unacceptable to user ' of the display.
  • input signals are carried by peripheral circuitry, commonly known as the tape carrier package (TCP) .
  • TCP tape carrier package
  • the rows and columns of the display are defined by powered lines formed by transparent conductors, usually formed from Indium Tin Oxide (ITO) , with input electrodes, usually also formed from ITO, at either end, to which the TCP is connected.
  • ITO Indium Tin Oxide
  • dead lines There are two main causes of dead lines : defective peripheral circuitry or damaged (open circuit) input electrodes. In order to effect a repair, or to determine whether a unit is economically repairable, it must be determined which of these is defective. Conventionally, attempts to cure dead lines begin with removal and replacement of the TCP, followed by a functional test to determine whether the replacement of the TCP has cured the fault. This in itself is a complex and laborious process. If the defect persists after replacement of the TCP, the TCP is again removed and visual inspection of the input electrodes is performed using a microscope. Such visual inspection is time-consuming and unreliable and, after inspection, it may still be uncertain whether it is the peripheral circuitry or the input electrodes which are defective. If the input electrodes are defective, the display unit will generally not be economically repairable.
  • the present invention seeks to make the process of testing the input electrodes more efficient and reliable. Given such a process, it becomes logical for the input electrodes to be tested first, following removal of the peripheral circuitry. If the input electrodes are found to be defective, no further action need be taken, on the basis that the display is not economically repairable. If no fault is found with the input electrodes, the peripheral circuitry may then be replaced.
  • a method of testing a defective flat panel video display comprises the steps of removing peripheral circuitry from the display, applying an electrical test signal directly to input electrodes of a plurality of adjacent lines of the display, and backlighting the display.
  • the test signal is applied by pressing an electrode formed from flexible conductive material into contact with the input electrodes of the plurality of adjacent lines.
  • an electrode formed from flexible conductive material ensures good electrical contact with the input electrodes.
  • the test signal simulates normal input signals which would be applied to the display in use, suitably comprising a square wave signal.
  • apparatus for testing a defective flat panel video display comprises signal generating means for generating an electrical test signal, test signal electrode means for applying the test signal directly to input electrodes of at least a plurality of adjacent lines of a display from which peripheral circuitry has been removed, and lighting means for backlighting the display.
  • the test signal electrode means comprises an electrode formed from flexible conductive material.
  • the signal generating means is adapted to generate signals simulating normal input signals which would be applied to the display in use.
  • the signal generating means is adapted to generate a square wave signal.
  • Fig. 1 is a schematic side view of illustrating one embodiment of the method and apparatus of the invention
  • Fig . 2 is a schematic perspective view illustrating part of a flat panel display under test in accordance with the invention
  • Fig. 3 is a schematic illustration showing how one type of flexible electrode is applied to input electrodes of a flat panel display in accordance with the invention.
  • Fig. 4 is a schematic illustration showing how the connection of a flexible electrode of the type shown in Fig. 3 to the input electrodes of a display depends on the relative pitches of conductive elements of the flexible electrode and the input electrodes of the display.
  • Fig. 1 shows a signal generator 10 connected to a flexible test signal electrode 11, which is placed in contact with input electrodes 12 of a flat panel display device 13, such as an LCD panel, from which peripheral circuitry has previously been removed.
  • the display 13 is supported by a support assembly 16 comprising a backlighting assembly 14 and a transparent or translucent screen 15 which is illuminated by the backlighting assembly 14 and upon which the display 13 is laid.
  • the test electrode 11 is generally rectangular and has a width sufficient to span the input electrodes of a plurality of lines of the display, such that the test signal is applied to a number of lines simultaneously.
  • the width of the test electrode 11, and hence the number of lines which it spans, may vary.
  • the test electrode 11 is pressed into contact with the input electrodes 12.
  • the flexible nature of the test electrode 11 ensures good electrical contact.
  • the test electrode may be formed from any of a number of flexible/resilient conductive materials, such as carbon-filled elastomers.
  • the display will be rejected as not being economically repairable. If no dead lines are detected, the display may be passed for the application of replacement peripheral circuitry.
  • test signal is not critical, as long as it is suitable for energising the display. Effectively, it simulates the types of input signal which would normally be applied to the display.
  • a low frequency square wave is generally suitable.
  • the test electrode comprises a simple block of flexible conductive material which simply bridges adjacent input electrodes.
  • a type of flexible connector material commonly known as a "zebra strip” 21, which comprises alternating conductive portions 22 (typically of carbon-filled elastomer) ) and insulating portions 24 (typically of silicone rubber), as seen in Fig. 3.
  • zebra strip a type of flexible connector material commonly known as a "zebra strip” 21, which comprises alternating conductive portions 22 (typically of carbon-filled elastomer) ) and insulating portions 24 (typically of silicone rubber), as seen in Fig. 3.
  • the pitch spatial frequency
  • each input electrode 12 will be contacted by at least one conductive portion 22 of the zebra strip, as seen in Fig. 3. If the pitch of zebra strip 21 is smaller than that of the input electrodes 12 (i.e. if the physical spacing of the conductive portions 22 of the zebra strip 21 is greater than that of the input electrodes 12), then some of the input electrodes 12 may not be contacted by any conductive portion 22 and will appear, wrongly, as dead lines, as seen in Fig. 4. For this reason, it is preferred that the test electrode is formed from continuous conductive material. Improvements and modifications may be incorporated without departing from the scope of the invention.

Abstract

Method and apparatus for testing a defective flat panel display to determine whether the fault lies with the input electrodes of the rows and columns of the display or the peripheral circuitry. The method comprises steps of removing peripheral circuitry from the display, applying an electrical test signal directly to input electrodes of a plurality of adjacent lines of the display, and backlighting the display. A fault lying with the input electrodes of the rows and columns of the display will then be visible, and the screen can be deemed uneconomial to repair. If the input electrodes of the rows and columns of the display function normally, the fault can be said to lie with the peripheral circuitry, which can then be replaced. Apparatus to perform this method includes signal generating means (10) for generating an electrical test signal, test signal electrode means (11) for applying the test signal electrode means for applying the test signal directly to input electrodes of at least a plurality of adjacent lines of a display (13) from which peripheral circuitry has been removed, and lighting means (14) for backlighting the display.

Description

METHOD AND APPARATUS FOR TESTING FLAT PANEL VIDEO
DISPLAYS
The present invention relates to methods and apparatus for testing flat panel video display devices, particularly liquid crystal displays (LCDs), such as are employed in laptop computers, flat panel video monitors etc. More specifically, the invention relates to the testing of display inputs and pixel addressing electrodes in diagnosing the causes of dead lines/blocks in the display.
A common problem occurring with liquid crystal displays is that of "dead" lines or blocks; i.e specific areas of the screen where the liquid crystals do not respond to the applied electric field. Such lines or blocks are referred to hereinafter simply as "dead lines". The presence of a dead line results in a horizontal or vertical line that cannot be refreshed by new data input to the display. A dead line is a permanent feature and is unacceptable to user' of the display. To form an image on the display screen, input signals are carried by peripheral circuitry, commonly known as the tape carrier package (TCP) . The rows and columns of the display are defined by powered lines formed by transparent conductors, usually formed from Indium Tin Oxide (ITO) , with input electrodes, usually also formed from ITO, at either end, to which the TCP is connected.
There are two main causes of dead lines : defective peripheral circuitry or damaged (open circuit) input electrodes. In order to effect a repair, or to determine whether a unit is economically repairable, it must be determined which of these is defective. Conventionally, attempts to cure dead lines begin with removal and replacement of the TCP, followed by a functional test to determine whether the replacement of the TCP has cured the fault. This in itself is a complex and laborious process. If the defect persists after replacement of the TCP, the TCP is again removed and visual inspection of the input electrodes is performed using a microscope. Such visual inspection is time-consuming and unreliable and, after inspection, it may still be uncertain whether it is the peripheral circuitry or the input electrodes which are defective. If the input electrodes are defective, the display unit will generally not be economically repairable.
The present invention seeks to make the process of testing the input electrodes more efficient and reliable. Given such a process, it becomes logical for the input electrodes to be tested first, following removal of the peripheral circuitry. If the input electrodes are found to be defective, no further action need be taken, on the basis that the display is not economically repairable. If no fault is found with the input electrodes, the peripheral circuitry may then be replaced.
In accordance with a first aspect of the invention, a method of testing a defective flat panel video display comprises the steps of removing peripheral circuitry from the display, applying an electrical test signal directly to input electrodes of a plurality of adjacent lines of the display, and backlighting the display.
By means of this test method, the presence of one or more dead lines amongst the plurality of lines to which the test signal is applied will be immediately apparent by direct, naked-eye observation of the screen.
Preferably, the test signal is applied by pressing an electrode formed from flexible conductive material into contact with the input electrodes of the plurality of adjacent lines. The use of a flexible electrode ensures good electrical contact with the input electrodes.
Preferably, the test signal simulates normal input signals which would be applied to the display in use, suitably comprising a square wave signal.
In accordance with a second aspect of the invention, apparatus for testing a defective flat panel video display comprises signal generating means for generating an electrical test signal, test signal electrode means for applying the test signal directly to input electrodes of at least a plurality of adjacent lines of a display from which peripheral circuitry has been removed, and lighting means for backlighting the display.
Preferably, the test signal electrode means comprises an electrode formed from flexible conductive material.
Preferably, the signal generating means is adapted to generate signals simulating normal input signals which would be applied to the display in use. Suitably, the signal generating means is adapted to generate a square wave signal.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Fig. 1 is a schematic side view of illustrating one embodiment of the method and apparatus of the invention;
Fig . 2 is a schematic perspective view illustrating part of a flat panel display under test in accordance with the invention;
Fig. 3 is a schematic illustration showing how one type of flexible electrode is applied to input electrodes of a flat panel display in accordance with the invention; and
Fig. 4 is a schematic illustration showing how the connection of a flexible electrode of the type shown in Fig. 3 to the input electrodes of a display depends on the relative pitches of conductive elements of the flexible electrode and the input electrodes of the display.
Referring now to the drawings, Fig. 1 shows a signal generator 10 connected to a flexible test signal electrode 11, which is placed in contact with input electrodes 12 of a flat panel display device 13, such as an LCD panel, from which peripheral circuitry has previously been removed. The display 13 is supported by a support assembly 16 comprising a backlighting assembly 14 and a transparent or translucent screen 15 which is illuminated by the backlighting assembly 14 and upon which the display 13 is laid.
As is best seen in Fig. 2, the test electrode 11 is generally rectangular and has a width sufficient to span the input electrodes of a plurality of lines of the display, such that the test signal is applied to a number of lines simultaneously. The width of the test electrode 11, and hence the number of lines which it spans, may vary. The test electrode 11 is pressed into contact with the input electrodes 12. The flexible nature of the test electrode 11 ensures good electrical contact. The test electrode may be formed from any of a number of flexible/resilient conductive materials, such as carbon-filled elastomers.
When a line of an LCD display is energised by an input signal it turns opaque. An unenergised line transmits light. Accordingly, when the display is back-lit and the test electrode is applied to energise a block of adjacent lines, "good" ("powered") lines 18 become opaque whilst dead lines 20 transmit light. When the test signal is applied to a plurality of adjacent lines simultaneously, dead lines are readily and immediately apparent to direct, naked-eye observation. The test electrode 11 is applied repeatedly across the width of the display and any dead lines can be quickly, easily and reliably identified.
Typically, if dead lines are identified at this stage, the display will be rejected as not being economically repairable. If no dead lines are detected, the display may be passed for the application of replacement peripheral circuitry.
The nature of the applied test signal is not critical, as long as it is suitable for energising the display. Effectively, it simulates the types of input signal which would normally be applied to the display. A low frequency square wave is generally suitable.
It is preferred that the test electrode comprises a simple block of flexible conductive material which simply bridges adjacent input electrodes. However, it may be convenient to use a type of flexible connector material commonly known as a "zebra strip" 21, which comprises alternating conductive portions 22 (typically of carbon-filled elastomer) ) and insulating portions 24 (typically of silicone rubber), as seen in Fig. 3. In this event, it is important that the pitch (spatial frequency) of the conductive portions 22 of the zebra strip suits the pitch of the input electrodes 12. Generally, as long as the pitch of zebra strip is greater than that of the input electrodes (i.e. the physical spacing of the conductive portions 22 is smaller than that of the input electrodes 12), then each input electrode 12 will be contacted by at least one conductive portion 22 of the zebra strip, as seen in Fig. 3. If the pitch of zebra strip 21 is smaller than that of the input electrodes 12 (i.e. if the physical spacing of the conductive portions 22 of the zebra strip 21 is greater than that of the input electrodes 12), then some of the input electrodes 12 may not be contacted by any conductive portion 22 and will appear, wrongly, as dead lines, as seen in Fig. 4. For this reason, it is preferred that the test electrode is formed from continuous conductive material. Improvements and modifications may be incorporated without departing from the scope of the invention.

Claims

1. A method of testing a defective flat panel video display comprising the steps of removing peripheral circuitry from the display, applying an electrical test signal directly to input electrodes of a plurality of adjacent lines of the display, and backlighting the display.
2. A method as claimed in Claim 1, wherein the test signal is applied by pressing an electrode formed from flexible conductive material into contact with the input electrodes of the plurality of adjacent lines.
3. A method as claimed in Claim 1 or Claim 2, wherein the test signal simulates normal input signals which would be applied to the display in use, suitably comprising a square wave signal.
4. Apparatus for testing a defective flat panel video display comprising signal generating means for generating an electrical test signal, test signal electrode means for applying the test signal directly to input electrodes of at least a plurality of adjacent lines of a display from which peripheral circuitry has been removed, and lighting means for backlighting the display.
5. Apparatus as claimed in Claim 4, wherein the test signal electrode means comprises an electrode formed from flexible conductive material.
6. Apparatus as claimed in Claim 4 or Claim 5, wherein the signal generating means is adapted to generate signals simulating normal input signals which would be applied to the display in use.
7. Apparatus as claimed in any of Claims 4 to 6 wherein the signal generating means is adapted to generate a square wave signal
PCT/GB2001/004932 2000-11-09 2001-11-07 Method and apparatus for testing flat panel video displays WO2002039130A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002212519A AU2002212519A1 (en) 2000-11-09 2001-11-07 Method and apparatus for testing flat panel video displays

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0027369A GB0027369D0 (en) 2000-11-09 2000-11-09 Methods and apparatus for testing flat panel video displays
GB0027369.8 2000-11-09

Publications (1)

Publication Number Publication Date
WO2002039130A1 true WO2002039130A1 (en) 2002-05-16

Family

ID=9902860

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2001/004932 WO2002039130A1 (en) 2000-11-09 2001-11-07 Method and apparatus for testing flat panel video displays

Country Status (4)

Country Link
AU (1) AU2002212519A1 (en)
GB (1) GB0027369D0 (en)
TW (1) TW567327B (en)
WO (1) WO2002039130A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5175504A (en) * 1991-06-17 1992-12-29 Photon Dynamics, Inc. Method and apparatus for automatically inspecting and repairing a simple matrix circuit panel
US5543729A (en) * 1991-09-10 1996-08-06 Photon Dynamics, Inc. Testing apparatus and connector for liquid crystal display substrates
US5764209A (en) * 1992-03-16 1998-06-09 Photon Dynamics, Inc. Flat panel display inspection system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5175504A (en) * 1991-06-17 1992-12-29 Photon Dynamics, Inc. Method and apparatus for automatically inspecting and repairing a simple matrix circuit panel
US5543729A (en) * 1991-09-10 1996-08-06 Photon Dynamics, Inc. Testing apparatus and connector for liquid crystal display substrates
US5764209A (en) * 1992-03-16 1998-06-09 Photon Dynamics, Inc. Flat panel display inspection system

Also Published As

Publication number Publication date
TW567327B (en) 2003-12-21
AU2002212519A1 (en) 2002-05-21
GB0027369D0 (en) 2000-12-27

Similar Documents

Publication Publication Date Title
KR100596965B1 (en) Module for appling driving signal, liquid crystal display assembly having the same and method for testing time of driving signal the same
KR100353955B1 (en) Liquid Crystal Display for Examination of Signal Line
US5543729A (en) Testing apparatus and connector for liquid crystal display substrates
KR20080066308A (en) Display panel, method of inspecting the panel and method of manufacturing the panel
KR20080048627A (en) Array substrate and display panel having the same
KR20060015201A (en) Array substrate and mother board and liquid crystal display having the same
CN101958093A (en) Testing device and testing method for display panel
US5473261A (en) Inspection apparatus and method for display device
KR100576629B1 (en) TFT array substrate of LCD device and method for testing the same
KR101107708B1 (en) Substrate for Thin Film Transistor Array in Liquid Crystal Display Device
WO2002039130A1 (en) Method and apparatus for testing flat panel video displays
US7518601B2 (en) Array substrate and display apparatus and method for manufacturing display apparatus
JP3586049B2 (en) LCD panel
KR100212276B1 (en) Electrostatic protected lcd panel, probing apparatus and monitoring method
KR100471782B1 (en) Defect Detection Method of LCD
US7049527B1 (en) Conductor-pattern testing method, and electro-optical device
KR101192102B1 (en) auto probe appratus and using the inspecting method for LCD panel using the same
KR100945951B1 (en) Probe unit for both visual inspection and gross test
JP3912856B2 (en) Inspection method for liquid crystal display device and liquid crystal display device
JP3485166B2 (en) Inspection method and inspection device for liquid crystal display device
JP2004045763A (en) Method for inspecting liquid crystal display panel and inspection device therefor
JP3177330B2 (en) Inspection device and inspection method for active matrix display device
JPH095768A (en) Inspection device for liquid crystal display element
JPH03142498A (en) Method and apparatus for inspecting thin-film transistor active matrix substrate
KR100322103B1 (en) Connecter for LCD functioning test

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

WWE Wipo information: entry into national phase

Ref document number: 2001980731

Country of ref document: EP

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWW Wipo information: withdrawn in national office

Ref document number: 2001980731

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP