WO2002052336A2 - Methods and apparatus for repairing inoperative pixels in a display - Google Patents

Methods and apparatus for repairing inoperative pixels in a display Download PDF

Info

Publication number
WO2002052336A2
WO2002052336A2 PCT/US2001/047191 US0147191W WO02052336A2 WO 2002052336 A2 WO2002052336 A2 WO 2002052336A2 US 0147191 W US0147191 W US 0147191W WO 02052336 A2 WO02052336 A2 WO 02052336A2
Authority
WO
WIPO (PCT)
Prior art keywords
pixel
inoperative
circuitry
accordance
display
Prior art date
Application number
PCT/US2001/047191
Other languages
French (fr)
Other versions
WO2002052336A3 (en
Inventor
Richard A. Keeney
Farhad Nourbakhsh
Anthony Clark
Original Assignee
Electronics For Imaging, Inc.
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 Electronics For Imaging, Inc. filed Critical Electronics For Imaging, Inc.
Priority to EP01995433A priority Critical patent/EP1344103A2/en
Publication of WO2002052336A2 publication Critical patent/WO2002052336A2/en
Publication of WO2002052336A3 publication Critical patent/WO2002052336A3/en

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/136Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G02F1/1362Active matrix addressed cells
    • G02F1/136259Repairing; Defects
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/136Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G02F1/1362Active matrix addressed cells
    • G02F1/136277Active matrix addressed cells formed on a semiconductor substrate, e.g. of silicon

Definitions

  • the present invention provides methods and apparatus for repairing inoperative pixels in a display.
  • the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and tying such pixels to the working drive circuit of a nearby pixel.
  • CMOS Complementary Metal Oxide Semiconductor
  • the yield of "perfect" display devices is estimated at less than 2% (assumed defect rate of 0.2 / cm 2 ).
  • Defects in the microelectronic circuitry can cause a variety of types of malfunctions in the resulting display, such as:
  • Stuck-ON Pixel These pixels are always ON. In a three-chip RGB (red, green, blue) system, they would be visible as a constant red, green, or blue dot in the display. Such stuck-ON pixels are much more visible in dark areas of the display than bright areas. Stuck-OFF Pixel These pixels are always OFF. In a three-chip RGB system, they would be visible as a constant cyan, magenta, or yellow dot in the display. Such stuck-OFF pixels are much more visible in the bright areas of the display than the dark areas.
  • RGB red, green, blue
  • Partial Response Some pixels may have a portion of their circuitry affected such that they partially respond to the intended color. Perhaps they are of reduced intensity or contrast, but they still track the intended value to some degree.
  • Defective Clump A significant portion of the circuitry in the visible area may be shared between clumps of pixels. A defect in this area may effect the entire clump of pixels and may take any of the above forms.
  • Dead Column / Row Defects in signals generated by the drive circuitry which are fed to every pixel in a column or row will manifest themselves in the entire column or row.
  • the manifestation may take a variety of forms. Although a display having any of the foregoing defects may still be useable, all such defects are significant enough that once noticed, the user will be unhappy. The only exception being perhaps a few isolated stuck-OFF pixels in the display used for the blue channel, due to the low contrast sensitivity of human vision to blue light.
  • a previously known method for dealing with such defects is to provide redundant circuitry in the display that can be selected to drive a pixel or column of pixels in the event of a defect in the primary circuitiy.
  • the methods and apparatus of the present invention provide the aforementioned and other advantages.
  • the present invention provides methods and apparatus for repairing inoperative pixels in a display.
  • the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and connecting such pixels to the working drive circuit of a nearby pixel.
  • the "repaired" pixel will then display the same value as the nearby pixel that it is connected to.
  • neighboring pixels are highly likely to be displaying similar values, the resulting slight error in the image is very well below acceptable limits for almost all applications.
  • Most viewers find it difficult to detect such an artifact at all even when it is pointed out to them. As the display resolution goes higher, this type of repair becomes even more difficult to detect.
  • an electronic display which is capable of repairing inoperative pixels.
  • the display comprises a plurality of pixels with drive circuitry for controlling the pixels.
  • Means for disconnecting an inoperative pixel from its defective drive circuitry are provided.
  • the inoperative pixel is then provided with a connection to a working drive circuit of a nearby pixel.
  • the means for connecting the inoperative pixel to a working drive circuit may comprise additional circuitry associated with each pixel in the display. This additional circuitry connects the inoperative pixel to the working drive circuit of a nearby pixel.
  • the additional circuitry may comprise a bypass bit latch.
  • the bypass bit When the bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel.
  • the bypass bit may be loaded from an external memory after the display is turned ON.
  • multiplexing circuitry associated with the bypass bit latch may be provided.
  • the additional circuitry may further comprise a tri-state transistor associated with each pixel connected to the bypass bit latch and a resistor coupling neighboring pixels.
  • the transistor is switched to bypass the defective drive circuitry so that the inoperative pixel is driven from the working drive circuit of a nearby pixel through the resistor.
  • the additional circuitry may comprise a resistive connection between neighboring pixel metal layers.
  • the defective drive circuitry can be discom ected from the inoperative by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the resistive connection.
  • the additional circuitry may comprise a capacitive connection between neighboring pixel metal layers.
  • the defective drive circuitry can be disconnected from the inoperative pixel by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the capacitive connection.
  • the via may be severed, for example, by laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, physical cutting or removal of the metal using a sharp or abrasive implement or probe, or by any other suitable technique.
  • the pixels may be repaired individually or in groups (i.e., groups of up to 8 adjacent inoperative pixels may be repaired without significantly impacting the quality of the display).
  • the display may also comprise test circuitry to identify the defective drive circuitry.
  • the pixel drive circuitry associated with each pixel may be located adjacent to each pixel or located separately from each pixel.
  • the display may be a liquid crystal micro-display or a similar display device.
  • Figure 1 illustrates an embodiment of a liquid crystal micro-display assembly in accordance with the present invention
  • Figure 2 shows a schematic representation of an embodiment of repair circuitry in accordance with the present invention
  • Figure 3 shows a schematic representation of a further embodiment of repair circuitry in accordance with the present invention.
  • Figure 4 shows an alternate embodiment of repair circuitry in accordance with the present invention
  • FIG. 5 shows another alternate embodiment of repair circuity in accordance with the present invention.
  • Figure 6 shows examples of various pixel repair configurations.
  • the present invention relates to methods and apparatus for repairing inoperative pixels in a display.
  • the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and connecting such pixels to the working drive circuit of a nearby pixel.
  • the invention is particularly adapted for use with a traditional reflective liquid crystal on complimentary metal oxide semiconductor (FLC-on-CMOS) micro-display assembly with the LC material being placed on top of a CMOS control chip. Pads on the top layer of the CMOS chip provide both electrical control of the LC material as well as the optical mirror for the light.
  • FLC-on-CMOS complimentary metal oxide semiconductor
  • Such a display may have 8.3 million pixels arranged as 3840 pixels by 2160 pixels. The pixels may be on a 15 ⁇ m pitch. The size of the active area of this exemplary display is thus 57.6 x 32.4mm. Additional control circuitry and frame buffer memory (e.g., Dynamic Random Access Memory (DRAM)) along the two long sides of the circuit may be 61.4 x 3mm. Input/output (I/O) pads and an LCD seal ring would add another couple few millimeters to the overall dimensions of the chip, but these areas would be relatively immune from the very small defects typical of the CMOS process. The invention is also applicable to displays of varying sizes and types. A significant amount of functionality in the circuitry under each pixel is desired.
  • DRAM Dynamic Random Access Memory
  • the basic modulation for each pixel may be, for example, a 10-bit counter running on a chirped clock to produce a log or gamma-corrected response.
  • Generation of the pulse timing required by the LC material is also required under each pixel. Diagnostic capabilities may be included to verify correct operation of the control circuit for each pixel.
  • an additional 10 bits of storage may be desired to allow loading of the data for a next frame to be distributed over the entire frame time. Fitting this circuitry in the available space has proven challenging and drives the design towards a larger pixel pitch compared to existing designs. The smallest feasible CMOS feature sizes are also utilized. Even still, for the desired complex pixel control functionality, typical prior art redundant repair circuitry is problematic to provide in the available space.
  • FIG. 1 illustrates the arrangement of a liquid crystal-micro display in accordance with the present invention.
  • Display area 10 is divided into several sections due to the differing impacts that defects in each section will have on the display yield.
  • Pixel drive and repair circuitry 12 covers the majority of the device area (e.g., the pixel drive circuitry comprises 92% of the active area or approximately 17.2 cm 2 and the pixel repair circuitry comprises 4% of the active area or approximately 0.07 cm 2 ). By providing the repair mechanisms described herein, most types of defects in this circuitry can be tolerated and still result in acceptable devices.
  • Signal distribution buffer circuitry 14 may comprise 4% of the active area of the display or approximately 0.07 cm 2 . Signals in the display are routed to every pixel in a column. Distribution buffer circuitry 14 will be required to fan these signals out over the large number of loads and distances and still meet timing requirements. Defects in these buffers will render large portions of the display inoperable and render the display unusable. Column signal generation logic (1.2 cm 2 ) and Buffer DRAM (1.8 cm 2 ) are provided at 16. Column signal generation logic generates the signals for each column. Defects in this area are highly likely to render the entire display unusable since the error is likely to impact a large area of the display such as an entire column or more. Buffer DRAM is similar to conventional DRAM. If yield is a problem in this area, traditional DRAM techniques of including spare rows and columns can be employed.
  • I/O pads 18 are provided. These features typically do not contribute to low yield. Cover Glass Glue-Down Area 20 also consumes a portion of the wafer, but typically does not have any features that would contribute to low yield.
  • an electronic display 10 is provided which is capable of repairing inoperative pixels.
  • the display comprises a plurality of pixels with drive circuitry 12 for controlling the pixels. Means for disconnecting an inoperative pixel from its defective drive circuitry are provided. The inoperative pixel is then provided with a connection to a working drive circuit of a nearby pixel.
  • the means for connecting the inoperative pixel to a working drive circuit may comprise additional circuitry associated with each pixel in the display that connects the inoperative pixel to the working drive circuit of a nearby pixel.
  • the additional circuitry may comprise discrete or integrated circuitry.
  • the additional circuitry may comprise bypass bit latches 34, 44 which can select the source of the drive signal for pixels 30, 40. When a bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel.
  • the bypass bit may be loaded from an external memory after the display is turned ON. For example, in Figure 2, assume that pixel 30 is inoperative due to defective drive circuitry 32.
  • bypass bit 34 associated with the inoperative pixel 30 is set such that defective drive circuitry 32 is bypassed and inoperative pixel 30 is driven by working drive circuitry 42 of a nearby pixel 40.
  • multiplexing circuitry 36, 46 associated with bypass bit latches 34, 44 may be provided.
  • the additional circuitry may alternatively comprise instate transistors 38, 48 associated with each respective pixel 30, 40.
  • Transistors 38, 48 are connected to respective bypass bit latches 34, 44 and resistor 50 couples neighboring pixels 30, 40.
  • Resistor 50 may be any suitable resistor, such as a discrete resistor, an integrated circuit resistor fabricated in metal, polysilicon, or any other suitable resistive material.
  • pixel 30 is inoperative due to defective drive circuitry 32.
  • bypass bit 34 is set, the transistor 38 is switched to bypass defective drive circuitry 32 so that inoperative pixel 30 is driven from working drive circuit 42 of nearby pixel 40 through the resistor 50.
  • the additional circuitry may comprise a resistor 52 coupled between pixel metal layers of nearby pixels 31, 41.
  • Resistor 52 may comprise a discrete or integrated circuit resistor fabricated in metal, polysilicon, or any other suitable resistive material. Assuming that pixel 31 is inoperative due to defective drive circuitry 32, defective drive circuitry 32 can be disconnected from the inoperative pixel 31 by severing a via 55 connecting defective drive circuitry 32 to inoperative pixel 31, such that inoperative pixel 31 is driven by a nearby pixel 41 through the resistor 52. Because the pixel drive waveform typically consists of pulses of very low duty cycle, resistor 52 typically will not contribute significantly to the power dissipation of the device.
  • resistor 52 typically will be sufficient to drive the pixel 31 with essentially the same waveform as pixel 41.
  • the additional circuitry may alternatively comprise a capacitor 54 coupled between pixel metal layers of nearby pixels 31, 41. Assuming pixel 31 is inoperative due to defective drive circuitry 32, the defective drive circuitry 32 can be disconnected from the inoperative pixel by severing a via 55 connecting the defective drive circuitry 32 to the inoperative pixel 31, such that the inoperative pixel 31 is driven by a nearby pixel 41 through the capacitor 54.
  • Capacitor 54 may be fo ⁇ ned from a pixel metal layer normally used for light-blocking or may comprise any other suitable capacitive connection.
  • the via 55 may be severed, for example, by laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, physical cutting or removal of the metal using a sharp or abrasive implement or probe, or by any other suitable technique.
  • the via 55 may comprise a fuseable link between the drive circuitry and the pixel, and the link may be "blown", e.g., by applying a suitable short circuit voltage across the link, or by any other suitable technique.
  • the pixels may be repaired individually or in groups.
  • the amount of circuitry per pixel is reduced by sharing the bypass bit latch amongst a group of pixels. If the drive circuit for any pixel in the group fails, the bypass bit is set for that group, and each pixel in the group is then driven by the circuitry of a nearby pixel.
  • the drive circuit used for each repaired pixel may be different or the same for each pixel in the group. Even though some working pixels are bypassed in the group, the overall quality of the display is still improved by removing the stuck-ON or stuck- OFF defect(s).
  • Groups may be any size depending on the demands of the application, but typically groups larger than 8 pixels begin to have diminishing returns in terms of space saved in relation to quality of the repair.
  • Figure 6 shows examples of various pixel repair configurations, including examples of individual pixel repair and examples of various pixel repair groupings.
  • the defective pixels 101 may be driven by an adjacent pixel located either to the left or the right of the defective pixel (e.g., pixels 102 and 103).
  • a 4 pixel group (2 X 2) of defective pixels is repaired by driving the defective pixels 201 using the drive circuitry of pixels located to the left (202, 203) or the right (204, 205) of the 4 pixel group.
  • an 8 pixel group (4 X 2) of defective pixels 301 is repaired using pixels located above (302, 303), below (304, 305), to the left (306, 307) and to the right (308, 309).
  • a 16 pixel group (4 X 4) of defective pixels 401 is repaired using pixels above (402, 403), below (404, 405), to the left (406, 407, 408, 409), and to the right (410, 411, 412, 413).
  • Pixels 402, 403, 404, and 405 are shown as driving a respective adjacent pixel as well as a respective pixel located in the interior of the 4 X 4 defective pixel block 401. It will be appreciated that any of the other pixels (406-413) can be used to drive an adjacent pixel and an interior pixel.
  • a defective pixel may be driven by any of the adjacent pixels (including for example, pixels located above, below, or diagonally from the defective pixels). Further, it will be appreciated that defective pixels may be repaired by connecting the defective pixels to the drive circuitry of non-adjacent pixels (as shown, for example, in repair example 400).
  • the display may also comprise test circuitry to identify the defective drive circuitry. For example, all the pixels in a row may be tested in parallel using wired-OR and wired- AND circuitry. Rows with an inoperative pixel will then be subject to an additional series of tests to identify the exact pixel in the row that is inoperative.
  • the pixel drive circuitry associated with each pixel may be located adjacent to each pixel or located separately from each pixel. Moving the drive circuitry for each pixel so it is not necessarily physically located under the pixel that it drives allows for nearby repair partner pixels with non-adjacent drive circuitry. Depending on the size of defects that may occur, the drive circuitry for repair partners can be located one, two, or more pixels away from the pixels that they drive. Since the total number of defects typically is small, the probability of two independent defects damaging any given pair of repair partner pixels becomes negligible.
  • the display may be a liquid crystal micro-display or other suitable displays that comprise integrated circuit manufacturing techniques.
  • the present invention provides an improved method and apparatus for repairing inoperative pixels in a display.
  • the invention provides an improved method and apparatus for repairing defective pixels in a liquid crystal micro-display without the need to provide redundant drive circuitry underneath each pixel.

Abstract

Methods and apparatus for repairing inoperative pixels in a display (10) are provided. In particular, the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels (30) from their defective drive circuitry (32) and tying such pixels to the working drive circuit (42) of a nearby pixel. A display can be repaired without the need to provide redundant drive circuitry underneath each pixel (30, 40).

Description

METHODS AND APPARATUS FOR REPAIRING INOPERATIVE PIXELS
IN A DISPLAY
BACKGROUND OF THE INVENTION
The present invention provides methods and apparatus for repairing inoperative pixels in a display. In particular, the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and tying such pixels to the working drive circuit of a nearby pixel.
Manufacturing of displays, such as liquid crystal (LC) micro-displays, with very large numbers of pixels is hampered by low yield rates due to the large area of semiconductor material (e.g., Complementary Metal Oxide Semiconductor (CMOS)) required for each device. Nevertheless, displays can actually tolerate a certain level of various types of defects and still be considered acceptable. Additionally, there are various techniques that have been developed and successfully applied to other display technologies that can reduce the visibility of some types of defects and dramatically increase the yield of acceptable displays.
For example, on a device size suitable to hold 8 million pixels (approximately 32 x 58 mm), without any repair strategy, the yield of "perfect" display devices is estimated at less than 2% (assumed defect rate of 0.2 / cm2). Defects in the microelectronic circuitry can cause a variety of types of malfunctions in the resulting display, such as:
Stuck-ON Pixel These pixels are always ON. In a three-chip RGB (red, green, blue) system, they would be visible as a constant red, green, or blue dot in the display. Such stuck-ON pixels are much more visible in dark areas of the display than bright areas. Stuck-OFF Pixel These pixels are always OFF. In a three-chip RGB system, they would be visible as a constant cyan, magenta, or yellow dot in the display. Such stuck-OFF pixels are much more visible in the bright areas of the display than the dark areas.
Stuck-Intermediate Some pixels can get stuck in an intermediate state. Depending on the intended color of the pixel and the surrounding area of the display, they will sometimes appear as red, green, or blue, and at other times will appear as the complement of the color channel affected.
Partial Response Some pixels may have a portion of their circuitry affected such that they partially respond to the intended color. Perhaps they are of reduced intensity or contrast, but they still track the intended value to some degree.
Defective Clump A significant portion of the circuitry in the visible area may be shared between clumps of pixels. A defect in this area may effect the entire clump of pixels and may take any of the above forms.
Dead Column / Row Defects in signals generated by the drive circuitry which are fed to every pixel in a column or row will manifest themselves in the entire column or row. The manifestation may take a variety of forms. Although a display having any of the foregoing defects may still be useable, all such defects are significant enough that once noticed, the user will be unhappy. The only exception being perhaps a few isolated stuck-OFF pixels in the display used for the blue channel, due to the low contrast sensitivity of human vision to blue light. A previously known method for dealing with such defects is to provide redundant circuitry in the display that can be selected to drive a pixel or column of pixels in the event of a defect in the primary circuitiy. As it is already difficult to fit all required circuitry in the space available in such micro — displays, the inclusion of redundant circuitry becomes problematic. It would be advantageous to provide a method of repairing inoperative pixels in a display without requiring redundant circuitry in order to increase the yield rate of such displays.
The methods and apparatus of the present invention provide the aforementioned and other advantages.
SUMMARY OF THE INVENTION
The present invention provides methods and apparatus for repairing inoperative pixels in a display. In particular, the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and connecting such pixels to the working drive circuit of a nearby pixel.
The "repaired" pixel will then display the same value as the nearby pixel that it is connected to. However, since in most images, neighboring pixels are highly likely to be displaying similar values, the resulting slight error in the image is very well below acceptable limits for almost all applications. Most viewers find it difficult to detect such an artifact at all even when it is pointed out to them. As the display resolution goes higher, this type of repair becomes even more difficult to detect.
In an illustrated embodiment of the present invention, an electronic display is provided which is capable of repairing inoperative pixels. The display comprises a plurality of pixels with drive circuitry for controlling the pixels. Means for disconnecting an inoperative pixel from its defective drive circuitry are provided. The inoperative pixel is then provided with a connection to a working drive circuit of a nearby pixel.
The means for connecting the inoperative pixel to a working drive circuit may comprise additional circuitry associated with each pixel in the display. This additional circuitry connects the inoperative pixel to the working drive circuit of a nearby pixel.
In one embodiment, the additional circuitry may comprise a bypass bit latch. When the bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel. The bypass bit may be loaded from an external memory after the display is turned ON. In addition, multiplexing circuitry associated with the bypass bit latch may be provided.
Alternatively, the additional circuitry may further comprise a tri-state transistor associated with each pixel connected to the bypass bit latch and a resistor coupling neighboring pixels. When the bypass bit is set, the transistor is switched to bypass the defective drive circuitry so that the inoperative pixel is driven from the working drive circuit of a nearby pixel through the resistor.
In a further embodiment, the additional circuitry may comprise a resistive connection between neighboring pixel metal layers. The defective drive circuitry can be discom ected from the inoperative by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the resistive connection.
Alternatively, the additional circuitry may comprise a capacitive connection between neighboring pixel metal layers. The defective drive circuitry can be disconnected from the inoperative pixel by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the capacitive connection.
The via may be severed, for example, by laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, physical cutting or removal of the metal using a sharp or abrasive implement or probe, or by any other suitable technique. The pixels may be repaired individually or in groups (i.e., groups of up to 8 adjacent inoperative pixels may be repaired without significantly impacting the quality of the display).
In a further embodiment, the display may also comprise test circuitry to identify the defective drive circuitry. The pixel drive circuitry associated with each pixel may be located adjacent to each pixel or located separately from each pixel.
The display may be a liquid crystal micro-display or a similar display device. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates an embodiment of a liquid crystal micro-display assembly in accordance with the present invention;
Figure 2 shows a schematic representation of an embodiment of repair circuitry in accordance with the present invention;
Figure 3 shows a schematic representation of a further embodiment of repair circuitry in accordance with the present invention;
Figure 4 shows an alternate embodiment of repair circuitry in accordance with the present invention;
Figure 5 shows another alternate embodiment of repair circuity in accordance with the present invention; and
Figure 6 shows examples of various pixel repair configurations.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to methods and apparatus for repairing inoperative pixels in a display. In particular, the present invention provides methods and apparatus for improving the effective yield rates of displays, such as liquid crystal micro-displays, by disconnecting inoperative pixels from their defective drive circuitry and connecting such pixels to the working drive circuit of a nearby pixel.
The invention is particularly adapted for use with a traditional reflective liquid crystal on complimentary metal oxide semiconductor (FLC-on-CMOS) micro-display assembly with the LC material being placed on top of a CMOS control chip. Pads on the top layer of the CMOS chip provide both electrical control of the LC material as well as the optical mirror for the light.
Such a display may have 8.3 million pixels arranged as 3840 pixels by 2160 pixels. The pixels may be on a 15μm pitch. The size of the active area of this exemplary display is thus 57.6 x 32.4mm. Additional control circuitry and frame buffer memory (e.g., Dynamic Random Access Memory (DRAM)) along the two long sides of the circuit may be 61.4 x 3mm. Input/output (I/O) pads and an LCD seal ring would add another couple few millimeters to the overall dimensions of the chip, but these areas would be relatively immune from the very small defects typical of the CMOS process. The invention is also applicable to displays of varying sizes and types. A significant amount of functionality in the circuitry under each pixel is desired.
The basic modulation for each pixel may be, for example, a 10-bit counter running on a chirped clock to produce a log or gamma-corrected response. Generation of the pulse timing required by the LC material is also required under each pixel. Diagnostic capabilities may be included to verify correct operation of the control circuit for each pixel. Finally, an additional 10 bits of storage may be desired to allow loading of the data for a next frame to be distributed over the entire frame time. Fitting this circuitry in the available space has proven challenging and drives the design towards a larger pixel pitch compared to existing designs. The smallest feasible CMOS feature sizes are also utilized. Even still, for the desired complex pixel control functionality, typical prior art redundant repair circuitry is problematic to provide in the available space.
Figure 1 illustrates the arrangement of a liquid crystal-micro display in accordance with the present invention. Display area 10 is divided into several sections due to the differing impacts that defects in each section will have on the display yield. Pixel drive and repair circuitry 12 covers the majority of the device area (e.g., the pixel drive circuitry comprises 92% of the active area or approximately 17.2 cm2 and the pixel repair circuitry comprises 4% of the active area or approximately 0.07 cm2). By providing the repair mechanisms described herein, most types of defects in this circuitry can be tolerated and still result in acceptable devices.
Signal distribution buffer circuitry 14 may comprise 4% of the active area of the display or approximately 0.07 cm2. Signals in the display are routed to every pixel in a column. Distribution buffer circuitry 14 will be required to fan these signals out over the large number of loads and distances and still meet timing requirements. Defects in these buffers will render large portions of the display inoperable and render the display unusable. Column signal generation logic (1.2 cm2) and Buffer DRAM (1.8 cm2) are provided at 16. Column signal generation logic generates the signals for each column. Defects in this area are highly likely to render the entire display unusable since the error is likely to impact a large area of the display such as an entire column or more. Buffer DRAM is similar to conventional DRAM. If yield is a problem in this area, traditional DRAM techniques of including spare rows and columns can be employed.
Input/output (I/O) pads 18 are provided. These features typically do not contribute to low yield. Cover Glass Glue-Down Area 20 also consumes a portion of the wafer, but typically does not have any features that would contribute to low yield. In an illustrated embodiment of the present invention as shown in Figure 1, an electronic display 10 is provided which is capable of repairing inoperative pixels. The display comprises a plurality of pixels with drive circuitry 12 for controlling the pixels. Means for disconnecting an inoperative pixel from its defective drive circuitry are provided. The inoperative pixel is then provided with a connection to a working drive circuit of a nearby pixel.
Using the drive circuitry 12 of a neighboring pixel to drive an otherwise inoperative pixel will result in the two pixels displaying the same intensity. Visual artifacts will typically be visible in the case of high contrast textures and edges moving across the two tied-together pixels at a slow rate.
The means for connecting the inoperative pixel to a working drive circuit may comprise additional circuitry associated with each pixel in the display that connects the inoperative pixel to the working drive circuit of a nearby pixel. The additional circuitry may comprise discrete or integrated circuitry. In one embodiment as shown in Figure 2, the additional circuitry may comprise bypass bit latches 34, 44 which can select the source of the drive signal for pixels 30, 40. When a bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel. The bypass bit may be loaded from an external memory after the display is turned ON. For example, in Figure 2, assume that pixel 30 is inoperative due to defective drive circuitry 32. After the display is turned ON, bypass bit 34 associated with the inoperative pixel 30 is set such that defective drive circuitry 32 is bypassed and inoperative pixel 30 is driven by working drive circuitry 42 of a nearby pixel 40. In addition, multiplexing circuitry 36, 46 associated with bypass bit latches 34, 44 may be provided. An advantage of such an arrangement is that testing and repair can be accomplished at any time in the manufacturing process, even after assembly of the LCD.
As shown in Figure 3, the additional circuitry may alternatively comprise instate transistors 38, 48 associated with each respective pixel 30, 40. Transistors 38, 48 are connected to respective bypass bit latches 34, 44 and resistor 50 couples neighboring pixels 30, 40. Resistor 50 may be any suitable resistor, such as a discrete resistor, an integrated circuit resistor fabricated in metal, polysilicon, or any other suitable resistive material. As an example, assume that pixel 30 is inoperative due to defective drive circuitry 32. When bypass bit 34 is set, the transistor 38 is switched to bypass defective drive circuitry 32 so that inoperative pixel 30 is driven from working drive circuit 42 of nearby pixel 40 through the resistor 50. An advantage of such an arrangement is that testing and repair can be accomplished at any time in the manufacturing process, even after assembly of the LCD.
In a further embodiment as shown in Figure 4, the additional circuitry may comprise a resistor 52 coupled between pixel metal layers of nearby pixels 31, 41. Resistor 52 may comprise a discrete or integrated circuit resistor fabricated in metal, polysilicon, or any other suitable resistive material. Assuming that pixel 31 is inoperative due to defective drive circuitry 32, defective drive circuitry 32 can be disconnected from the inoperative pixel 31 by severing a via 55 connecting defective drive circuitry 32 to inoperative pixel 31, such that inoperative pixel 31 is driven by a nearby pixel 41 through the resistor 52. Because the pixel drive waveform typically consists of pulses of very low duty cycle, resistor 52 typically will not contribute significantly to the power dissipation of the device.
Additionally, since the current flowing for each pixel typically is very small, resistor 52 typically will be sufficient to drive the pixel 31 with essentially the same waveform as pixel 41.
As shown in Figure 5, the additional circuitry may alternatively comprise a capacitor 54 coupled between pixel metal layers of nearby pixels 31, 41. Assuming pixel 31 is inoperative due to defective drive circuitry 32, the defective drive circuitry 32 can be disconnected from the inoperative pixel by severing a via 55 connecting the defective drive circuitry 32 to the inoperative pixel 31, such that the inoperative pixel 31 is driven by a nearby pixel 41 through the capacitor 54. Capacitor 54 may be foπned from a pixel metal layer normally used for light-blocking or may comprise any other suitable capacitive connection. The via 55 may be severed, for example, by laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, physical cutting or removal of the metal using a sharp or abrasive implement or probe, or by any other suitable technique. The via 55 may comprise a fuseable link between the drive circuitry and the pixel, and the link may be "blown", e.g., by applying a suitable short circuit voltage across the link, or by any other suitable technique.
The pixels may be repaired individually or in groups. In one embodiment of the invention, the amount of circuitry per pixel is reduced by sharing the bypass bit latch amongst a group of pixels. If the drive circuit for any pixel in the group fails, the bypass bit is set for that group, and each pixel in the group is then driven by the circuitry of a nearby pixel. The drive circuit used for each repaired pixel may be different or the same for each pixel in the group. Even though some working pixels are bypassed in the group, the overall quality of the display is still improved by removing the stuck-ON or stuck- OFF defect(s). Groups may be any size depending on the demands of the application, but typically groups larger than 8 pixels begin to have diminishing returns in terms of space saved in relation to quality of the repair.
Figure 6 shows examples of various pixel repair configurations, including examples of individual pixel repair and examples of various pixel repair groupings. In the repair example 100, the defective pixels 101 may be driven by an adjacent pixel located either to the left or the right of the defective pixel (e.g., pixels 102 and 103). In repair example 200, a 4 pixel group (2 X 2) of defective pixels is repaired by driving the defective pixels 201 using the drive circuitry of pixels located to the left (202, 203) or the right (204, 205) of the 4 pixel group. In repair example 300, an 8 pixel group (4 X 2) of defective pixels 301 is repaired using pixels located above (302, 303), below (304, 305), to the left (306, 307) and to the right (308, 309). In repair example 400, a 16 pixel group (4 X 4) of defective pixels 401 is repaired using pixels above (402, 403), below (404, 405), to the left (406, 407, 408, 409), and to the right (410, 411, 412, 413). Pixels 402, 403, 404, and 405 are shown as driving a respective adjacent pixel as well as a respective pixel located in the interior of the 4 X 4 defective pixel block 401. It will be appreciated that any of the other pixels (406-413) can be used to drive an adjacent pixel and an interior pixel.
The repair examples shown in Figure 6 are illustrative examples, and it will be appreciated that a defective pixel may be driven by any of the adjacent pixels (including for example, pixels located above, below, or diagonally from the defective pixels). Further, it will be appreciated that defective pixels may be repaired by connecting the defective pixels to the drive circuitry of non-adjacent pixels (as shown, for example, in repair example 400).
In a further embodiment, the display may also comprise test circuitry to identify the defective drive circuitry. For example, all the pixels in a row may be tested in parallel using wired-OR and wired- AND circuitry. Rows with an inoperative pixel will then be subject to an additional series of tests to identify the exact pixel in the row that is inoperative.
The pixel drive circuitry associated with each pixel may be located adjacent to each pixel or located separately from each pixel. Moving the drive circuitry for each pixel so it is not necessarily physically located under the pixel that it drives allows for nearby repair partner pixels with non-adjacent drive circuitry. Depending on the size of defects that may occur, the drive circuitry for repair partners can be located one, two, or more pixels away from the pixels that they drive. Since the total number of defects typically is small, the probability of two independent defects damaging any given pair of repair partner pixels becomes negligible. The display may be a liquid crystal micro-display or other suitable displays that comprise integrated circuit manufacturing techniques.
It should now be appreciated that the present invention provides an improved method and apparatus for repairing inoperative pixels in a display. In particular, the invention provides an improved method and apparatus for repairing defective pixels in a liquid crystal micro-display without the need to provide redundant drive circuitry underneath each pixel.
Although the invention has been described in connection with various preferred embodiments, it should be appreciated that numerous adaptations and modifications can be made thereto without departing from the scope of the invention as set forth in the claims. In particular, the invention is not limited to liquid crystal micro displays, and can be used in connection with the many different types of display technology.

Claims

What is claimed is:
1. A method for repairing inoperative pixels in a display, comprising: identifying defective drive circuitry for the inoperative pixel; disconnecting the defective drive circuitry from the inoperative pixel; and connecting the inoperative pixel to a working drive circuit of a nearby pixel.
2. A method in accordance with claim 1, wherein the step of connecting the inoperative pixel to a working drive circuit of a nearby pixel further comprises: providing additional circuitry associated with each pixel in the display, which circuitry connects the inoperative pixel to the working drive circuit of a nearby pixel.
3. A method in accordance with claim 2, wherein the additional circuitry comprises a bypass bit latch, such that when the bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel.
4. A method in accordance with claim 3, wherein the bypass bit is loaded from an external memory after the display is turned on.
5. A method in accordance with claim 3, wherein the step of providing additional circuitry further comprises: multiplexing the drive circuits of each pixel with the drive circuit of a nearby pixel.
6. A method in accordance with claim 3, wherein the additional circuitry further comprises: a tri-state transistor associated with each pixel connected to the bypass bit latch; and a resistor coupling neighboring pixels; such that when the bypass bit is set, the transistor is switched to bypass the defective drive circuitry so that the inoperative pixel is driven from the working drive circuit of a nearby pixel through the resistor.
7. A method in accordance with claim 2, wherein the additional circuitry comprises: a resistive connection between neighboring pixel metal layers; wherein disconnecting the defective drive circuitry is accomplished by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the resistive connection.
8. A method in accordance with claim 7, wherein the via is severed by one of laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, or physical cutting or removal of the metal using a sharp or abrasive implement or probe.
9. A method in accordance with claim 2, wherein the additional circuitry comprises: a capacitive connection between neighboring pixel metal layers; wherein disconnecting the defective drive circuitry is accomplished by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the capacitive connection.
10. A method in accordance with claim 9, wherein the via is severed by one of laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, or physical cutting or removal of the metal using a sharp or abrasive implement or probe.
11. A method in accordance with claim 1 , wherein the pixels are repaired in groups.
12. A method in accordance with claim 1, wherein identifying defective drive circuitry comprises the further step of providing test circuitry associated with the display.
13. A method in accordance with claim 1, wherein the pixel drive circuitry associated with each pixel is located separately from each pixel.
14. A method in accordance with claim 1, wherein the display is a liquid crystal micro-display.
15. An electronic display apparatus capable of repairing inoperative pixels, comprising: a plurality of pixels; drive circuitry for controlling the pixels; means for disconnecting defective drive circuitry from an inoperative pixel; and means for connecting the inoperative pixel to a working drive circuit of a nearby pixel.
16. Apparatus in accordance with claim 15, wherein the means for connecting the inoperative pixel to a working drive circuit comprises: additional circuitry associated with each pixel in the display, which circuitry connects the inoperative pixel to the working drive circuit of a nearby pixel.
17. Apparatus in accordance with claim 16, wherein the additional circuitry comprises a bypass bit latch, such that when the bypass bit is set, the defective drive circuitry is bypassed and the inoperative pixel is driven from the working drive circuit of a nearby pixel.
18. Apparatus in accordance with claim 17, wherein the bypass bit is loaded from an external memory after the display is turned on.
19. Apparatus in accordance with claim 17, wherein the additional circuitry further comprises: multiplexing circuitry associated with the bypass bit latch.
20. Apparatus in accordance with claim 17, wherein the additional circuitry further comprises: a tri-state transistor associated with each pixel connected to the bypass bit latch; and a resistor coupling neighboring pixels; such that when the bypass bit is set, the transistor is switched to bypass the defective drive circuitry so that the inoperative pixel is driven from the working drive circuit of a nearby pixel through the resistor.
21. Apparatus in accordance with claim 16, wherein the additional circuitry comprises: a resistive connection between neighboring pixel metal layers; wherein the defective drive circuitry can be disconnected from the inoperative pixel by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the resistive connection.
22. Apparatus in accordance with claim 21, wherein the via is severed by one of laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, or physical cutting or removal of the metal using a sharp or abrasive implement or probe.
23. Apparatus in accordance with claim 16, wherein the additional circuitry comprises: a capacitive connection between neighboring pixel metal layers; wherein the defective drive circuitry can be disconnected from the inoperative pixel using by severing a via connecting the defective drive circuitry to the inoperative pixel, such that the inoperative pixel is driven by a nearby pixel through the capacitive connection.
24. Apparatus in accordance with claim 23, wherein the via is severed by one of laser ablation, melting or ablation of a fusible link by passing sufficient current through it, selective chemical etching using a photoresist or other selection means, melting or ablation with an electron beam, melting or ablation with a focused microwave or other electro-magnetic beam, electro-ionic erosion, or physical cutting or removal of the metal using a sharp or abrasive implement or probe.
25. Apparatus in accordance with claim 15, wherein the pixels are repaired in groups.
26. Apparatus in accordance with claim 15, further comprising test circuitry to identify the defective drive circuitry.
27. Apparatus in accordance with claim 15, wherein the pixel drive circuitry associated with each pixel is located separately from each pixel.
28. Apparatus in accordance with claim 15, wherein the display comprises a liquid crystal micro-display.
PCT/US2001/047191 2000-12-22 2001-12-03 Methods and apparatus for repairing inoperative pixels in a display WO2002052336A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP01995433A EP1344103A2 (en) 2000-12-22 2001-12-03 Methods and apparatus for repairing inoperative pixels in a display

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/748,623 US7280090B2 (en) 2000-12-22 2000-12-22 Methods and apparatus for repairing inoperative pixels in a display
US09/748,623 2000-12-22

Publications (2)

Publication Number Publication Date
WO2002052336A2 true WO2002052336A2 (en) 2002-07-04
WO2002052336A3 WO2002052336A3 (en) 2003-03-13

Family

ID=25010222

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/047191 WO2002052336A2 (en) 2000-12-22 2001-12-03 Methods and apparatus for repairing inoperative pixels in a display

Country Status (3)

Country Link
US (3) US7280090B2 (en)
EP (1) EP1344103A2 (en)
WO (1) WO2002052336A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7460688B2 (en) * 2004-12-09 2008-12-02 Aptina Imaging Corporation System and method for detecting and correcting defective pixels in a digital image sensor

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4622674B2 (en) * 2005-05-23 2011-02-02 パナソニック株式会社 Liquid crystal display device
US7551215B2 (en) * 2006-03-15 2009-06-23 Dalsa Corporation CMOS-based sensor apparatus with cells that comprise a redundancy facility that is selectively activatable for isolating a metal-to-metal short on the basis of externally applied control actuation
KR101255311B1 (en) * 2006-06-29 2013-04-15 엘지디스플레이 주식회사 Flat Panel Display and Method of Controlling Picture Quality thereof
JP4277055B2 (en) * 2007-05-29 2009-06-10 シャープ株式会社 Drive circuit, display device, and television system
US8587573B2 (en) * 2008-02-28 2013-11-19 Sharp Kabushiki Kaisha Drive circuit and display device
EP2256720A1 (en) 2009-05-29 2010-12-01 Koninklijke Philips Electronics N.V. An intelligent lighting tile system powered from multiple power sources
TWI543130B (en) * 2009-05-29 2016-07-21 皇家飛利浦電子股份有限公司 Cuttable display device, method of providing a cut-to-measure display device for displaying an image using a cuttable display device, and computer-implemented method of positioning a closed two-dimensional contour relative to a two-dimensional lattice of
JP5379664B2 (en) * 2009-12-11 2013-12-25 キヤノン株式会社 Image display device and control method thereof
KR102163034B1 (en) * 2013-12-03 2020-10-07 삼성전자주식회사 Method, apparatus and storage medium for compensating for defect pixel of display
CN107750377B (en) * 2015-06-10 2021-07-09 苹果公司 Display panel redundancy scheme
TWI668508B (en) 2018-08-13 2019-08-11 友達光電股份有限公司 Pixel unit

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0375233A2 (en) * 1988-12-20 1990-06-27 Seiko Epson Corporation Active matrix type display device

Family Cites Families (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2554622B1 (en) * 1983-11-03 1988-01-15 Commissariat Energie Atomique METHOD FOR MANUFACTURING A MATRIX OF ELECTRONIC COMPONENTS
EP0182645B1 (en) * 1984-11-16 1991-01-23 Matsushita Electric Industrial Co., Ltd. Active matrix circuit for liquid crystal displays
US4825201A (en) 1985-10-01 1989-04-25 Mitsubishi Denki Kabushiki Kaisha Display device with panels compared to form correction signals
US5043655A (en) 1989-03-14 1991-08-27 John Fluke Mfg. Co., Inc. Current sensing buffer for digital signal line testing
JP2669954B2 (en) 1991-05-08 1997-10-29 シャープ株式会社 Active matrix display
US5235272A (en) 1991-06-17 1993-08-10 Photon Dynamics, Inc. Method and apparatus for automatically inspecting and repairing an active matrix LCD panel
US5175504A (en) 1991-06-17 1992-12-29 Photon Dynamics, Inc. Method and apparatus for automatically inspecting and repairing a simple matrix circuit panel
FR2679687B1 (en) * 1991-07-26 1997-03-14 Commissariat Energie Atomique LARGE-DIMENSIONAL IMAGE DISPLAY DEVICE OR SOCKET.
US5260818A (en) 1992-05-11 1993-11-09 Industrial Technology Research Institute Display panel provided with repair capability of defective elements
US5659374A (en) 1992-10-23 1997-08-19 Texas Instruments Incorporated Method of repairing defective pixels
US5532853A (en) 1993-03-04 1996-07-02 Samsung Electronics Co., Ltd. Reparable display device matrix for repairing the electrical connection of a bonding pad to its associated signal line
US6313889B1 (en) 1993-03-04 2001-11-06 Samsung Electronics Co., Ltd. Matrix-type display device capable of being repaired in pixel unit
JPH06308532A (en) * 1993-04-27 1994-11-04 Sanyo Electric Co Ltd Liquid crystal display device
KR970010774B1 (en) 1993-12-22 1997-06-30 엘지전자 주식회사 Thin film transistor for liquid crystal device
JP3263250B2 (en) 1994-08-24 2002-03-04 株式会社東芝 Liquid crystal display
JPH08201841A (en) 1994-11-24 1996-08-09 Toshiba Electron Eng Corp Display device and its inspection method
TW280898B (en) * 1994-12-28 1996-07-11 Sharp Kk The matrix type image display apparatus
KR0169385B1 (en) 1995-03-10 1999-03-20 김광호 Thin film transistor substrate for liquid crystal and its manufacturing method
JPH095786A (en) * 1995-06-21 1997-01-10 Advanced Display:Kk Tft array substrate as well as liquid crystal display device formed by using the tft array substrate and production of tft array substrate
JPH0954340A (en) * 1995-08-11 1997-02-25 Sharp Corp Active matrix substrate and method for correcting defect of display device
KR0149309B1 (en) 1995-09-06 1998-10-15 김광호 Lcd with repair line
TW317629B (en) * 1995-11-01 1997-10-11 Samsung Electronics Co Ltd
US6205239B1 (en) 1996-05-31 2001-03-20 Texas Instruments Incorporated System and method for circuit repair
JP4086925B2 (en) 1996-12-27 2008-05-14 株式会社半導体エネルギー研究所 Active matrix display
US6256076B1 (en) * 1997-03-19 2001-07-03 Samsung Electronics Co., Ltd. Liquid crystal displays having switching elements and storage capacitors and a manufacturing method thereof
US6518945B1 (en) * 1997-07-25 2003-02-11 Aurora Systems, Inc. Replacing defective circuit elements by column and row shifting in a flat-panel display
US5976978A (en) 1997-12-22 1999-11-02 General Electric Company Process for repairing data transmission lines of imagers
US6259424B1 (en) * 1998-03-04 2001-07-10 Victor Company Of Japan, Ltd. Display matrix substrate, production method of the same and display matrix circuit
US6339417B1 (en) * 1998-05-15 2002-01-15 Inviso, Inc. Display system having multiple memory elements per pixel
US6147668A (en) * 1998-06-20 2000-11-14 Genesis Microchip Corp. Digital display unit of a computer system having an improved method and apparatus for sampling analog display signals
US6005649A (en) * 1998-07-22 1999-12-21 Rainbow Displays, Inc. Tiled, flat-panel microdisplay array having visually imperceptible seams
JP3761344B2 (en) * 1998-12-01 2006-03-29 トヨタ自動車株式会社 Welding gun and sensor calibration method using it, welding control method, welding spot position accuracy change management method
US6392427B1 (en) 1998-12-21 2002-05-21 Kaitech Engineering, Inc. Testing electronic devices
US6618115B1 (en) * 1999-11-19 2003-09-09 Semiconductor Energy Laboratory Co., Ltd. Defective pixel compensation system and display device using the system
US6816143B1 (en) * 1999-11-23 2004-11-09 Koninklijke Philips Electronics N.V. Self diagnostic and repair in matrix display panel

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0375233A2 (en) * 1988-12-20 1990-06-27 Seiko Epson Corporation Active matrix type display device

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 02, 31 March 1995 (1995-03-31) & JP 06 308532 A (SANYO ELECTRIC CO LTD), 4 November 1994 (1994-11-04) *
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 05, 30 May 1997 (1997-05-30) & JP 09 005786 A (ADVANCED DISPLAY:KK), 10 January 1997 (1997-01-10) *
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 06, 30 June 1997 (1997-06-30) & JP 09 054340 A (SHARP CORP), 25 February 1997 (1997-02-25) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7460688B2 (en) * 2004-12-09 2008-12-02 Aptina Imaging Corporation System and method for detecting and correcting defective pixels in a digital image sensor

Also Published As

Publication number Publication date
US7911433B2 (en) 2011-03-22
US20070279423A1 (en) 2007-12-06
US7911432B2 (en) 2011-03-22
US20070279424A1 (en) 2007-12-06
US20020113766A1 (en) 2002-08-22
EP1344103A2 (en) 2003-09-17
WO2002052336A3 (en) 2003-03-13
US7280090B2 (en) 2007-10-09

Similar Documents

Publication Publication Date Title
US7911432B2 (en) Methods and apparatus for repairing inoperative pixels in a display
US11568789B2 (en) Display panel redundancy schemes
US7816939B2 (en) Liquid crystal display panel and testing and manufacturing methods thereof
US7038484B2 (en) Display device
TWI385453B (en) Liquid crystal display
KR100222311B1 (en) Array substrate of liquid crystal display device, liquid crystal display device with array substrate and manufacturing method of array substrate
US6246074B1 (en) Thin film transistor substrate with testing circuit
US6518945B1 (en) Replacing defective circuit elements by column and row shifting in a flat-panel display
US6590624B1 (en) LCD panels including interconnected test thin film transistors and methods of gross testing LCD panels
JPH11167129A (en) Liquid crystal display device having electrostatic protective circuit and display inspection method utilize this circuit
KR20150101066A (en) Display apparatus and test method thereof
US7796222B2 (en) Display device, inspection method for display device, and inspection device for display device
KR20200046434A (en) Display panel and method of deactivating light emitting diode in display panel
EP1421433B1 (en) Liquid crystal display with redundant column drive circuitry
US11308831B2 (en) LED display panel and repairing method
JP4294096B2 (en) Improved active matrix ESD protection and test system
JP4252528B2 (en) Active matrix type liquid crystal display panel and inspection method thereof
KR101594622B1 (en) Liquid Crystal Display device
KR20070032485A (en) Organic Electroluminescence Array Substrate for performing Sheet Unit Test
AU2002226013A1 (en) Methods and apparatus for repairing inoperative pixels in a display
KR20040061951A (en) PAD structure of small size Liquid Crystal Display for test
JPH079521B2 (en) Method of manufacturing active matrix substrate capable of detecting and repairing point defects
JP2006267787A (en) Display panel and its manufacturing method
KR100819865B1 (en) Substrate for liquid crystal display device
KR19990081493A (en) Liquid Crystal Display with Multiple Repair Lines

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

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: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM 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

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
AK Designated states

Kind code of ref document: A3

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: A3

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM 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: 2002226013

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 2001995433

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2001995433

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWW Wipo information: withdrawn in national office

Ref document number: 2001995433

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP