JP2001133803A - Method of producing liquid crystal display device, liquid crystal display device and laser repair device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a liquid crystal display device by which various kinds of defective pixels such as a bright spot defect can be repaired. SOLUTION: The method of producing the liquid crystal display device having at least two switching elements provided for each pixel includes a process of selecting a switching element to be connected to the pixel having defects and of connecting the selected element to the pixel and a process of irradiating the defective pixel with laser light to at least modify the alignment film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device obtained by repairing a defective portion (defective pixel) of a display screen by irradiating a laser beam, a liquid crystal display device, and these liquid crystal displays. The present invention relates to a laser repair device used in a device manufacturing method.

[0002]

2. Description of the Related Art In recent years, as a display device used for a personal computer, a word processor, or the like, a liquid crystal display device (LCD: low power consumption, thin and lightweight) has been developed.
Liquid Crystal Display) is often used. Among them, as an example, a thin film transistor (TFT) mainly composed of an amorphous silicon (a-Si) film is exemplified.
An active matrix liquid crystal display device that uses thin film transistors (TFTs) as switching elements corresponding to pixels has a low contrast and response deterioration even when configured with a large number of pixels, and is capable of halftone display. It is used as a display device for televisions and office automation.

The TFT is formed on an array substrate, and charges and discharges a pixel electrode constituting a pixel to generate a potential difference between the array substrate and a counter substrate. It adjusts the arrangement of molecules. In recent years, the number of pixels has been increased from several hundred thousand to 100, as a display portion of a liquid crystal display device has become larger or more sophisticated.
It has become more than ten thousand. In other words, it is very difficult to manufacture such a pixel so as to display without causing a defect. For this reason, the TFT cannot be driven normally for some reason, the pixel electrode is not formed properly, or the pixel is not connected to the array substrate. There is a problem that a defective pixel is generated due to a defect that a foreign substance is interposed between the counter substrate and a correct voltage cannot be applied to the pixel electrode, and a normal screen cannot be displayed.

In order to repair (repair) such a defective pixel, a method of processing the alignment film using a laser beam to reduce the transmittance and the reflectance of the pixel so as to correct the defect so that the defect appears to be free. For example, Japanese Patent Application Laid-Open Nos. 60-243635, 5-29787, 5-31
No. 3,167, JP-A-7-225381, JP-A-8-15660, JP-A-9-258155 and the like (these methods are collectively referred to as the first method).
Of the prior art).

Further, a method of repairing a defective pixel by applying a DC voltage by providing a redundant circuit (spare wiring) for relieving the operation of the TFT is disclosed in, for example, JP-A-63-136076 and JP-A-2-3023. No., JP-A-9-80470
JP, JP-A-10-104648, JP-A-10-104648
And Japanese Patent Application Laid-Open No. Hei 10-319438.
Of the prior art).

A method of directly connecting a gate electrode and a drain electrode at a defective portion via a semiconductor layer or an interlayer insulating film by using a laser beam to repair a defective pixel and applying a DC voltage thereto is also disclosed in, for example, Japanese Patent Application Laid-Open No. HEI 9-260,086. It is disclosed in Japanese Patent Application Laid-Open No. 5-210111 (this method is referred to as a third conventional example).

[0007]

However, according to the first conventional example, there is a high probability that laser light irradiation itself succeeds (9).
(0% or more), but the mechanism for repairing defective pixels is not sufficiently disclosed, so that too much energy of the laser beam may be applied to damage the liquid crystal display device, or the corrected pixels may not operate and become black. (In the case of the normally white mode), the transmittance and the reflectance of light at the defective pixel may not meet the preset product standard in some cases.

Further, according to the second conventional example, high display quality can be ensured, but fine work is required, so that the probability of successful laser beam irradiation itself decreases. Although effective for repairing defective pixels caused by TFT malfunctions, defects caused by improper formation of TFTs and wiring and foreign matter caught between the array substrate and the opposing substrate are considered. It is not effective for caused defects. Due to these causes, the probability of successful repair of the defective pixel has been low in total (about 30 to 50%).

In addition, according to the third conventional example, ions present together with the liquid crystal molecules accumulate in the pixel electrode corresponding to the defective pixel due to the DC voltage applied to the pixel electrode, and the life of the liquid crystal display device is reduced. Was to be shortened.

The present invention has been made in view of the above circumstances, and has as its object to positively use a mechanism for repairing a defective pixel and to prevent TFTs and wiring from being formed properly. And defects caused by foreign matter between the array substrate and the opposing substrate, and suppressing the accumulation of ions in the pixel electrode corresponding to the defective pixel. An object of the present invention is to provide a method for manufacturing a liquid crystal display device, a liquid crystal display device, and a laser repair device used for the method for manufacturing these liquid crystal display devices.

[0011]

According to the first aspect of the present invention, at least a first electrode and a first alignment film are formed on a first substrate, and at least a second electrode and a first alignment film are formed on a second substrate. Forming an electrode and a second alignment film, and sealing the substrates while facing each other with a liquid crystal interposed between the first substrate and the second substrate; Performing a test by displaying a screen with a potential difference between the first electrode and the second electrode, and repairing a defective portion of a pixel constituting the screen detected by the test. In the method of manufacturing a liquid crystal display device, wherein the step of repairing,
Selectively and electrically connecting one of the switching elements to the pixel with respect to the switching element at least two of which are mechanically connected to each of the pixels corresponding to the defective pixel; Irradiating the laser beam to the pixel having the defect to at least change the quality of the first alignment film or the second alignment film.

According to a second aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the first aspect, the step of changing the quality of the first alignment film or the second alignment film includes changing one switching element. The method is characterized in that the process is performed on a pixel whose defect is not repaired despite the step of selectively and electrically connecting to the pixel.

According to a third aspect of the present invention, in a method of manufacturing a liquid crystal display device according to the first or second aspect,
The laser light may be 20 ns to 20 ns in a case where the switching element is selectively and electrically connected to the pixel.
It has a pulse width of 0 ns, and 10 ns in the case of the step of at least altering the first alignment film or the second alignment film.
It has the following pulse width.

According to a fourth aspect of the present invention, at least a first electrode and a first alignment film are formed on a first substrate, and at least a second electrode and a second alignment film are formed on a second substrate. A step of forming an alignment film, a step of sealing the first substrate and the second substrate while opposing each other in a state where liquid crystal is interposed between the first substrate and the second substrate, Performing a test by causing a potential difference between the second electrode and the screen to display a screen, and irradiating a laser beam to a pixel of a portion where a defect of a pixel constituting the screen detected in the test has occurred; Repairing the defective pixel by modifying at least the first alignment film or the second alignment film, wherein the repairing is performed by the repairing step. , For the defective pixel Irradiating a pulsed laser beam having an irradiation surface smaller than the size of the pixel so that the plurality of irradiation surfaces are separated from each other, and the irradiation step substantially eliminates the alignment film on the irradiation surface and For the alignment film in the peripheral portion of the irradiation surface, scattered matter is deposited by the energy of the laser light in a ripple shape around the irradiation surface, and the scattered material and the annihilation deposited in the ripple shape. A step of reducing the transmittance or reflectance of light in the pixel having the defect compared to before the irradiation of the laser light.

According to a fifth aspect of the present invention, there is provided a first substrate on which at least a first electrode and a first alignment film are formed, and a second substrate on which at least a second electrode and a second alignment film are formed. And the first substrate and the second substrate are sealed between the first substrate and the second substrate, and are arranged in a predetermined direction based on the orientation imparted to the first alignment film and the second alignment film. A plurality of liquid crystals whose light transmittance or reflectance by the liquid crystal changes based on the orientation according to a potential difference caused by application of a voltage between the liquid crystal and the first electrode and the second electrode. In the liquid crystal display device, the plurality of pixels further include a switching element corresponding to each of the pixels, at least two of which are provided for each of the pixels. , The plurality of pixels Also one, wherein the irradiation of the laser beam first alignment film and the second alignment film is characterized by having at least altered portion.

According to a sixth aspect of the present invention, there is provided a first substrate on which at least a first electrode and a first alignment film are formed, and a second substrate on which at least a second electrode and a second alignment film are formed. And the first substrate and the second substrate are sealed between the first substrate and the second substrate, and are arranged in a predetermined direction based on the orientation imparted to the first alignment film and the second alignment film. A plurality of liquid crystals whose light transmittance or reflectance by the liquid crystal changes based on the orientation according to a potential difference caused by application of a voltage between the liquid crystal and the first electrode and the second electrode. And a pulsed laser beam having an irradiation surface smaller than the size of these pixels is irradiated so that the plurality of irradiation surfaces are separated from each other. The alignment film on the two irradiated surfaces is almost A portion, the alignment film in the peripheral portion of the irradiation surface, and having a debris was deposited moiety by energy of the laser beam around the irradiated surface ripples shape.

According to a seventh aspect of the present invention, there is provided a laser light source for irradiating a laser light to an alignment film constituting the liquid crystal panel, and a laser light for adjusting a pulse width of the laser light emitted from the laser light source. A laser repair device, comprising: a control device; a mounting table on which the liquid crystal panel is installed; and scanning means for relatively scanning the laser light with respect to the liquid crystal panel. Is characterized in that the pulse width is adjusted by adjusting energy input to the laser light source for excitation.

According to another aspect of the present invention, there is provided a laser light source for irradiating the alignment film constituting the liquid crystal panel with laser light, and a laser light for adjusting a pulse width of the laser light emitted from the laser light source. A laser repair device, comprising: a control device; a mounting table on which the liquid crystal panel is installed; and scanning means for relatively scanning the laser light with respect to the liquid crystal panel. Is characterized in that the pulse width is adjusted by adjusting the energy input to the Q switch constituting the laser light source for opening and closing.

According to these inventions, a mechanism for repairing a defective pixel is positively used, and a defect caused by improper formation of a TFT or a wiring or a foreign substance between an array substrate and a counter substrate are generated. It is also possible to cope with a defect caused by being sandwiched, and to suppress accumulation of ions in a pixel electrode corresponding to a defective pixel. Therefore, as a result, a liquid crystal display device having good display characteristics can be obtained.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a liquid crystal display device of a transmission mode and an active matrix type in a normally white mode according to a first embodiment of the present invention. (5 inch square) will be described as an example.
The present invention can be applied to a normally black mode or reflection type liquid crystal display device.

FIG. 1 is a sectional view of a pixel portion of the liquid crystal display device according to the present embodiment, and FIG. 2 is a top view of the pixel portion. FIG. 1 shows a cross section taken along line YY ′ of FIG. In this liquid crystal display device 1, an array substrate 2 (an example of a first substrate) and an opposing substrate 3 (an example of a second substrate) are formed of a first alignment film 4 and a second alignment film 5 made of polyimide, respectively. , A spacer (not shown) is used as a support, and is sealed with a sealant (not shown) while holding a twisted nematic liquid crystal composition (hereinafter, simply referred to as liquid crystal) 6. The molecules of the liquid crystal 6 are twisted by 90 ° between the array substrate 2 and the opposing substrate 3. A first polarizing plate 7 and a second polarizing plate 8 are respectively attached to the outer surfaces of the array substrate 2 and the counter substrate 3 in a state where their polarization axes are orthogonal to each other (cross Nicol state). It is attached.

The liquid crystal 6 may be filled by dropping the liquid crystal onto the array substrate 2 or the opposing substrate 3 before sealing with the sealant, and then bonding the array substrate 2 and the opposing substrate 3 together. After the sealing with the sealing agent, the liquid crystal 6 may be injected or vacuum-sucked from the sealing agent inlet into the sealed space between the array substrate and the counter substrate formed by the sealing.

In the array substrate 2, 640 × 3 signal lines (also referred to as source electrode lines) 1 on a transparent glass substrate 9.
0 and 480 scanning lines (also referred to as gate electrode lines) 11 are formed so as to be substantially orthogonal to each other. In the vicinity of the intersection of each signal line 10 and scanning line 11, a pixel electrode 13 is arranged via a TFT 12 as a switching element. The pixel electrode 13 has a side along the signal line 10 of 80 μm and a side along the scanning line 11 at 60 μm. Such pixel electrodes 13 are arranged vertically and horizontally at a pitch of 100 μm and form the display surface of the liquid crystal display device 1.

As shown in FIG. 3, a schematic configuration of an LCD unit is shown. A scanning unit and a signal line are controlled by a driving unit (not shown in detail) including a gate driver and a source driver. Normally, a driver module is connected to the outside of the display surface).
The video signal and the synchronization signal from the signal control unit and the power from the power supply are input to each driver.

The gate driver is used for one frame (60H
Once in z), this is a digital circuit having a function of selecting each scanning line, and operates in a cycle of a scanning time (15 to 40 μs). The source driver is a transparent anisotropic conductive film (hereinafter referred to as ITO (Indium Tin)) formed on the array substrate 2.
Oxide) film between the pixel electrode 13 (an example of a first electrode) and an opposing electrode (an example of a second electrode) also formed of an ITO film on the opposing substrate 3. The liquid crystal 6 operates by generating a potential difference.

More specifically, a circuit for applying a voltage corresponding to video information through the TFT 12 by applying a voltage to the scanning line is formed. At this time, if the DC power is continuously applied to the liquid crystal 6, the display deteriorates. Therefore, the AC power is applied to the counter electrode, and the voltages having the opposite polarities are alternately applied. This is called inversion driving, whereby the source driver operates at a high frequency of 20 to 100 (Hz).

The TFT 12 uses the scanning line 11 itself as a gate electrode. On the glass substrate 9, first, SiO _x , SiN _x , and further, TEOS (Tetra Et
hylOrtho Silicate: An undercoat (insulating film) 14 made of Si [OC ₂ H ₅ ] ₄ ) or the like, and an amorphous silicon (a-Si: H) film (hereinafter, an amorphous semiconductor film containing hydrogen) , Simply referred to as a semiconductor film) 15
Are sequentially laminated to form a film. Here,
Usually, CVD (Chemical Vapor Deposi
Option) is used.

On the semiconductor film 15, a channel protective film 16 self-aligned with the scanning line 11 and formed using SiN _x is arranged. The semiconductor film 15 is an n ⁺ -type a-Si disposed as a low-resistance semiconductor film 17:
It is electrically connected to each pixel electrode 13 via the H film and the source electrode 18. The semiconductor film 15 is electrically connected to the signal line 10 via an n ⁺ -type a-Si: H film (low-resistance semiconductor film) 17 and a drain electrode 19 extending from the signal line 10. I have.

An auxiliary capacitance line 20 is formed substantially parallel to the scanning line 11 and has an area overlapping with the pixel electrode 13, and is formed by the pixel electrode 13 and the auxiliary capacitance line 20. An auxiliary capacitance (Cs) is formed. The auxiliary capacitance line 20 is set to have substantially the same potential as the counter electrode 3.

In the counter substrate 3, on the transparent glass substrate 9, a gap between the TFT 12 and the signal line 10 formed on the array substrate 2 and the pixel electrode 13 and a scanning line 11 are formed.
In order to shield each of the gaps between the pixel electrode 13 and the pixel electrode 13 from each other, Cr (chromium)
Light shielding layer 21 (BM: BrackMat
rix). These structures are based on PEP (Photo Eng
raving Process).

Each of the matrix patterns in the light-shielding layer 21 has three primary colors of red (R), green (G), and blue (B) in order to realize color display on the display surface. A color portion 22 is provided by a filter, and a counter electrode 24 made of a transparent ITO film is provided via an organic protective film 23. Such a normally white mode liquid crystal display device 1
Will be described below with reference to FIG.

In this specification, the TN mode (Twisted
Nematic Mode) will be described as an example, but since the principle of operation using an alignment film and liquid crystal molecules remains unchanged, a chiral nematic liquid crystal composition or a chiral compound can be used instead of a nematic liquid crystal composition. STN added
Mode (Super Twisted Nematic Mode), DSTN mode (Double Super Twisted Nematic Mode), TSTN
FSTN mode (Film Super Twisted NematicMode) in addition to mode (Triple SuperTwisted Nematic Mode)
) And a ferroelectric liquid crystal (FLC) mode (Ferroelect) composed of a chiral smectic liquid crystal composition.
ric Liquid Crystal Mode) is also an object of the present invention.

The liquid crystal molecules constituting the liquid crystal 6 have individual polarities and are arranged in a certain direction when an electric field is applied. The display of the screen by the liquid crystal utilizes this property. First, as shown in FIG. 4A, when the potential difference between the pixel electrode 13 and the counter electrode 24 is from the threshold voltage at which the liquid crystal 6 is oriented to 0 (V), the incident light is the first light. The liquid crystal 6 is converted into linearly polarized light by the polarizing plate 7 and passes through the second polarizing plate 5 while the polarization axis is rotated by 90 ° substantially along the alignment direction of each liquid crystal molecule constituting the liquid crystal 6.
As a result, incident light is emitted to the display screen of the liquid crystal display device 1 to represent a white (bright) pixel. this is,
This is because the first polarizing plate 7 and the second polarizing plate 8 are arranged at crossed Nicols.

On the other hand, as shown in FIG.
When the potential difference between the pixel electrode 13 and the counter electrode 24 is larger than the threshold voltage at which the liquid crystal 6 causes alignment, each liquid crystal molecule is arranged along the electric field, so that the incident light Are converted into linearly polarized light by the first polarizing plate 7 and try to pass through the liquid crystal 6 as they are. However, the linearly polarized light passing through the liquid crystal 6 is transmitted to the second polarizing plate 8.
Has a polarization axis shifted by 90 ° from that of transmitting the incident light, and cannot pass through the second polarizing plate 8. As a result, the incident light is not emitted to the display screen of the liquid crystal display device 1 and represents a black (dark) pixel. This is because the first polarizing plate 7 and the second polarizing plate 8 are arranged at parallel Nicols.

The above is the description of the normally white mode. In the case of the normally black mode, only the display of white pixels and black pixels is switched, and the operation itself is not changed. The only difference is that the colors of the display pixels are switched between the above and below threshold voltages depending on the mode.

Next, in the liquid crystal display device 1 of such a normally white mode, a conductive foreign matter is mixed between the pixel electrode 13 and the counter electrode 24 during the manufacturing process and the pixel electrode 13 13 and the counter electrode 24 become almost the same potential, and the pixel electrode and the auxiliary capacitance line 2
0 is short-circuited due to insulation failure of the insulating film 14, and the pixel electrode 1
For example, the potential difference between the pixel electrode 13 and the counter electrode 24 is almost zero due to factors such as the fact that the potential of the pixel electrode 3 and the potential of the counter electrode 24 become substantially the same with respect to the auxiliary capacitance line 20.
(V). In this case, the transmittance on the display screen of the liquid crystal display device 1 is always high, and a bright spot defect occurs.

In this embodiment, a pixel having a bright spot defect is detected as follows. First, a signal voltage (V _sig ) whose polarity is inverted to +5 (V) and -5 (V) is applied to the signal line 10 of the liquid crystal display device 1 every frame time centering on a certain voltage. By applying a counter voltage (V _com ) of 5 (V) to the counter electrode 24 and a voltage of 5 (V) to the auxiliary capacitance line 20, each scanning line 11
, A pulse-like scanning voltage (V _g ) is sequentially supplied to
Display black (dark).

Then, the display brightness of any 100 display pixels located at the periphery and the center of the display screen is detected, and
The average value is stored as “reference black level”. Thereafter, the display screen is sequentially scanned to detect a pixel whose luminance displayed by the reference black level is 30% or more, and stores the position. The pixel corresponding to this position is processed as a pixel having a bright spot defect.

A method of repairing a pixel in which a bright spot defect thus detected has occurred by irradiating a laser beam will be described below. First, FIG. 5 shows a laser repair device 25 for performing this correction.
Is shown. As the laser oscillator 26, an Nd: YAG laser of AO (acousto-optic) -Q switch operation using a semiconductor laser (Laser Diode: hereinafter, referred to as LD) as an excitation light source is used. Since a versatile objective lens for an optical microscope is used as the processing objective lens 27, the laser beam from the laser oscillator 26 may be a fundamental wave of Nd: YAG laser or Nd: YLF laser, Harmonics, and furthermore, third and fourth harmonics of ultraviolet light can be used. Also, LD
Can be replaced with a krypton arc lamp.

The laser repair device 25 can change the pulse width of laser light (the reciprocal of “repetition frequency × 2”) so as to be compatible with the repair method described at the end of this specification. In a general AO-Q switch operated solid-state laser, the length of the laser resonator (laser oscillator 2
When the distance between a pair of resonant mirrors constituting the laser beam 6 is constant, the pulse width changes due to the excitation input (the magnitude of the power applied to the LD) and the energy loss inside the laser resonator.

That is, when the excitation input decreases or the energy loss inside the laser resonator increases,
Taking advantage of the fact that the pulse width increases, the energy loss inside the laser resonator can be controlled by changing the magnitude of the power applied to the AO-Q switch at the timing when the laser light is emitted. When the control is not performed by the power applied to the AO-Q switch, the control can be performed by changing the magnitude of the power applied to the LD. The magnitude of the power is adjusted by adjusting the power supplied from the laser power supply 28.

Here, an example will be specifically shown in the case where the magnitude of the power applied to the LD is changed. When the applied current is changed while the applied voltage is constant (usually about 2 to 3 (V)) and the repetition frequency of the laser light is 1 kHz or less, the applied current to the LD and the pulse of the laser light are changed. The relationship between the width (represented by the dotted line) and the relationship between the current applied to the LD and the energy of the laser beam (represented by the solid line) are as shown in FIG. In the case of this graph, since the current applied to the LD corresponds to the excitation input, it can be seen that the smaller the current applied to the LD, the longer the pulse width and the smaller the energy of the laser light. That is, it can be seen that when the length of the laser resonator is constant, the pulse width of the laser light changes depending on the excitation input.

However, when the pulse width is changed by such a method, the energy of the laser beam also changes. Therefore, in order to repair the defective pixel with the optimum energy, the laser repair device 25 uses a variable attenuator ( Preferably, a variable optical attenuator 29 is provided. Adjusting the variable attenuator 29 and adjusting the LD
In combination with adjusting the magnitude of the power applied to the AO-Q switch or the magnitude of the power applied to the AO-Q switch, it is possible to easily repair the defective pixel with the optimum energy by using one laser oscillator. That is because

The other components of the laser repair device 25 include a shutter 30 for turning on / off the laser beam passing through the variable attenuator 29, and a liquid crystal panel having defective pixels (a display panel of a liquid crystal display device without an exterior package). ) An XY stage 32 as one of means for placing the laser beam 31 and relatively scanning the laser beam and the liquid crystal panel 31;
A mirror 33 for guiding the laser light to the XY stage 32; a processing objective lens 27 for condensing and irradiating the laser light to the defective pixel; and a camera 34 for imaging the repair status of the defective pixel
And a light 36 for illuminating the liquid crystal panel 31 through an opening 35 provided in the XY stage 32. In addition, it controls the applied power supplied from the laser power supply 28 to the LD, the applied power supplied to the AO-Q switch, the opening and closing of the shutter 30, the optical attenuation rate of the variable attenuator 29, and the operation of the XY table 32. It has a controller 37 that performs the operation.

Here, the repair of a defective pixel performed by the laser repair device 25 will be described. Here, “repair of defective pixels” is based on the transmittance described above, and a backlight of 650 (lx) is arranged on the back surface of the array substrate 2 and illuminated.
Assuming that the transmittance of a pixel having the most severe luminescent spot defect in the following description is 100%, it indicates a decrease to 20% or less after processing by a laser beam. For example, the most severe bright spot defect is that the pixel electrode 13 and the auxiliary capacitance line 20 are short-circuited, and the pixel electrode 13 and the counter electrode 2
This is a case where the potential difference from the signal No. 4 becomes almost 0 (V). In this case, when a voltage difference higher than the above-described threshold voltage for the liquid crystal 6 is applied between the pixel electrode 13 and the counter electrode 24, almost 100% similarly to the transmittance of a normal pixel.
Has a transmittance of

Now, as shown in FIG. 7, it is desirable that the laser beam is irradiated from the second alignment film 5 and connects the focal point in the liquid crystal 6 here. The fact that the light-converging point is not located on the array substrate 2 or the counter substrate 3 is strong against the pixel electrode 13 or the counter electrode 24 itself, the first alignment film 4 or the second alignment film 5. This is to prevent energy from being applied and causing damage. Further, needless to say, laser light may be similarly incident from the first alignment film 4.

The light emitted from the laser oscillator 26 (Nd:
YAG) the laser light has a wavelength of 1.06 (μm) and the diameter of the laser spot on the defective pixel (the diameter of the irradiation surface of the laser light)
Is irradiated in a state of 2.5 (μm). At this time, the repetition frequency is 100 (Hz), the scanning speed at the defective pixel is 1 (mm / s), and the output of the laser beam to be applied is 2 (μJ / pulse). The outline of the positional relationship between the laser beam and the defective pixel in this scanning is as shown in FIG. 8, and the laser beam scans the inside of the defective pixel while turning it up and down.

FIG. 9 shows this in more detail. Along the longitudinal direction of the scanning line 11, the edge of the pixel electrode 13 from one end (for example, point a in the figure) to the other end (for example, point b in the figure) of the pixel electrode 13 in which a defect occurs is shown. The scanning is performed in parallel with the side, and the scanning direction is turned upward at the other end in the same direction (for example, up to the point c in the drawing), and the scanning is sequentially performed. Here, the distance L from the end of the opening (light transmitting portion) defined by the light shielding layer 21 is at least 7 μm at the one end (point a), which is the scanning start point.
It is desirable that m be apart. If the distance L is too small, the scattered matter generated by the irradiation of the laser beam, which will be described later, may scatter to the pixel electrode 13 which performs normal display, which may cause a new display defect. is there.

Here, an enlarged view of FIG. 9 is shown in FIG. 10, and the features of the laser irradiation will be described. FIG. 10A shows a method of scanning while overlapping a laser irradiation surface, which has been performed before, and FIG. 10B shows a method of discretely scanning a laser irradiation surface, which has been performed this time. . 9 and 10 (b), "d" indicates the diameter (diameter) of the laser light irradiation surface, and "P" indicates the center-to-center distance (pitch) of each irradiation surface. This pitch can be changed by changing the scanning speed or the repetition frequency.

Here, in the scanning method having the overlap ratio performed in FIG. 10A and the discrete scanning method performed in FIG. Consider the input energy under the precondition that are the same. It should be noted that FIG.
11B shows an irradiation surface per unit area when there is an overlap, and FIG. 11B shows an irradiation surface per unit area when P / d = 2 and discrete. In both figures, the unit area where the irradiation surface is formed is a portion surrounded by a broken line.

In the case of FIG. 11A, the processing time of about 30 seconds per pixel was required because of the large number of laser beam irradiations. The output of the laser light to be applied is 0.5
(ΜJ / pulse). In contrast, FIG.
In the case of (b), the processing time of about 3 seconds per pixel was sufficient because the number of laser beam irradiations was small. The output of the irradiated laser beam was 2 (μJ / pulse).
Comparing the data on the two methods, it can be seen that the product of the irradiation time and the energy per pulse is significantly different.

In other words, in the case of FIG. 11A, the irradiation energy per unit area is 0.5.times. 8 = 4 (μJ / pulse). On the other hand, in the case of FIG. 11B, irradiation is performed four times. However, since irradiation is performed in a discrete state of P / d = 2, irradiation is performed only on the hatched portion. Therefore, since irradiation is performed 0.25 times per unit area, the irradiation energy per unit area is 2 × 4 × 0.25 = 2 (μJ / pul)
se). That is, the total amount of irradiation energy per unit area is の of that in the case of FIG.

As a result, it can be seen that the total amount of the irradiation energy is small in the method of discrete irradiation as shown in FIG. 11B even if the irradiation energy per pulse is large. The fact that the total irradiation energy is small in addition to the short irradiation time is effective in consideration of damage to the array substrate 2 and the counter substrate 3. In addition, since the energy per irradiation is large and the number of times of irradiation is small, the processing margin can be provided with a margin of about ± 10%.

Contrary to this, in the overlapping irradiation method as shown in FIG. 11 (a), the irradiation energy per irradiation is small and the number of irradiations is large, so that the processing margin should be narrowed to about ± 5%. I can only do it. When they overlap, the irradiation energy per unit area increases, and even if the energy slightly increases due to the output fluctuation of the laser oscillator 26, the structure such as the color portion 22 is damaged by the heat energy and a new defect is generated. Cause.

In this overlapping method, the liquid crystal 6 is heated by the irradiation energy,
May be vaporized to generate a large number of bubbles. In addition, the position and size of the laser light irradiation surface change due to randomly generated air bubbles, and the heat energy of the laser light is directly applied to the surface of the array substrate 2 or the opposing substrate 3 from which the liquid crystal 6 has been removed due to the air bubbles. The damage caused is increased, which may cause a new defect.

First, the first alignment film 4 and the second alignment film 5 are obtained by rubbing a polyimide film having a thickness of several tens of nanometers (nm). Not affecting display quality (± 10%)
Is managed in the range. In repairing a defective pixel, a portion having a good repair and a portion having a bad repair occur due to the variation of the film thickness of ± 10% (that is, disturbance). In some cases, a decrease cannot be achieved (when the reproducibility of restoration is insufficient).

When the processing margin for the energy of laser irradiation is large enough to tolerate this disturbance, the reproducibility of restoration can be sufficiently obtained even if the processing is performed under the same conditions. As described above, according to the discrete irradiation method of the present invention, the processing margin can be set to ± 10%, and the processing margin can be made larger than the overlapping irradiation method.

Actually, a proper repair condition when the overlap ratio is 50% is that the laser spot diameter is 2.5%.
(Μm), scanning speed 1 (mm / s), repetition frequency 1 (kHz), irradiation energy 0.50 to 0.55
(ΜJ / Pulse), but the processing margin was ± 5
%, The probability of success in repairing defective pixels was only 70%.

On the other hand, when P / d = 2, an appropriate repair condition is that the laser spot diameter is 2.5 (μm).
m), scanning speed 1 (mm / s), repetition frequency 1
00 (Hz), irradiation energy is 1.0 to 2.0 (μJ
/ Pulse) and the processing margin is as high as ± 10%, so that the probability of success in repairing a defective pixel is 100%.
Became.

Next, the reason why defective pixels are repaired by this discrete laser irradiation method will be described with reference to FIG. FIG. 12A is an enlarged top view of a portion that has been subjected to laser irradiation, and FIG. 12B is a cross-sectional view taken along line XX ′. As can be seen from FIG. 12 (a), the surface of the laser light irradiation surface 38 is centered, and the peripheral portion of the surface is rippled like "smear".
Has occurred. This "stain" is not shown at all in the first conventional example, and the feature of the present invention is that the defective pixel is repaired by using the stain (a mechanism not disclosed in the first conventional example). Is what it is.

As can be seen from FIG. 12B, the first alignment film 4 is irradiated on the irradiation surface 38 of the laser beam by the irradiation energy.
Are cut down to reach the pixel electrode 13 formed of the ITO film, and particularly when the laser beam is incident from the side of the array substrate 2, the laser light reaches the peripheral color portion 22 and the first alignment film 4.
Form a portion that has almost disappeared. And polyimide, I
As shown in FIG. 12 (a), a scattered substance 39 composed of a solidified product of TO or a dye or a solidified product of altered liquid crystal is formed around a laser light irradiation surface 38 (at a position corresponding to "stain"). Scattered around the irradiation surface 38 of the
The fine rubbing grooves (not shown) formed on the surface of the first alignment film 4 are filled. Therefore, since the homology of the liquid crystal 6 changes, it is considered that the first alignment film 4 forms a deteriorated portion in a macroscopic view, and this causes a smear.

As a result, since the rubbing groove is filled up with the scattered matter 39, each liquid crystal molecule constituting the liquid crystal 6 is generated by the voltage applied between the pixel electrode 13 and the counter electrode 24. It cannot be arranged along the electric field. Then, since the liquid crystal 6 cannot be oriented (the orientation is reduced), the passage or reflection of light through the liquid crystal 6 is hindered, resulting in defective pixels.

That is, in the overlapping method as shown in FIG. 10A, not only the alignment film, the ITO film, and the color portion are cut on the scanning surface, but also the irradiation energy per pulse is small. No "smell" was formed. However, according to the method of the present invention, only the laser light irradiation surface 38 needs to be scraped off, and the other regions disturb the alignment of the liquid crystal molecules by the scattered matter 39, thereby correcting the defective pixel. (Here, the transmittance is reduced), so that the entire liquid crystal panel 31 is less damaged.

In this overlapping method, 8
When operated in a dry environment at 5 ° C., an increase in transmittance was confirmed. On the other hand, in this method, there was almost no change in transmittance. This is considered to be because the rubbing groove is filled up with the scattered matter 39 in this method, and it is difficult for the orientation to recover even after the temperature increased by the laser irradiation decreases.

FIG. 13 shows the relationship between P / d and transmittance T, and FIG. 14 shows the relationship between P / d and irradiation energy E. In consideration of the margin, each value changes in the portion surrounded by the oblique line, but according to FIG. 13, P / d is 2
It can be seen that the transmittance becomes the lowest when Ｐ3, and that the irradiation energy can be maximized when P / d is 2３3 according to FIG. From these results, P /
It can be seen that the repair of the defective pixel can be realized under the optimum condition when d is 2-3.

The above-described method of repairing defective pixels by irradiating a laser beam discretely and using "stain" formed on the display surface is applicable to a display device having an alignment film in principle. Therefore, the application of this method is not limited to the active matrix type liquid crystal display device using a TFT as a switching element described in the description. For example,
An MIM (Metal Inslator Metal) may be used, or a simple / matrix liquid crystal display device that does not use a switching element may be used. Furthermore, a plasma address type liquid crystal display device (PALC: Plasma Address Liquid Crystal)
).

Although the description has been made by taking a pixel having a bright spot defect as an example, the present method is also effective for other defect modes. For example, abnormal operation of a switching element due to electrostatic breakdown, short-circuiting of an electrode or wiring due to breakage of an interlayer insulating film, and missing or abnormal alignment of a pixel electrode.

Next, in addition to the method of restoring defective pixels by irradiating a laser beam discretely as described above, another method of restoring is described below. This method can be said to be a method combining the first conventional example and the second conventional example. However, in each conventional example, the idea of complementing the omission of correction of defective pixels by each other's method is disclosed. Not in. This method is preferably performed using the laser repair device 25 shown in FIG.

As shown in FIGS. 15 to 18, in the method described here, one pixel electrode 13 is used as in the second conventional example.
, Two (plural) TFTs (switching elements) are provided. As shown in FIG. 15, one is a main TFT 40 mechanically and electrically connected to the pixel electrode 13 by wiring, and the other is mechanically connected to the pixel electrode 13 but is electrically connected to the pixel electrode 13. The sub-TFT 42 is not illustrated (it is mechanically in contact with the wiring 43 extending from the scanning line 11 insulated by the interlayer insulating film 41). First, through the above-described pixel defect detection, a pixel having a defect is detected.

Next, when the location where the pixel defect has occurred can be specified, first, as shown in FIG. 16, for the defective pixel caused by the malfunction of the main TFT 40, the wiring 43 connecting the main TFT 40 and the scanning line 11 is repaired by laser. Cutting is performed by a laser beam used in the device 25. In this case, the pulse width of the laser light is set to be as short as 10 (ns) or less in order to melt and cut the wiring, and the laser light is cut by irradiation.

Next, as shown in FIG. 17, a sub-TFT 42 connected to the pixel electrode 13 is selected, and the pixel electrode 13 and the sub-TFT 42 which are electrically separated from the main TFT 40 by the interlayer insulating film 41 are separated by a laser repair device 25. And selectively connect them electrically. Specifically, as shown in FIG. 18 as a cross-sectional view taken along the line AA ′ in FIG. 17, the pixel electrode 13 and the electrode of the sub-TFT 42 are fusion-connected with a laser beam via an interlayer insulating film 41. Therefore, the pulse width of the laser beam is 10 (ns) here.
It is set as short as below, and both are connected by irradiating pulse laser light.

When the pixel defect is repaired by this processing, the pixel operates normally, but the TFT operates normally.
Pixel defects that are not a factor due to the operation failure cannot be repaired, and there is a variation in processing accuracy due to laser light. Therefore, only this method can repair only about 30 to 50% of the entire pixel defects.

Therefore, after the replacement of the sub-TFT 42, the pixel defect is inspected again. If the pixel defect is still found, the above-described method of discretely irradiating a laser beam is used, for example. The defective pixel is also repaired by utilizing the disorder of the alignment film as shown in the first conventional example. FIG. 19 is a flow chart showing a series of these steps (switching to the sub-TFT 42 is a type of switching to a redundant circuit).

In this case, the pulse width of the laser beam used in the laser repair device 25 is 20 to 200.
(Ns). Of course, instead of the first conventional example, the above-described laser light is radiated discretely to “smear”.
May be formed to repair defective pixels.

Although an active matrix type liquid crystal display device using TFTs as switching elements has been described as an example, a MIM type liquid crystal display device may be used instead.

[0076]

According to the present invention, it is possible to achieve correction of defective pixels while suppressing thermal damage to the liquid crystal panel.
Further, it is possible to correct a defective pixel accurately corresponding to various defect modes such as a malfunction of a switching element. That is, according to the present invention, it is possible to manufacture a liquid crystal display device in which a defective pixel has been successfully repaired. Further, it is also possible to provide a laser repair device used for such repair.

[Brief description of the drawings]

FIG. 1 is a top view illustrating a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display device of the present invention taken along line YY ′ in FIG. 1;
Sectional view at the line.

FIG. 3 is a schematic configuration diagram showing the entire liquid crystal display device of the present invention.

FIG. 4 is a perspective view illustrating a display principle of the liquid crystal display device of the present invention.

FIG. 5 is a schematic configuration diagram showing the entire laser repair device of the present invention.

FIG. 6 is a graph showing the relationship between the current applied to the LD and the pulse width of the laser beam, and the relationship between the current applied to the LD and the energy of the laser beam according to the present invention.

FIG. 7 is a cross-sectional view showing a laser light irradiation state in the liquid crystal display device manufacturing method of the present invention.

FIG. 8 is a perspective view schematically showing a positional relationship between a laser beam and a defective pixel.

FIG. 9 is a top view schematically showing a positional relationship between a laser beam and a defective pixel.

FIG. 10A is an enlarged top view showing a positional relationship between laser light irradiation surfaces when overlapping,
FIG. 2B is an enlarged top view showing a positional relationship between the respective irradiation surfaces of the laser beam when the laser beams are separated.

11A is an enlarged top view per unit area in FIG. 10A, and FIG. 11B is an enlarged top view per unit area in FIG. 10B.

12A is an enlarged top view of a portion irradiated with laser by the method of manufacturing a liquid crystal display device of the present invention, and FIG. 12B is a cross-sectional view taken along line XX ′ of FIG.

FIG. 13 is a graph showing the relationship between P / d and transmittance T.

FIG. 14 is a graph showing the relationship between P / d and irradiation energy E.

FIG. 15 is a top view showing a relationship between a pixel electrode and a main TFT and a sub TFT in the liquid crystal display device of the present invention.

FIG. 16 is a top view showing a state where the wiring connecting the main TFT and the pixel electrode in FIG. 15 is cut by laser light.

FIG. 17 is a top view showing a state where the wiring connecting the sub-TFT and the pixel electrode in FIG. 15 is connected by laser light.

FIG. 18 is a sectional view taken along line A-A ′ of FIG. 18;

FIG. 19 is a flowchart showing a series of steps of FIGS. 15 to 17;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Array substrate, 3 ... Counter substrate, 4
... first alignment film 5 ... second alignment film, 6 ... liquid crystal, 7 ... first polarizing plate, 8 ...
Second polarizing plate 9: glass substrate, 10: signal line, 11: scanning line, 12 ...
TFT 13: pixel electrode, 14: undercoat, 15: amorphous silicon film 16: channel protective film, 17: n ⁺ type hydrogenated amorphous silicon film 18: source electrode, 19: drain electrode, 20: auxiliary capacitance line, 21 ... Light-shielding layer 22: color portion, 23: organic protective film, 24: counter electrode, 2
5 laser repair device 26 laser oscillator 27 processing objective lens 28
Laser power supply 29: variable attenuator, 30: shutter, 31
... Liquid crystal panel 32 ... XY stage, 33 ... Mirror, 34 ... Camera, 3
5. Opening 36. Light, 37. Controller, 38. Irradiation surface, 3.
9: flying object 40: main TFT, 41: sub TFT, 42: interlayer insulating film, 43: wiring

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA03 FA10 FA12 FA13 FA15 FA16 FA18 FA24 FA30 HA08 JA05 MA18 2H092 JA26 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB42 JB52 JB57 JB63 JB69 JB72 JB73 JB07 MA05 MA05 MA05 MA16 MA18 MA19 MA20 MA22 MA27 MA32 MA35 MA37 MA41 MA52 MA56 NA04 NA13 NA25 NA27 NA29 PA02 QA07 4E068 AH00 CA03 CB01 DA09 5F110 AA27 BB01 DD02 DD13 DD14 GG02 GG15 GG44 HK09 HK16 NN12 NN24 NN46 NN73

Claims (8)

[Claims] A step of forming at least a first electrode and a first alignment film on a first substrate; a step of forming at least a second electrode and a second alignment film on a second substrate. A step of sealing the first substrate and the second substrate while interposing these substrates in a state where liquid crystal is interposed between the first substrate and the second substrate; A liquid crystal display device comprising: a step of performing an inspection by displaying a screen with a potential difference therebetween; and a step of repairing a defective portion of a pixel constituting the screen detected by the inspection. In the manufacturing method, the repairing step includes, before the one pixel having one of the switching elements, at least two of which are mechanically connected to each of the pixels having the defect. A step of selectively and electrically connecting to a pixel; and a step of irradiating the laser beam to the pixel having the defect to change at least the first alignment film or the second alignment film. A method for manufacturing a liquid crystal display device, comprising: 2. The method according to claim 1, wherein the step of changing the quality of the first alignment film or the second alignment film includes the step of selectively and electrically connecting one switching element to the pixel. 2. The method according to claim 1, wherein the process is performed on pixels that are not repaired. 3. The method according to claim 2, wherein the laser beam has a pulse width of 20 ns to 200 ns in a case where the switching element is selectively and electrically connected to the pixel, and the laser beam has a pulse width of 20 ns to 200 ns. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein a pulse width of 10 ns or less is used in a step of at least altering the alignment film. 4. A step of forming at least a first electrode and a first alignment film on a first substrate; and a step of forming at least a second electrode and a second alignment film on a second substrate. A step of sealing the first substrate and the second substrate while interposing these substrates in a state where liquid crystal is interposed between the first substrate and the second substrate; Performing a test by displaying a screen with a potential difference therebetween, and irradiating a laser beam to a pixel of a portion where a defect of a pixel constituting the screen detected in the test has occurred, and at least the first alignment film. Or repairing the pixel having the defect by altering the second alignment film, wherein the repairing is performed on the pixel having the defect. Than the size of this pixel Irradiating a plurality of irradiation surfaces with pulsed laser light having different irradiation surfaces so that the irradiation surfaces are separated from each other; and performing the irradiation process to substantially eliminate the alignment film on the irradiation surface and to provide a peripheral portion of the irradiation surface. Scattered matter is deposited on the alignment film in the form of a ripple around the irradiation surface by the energy of the laser light, and the scattered matter deposited in a ripple and the disappearance cause the laser light to be deposited. A step of reducing the transmittance or reflectance of light in the pixel where the defect has occurred before the irradiation of the liquid crystal display. 5. A first substrate on which at least a first electrode and a first alignment film are formed; a second substrate on which at least a second electrode and a second alignment film are formed; A liquid crystal sealed between the first substrate and the second substrate and arranged in a predetermined direction based on the orientation provided to the first alignment film and the second alignment film; And a plurality of pixels whose transmittance or reflectance of light by the liquid crystal changes based on the orientation according to a potential difference generated by application of a voltage between the second electrode and the second electrode. In the liquid crystal display device, the plurality of pixels may include at least two switching elements provided for each of the plurality of pixels corresponding to the plurality of pixels. One is the laser light The liquid crystal display device wherein the morphism first alignment film and the second alignment film is characterized by having at least altered portion. 6. A first substrate on which at least a first electrode and a first alignment film are formed; a second substrate on which at least a second electrode and a second alignment film are formed; A liquid crystal sealed between the first substrate and the second substrate and arranged in a predetermined direction based on the orientation provided to the first alignment film and the second alignment film; And a plurality of pixels whose transmittance or reflectance of light by the liquid crystal changes based on the orientation according to a potential difference generated by application of a voltage between the second electrode and the second electrode. In the liquid crystal display device, pulsed laser light having an irradiation surface smaller than the size of these pixels is irradiated so that the plurality of irradiation surfaces are separated from each other, and at least two alignment films on the irradiation surfaces. And the irradiation The liquid crystal display device with respect to the alignment layer in the peripheral portion, and having a debris was deposited moiety by energy of the laser beam around the irradiated surface ripples shaped. 7. A laser light source for irradiating a laser beam to an alignment film constituting a liquid crystal panel, a laser light control device for adjusting a pulse width of a laser beam emitted from the laser light source, and the liquid crystal panel includes: A mounting table to be installed, and a scanning unit for scanning the laser light relative to the liquid crystal panel, wherein the laser light control device is configured to excite the laser light source. Wherein the pulse width is adjusted by adjusting energy input to the laser repair device. 8. A laser light source that irradiates a laser beam to an alignment film forming a liquid crystal panel, a laser light control device that adjusts a pulse width of a laser beam emitted from the laser light source, and the liquid crystal panel includes: A laser repair device comprising: a mounting table to be installed; and a scanning unit that relatively scans the laser beam with respect to the liquid crystal panel. A laser repair apparatus wherein the pulse width is adjusted by adjusting energy input to the switch for opening and closing.