JP2003344220A - Manufacturing method for liquid crystal display, and device and method for inspecting ghost defect for liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quantitatively and objectively determine a ghost defect in a liquid crystal display in a short time. <P>SOLUTION: In the present invention, an inspection image is displayed in an inspection area, using as an inspection area a partial area of a display area in the liquid crystal display serving as an inspection object, and using an area in the vicinity of the inspection area as a comparison area, and the brightness of the inspection area and the brightness of the comparison area are measured to determine the presence of the ghost defect in the liquid crystal display, based on a ratio of the brightness of the comparison area to the brightness of the inspection area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, a ghost defect inspection device for a liquid crystal display device, and a ghost defect inspection method.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices using liquid crystals have been widely used as display devices for displaying images.

In such a liquid crystal display device, a ghost phenomenon occurs in which the same image is displayed thinly in the vicinity of a predetermined image due to the individual differences in the components that occur during the manufacturing process, and the display area of the liquid crystal display device. There is a possibility that the image quality of the image displayed on the screen may deteriorate.

Particularly, a liquid crystal cell and a thin film transistor (TFT) are arranged in a lattice arrangement.
or)), and the active matrix drive type liquid crystal display device represented by the TFT drive type which displays an image by sequentially switching controlling the same thin film transistor using a shift register is as follows. The ghost phenomenon might occur for some reason.

That is, in a liquid crystal display device of the active matrix drive system, a pulse clock signal and an inverted clock signal obtained by inverting the clock signal are provided to a shift register which constitutes a horizontal drive circuit of the liquid crystal display device. The shift register is supplied with these signals to drive the shift register, and the shift register sequentially controls switching of the thin film transistors. Then, normally, the horizontally adjacent thin film transistors are sequentially turned on, whereby the horizontally adjacent liquid crystal cells are sequentially driven,
A predetermined image is displayed in the display area of the liquid crystal display device. However, when the phase difference between the clock signal supplied to the shift register and the inverted clock signal exceeds the allowable range, the horizontally adjacent thin film transistors are also in the ON state even though the predetermined thin film transistors are in the ON state. Then, the driving of the adjacent liquid crystal cell is started during the driving of the predetermined liquid crystal cell, and as a result, the two liquid crystal cells adjacent in the horizontal direction are temporarily driven at the same time. A ghost phenomenon may occur in which not only a predetermined image is displayed in the display area of the display device, but also the same image is displayed thinly in the vicinity of the side of the predetermined image.

Therefore, conventionally, in the manufacturing process of a liquid crystal display device, a predetermined inspection image (for example, an image of vertical stripes) is displayed on the liquid crystal display device, and the inspector visually observes the inspection image to determine an allowable range. For the liquid crystal display device in which the ghost phenomenon exceeding the above has occurred, the liquid crystal display device is determined to be a ghost defect and discarded, and only the liquid crystal display device not determined to be the ghost defect is shipped as a finished product.

As described above, in the past, a ghost defect inspection was visually conducted by an inspector at the time of manufacturing a liquid crystal display device.

[0008]

However, in the ghost defect inspection in the conventional manufacturing process of the liquid crystal display device, the ghost defect of the liquid crystal display device is judged based on the subjective observation and judgment by the inspector. The presence / absence of the liquid crystal display device was inspected, and no quantitative objective judgment was made on the ghost defect of the liquid crystal display device.

Therefore, in the conventional ghost defect inspection, the judgment result may differ depending on the inspector who judges the ghost defect of the liquid crystal display device, and the liquid crystal display device to be judged as a good product is a defective product. There is a risk that the liquid crystal display device may be erroneously determined and the manufacturing yield of the liquid crystal display device may be reduced.

Further, since the inspector determines the ghost defect instead of mechanically determining the ghost defect,
It takes a lot of time and labor to judge a ghost defect, and the man-hours and the manufacturing cost of the liquid crystal display device may increase accordingly.

Therefore, in the present invention, as an inspection for a ghost defect in the manufacturing process of a liquid crystal display device, a quantitative and objective determination can be automatically performed in a short time.

[0012]

That is, according to the present invention according to claim 1, only a liquid crystal display device which is not judged to be a ghost defect is inspected during the manufacturing process of the liquid crystal display device and a finished product. In the method of manufacturing a liquid crystal display device shipped as a product, a part of the display area of the liquid crystal display device to be inspected is set as the inspection region, and a region near the inspection region is set as the comparison region, and the inspection image is displayed in the inspection region. Is displayed, the luminance of the inspection area and the luminance of the comparison area are measured, and the presence or absence of a ghost defect in the liquid crystal display device is determined based on the ratio of the luminance of the comparison area to the luminance of the inspection area.

Further, in the present invention according to claim 2, the presence or absence of a ghost defect is inspected in the manufacturing process of the liquid crystal display device,
In a method of manufacturing a liquid crystal display device, which ships only a liquid crystal display device that is not determined to be a ghost defect as a finished product,
A part of the display area of the liquid crystal display device to be inspected is set as the inspection area, the area in the vicinity of the inspection area is set as the comparison area, and the area other than the inspection area and the comparison area is set as the reference area. The inspection image is displayed, the luminance of the inspection area, the luminance of the comparison area, and the luminance of the reference area are measured, and the difference between the luminance of the inspection area and the luminance of the reference area is set as the difference inspection area luminance, and the comparison area The difference between the brightness and the brightness of the reference area is defined as the difference comparison area brightness, and the presence or absence of a ghost defect in the liquid crystal display device is determined based on the ratio of the difference comparison area brightness to the difference inspection area brightness.

In the present invention according to claim 3, an active matrix drive type liquid crystal display device is used as the liquid crystal display device to be inspected according to claim 1 or 2, and the liquid crystal display device is driven in the horizontal direction. It was decided to measure the brightness of the liquid crystal display device after changing the phases of the clock signal and the inverted clock signal supplied to the shift register constituting the circuit.

Further, in the present invention according to claim 4, in a ghost defect inspection device for inspecting the presence or absence of a ghost defect of a liquid crystal display device, a part of the display region of the liquid crystal display device to be inspected is inspected. A liquid crystal display device driving unit for displaying an inspection image in the inspection region and a region near the inspection region as a comparison region, and a luminance measuring unit for measuring the luminance of the inspection region and the luminance of the comparison region, and the same luminance. A ghost defect determination unit that determines the presence or absence of a ghost defect in the liquid crystal display device based on the ratio of the brightness of the comparison region to the brightness of the inspection region measured by the measurement unit.

Further, in the present invention according to claim 5, in a ghost defect inspection device for inspecting the presence or absence of a ghost defect of a liquid crystal display device, a part of the display region of the liquid crystal display device to be inspected is set as an inspection region. , A liquid crystal display drive unit for displaying an inspection image in the inspection area, a region near the inspection region as a comparison region, and a region other than the comparison region and the inspection region as a reference region, the brightness of the inspection region And a luminance measuring unit that respectively measures the luminance of the comparison region and the luminance of the reference region, and the difference between the luminance of the inspection region and the luminance of the reference region measured by the luminance measurement unit is the difference inspection region luminance, and the comparison region The difference between the luminance of the reference area and the luminance of the reference area is defined as the difference comparison area luminance, and the presence or absence of a ghost defect in the liquid crystal display device is determined based on the ratio of the difference comparison area luminance to the difference inspection area luminance. Paste and defect determining unit, and to be provided with a.

In the present invention according to claim 6, an active matrix drive type liquid crystal display device is used as the liquid crystal display device to be inspected according to claim 4 or 5, and the liquid crystal display device drive section is It was decided that the phase of the clock signal and the inverted clock signal supplied to the shift register constituting the horizontal drive circuit of the liquid crystal display device could be changed.

Further, in the present invention according to claim 7, in a ghost defect inspection method for inspecting a ghost defect of a liquid crystal display device, a part of the display region of the liquid crystal display device to be inspected is set as an inspection region. In addition, the area near the inspection area is set as a comparison area, the inspection image is displayed in the inspection area, the luminance of the inspection area and the luminance of the comparison area are measured, and the luminance of the comparison area is based on the ratio of the luminance of the comparison area to the luminance of the inspection area. It was decided to judge whether or not there was a ghost defect in the liquid crystal display device.

According to the present invention of claim 8, in a ghost defect inspection method for inspecting a ghost defect of a liquid crystal display device, a part of the display region of the liquid crystal display device to be inspected is set as an inspection region. , The area in the vicinity of the inspection area as the comparison area, the area other than the inspection area and the comparison area as the reference area, the inspection image is displayed in the inspection area, and the brightness of the inspection area and the brightness of the comparison area and the reference area Each of the luminance is measured, and the difference between the luminance of the inspection area and the luminance of the reference area is set as the difference inspection area luminance, and the difference between the luminance of the comparison area and the luminance of the reference area is set as the difference comparison area luminance.
The presence or absence of a ghost defect in the liquid crystal display device is determined based on the ratio of the difference comparison area brightness to the difference inspection area brightness.

Further, in the present invention according to claim 9, an active matrix drive type liquid crystal display device is used as the liquid crystal display device to be inspected according to claim 7 or 8, and the liquid crystal display device is driven in the horizontal direction. It was decided to measure the brightness of the liquid crystal display device after changing the phases of the clock signal and the inverted clock signal supplied to the shift register constituting the circuit.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The liquid crystal display device 1 according to the present invention is driven by a TFT drive system which is a typical example of an active matrix drive system, and a circuit board 3 is connected to a liquid crystal panel 2 as shown in FIG. It has a structure.

As shown in FIG. 1, the liquid crystal panel 2 is provided with a pair of liquid crystal cells 4 and thin film transistors 5 arranged in a lattice arrangement, and is connected to the thin film transistors 5 by turning on the thin film transistors 5. Liquid crystal cell 4
I am trying to drive.

A drive circuit 6 for driving the liquid crystal panel 2 is mounted on the circuit board 3 as shown in FIG.

The drive circuit 6 includes a horizontal drive circuit 7 for sequentially driving the liquid crystal cells 4 arranged in the liquid crystal panel 2 in the horizontal direction, and a liquid crystal cell 4 arranged in the liquid crystal panel 2 in the vertical direction. Vertical drive circuit 8 for driving
And an interface circuit 9 for various signals supplied from the outside of the liquid crystal display device 1 to control the horizontal and vertical driving circuits 7 and 8, and power is supplied to each circuit 7, 8 and 9. It is composed of a power supply circuit (not shown).

Here, the horizontal driving circuit 7 is connected to the shift register 10 with the gate transistors 11 corresponding to the number of horizontal pixels through the switching signal line 12, and the shift register 10 sends the interface circuit 9 a clock signal. line
13 and the inverted clock signal line 14 are connected, while
Each gate transistor 11 is connected to the interface circuit 9 via a video signal line 15, and is also connected via a video signal supply line 16 to the thin film transistors 5 vertically arranged in the liquid crystal panel 2 in the vertical direction. It is connected.

Then, the horizontal driving circuit 7 sequentially turns on the gate transistors 11 arranged in the horizontal direction by using the clock signal 17 and the inverted clock signal 18 supplied from the interface circuit 9, whereby the interface circuit 9 is turned on. The video signal 19 supplied from the above is supplied to the thin film transistor 5 connected to the gate transistor 11 in the ON state.

On the other hand, the vertical drive circuit 8 comprises a shift register 21 connected to the thin film transistors 5 horizontally arranged in the liquid crystal panel 2 by the number of pixels in the horizontal direction via a synchronization signal line 20, and the shift register 21 is the same. Reference numeral 21 denotes a horizontal synchronizing signal line 22 and an inverted horizontal synchronizing signal line 23 in the interface circuit 9.
Connected through and.

Then, the vertical driving circuit 8 uses the horizontal synchronizing signal 24 and the inverted horizontal synchronizing signal 25 supplied from the interface circuit 9 to sequentially turn on the thin film transistors 5 arranged in the horizontal direction by the shift register 21 in the vertical direction. I am trying to.

Therefore, the liquid crystal display device 1 simultaneously supplies the video signals 19 to the thin-film transistors 5 arranged in the vertical direction on the liquid crystal panel 2 by the horizontal driving circuit 7 for the number of pixels in the vertical direction, and at the same time, in the vertical direction arranged in the vertical direction. Only one thin film transistor 5 among the thin film transistors 5 corresponding to the number of pixels is selected by the vertical drive circuit 8, and only this one thin film transistor 5 is turned on, and only the liquid crystal cell 4 forming a pair with the thin film transistor 5 has an image. It is designed to supply signal 19. By sequentially supplying the video signal 19 to one liquid crystal cell 4 to all the liquid crystal cells 4 of the liquid crystal panel 2, an image corresponding to the video signal 19 can be displayed on the liquid crystal display device 1. .

The liquid crystal display device 1 is constructed as described above, and is generally manufactured as follows.

That is, the liquid crystal panel 2 and the circuit board 3 are manufactured separately, and then the liquid crystal panel 2 and the circuit board 3 are individually inspected for operation, and then the liquid crystal panel 2 determined to be non-defective. And the circuit board 3 are connected to each other, various inspections are performed thereafter, and only the products determined to be non-defective in all the inspections are shipped as finished products.

Among the inspections performed on the liquid crystal display device 1 in which the liquid crystal panel 2 and the circuit board 3 are connected, the ghost defect inspection, which is the subject matter of the present invention, will be described below.

FIG. 2 is a block diagram showing the configuration of a ghost defect inspection device 30 for inspecting the liquid crystal display device 1 for the presence or absence of a ghost defect.
The liquid crystal display device drive unit 33 for displaying the inspection image 32 (see FIG. 4) in the display region 31 (see FIG. 3) of the liquid crystal display device 1 to be inspected, and the brightness of a predetermined portion of the display region 31 of the liquid crystal display device 1. And a ghost defect determination unit 35 that determines the presence or absence of a ghost defect in the liquid crystal display device 1 based on the brightness measured by the brightness measurement unit 34.

Here, the liquid crystal display device driving section 33 supplies the interface circuit 9 of the liquid crystal display device 1 with a video signal 19, a clock signal 17, an inverted clock signal 18, a horizontal synchronizing signal 24, an inverted horizontal synchronizing signal 25, and a power source. In addition, the liquid crystal display drive unit 33 has a built-in delay circuit, and the clock signal 17 and the inverted clock signal 18 are supplied to the interface circuit 9 at different timings by using the delay circuit. Thus, as shown in FIG. 5, the phases of the clock signal 17 and the inverted clock signal 18 can be changed back and forth.

As shown in FIG. 2, the brightness measuring section 34 also includes an image input device 36 for taking an image of the entire display area 31 of the liquid crystal display device 1, and an image of the image taken by the image input device 36. The brightness calculation device 37 calculates only the brightness of a predetermined portion based on a signal. As described above, when the luminance of a predetermined portion is calculated from the entire image of the display area 31 of the liquid crystal display device 1, the luminance of a plurality of portions can be measured in a short time and the inspection time can be shortened. Can be realized. The brightness measuring unit 34 may have a structure in which a brightness measuring device that measures the brightness of a predetermined portion is movably arranged above the liquid crystal display device 1.

Then, the ghost defect inspection device 30 determines whether or not there is a ghost defect in the liquid crystal display device 1 as described below.

First, as shown in FIG. 3, the liquid crystal display device 1
A vertically long rectangular inspection area 38 is set in the substantially central portion of the display area 31, and vertically long rectangular comparison areas 39 and 40 are set at positions near the left and right of the same inspection area 38.
Vertically long rectangular reference areas 41 and 42 are set in the left and right portions of 1. Each of the regions 38 to 42 has a width of about three pixels (the liquid crystal cell 4 and the thin film transistor 5).

Next, the liquid crystal display drive unit 33 displays the inspection image 32 shown in FIG. 4 in the display area 31 of the liquid crystal display 1. The inspection image 32 is an image in which a black vertical line is formed in a portion corresponding to the inspection area 38.

Next, the ghost defect inspection apparatus 30 uses the ghost defect inspection method described below to perform the liquid crystal display device 1.
It is determined whether or not there is a ghost defect.

As such a ghost defect inspection method, a ghost defect is determined by taking into consideration the brightness of the inspection region 38 and the brightness of the comparison regions 39, 40 and the brightness of the reference regions 41, 42. In some cases, the ghost defect may be determined by measuring the luminance while making the phases of the clock signal 17 and the inverted clock signal 18 of the liquid crystal display device 1 different from each other. These will be described below in order.

(First Ghost Defect Inspection Method) The first ghost defect inspection method is, as shown in FIG.
The ghost defect is determined only on the basis of the brightness of the image and the brightness of the comparison areas 39 and 40.

That is, the inspection image 32 is displayed on the liquid crystal display device 1 by the liquid crystal display device drive section 33 (step S
1) After that, the brightness measuring unit 34 measures the brightness of the inspection area 38 and the brightness of the comparison area 40 (steps S2 and S).
3). Here, the comparison area 40 on the right side of the inspection area 38 is
The brightness is measured for. This is because, generally, a ghost image is likely to occur on the right side of a predetermined image.
Therefore, when the ghost image is generated on the left side of the predetermined image, the brightness of the comparison area 39 on the left side of the inspection area 38 is measured.

Next, a comparison area for the brightness of the inspection area 38
The ratio (%) of 40 luminances is calculated, and the ratio is compared with a predetermined value set in advance (step S4).

When the ratio of the brightness of the comparison area 40 to the brightness of the inspection area 38 is less than or equal to a predetermined value, the liquid crystal display device 1 is determined to be a ghost defect (step S5).
Only the liquid crystal display device 1 that is not determined to be a ghost defect is determined to be a non-defective product (step S6).

As described above, according to the first ghost defect inspection method, the brightness of the inspection area 38 displaying the inspection image 32 and the brightness of the comparison area 40 are respectively measured, and the comparison area 40 with respect to the brightness of the inspection area 38 is measured. Since the presence / absence of a ghost defect in the liquid crystal display device 1 is determined based on the ratio of the luminance of the liquid crystal display device 1, quantitative objective determination of the ghost defect in the liquid crystal display device 1 can be automatically performed in a short time. Thus, the manufacturing time of the liquid crystal display device 1 can be shortened and the manufacturing cost can be reduced.

(Second Ghost Defect Inspecting Method) As shown in FIG. 7, the second ghost defect inspecting method is performed a plurality of times while changing the phases of the clock signal 17 and the inverted clock signal 18 of the liquid crystal display device 1. The brightness of the inspection area 38 and the brightness of the comparison areas 39 and 40 are measured over the entire range, and the ghost defect is determined based on the brightness of the inspection area 38 and the brightness of the comparison areas 39 and 40.

That is, the inspection image 32 is displayed on the liquid crystal display device 1 by the liquid crystal display device drive section 33 (step S1).
1) After that, the brightness measuring section 34 measures the brightness of the inspection area 38 and the brightness of the comparison area 40 (steps S12 and S).
13). Here again, the comparison area on the right side of the inspection area 38
The brightness is measured about 40.

Next, a comparison area for the luminance of the inspection area 38
The ratio (%) of the luminance of 40 is calculated, and this ratio is compared with a preset predetermined value (step S14).

If the ratio of the brightness of the comparison area 40 to the brightness of the inspection area 38 is less than or equal to a predetermined value, the liquid crystal display device 1 is determined to be a ghost defect (step S15).

On the other hand, when it is not determined that the ghost is defective in step S14, the phases of the clock signal 17 and the inverted clock signal 18 of the liquid crystal display device 1 are slightly changed, and then the steps S11 to S14 are performed. Repeated a predetermined number of times (steps S16 and S17).
For example, the phases of the clock signal 17 and the inverted clock signal 18 are shifted four times by 1/10 cycle of the clock signal 17.

Then, even if the phases of the clock signal 17 and the inverted clock signal 18 are changed, only the liquid crystal display device 1 which is not determined to be a ghost defect in step S14 is determined to be a non-defective product (step S18).

As described above, according to the second ghost defect inspection method, the phases of the clock signal 17 and the inverted clock signal 18 supplied to the shift register 10 constituting the horizontal drive circuit 7 of the liquid crystal display device 1 are changed. However, since the brightness of the inspection area 38 and the brightness of the comparison area 40 are measured, by changing the phases of the clock signal 17 and the inverted clock signal 18, the ghost defect is likely to occur in the liquid crystal display device 1. The presence / absence of a ghost defect can be inspected, and the ghost defect of the liquid crystal display device 1 can be determined more accurately as compared with the first ghost defect inspection method.

(Third Ghost Defect Inspection Method) The third ghost defect inspection method is as shown in FIG.
Brightness of the reference area 41, 42 as well as the brightness of the comparison area 39, 40
The ghost defect is also determined by taking into consideration the luminance of.

That is, the inspection image 32 is displayed on the liquid crystal display device 1 by the liquid crystal display device drive section 33 (step S2).
1) After that, the brightness measuring unit 34 measures the brightness of the inspection area 38, the brightness of the comparison area 40, and the brightness of the reference areas 41, 42 (steps S22, S23, S24). Note that, here, the luminance is measured for the comparison area 40 on the right side of the inspection area 38. The brightness of the reference areas 41 and 42 is the average value of the brightness of the left reference area 41 and the brightness of the right reference area 42.

Next, the brightness of the inspection area 38 and the reference areas 41 and 42
Is calculated as the difference inspection area brightness (step S25), and the difference between the brightness of the comparison area 40 and the brightness of the reference areas 41, 42 is calculated, and the difference of the brightness is calculated. Is the difference comparison area brightness (step S26).

Next, the ratio (%) of the difference comparison area brightness to the difference inspection area brightness is calculated, and the ratio is compared with a preset predetermined value (step S27).

When the ratio of the difference comparison area brightness to the difference inspection area brightness is less than or equal to a predetermined value, the liquid crystal display device 1 is determined to be a ghost defect (step S28), while the liquid crystal not determined to be a ghost defect is determined. Only the display device 1 is determined to be non-defective (step S29).

As described above, according to the third ghost defect inspection method, the luminance of the inspection area 38 displaying the inspection image 32, the luminance of the comparison area 40, and the luminance of the reference areas 41, 42 are measured, respectively, and the inspection area is measured. Liquid crystal display based on the ratio of the difference between the brightness of the comparison area 40 and the brightness of the reference areas 41 and 42 (the difference comparison area brightness) to the difference between the brightness of the 38 and the brightness of the reference areas 41 and 42 (the difference inspection area brightness) Since the presence / absence of a ghost defect in the device 1 is determined, even if a noise component is superimposed on the inspection image 32 displayed in the display area 31 of the liquid crystal display device 1, the noise component is used for the luminance in the reference areas 41, 42. And subtracting the brightness in the reference areas 41 and 42 from the brightness of the inspection area 38 and the brightness of the comparison area 40 cancels the noise component from the brightness of the inspection area 38 and the brightness of the comparison area 40. The inspection area 38 with noise removed and comparison The luminance ratio in the region 40 can be obtained, and the ghost defect of the liquid crystal display device 1 can be determined more accurately as compared with the first ghost defect inspection method.

(Fourth Ghost Defect Inspecting Method) As shown in FIG. 9, the fourth ghost defect inspecting method is performed a plurality of times while changing the phases of the clock signal 17 and the inverted clock signal 18 of the liquid crystal display device 1. The luminance of the inspection area 38, the luminance of the comparison areas 39, 40, and the luminance of the reference areas 41, 42 are measured over the luminance of the inspection area 38 and the comparison areas 39, 40, as well as the luminance of the reference areas 41, 42. The ghost defect is determined by taking this into consideration.

That is, the inspection image 32 is displayed on the liquid crystal display device 1 by the liquid crystal display device drive section 33 (step S3).
1) After that, the brightness measuring unit 34 measures the brightness of the inspection area 38, the brightness of the comparison area 40, and the brightness of the reference areas 41, 42 (steps S32, S33, S34). Note that, here, the luminance is measured for the comparison area 40 on the right side of the inspection area 38. The brightness of the reference areas 41 and 42 is the average value of the brightness of the left reference area 41 and the brightness of the right reference area 42.

Next, the brightness of the inspection area 38 and the reference areas 41 and 42
Is calculated as the difference inspection area brightness (step S35), and the difference between the brightness of the comparison area 40 and the brightness of the reference areas 41, 42 is calculated, and the difference of the brightness is calculated. Is the difference comparison area brightness (step S36).

Next, the ratio (%) of the difference comparison area brightness to the difference inspection area brightness is calculated, and this ratio is compared with a preset predetermined value (step S37).

If the ratio of the brightness of the difference comparison area to the brightness of the difference inspection area is less than or equal to a predetermined value, the liquid crystal display device 1 is determined to be a ghost defect (step S38).

On the other hand, if it is not determined in step S37 that the ghost is defective, the phases of the clock signal 17 and the inverted clock signal 18 of the liquid crystal display device 1 are slightly changed, and then the steps S31 to S37 are performed. Repeated a predetermined number of times (steps S39, S40).
For example, the phases of the clock signal 17 and the inverted clock signal 18 are shifted four times by 1/10 cycle of the clock signal 17.

Then, even if the phases of the clock signal 17 and the inverted clock signal 18 are changed, only the liquid crystal display device 1 which is not determined to be a ghost defect in step S38 is determined to be a non-defective product (step S41).

As described above, according to the fourth ghost defect inspection method, the phases of the clock signal 17 and the inverted clock signal 18 supplied to the shift register 10 constituting the horizontal drive circuit 7 of the liquid crystal display device 1 are changed. However, since the brightness of the inspection area 38, the brightness of the comparison area 40, and the brightness of the reference areas 41 and 42 are measured, by changing the phases of the clock signal 17 and the inverted clock signal 18, a ghost defect occurs in the liquid crystal display device 1. The presence or absence of a ghost defect can be inspected in a state in which the ghost defect is likely to occur, and the ghost defect of the liquid crystal display device 1 can be determined more accurately as compared with the third ghost defect inspection method.

In the first to fourth ghost defect inspection methods, as the inspection image 32, an image in which black vertical lines are formed on a white background is used as shown in FIG. When a ghost image appears in the comparison areas 39, 40 becomes a gray vertical line, the inspection area 38 has the lowest brightness, the comparison areas 39, 40 have the lowest brightness, and the reference areas 41, 42 have the highest brightness. Get higher Therefore, in the first to fourth ghost defect inspection methods, the inspection area
38 brightness (including difference inspection area brightness) and comparison area 39,40
In comparison with the luminance of (including the difference comparison area luminance),
If each ratio is less than or equal to a predetermined value, it is determined as a ghost defect. Therefore, when an image in which a white vertical line is formed on a black background is used as the inspection image 32, the relationship of luminance is reversed, and the luminance of the inspection area 38 (including the difference inspection area luminance) and the comparison area 39 In comparison with the luminances of 40 and 40 (including the luminance of the difference comparison area), if the respective ratios are equal to or more than a predetermined value, it may be determined as a ghost defect.

In the second or fourth ghost defect inspection method, the clock signal 17 and the inverted clock signal
Since the ghost phenomenon is more likely to occur as the phase difference with 18 increases, as the phase difference between the clock signal 17 and the inverted clock signal 18 increases, the luminance of the inspection area 38 (including the difference inspection area luminance) The predetermined value to be compared with the ratio of the brightness of the comparison areas 39 and 40 (including the brightness of the difference comparison area) may be changed to be large.

[0070]

The present invention is carried out in the form described above, and has the following effects.

That is, according to the present invention, the brightness of the inspection area on which the inspection image is displayed and the brightness of the comparison area in the vicinity of the inspection area are measured, and the liquid crystal display is performed based on the ratio of the brightness of the comparison area to the brightness of the inspection area. Since the presence / absence of a ghost defect of the device is determined, it is possible to quantitatively and objectively determine the ghost defect of the liquid crystal display device automatically in a short time.

As a result, the manufacturing time of the liquid crystal display device can be shortened and the manufacturing cost can be reduced.

In particular, the brightness of the inspection area displaying the inspection image, the brightness of the comparison area near the inspection area, and the brightness of the reference area other than the inspection area and the comparison area are measured, and the brightness of the inspection area and the brightness of the reference area are measured. When the presence or absence of a ghost defect in the liquid crystal display device is determined based on the ratio of the difference between the brightness of the comparison area and the brightness of the reference area (the difference comparison area brightness) with respect to the difference (difference inspection area brightness). Even if a noise component is superimposed on the image displayed in the display area of the liquid crystal display device, the noise component can be measured as the brightness in the reference area, and the brightness in the reference area can be compared with the brightness in the inspection area. By subtracting from the brightness of the area, the noise can be canceled from the brightness of the inspection area and the brightness of the comparison area, and the ratio of the brightness in the inspection area and the comparison area from which the noise is removed can be obtained. Can, it is possible to perform the ghost decision of failure of the liquid crystal display device more accurately.

In the case where the brightness of the inspection area, the comparison area, or the reference area is measured while changing the phases of the clock signal and the inverted clock signal supplied to the shift register constituting the horizontal drive circuit of the liquid crystal display device. In addition, by changing the phase of the clock signal and the inverted clock signal, it is possible to inspect the presence or absence of a ghost defect in a state in which the ghost defect is likely to occur in the liquid crystal display device. The defect can be determined more accurately.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a liquid crystal display device according to the present invention.

FIG. 2 is a block diagram showing the configuration of a ghost defect inspection device.

FIG. 3 is an explanatory diagram showing a display area of a liquid crystal display device.

FIG. 4 is an explanatory view showing an inspection image.

FIG. 5 is an explanatory diagram showing a clock signal and an inverted clock signal.

FIG. 6 is a flowchart showing a first ghost defect inspection method.

FIG. 7 is a flowchart showing a second ghost defect inspection method.

FIG. 8 is a flowchart showing a third ghost defect inspection method.

FIG. 9 is a flowchart showing a fourth ghost defect inspection method.

[Explanation of symbols]

1 Liquid crystal display 2 LCD panel 3 circuit board 4 Liquid crystal cell 5 thin film transistor 6 drive circuit 7 Horizontal drive circuit 8 Vertical drive circuit 9 Interface circuit 10 shift register 11 Gate transistor 13 Clock signal line 14 Inverted clock signal line 15 Video signal line 17 clock signal 18 Inverted clock signal 19 Video signal 30 Ghost defect inspection device 31 Display area 32 inspection image 33 Liquid crystal display drive unit 34 Luminance measurement section 35 Ghost defect determination unit 38 Inspection area 39,40 Comparison area 41,42 Reference area

Claims (9)

[Claims] 1. A method of manufacturing a liquid crystal display device, wherein a liquid crystal display device is inspected for ghost defects during a manufacturing process, and only liquid crystal display devices that are not determined to be ghost defects are shipped as finished products. The inspection area is a part of the display area of the liquid crystal display device, and the area near the inspection area is the comparison area. The inspection image is displayed in the inspection area. And the presence or absence of a ghost defect in the liquid crystal display device based on the ratio of the luminance of the comparison region to the luminance of the inspection region. 2. A method of manufacturing a liquid crystal display device, wherein a liquid crystal display device is inspected for ghost defects during the manufacturing process, and only liquid crystal display devices that are not determined to be ghost defects are shipped as finished products. A part of the display area of the liquid crystal display device to be the inspection area, the area in the vicinity of the inspection area as the comparison area, the inspection area and the area other than the comparison area as the reference area, and the inspection image in the inspection area. Is displayed, and the luminance of the inspection area, the luminance of the comparison area, and the luminance of the reference area are respectively measured, and the difference between the luminance of the inspection area and the luminance of the reference area is set as the difference inspection area luminance, and the luminance of the comparison area and The difference from the brightness of the reference area is defined as the difference comparison area brightness, and the presence or absence of a ghost defect of the liquid crystal display device is determined based on the ratio of the difference comparison area brightness to the difference inspection area brightness. Method of manufacturing a crystal display device. 3. An active matrix liquid crystal display device is used as the liquid crystal display device to be inspected,
3. The brightness of the liquid crystal display device is measured after changing the phases of a clock signal and an inverted clock signal supplied to a shift register which constitutes a horizontal driving circuit of the liquid crystal display device. Manufacturing method of the liquid crystal display device of. 4. A ghost defect inspection apparatus for inspecting a liquid crystal display device for the presence or absence of a ghost defect, wherein a part of the display area of the liquid crystal display device to be inspected is an inspection area, and the inspection area is A liquid crystal display drive unit for displaying an inspection image, a region near the inspection region as a comparison region, a luminance measuring unit for measuring the luminance of the inspection region and the luminance of the comparison region, and the inspection region measured by the luminance measuring unit. A ghost defect inspection unit for a liquid crystal display device, comprising: a ghost defect determination unit that determines the presence or absence of a ghost defect of the liquid crystal display device based on the ratio of the brightness of the comparison area to the brightness of the. 5. A ghost defect inspection device for inspecting a liquid crystal display device for the presence or absence of a ghost defect, wherein a part of the display region of the liquid crystal display device to be inspected is an inspection region, and an inspection image is provided in the inspection region. And a liquid crystal display device drive unit for displaying, and a region near the inspection region as a comparison region,
A brightness measurement unit that measures the brightness of the inspection region, the brightness of the comparison region, and the brightness of the reference region, respectively, using the comparison region and a region other than the inspection region as a reference region, and the brightness of the inspection region measured by the brightness measurement unit. And the brightness of the reference area as the difference inspection area brightness, and the difference between the comparison area brightness and the reference area brightness as the difference comparison area brightness, based on the ratio of the difference comparison area brightness to the difference inspection area brightness. A ghost defect inspecting apparatus for a liquid crystal display device, comprising: a ghost defect determining section for determining whether or not there is a ghost defect in the liquid crystal display device. 6. An active matrix drive type liquid crystal display device is used as the inspection target liquid crystal display device,
6. The liquid crystal display device driving unit is configured so as to be able to change the phases of a clock signal and an inverted clock signal supplied to a shift register that constitutes a horizontal drive circuit of the liquid crystal display device. A device for inspecting ghost defects of the liquid crystal display device described. 7. A ghost defect inspection method for inspecting a liquid crystal display device for the presence or absence of a ghost defect, wherein a part of the display region of the liquid crystal display device to be inspected is set as an inspection region and The neighboring area is used as the comparison area, the inspection image is displayed in the inspection area, the luminance of the inspection area and the luminance of the comparison area are measured, and the ghost defect of the liquid crystal display device is based on the ratio of the luminance of the comparison area to the luminance of the inspection area. A method for inspecting a ghost defect of a liquid crystal display device, characterized by determining the presence or absence of 8. A ghost defect inspection method for inspecting a liquid crystal display device for the presence or absence of a ghost defect, wherein a part of the display region of the liquid crystal display device to be inspected is an inspection region.
An area near the inspection area is used as a comparison area, an area other than the inspection area and the comparison area is used as a reference area, and an inspection image is displayed in the inspection area. The brightness of the inspection area, the brightness of the comparison area, and the brightness of the reference area are displayed. And the difference between the luminance of the inspection area and the luminance of the reference area as the difference inspection area luminance, and the difference between the luminance of the comparison area and the reference area as the difference comparison area luminance. A method for inspecting a ghost defect in a liquid crystal display device, comprising: determining the presence or absence of a ghost defect in the liquid crystal display device based on the ratio of the brightness of the difference comparison area to the. 9. An active matrix liquid crystal display device is used as the liquid crystal display device to be inspected,
9. The brightness of the liquid crystal display device is measured after changing the phases of a clock signal and an inverted clock signal supplied to a shift register forming a horizontal driving circuit of the liquid crystal display device. Ghost defect inspection method for liquid crystal display device.