Display device and method for manufacturing the same

A display device includes a first translucent substrate, a second translucent substrate that is disposed on a display surface side while opposed to the first translucent substrate, and a first light reduction unit that reduces a transmission amount of visible light while overlapping a bright point defect portion in planar view in at least one of the first translucent substrate and the second translucent substrate. The first light reduction unit has a circular shape including a first region disposed in a center and a second region disposed around the first region, and transmittance to the visible light in the first region is higher than transmittance to the visible light in the second region.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP 2018-015421 filed on Jan. 31, 2018, the content of which is hereby incorporated by reference into this application.

TECHNICAL FIELD

The present invention relates to a liquid crystal display device and a method of driving the liquid crystal display device.

BACKGROUND

For example, in a liquid crystal display device among various display devices, an electric field generated between a pixel electrode and a common electrode, which are formed in each pixel region, is applied to liquid crystal to drive the liquid crystal, thereby adjusting an amount of light transmitted through a region between the pixel electrode and the common electrode to display an image.

A known problem with for example, a conventionally liquid crystal display device, is so-called a bright point defect (also referred to as a pixel defect), in which display luminance of the pixel is higher than desired luminance may be generated in a process of manufacturing liquid crystal display device. The bright point defects is caused, for example, by mixing a foreign matter between a pair of substrates in the manufacturing process of the liquid crystal display device, and an alignment of the liquid crystal is confused, or the pixel electrodes and the common electrode are short-circuited by the foreign matter.

A prior art discloses a method for correcting the bright spot defect that laser light is irradiated inside the glass substrate to form light reduction unit so as to cover a region where the bright spot defect is generated in plan view, in order to decrease an amount of transmitting light transmitted (for example, see Unexamined Japanese Patent Publication No. 2017-151414).

However, when the light reduction unit is formed to cover the region where the bright point defect is generated, for example, in the case that the light reduction unit is formed by irradiating the translucent substrate with the laser beam while scanning the translucent substrate with the laser beam, distortion is generated in a region where a scanning direction is turned back in the translucent substrate, and the light may leak from the distortion.

The present disclosure is made in view of the above-described circumstances, and an object of the present disclosure is to provide a display device in which degradation of display quality due to the bright point defect is prevented and a method for manufacturing a display device.

SUMMARY

In one general aspect, the instant application describes a display device including a first translucent substrate, a second translucent substrate that is disposed on a display surface side while opposed to the first translucent substrate, and a first light reduction unit that reduces a transmission amount of visible light while overlapping a bright point defect portion in planar view in at least one of the first translucent substrate and the second translucent substrate. The first light reduction unit has a circular shape including a first region disposed in a center and a second region disposed around the first region, and transmittance to the visible light in the first region is higher than transmittance to the visible light in the second region.

The above general aspect may include one or more of the following features. The second region may include a spiral first low transmittance region. The transmittance to the visible light in the first low transmittance region may be lower than the transmittance to the visible light in other regions of the second region.

The display device may further includes a second light reduction unit that is provided in the second translucent substrate to reduce the transmission amount of the visible light. The first light reduction unit is provided in the second translucent substrate. The second light reduction unit may has a circular shape including a third region disposed in the center and a fourth region disposed around the third region. The transmittance to the visible light in the third region may be higher than the transmittance to the visible light in the fourth region. The first region and the fourth region may overlap each other in planar view while the second region and the third region may overlap each other in planar view.

The second region may include a spiral first low transmittance region. The fourth region may include a spiral second low transmittance region. The transmittance to the visible light in the first low transmittance region may be lower than the transmittance to the visible light in other regions of the second region. The transmittance to the visible light in the second low transmittance region may be lower than the transmittance to the visible light in other regions of the fourth region.

The display device may further include a second light reduction unit that is provided in the second translucent substrate to reduce the transmission amount of the visible light. The first light reduction unit may be provided in the second translucent substrate. The second light reduction unit may has a circular shape including a third region disposed in the center and a fourth region disposed around the third region. The transmittance to the visible light in the fourth region may be higher than the transmittance to the visible light in the third region. The second light reduction unit may overlap at least a part of the first light reduction unit in planar view.

The first light reduction unit may be disposed closer to the display surface side than the second light reduction unit. A diameter of the first light reduction unit may be larger than a diameter of the second light reduction unit.

The second light reduction unit may be disposed closer to the display surface side than the first light reduction section. A diameter of the second light reduction unit may be larger than a diameter of the first light reduction unit.

The second region may include a spiral first low transmittance region. The third region may include a spiral second low transmittance region. The transmittance to the visible light in the first low transmittance region may be lower than the transmittance to the visible light in other regions of the second region. The transmittance to the visible light in the second low transmittance region may be lower than the transmittance to the visible light in other regions of the third region.

The first region and the third region may overlap each other in planar view.

The display device may further include a liquid crystal layer that is disposed between the first translucent substrate and the second translucent substrate and includes the bright point defect portion.

In another general aspect, a method for manufacturing a display device of the instant application, the display device including a first translucent substrate and a second translucent substrate that is disposed on a display surface side while opposed to the first translucent substrate, the method including a detection step of detecting a bright point defect portion of a pixel by performing lighting inspection of the display device, and a first irradiation step of performing irradiation of an energy beam focused on an inside of at least one of the first translucent substrate and the second translucent substrate. In the first irradiation step, a circular first light reduction unit that covers the bright point defect portion when the first light reduction unit is viewed from a display surface side is formed by performing spiral scanning with the energy beam.

The above general aspect may include one or more of the following features. In the first irradiation step, the scanning may be performed with the energy beam from an outer circumferential side to an inner circumferential side.

The method may further include a second irradiation step of performing irradiation of the energy beam focused on an inside of the second translucent substrate while performing the spiral scanning with the energy beam, and forming a second light reduction unit. In the first irradiation step, the irradiation of the energy beam may be performed such that the energy beam is focused on the inside of the second translucent substrate. A focal position of the energy beam in the first irradiation step may be closer to the display surface side than a focal position of the energy beam in the second irradiation step. The first light reduction unit may overlap at least a part of the second light reduction unit in planar view.

In the second irradiation step, scanning may be performed with the energy beam from an outer circumferential side to an inner circumferential side. An irradiation end position in the first irradiation step and an irradiation end position in the second irradiation step may not overlap each other in planar view.

In the second irradiation step, scanning may be performed with the energy beam from an inner circumferential side to an outer circumferential side.

The focal position of the energy beam in the first irradiation step may be closer to the display surface side than the focal position of the energy beam in the second irradiation step. A diameter of the first light reduction unit may be larger than a diameter of the second light reduction unit.

The focal position of the energy beam in the second irradiation step may be closer to the display surface side than the focal position of the energy beam in the first irradiation step. A diameter of the second light reduction unit may be larger than a diameter of the first light reduction unit.

The first irradiation step may includes a first intensity irradiation step of performing irradiation of the energy beam having first irradiation intensity, and a second intensity irradiation step of performing irradiation of the energy beam having second irradiation intensity weaker than the first irradiation intensity after the first intensity irradiation step.

According to the display device of the present disclosure, the deterioration of display quality due to the bright point defect can be prevented.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiment of the present application takes a liquid crystal display device as an example of a display device of the present application. However, the present application is not limited thereto, but the display device may be another kind of display, such as an organic EL display or a plasma display.

FIG. 1is a plan view illustrating an overall configuration of liquid crystal display device LCD according to the exemplary embodiment of the present disclosure. Liquid crystal display device LCD includes display panel DP that displays an image, a display panel driving circuit (data line driving circuit30, gate line driving circuit31) that drives display panel DP, a control circuit (not illustrated) that controls the display panel driving circuit, and backlight134that emits backlight light to display panel DP from a rear surface side.

FIG. 2is a plan view illustrating a configuration of a part of display panel DP.FIG. 3is an end view of a cut portion taken along line A1-A2inFIG. 2.FIGS. 2 and 3illustrate one pixel P.

Display panel DP includes thin film transistor substrate SUB1(hereinafter, referred to as TFT substrate SUB1) disposed on the rear surface side, color filter substrate SUB2(hereinafter, referred to as CF substrate SUB2) that is disposed on a display surface side while opposed to TFT substrate SUB1), and liquid crystal layer LC sandwiched between TFT substrate SUB1and CF substrate SUB2.

In TFT substrate SUB1, a plurality of data lines DL extending in a column direction and a plurality of gate lines GL extending in a row direction are formed, and thin film transistor TFT is formed near an intersection of each of the plurality of data lines DL and each of the plurality of gate lines GL. A rectangular region surrounded by two adjacent data lines DL and two adjacent gate lines GL is defined as one pixel P. A plurality of pixels P are arranged in a matrix on TFT substrate SUB1.

Pixel electrode PIT (display electrode) made of a transparent (translucent) conductive film such as indium tin oxide (ITO) is formed in pixel P. As illustrated inFIG. 2, pixel electrode PIT includes opening32(for example, a slit), and is formed into a stripe shape. In thin film transistor TFT, semiconductor layer SEM made of amorphous silicon (a-Si) is formed on gate insulator GSN (seeFIG. 3), and drain electrode DM and source electrode SM are formed on semiconductor layer SEM (seeFIG. 2). Drain electrode DM is electrically connected to data line DL. Source electrode SM and pixel electrode PIT are electrically connected to each other through contact hole CONT.

A laminated structure of each unit constituting pixel P is not limited to the configurations inFIG. 3, but any known configuration can be applied. For example, in the configuration ofFIG. 3, in TFT substrate SUB1, gate line GL (seeFIG. 2) is formed on first glass substrate GB1(first translucent substrate), and the gate insulator GSN is formed so as to cover gate line GL. Data line DL is formed on gate insulator GSN, and insulator PAS is formed so as to cover data line DL. Common electrode CIT (display electrode) is formed on insulator PAS, and an upper insulator UPAS is formed so as to cover common electrode CIT. Further, pixel electrode PIT is formed on upper insulator UPAS, and alignment film AF is formed so as to cover pixel electrode PIT. First polarizing plate POL1is formed on the rear surface side of first glass substrate GB1.

In CF substrate SUB2ofFIG. 3, black matrix BM (light shielding unit) and color filter CF (for example, a red portion, a green portion, and a blue portion) (light transmission unit) are formed on a lower surface side of second glass substrate GB2(second translucent substrate), and overcoat layer OC is formed so as to cover black matrix BM and color filter CF. Second polarizing plate POL2is formed on the display surface side of second glass substrate GB2. Thus, second glass substrate GB2is located on the display surface side while opposed to first glass substrate GB1, and liquid crystal layer LC is located between first glass substrate GB1and second glass substrate GB2.

According to the configuration inFIG. 3, liquid crystal display device LCD has what is called an IPS (In Plane Switching) system, but liquid crystal display device LCD of the exemplary embodiment is not limited this configuration.

A method for driving liquid crystal display device LCD will briefly be described below. A scanning gate voltage output from gate line driving circuit31is supplied to gate line GL, and a video data voltage outputted from data line driving circuit30is supplied to data line DL. When a gate-on voltage is supplied to gate line GL, semiconductor layer SEM of thin film transistor TFT becomes low resistance, and the data voltage supplied to data line DL is supplied to pixel electrode PIT through source electrode SM. A common voltage output from a common electrode driving circuit (not illustrated) is supplied to common electrode CIT. Consequently, an electric field (driving electric field) is generated between pixel electrode PIT and common electrode CIT, and liquid crystal layer LC is driven by the electric field to display an image.

At this point, the bright point defect (pixel defect) in which display luminance of the pixel is higher than desired luminance may be generated in a process of manufacturing liquid crystal display device LCD.FIG. 4illustrates an example of the case that pixel P becomes bright point defect unit133.FIG. 4exemplifies the case that foreign matter33such as an organic substance and metal is mixed between TFT substrate SUB1and CF substrate SUB2in the process of manufacturing liquid crystal display device LCD. In pixel P ofFIG. 4, alignment of the liquid crystal is confused by the foreign matter (contaminant)33, and light leakage of backlight light34is generated to form bright point defect portion133having the bright point defect.

Liquid crystal display device LCD of the exemplary embodiment has a configuration that prevents the bright point defect. Specifically, as illustrated inFIG. 5, first light reduction unit1that decreasing an amount of visible light transmitted through backlight light34is formed in second glass substrate GB2of CF substrate SUB2.

First light reduction unit1is disposed so as to overlap bright point defect portion133in planar view. In the exemplary embodiment, the first light reduction unit1is formed so as to cover bright point defect portion133caused by foreign matter33when viewed from the display surface side of second glass substrate GB2. That is, when being viewed from the display surface side, the first light reduction unit1covers bright point defect portion133in at least one of first glass substrate GB1and second glass substrate GB2.

FIG. 6is a schematic perspective view illustrating first light reduction unit1of the exemplary embodiment. In the exemplary embodiment, first light reduction unit1has a circular shape. The circular shape includes not only a true circle but also an ellipse and the like. Circular first light reduction unit1includes first region11disposed in the center and second region12disposed around first region11. An area of first region11disposed in the center is smaller than an area of second region12.

In the exemplary embodiment, transmittance to the visible light in first region11is higher than transmittance to the visible light in second region12. First light reduction unit1of the exemplary embodiment further includes spiral first low transmittance region10, and spiral first low transmittance region10is disposed in second region12. First low transmittance region10has the lower transmittance to the visible light as compared with other regions in second region12.

The irradiation of the laser beam is performed such that a focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from an outer circumferential side of first light reduction unit1to an inner circumferential side, which allows the formation of first light reduction unit1inFIG. 6. At this point, the irradiation of the laser beam is ended in first region11that is a central portion of first light reduction unit1, so that the slight distortion is generated in first region11. For this reason, the transmittance to the visible light in first region11is slightly higher than the transmittance to the visible light in second region12.

The area of the region where the distortion is generated can be suppressed by adopting the configuration of the present disclosure. For example, after the scanning is performed with the laser beam in a first direction, the scanning direction with the laser beam is turned back in an opposite direction to the first direction, and the scanning with the laser beam is performed in the opposite direction. In repeating the scanning, the distortion is generated in all the turn-back regions relating to the scanning with the laser beam. On the other hand, by adopting the configuration of the present disclosure, the region where the distortion is generated can be concentrated in first region11that is the central region of the first light reduction unit. As a result, the degradation of the display quality due to the bright point defect can be prevented.

FIG. 7illustrates another configuration that prevents the bright point defect in liquid crystal display device LCD according to a first modification of the exemplary embodiment.

In the first modification, second light reduction unit2is formed at a position (rear surface side) deeper than a focal position during the formation of first light reduction unit1. Second light reduction unit2is planarly disposed, and formed so as to cover bright point defect portion133caused by foreign matter33when viewed from the display surface side of second glass substrate GB2. That is, second light reduction unit2that covers bright point defect portion133when viewed from the display surface side is disposed in at least one of first glass substrate GB1and second glass substrate GB2. Second light reduction unit2reduces the amount of the visible light transmitted through backlight light34.

FIG. 8is a schematic perspective view illustrating first light reduction unit1and second light reduction unit2of the first modification of the exemplary embodiment. In the first modification ofFIG. 8, each of first light reduction unit1and second light reduction unit2has a circular shape. The circular shape includes not only a true circle but also an ellipse. Circular first light reduction unit1includes first region11disposed in the center and second region12disposed around first region11. Similarly, circular second reduction unit2includes third region23A disposed in the center and fourth region24A disposed around third region23A. Even in the first modification, in first light reduction unit1, the area of first region11disposed in the center is smaller than the area of second region12. Similarly, in second dimming section2, the area of third region23A disposed in the center is smaller than the area of fourth region24A.

In the first modification, the transmittance to the visible light in first region11is higher than the transmittance to the visible light in second region12. The transmittance to the visible light in third region23A is higher than the transmittance to the visible light in fourth region24A. First light reduction unit1of the first modification further includes spiral first low transmittance region10, and spiral first low transmittance region10is disposed in second region12. Similarly, second light reduction unit2includes spiral second low transmittance region20, and spiral second low transmittance region20is disposed in fourth region24A. Second low transmittance region20has lower transmittance to the visible light as compared with other regions in fourth region24A.

As illustrated inFIG. 8, in the first modification, first light reduction unit1is disposed on the display surface side with respect to second light reduction unit2, and a center axis of first light reduction unit1is disposed so as not to overlap a center axis of second light reduction unit2in planar view. More specifically, in planar view, first region11of first light reduction unit1does not overlap third region23A of second light reduction unit2, first region11of first light reduction unit1overlaps fourth region24A of second light reduction unit2, and third region23A of second light reduction unit2overlaps second region12of first light reduction unit1.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the configuration. That is, first region11of first light reduction unit1and third region23A of second light reduction unit2may include the distortion, and first region11and third region23A are higher than second region12and fourth region24A in the transmittance to the visible light. For this reason, first region11having the higher transmittance and fourth region24A having the transmittance lower than that of first region11overlap each other in planar view, and third region23A having the higher transmittance and second region12having the transmittance lower than that of third region23A overlap each other in planar view. With this configuration, the light generated due to bright point defect portion133can be prevented from exiting from first region11and third region23A onto the display surface side.

FIG. 9illustrates another configuration that prevents the bright point defect in liquid crystal display device LCD according to a second modification of the exemplary embodiment.

In the second modification, second light reduction unit2B is formed at a position (rear surface side) deeper than the focal position during the formation of first light reduction unit1. Second light reduction unit2B is planarly disposed, and formed so as to cover bright point defect portion133caused by foreign matter33when viewed from the display surface side of second glass substrate GB2. That is, second light reduction unit2B that covers bright point defect portion133when viewed from the display surface side is disposed in at least one of first glass substrate GB1and second glass substrate GB2. Second light reduction unit2B reduces the amount of the visible light transmitted through backlight light34.

FIG. 10is a schematic perspective view illustrating first light reduction unit1of the first modification of the exemplary embodiment and second light reduction unit2B. In second modification ofFIG. 10, each of first light reduction unit1and second light reduction unit2B has a circular shape. The circular shape includes not only a true circle but also an ellipse. Circular first light reduction unit1includes first region11disposed in the center and second region12disposed around first region11. Circular second light reduction unit2B includes third region23B disposed in the center and fourth region24B disposed around third region23B.

The second modification is different from the first modification in the configuration of the second light reduction unit2B.

First light reduction unit1is configured such that the area of first region11disposed in the center is smaller than the area of the second region12, and second light reduction unit2B is configured such that the area of fourth region24B disposed around third region23B is smaller than the area of third region23B.

In first light reduction unit1, the transmittance to the visible light in first region11is higher than the transmittance to the visible light in second region12. On the other hand, in the second modification, in second light reduction unit2B, the transmittance to the visible light in fourth region24B is higher than the transmittance to the visible light in third region23B. First light reduction unit1of the second modification includes spiral first low transmittance region10, and spiral first low transmittance region10is disposed in second region12. On the other hand, second light reduction unit2B includes spiral second low transmittance region20B in third region23B. Second low transmittance region20B has the lower transmittance to the visible light as compared with other regions in third region23B.

The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the inner circumferential side of second light reduction unit2B to the outer circumferential side, which allows the formation of second light reduction unit2B inFIG. 10. At this point, the irradiation of the laser beam is ended in fourth region24B that is a circumferential portion of second light reduction unit2B, so that the slight distortion is generated in fourth region24B. For this reason, the transmittance to the visible light in fourth region24B is slightly higher than the transmittance to the visible light in third region23B.

As illustrated inFIG. 10, in the second modification, first light reduction unit1is disposed on the display surface side with respect to second light reduction unit2B, and first region11of first light reduction unit1is disposed so as to overlap third region23B of second light reduction unit2B in planar view. Second region12of first light reduction unit1is disposed so as to overlap fourth region24B of second light reduction unit2B in planar view.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the configuration. That is, first region11of first light reduction unit1and fourth region24B of second light reduction unit2B may include the distortion, and first region11and fourth region24B are higher than second region12and third region23B in the transmittance to the visible light. For this reason, first region11having the higher transmittance and third region23B having the transmittance lower than that of first region11overlap each other in planar view, and fourth region24B having the higher transmittance and second region12having the transmittance lower than that of fourth region24B overlap each other in planar view, which allows the light generated due to bright point defect portion133to be prevented from exiting from first region11and fourth region24B onto the display surface side.

Further, in the second modification, as illustrated inFIG. 10, a diameter of first light reduction unit1disposed on the display surface side is larger than a diameter of second light reduction unit2B disposed on the rear surface side. With such a configuration, second region12of first light reduction unit1covers fourth region24B of second light reduction unit2B in planar view, so that the light that leaks from fourth region24B can be prevented from exiting onto the display surface side.

FIG. 11illustrates another configuration that prevents the bright point defect in liquid crystal display device LCD according to a third modification of the exemplary embodiment.

In the third modification, second light reduction unit2C is formed on the display surface side of the focal position during the formation of first light reduction unit1. Second light reduction unit2C is planarly disposed, and formed so as to cover bright point defect portion133caused by foreign matter33when viewed from the display surface side of second glass substrate GB2. That is, second light reduction unit2C that covers bright point defect portion133when viewed from the display surface side is disposed in at least one of first glass substrate GB1and second glass substrate GB2.

FIG. 12is a schematic perspective view illustrating first light reduction unit1of the first modification of the exemplary embodiment and second light reduction unit2C. In the third modification ofFIG. 12, each of first reduction unit1and second reduction unit2C has a circular shape. The circular shape includes not only a true circle but also an ellipse. The circular first light reduction unit1includes first region11disposed in the center and second region12disposed around first region11. Circular second light reduction unit2C includes third region23C disposed in the center and fourth region24C disposed around third region23C.

In first light reduction unit1, the area of first region11disposed in the center is smaller than the area of second region12. On the other hand, in second reduction unit2C, the area of fourth region24C disposed around third region23C is smaller than the area of third region23C.

In first light reduction unit1, the transmittance to the visible light in first region11is higher than the transmittance to the visible light in second region12. On the other hand, in second light reduction unit2C, the transmittance to the visible light in fourth region24C is higher than the transmittance to the visible light in third region23C. First light reduction unit1of the third modification includes spiral first low transmittance region10, and spiral first low transmittance region10is disposed in second region12. On the other hand, second light reduction unit2C includes spiral second low transmittance region20C in third region23C. Second low transmittance region20C has the lower transmittance to the visible light as compared with other regions in third region23C.

The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the inner circumferential side of second light reduction unit2C to the outer circumferential side, which allows the formation of second light reduction unit2C inFIG. 12. At this point, the irradiation of the laser beam is ended in fourth region24C that is a circumferential portion of second light reduction unit2C, so that the slight distortion is generated in fourth region24C. For this reason, the transmittance to the visible light in fourth region24C is slightly higher than the transmittance to the visible light in third region23C.

As illustrated inFIG. 12, in the third modification, second light reduction unit2C is disposed on the display surface side with respect to first light reduction unit1, and third region23C of second light reduction unit2C is disposed so as to overlap first region11of first light reduction unit1in planar view.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the configuration. That is, first region11of first light reduction unit1may include the distortion, and first region11is higher than second region12in the transmittance to the visible light. For this reason, first region11having the higher transmittance and third region23C having the transmittance lower than that of first region11overlap each other in planar view, which allows the light generated due to bright point defect portion133to be prevented from exiting from first region11onto the display surface side.

Further, in the third modification, as illustrated inFIG. 12, the diameter of second light reduction unit2C disposed on the display surface side is larger than the diameter of first light reduction unit1disposed on the rear surface side. Furthermore, second region23C where the transmittance can be decreased is configured to cover first light reduction unit1in planar view. Consequently, the light that leaks from first light reduction unit1can be prevented from exiting onto the display surface side.

[Method for Manufacturing Liquid Crystal Display Device]

A method for manufacturing liquid crystal display device LCD will be described below. As the method for manufacturing liquid crystal display device LCD, a description will be given of a method for manufacturing the display device including first glass substrate GB1(first translucent substrate) and second glass substrate GB2(second translucent substrate) that is located on the display surface side while opposed to first glass substrate GB1.

The method for manufacturing the display device according to the exemplary embodiment includes a step of preparing TFT substrate SUB1, a step of preparing CF substrate SUB2, a step of bonding TFT substrate SUB1and CF substrate SUB2, a liquid crystal injecting step, a detection step of detecting the bright point defect portion of the pixel by performing a lighting inspection on display panel DP, and a step of repairing the bright point defect.

Among the above steps, a known method can be applied to the step of preparing TFT substrate SUB1, the step of preparing CF substrate SUB2, the step of bonding TFT substrate SUB1and CF substrate SUB2, the liquid crystal injection step, and the detection step.

For example, the step of preparing TFT substrate SUB1includes a step of forming gate line GL, data line DL, pixel electrode PIT, common electrode CIT, various insulators, and first polarizing plate POL1on first glass substrate GB1. Pixel P defined by TFT substrate SUB1may include red pixel Pr corresponding to red, green pixel Pg corresponding to green, and blue pixel Pb corresponding to blue. The step of manufacturing CF substrate SUB2includes a step of forming black matrix BM, color filter CF, and second polarizing plate POL2on second glass substrate GB2.

In the method for manufacturing the display device according to the exemplary embodiment, the detecting step and the bright point defect repairing step will be described below.

FIG. 13is a flowchart of a method for repairing a bright point defect.FIG. 14is a block diagram illustrating display device manufacturing apparatus95that can perform the method for repairing the bright point defect.

Display device manufacturing apparatus95includes at least inspection device90included in an inspection device that detects the bright point defect of the pixel by performing the lighting inspection on the display device and a bright point defect repairing device6. Manufacturing apparatus95may further include control device93and calculator91. Control device93controls operations of inspection device90, calculator91, and bright point defect repairing device6. Calculator91performs a predetermined calculation as described later. Inspection device90includes an inspection optical system including a microscope.

On a detection step, inspection device90detects the bright point defect. For example, inspection device90lights all display panels DP or lights display panels DP line by line, and measures the luminance of each pixel (step S001). Alternatively, the display panel DP is set in the black display state, and the luminance of each pixel may be measured by emitting the backlight light34from the rear surface side of display panel DP.

Inspection device90detects the pixel in which the luminance exceeding a threshold is measured as the bright point defect portion133(pixel defect portion) (step S002). Inspection device90outputs positional information about the pixel detected as the bright point defect portion133to bright point defect repairing device6(to be described later). Bright point defect portion133may be visually detected by an operator.

In the case that bright point defect portion133is detected in step S002, the process proceeds to a bright point defect repairing step (step S030). When bright point defect portion133is not detected, the flowchart is ended.

FIG. 15illustrates a schematic configuration of bright point defect repairing device6that performs the bright point defect repairing step (step S030). Bright point defect repairing device6includes ultrashort pulse laser oscillation mechanism7, irradiation optical system52including high condensing lens8, and moving device92that moves the irradiation position of the laser beam of the irradiation optical system52.

In the bright point defect repairing step (step S030), in the exemplary embodiment, a laser beam having a wavelength of 1552 nm and a pulse width of 800 fs is used as an example in ultrashort pulse laser oscillation mechanism7.

The bright point defect repairing step (step S030) includes steps S003to S006.

In the bright point defect repairing step (step S030), bright point defect repairing device6first acquires the positional information and shape information (for example, position, size, shape) about the pixel having the bright point defect from inspection device90(Step S003).

Subsequently, based on the acquired shape information, calculator91calculates the shape information and the positional information (for example, position, size, shape) of first light reduction unit1formed by the irradiation of ultrashort pulse laser beam4(Step S004).

Subsequently, under the control of control device93, an optical system such as high condensing lens8of bright point defect repairing device6is positioned based on the positional information about first light reduction unit1, the positional information being calculated by the calculator91.

Subsequently, under the control of control device93, bright point defect repairing device6adjusts the position of focal point F of ultrashort pulse laser beam4such that the position of focal point F is matched with a desired position in second glass substrate GB2. The position of focal point F is adjusted based on, for example, a size of the foreign matter causing the bright point defect or a measured luminance value. For example, as illustrated inFIG. 14, the adjustment is performed such that the position of focal point F of ultrashort pulse laser beam4is matched with the side close to foreign matter33in second glass substrate GB2.

Subsequently, under the control of control device93, the bright point defect repairing device6causes ultrashort pulse laser oscillation mechanism7to emit ultrashort pulse laser beam4. Consequently, ultrashort pulse laser beam4emitted from ultrashort pulse laser oscillation mechanism7is focused and irradiated on focal point F in second glass substrate GB2through high condensing lens8.

Under the control of control device93, ultrashort pulse laser beam4is continuously emitted while the irradiation position (first irradiation position) of ultrashort pulse laser beam4is moved by moving device92(first irradiation step), thereby forming first light reduction unit1(step S005). Through step S005, the bright point defect repairing step (step S030) is completed (step S006).

In the first irradiation step, the irradiation is performed with ultrashort pulse laser beam4focused on the first irradiation position in at least one of first glass substrate GB1and second glass substrate GB2, thereby forming first light reduction unit1that covers bright point defect portion133when viewed from the display surface side as illustrated inFIGS. 5 and 6. The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the outer circumferential side of first light reduction unit1to the inner circumferential side, which allows the formation of first light reduction unit1. At this point, the irradiation of the laser beam is ended in first region11that is the central portion of first light reduction unit1, so that the slight distortion is generated in first region11. For this reason, the transmittance to the visible light in first region11is slightly higher than the transmittance to the visible light in second region12.

The area of the region where the distortion is generated can be suppressed to a minimum level by adopting the manufacturing method of the present disclosure. For example, after the scanning is performed with the laser beam in a first direction, the scanning direction with the laser beam is turned back in an opposite direction to the first direction, and the scanning with the laser beam is performed in the opposite direction. In repeating the scanning, the distortion is generated in all the turn-back regions relating to the scanning with the laser beam. On the other hand, by adopting the manufacturing method of the present disclosure, the region where the distortion is generated can be concentrated in first region11that is the central region of the first light reduction unit. As a result, the degradation of the display quality due to the bright point defect can be prevented.

Desirably the first irradiation step includes a first intensity irradiation step of irradiating the irradiation position with the energy beam having first irradiation intensity and a second intensity irradiation step of irradiating the irradiation position the energy beam having second irradiation intensity lower than the first irradiation intensity after the first intensity irradiation step. That is, in timing of forming second region12by performing the irradiation of the laser beam from the outer circumferential side of first light reduction unit1, the decrease in transmittance in second region12is effective by performing the irradiation of the laser beam having a certain degree of intensity. On the other hand, at the timing of irradiation onto first region11where the distortion is easily generated, first region11being an end position of the laser beam irradiation, the decreasing in irradiation intensity of the laser beam can prevent the generation of the distortion, and prevent the light from leaking from the bright point defect portion in first region11.

In a first modification, in addition to the first irradiation step, step S005above described includes a second irradiation step of performing the irradiation of ultrashort pulse laser beam4under the control of the control device93while focusing ultrashort pulse laser beam4on a position (rear surface side) deeper than the focal position during the formation of first light reduction unit1. Second light reduction unit2is formed through the second irradiation step.

In the second irradiation step, the irradiation is performed with ultrashort pulse laser beam4focused on the first irradiation position in at least one of first glass substrate GB1and second glass substrate GB2, thereby forming second light reduction unit2that covers bright point defect portion133when viewed from the display surface side as illustrated inFIGS. 7 and 8. The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the outer circumferential side of second light reduction unit2to the inner circumferential side, which allows the formation of second light reduction unit2. At this point, the irradiation of the laser beam is ended in third region23A that is a central portion of second light reduction unit2, so that the slight distortion is generated in third region23A. For this reason, the transmittance to the visible light in third region23A is slightly higher than the transmittance to the visible light in fourth region24A.

As illustrated inFIG. 8, in the first modification, first light reduction unit1is disposed on the display surface side with respect to second light reduction unit2, and a center axis of first light reduction unit1is disposed so as not to overlap a center axis of second light reduction unit2in planar view. More specifically, in planar view, first region11of first light reduction unit1does not overlap third region23A of second light reduction unit2, first region11of first light reduction unit1overlaps fourth region24A of second light reduction unit2, and third region23A of second light reduction unit2overlaps second region12of first light reduction unit1.

In this way, the configuration in which the center axis of first light reduction unit1and the center axis of second light reduction unit2do not overlap each other can be implemented by a method in which the irradiation end position of the laser beam in the first irradiation step and the irradiation end position of the laser beam in the second irradiation step do not overlap each other in planar view. For example, in the case that the second irradiation step is performed after the first irradiation step, the irradiation of the second irradiation step is ended at the position overlapping second region12of first light reduction unit1formed through the first irradiation step in planar view, which allows the implementation of the configuration in which first region11of first light reduction unit1and third region23A of second light reduction unit2do not overlap each other. In the case that the first irradiation step is performed after the second irradiation step, the irradiation of the first irradiation step is ended at the position overlapping fourth region24A of second light reduction unit2formed through the second irradiation step in planar view, which allows the implementation of the configuration in which first region11of first light reduction unit1and third region23A of second light reduction unit2do not overlap each other in planar view.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the manufacturing method. That is, first region11of first light reduction unit1and third region23A of second light reduction unit2may include the distortion, and first region11and third region23A are higher than second region12and fourth region24A in the transmittance to the visible light. For this reason, first region11having the higher transmittance and fourth region24A having the transmittance lower than that of first region11overlap each other in planar view, and third region23A having the higher transmittance and second region12having the transmittance lower than that of third region23A overlap each other in planar view, which allows the light generated due to bright point defect portion133to be prevented from exiting from first region11and third region23A onto the display surface side.

Desirably the first irradiation step and the second irradiation step include a first intensity irradiation step of irradiating the irradiation position with the energy beam having first irradiation intensity and a second intensity irradiation step of irradiating the irradiation position the energy beam having second irradiation intensity lower than the first irradiation intensity after the first intensity irradiation step. That is, in timing of forming second region12and fourth region24A by performing the irradiation of the laser beam from the outer circumferential side of first light reduction unit1and second light reduction unit2, respectively, the decrease in transmittance in second region12and fourth region24A is effective by performing the irradiation of the laser beam having a certain degree of intensity. On the other hand, at the timing of irradiation onto first region11and third region23A where the distortion is easily generated, first region11and third region23A being the end position of the laser beam irradiation, the decreasing in irradiation intensity of the laser beam can prevent the generation of the distortion, and prevent the light from leaking from the bright point defect portion in first region11and third region23A.

In a second modification, in addition to the first irradiation step, step S005above described includes the second irradiation step of performing the irradiation of ultrashort pulse laser beam4under the control of the control device93while focusing ultrashort pulse laser beam4on a position (rear surface side) deeper than the focal position during the formation of first light reduction unit1. Second light reduction unit2B is formed through the second irradiation step.

In the second irradiation step, the irradiation is performed with ultrashort pulse laser beam4focused at the first irradiation position in at least one of first glass substrate GB1and second glass substrate GB2, thereby forming second light reduction unit2B that covers bright point defect portion133when viewed from the display surface side as illustrated inFIGS. 9 and 10. The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the inner circumferential side of second light reduction unit2B to the outer circumferential side, which allows the formation of second light reduction unit2B. At this point, the irradiation of the laser beam is ended in fourth region24B that is a circumferential portion of second light reduction unit2B, so that the slight distortion is generated in fourth region24B. For this reason, the transmittance to the visible light in fourth region24B is slightly higher than the transmittance to the visible light in third region23B.

As illustrated inFIG. 10, in the second modification, first light reduction unit1is disposed on the display surface side with respect to second light reduction unit2B, and first region11of first light reduction unit1is disposed so as to overlap third region23B of second light reduction unit2B in planar view. Second region12of first light reduction unit1is disposed so as to overlap fourth region24B of second light reduction unit2B in planar view.

In this way, in order implement the configuration in which first region11of first light reduction unit1and third region23B of second light reduction unit2B overlap each other, for example, in the case that the second irradiation step is performed after the first irradiation step, the irradiation of the second irradiation step is started at the position overlapping first region11of first light reduction unit1formed through the first irradiation step in planar view, which allows the implementation of the configuration in which first region11of first light reduction unit1and third region23B of second light reduction unit2B overlap each other in planar view. In the case that the first irradiation step is performed after the second irradiation step, the irradiation of the first irradiation step is started at the position overlapping fourth region24B of second light reduction unit2B formed through the second irradiation step in planar view, which allows the implementation of the configuration in which second region12of first light reduction unit1and fourth region24B of second light reduction unit2B overlap each other in planar view.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the manufacturing method. That is, first region11of first light reduction unit1and fourth region24B of second light reduction unit2B may include the distortion, and first region11and fourth region24B are higher than second region12and third region23B in the transmittance to the visible light. For this reason, first region11having the higher transmittance and third region23B having the transmittance lower than that of first region11overlap each other in planar view, and fourth region24B having the higher transmittance and second region12having the transmittance lower than that of fourth region24B overlap each other in planar view. With this configuration, the light generated due to bright point defect portion133can be prevented from exiting from first region11and fourth region24B onto the display surface side.

Further, in the second modification, as illustrated inFIG. 10, the diameter of first light reduction unit1disposed on the display surface side is larger than the diameter of second light reduction unit2B disposed on the rear surface side. With such a configuration, second region12of first light reduction unit1covers fourth region24B of second light reduction unit2B in planar view, so that the light that leaks from fourth region24B can be prevented from exiting onto the display surface side.

In order to implement the configuration in which the diameter of first light reduction unit1disposed on the display surface side is larger than the diameter of second light reduction unit2B disposed on the rear surface side, for example, in the case that the second irradiation step is performed after the first irradiation step, the irradiation of the spiral laser beam is ended in the second irradiation step on the inner circumferential side of the outer shape of first light reduction unit1formed through the first irradiation step. In the case that the first irradiation step is performed after the second irradiation step, the irradiation of the spiral laser beam is started in the first irradiation step from the outer circumferential side of the outer shape of second light reduction unit2B formed through the second irradiation step.

Desirably the first irradiation step and the second irradiation step respectively include the first intensity irradiation step of irradiating the irradiation position with the energy beam having first irradiation intensity and the second intensity irradiation step of irradiating the irradiation position the energy beam having second irradiation intensity lower than the first irradiation intensity after the first intensity irradiation step. That is, in timing of forming second region12by performing the irradiation of the laser beam from the outer circumferential side of first light reduction unit1, and in timing of forming third region23B by performing the irradiation of the laser beam from the inner circumferential side of second light reduction unit2B, the decrease in transmittance in second region12and third region23B is effective by performing the irradiation of the laser beam having a certain degree of intensity. On the other hand, at the timing of irradiation onto first region11and fourth region24B where the distortion is easily generated, first region11and fourth region24B being the end position of the laser beam irradiation, the decreasing in irradiation intensity of the laser beam can prevent the generation of the distortion, and prevent the light from leaking from the bright point defect portion in first region11and fourth region24B.

In a third modification, in addition to the first irradiation step, step S005above described includes the second irradiation step of performing the irradiation of ultrashort pulse laser beam4under the control of the control device93while focusing ultrashort pulse laser beam4on the display surface side with respect to the focal position during the formation of first light reduction unit1. Second light reduction unit2C is formed through the second irradiation step.

In the second irradiation step, the irradiation is performed with ultrashort pulse laser beam4focused at the first irradiation position in at least one of first glass substrate GB1and second glass substrate GB2, thereby forming second light reduction unit2C that covers bright point defect portion133when viewed from the display surface side as illustrated inFIGS. 11 and 12. The irradiation of the laser beam is performed such that the focal point is formed within glass substrate GB, and the scanning is spirally performed with the laser beam from the inner circumferential side of second light reduction unit2C to the outer circumferential side, which allows the formation of second light reduction unit2C. At this point, the irradiation of the laser beam is ended in fourth region24C that is a circumferential portion of second light reduction unit2C, so that the slight distortion is generated in fourth region24C. For this reason, the transmittance to the visible light in fourth region24C is slightly higher than the transmittance to the visible light in third region23C.

As illustrated inFIG. 12, in the third modification, second light reduction unit2C is disposed on the display surface side with respect to first light reduction unit1, and first region11of first light reduction unit1is disposed so as to overlap third region23C of second light reduction unit2C in planar view.

In this way, in order implement the configuration in which first region11of first light reduction unit1and third region23C of second light reduction unit2C overlap each other, for example, in the case that the second irradiation step is performed after the first irradiation step, the irradiation of the second irradiation step is started at the position overlapping first region11of first light reduction unit1formed through the first irradiation step in planar view, which allows the implementation of the configuration in which first region11of first light reduction unit1and third region23C of second light reduction unit2C overlap each other in planar view.

The degradation of the display quality due to the bright point defects can further be prevented by adopting the manufacturing method. That is, first region11of first light reduction unit1may include the distortion, and first region11is higher than second region12and third region23C in the transmittance to the visible light. For this reason, first region11having the higher transmittance and third region23C having the transmittance lower than that of first region11overlap each other in planar view, which allows the light generated due to bright point defect portion133to be prevented from exiting from first region11onto the display surface side.

Further, in the third modification, as illustrated inFIG. 12, the diameter of second light reduction unit2C disposed on the display surface side is larger than the diameter of first light reduction unit1disposed on the rear surface side. In addition, third region23C of second light reduction unit2C covers first light reduction unit1in planar view. Thus, the light that leaks from first light reduction unit1can be prevented from exiting onto the display surface side.

In order to implement the configuration in which the diameter of second light reduction unit2C disposed on the display surface side is larger than the diameter of first light reduction unit1disposed on the rear surface side, for example, in the case that the second irradiation step is performed after the first irradiation step, the irradiation of the spiral laser beam is continued in the second irradiation step to the outer circumferential side of the outer shape of first light reduction unit1formed through the first irradiation step. In the case that the first irradiation step is performed after the second irradiation step, the irradiation of the spiral laser beam is started in the first irradiation step from the inner circumferential side of the outer shape of second light reduction unit2C formed through the second irradiation step.

Desirably the first irradiation step and the second irradiation step respectively include the first intensity irradiation step of irradiating the irradiation position with the energy beam having first irradiation intensity and the second intensity irradiation step of irradiating the irradiation position the energy beam having second irradiation intensity lower than the first irradiation intensity after the first intensity irradiation step. That is, in timing of forming second region12by performing the irradiation of the laser beam from the outer circumferential side of first light reduction unit1, and in timing of forming third region23C by performing the irradiation of the laser beam from the inner circumferential side of second light reduction unit2C, the decrease in transmittance in second region12and third region23C is effective by performing the irradiation of the laser beam having a certain degree of intensity. On the other hand, at the timing of irradiation onto first region11and fourth region24C where the distortion is easily generated, first region11and fourth region24C being the end position of the laser beam irradiation, the decreasing in irradiation intensity of the laser beam can prevent the generation of the distortion, and prevent the light from leaking from the bright point defect portion in first region11and fourth region24C.

In the above description, the bright point defects are illustrated in the case that foreign matter33are mixed between TFT substrate SUB1and CF substrate SUB2. However, the cause of the bright point defect is not limited to the case that foreign matter33are mixed between TFT substrate SUB1and CF substrate SUB2. For example, light leakage due to a defect of thin film transistor TFT or light leakage due to a spacer disposed between the substrates may be generated. The bright point defect repairing method according to the method for manufacturing the liquid crystal display device in the present disclosure can also be applied to these bright point defects.

The position where foreign matter33, which may cause the bright point defect, is mixed is not limited to the position between TFT substrate SUB1and CF substrate SUB2. For example, the bright point defects may be generated even if foreign matter33is mixed between first glass substrate GB1and first polarizing plate POL1. In this case, first light reduction unit1and second light reduction units2,2B,2C may be formed near foreign matter33in first glass substrate GB1. The bright point defects may be generated even when foreign matter33is mixed between second glass substrate GB2and second polarizing plate POL2. In this case, first light reduction unit1and second light reduction units2,2B,2C may be formed near foreign matter33in second glass substrate GB2. In this way, foreign matter33may be mixed into an unspecified position of display panel DP. For this reason, in one display panel DP, in the case that foreign matter33causing the bright point defect is mixed in the position (first position) between first glass substrate GB1and first polarizing plate POL1and the position (second position) between second glass substrate GB2and second polarizing plate POL2, the first light reduction unit1may be formed near foreign matter33in first glass substrate GB1according to foreign matter33at the first position, and second light reduction units2,2B,2C may be formed near foreign matter33in second glass substrate GB2according to foreign matter33at the second position. In this case, in consideration of working efficiency of the bright point defect repairing step, first light reduction unit1and the second light reduction units2,2B,2C may be formed on the display surface side of second glass substrate GB2. First reduction unit1and second reduction units2,2B,2C may be formed so as to have different transmittances.

Although the exemplary embodiment of the present disclosure is described above, the present disclosure is not limited to the exemplary embodiment. Various modifications of the exemplary embodiment appropriately made by those skilled in the art without departing from the scope of the present disclosure are also included in the technical scope of the present disclosure.

By appropriately combining the above exemplary embodiment and any one of the above modifications, it is possible to obtain each of the effects of the above exemplary embodiment and the above modifications. The combinations of the modifications, the combinations of the exemplary embodiment and the modifications, or the combinations of the features in the exemplary embodiment and different modifications can also be made.