Patent Application
20100178831
The present invention relates to a drill for repairing a point defect in a liquid crystal device and a method of manufacturing the liquid crystal device.
There is a method of manufacturing a liquid crystal device, which is such as follows: providing a switching element (for example, a TFT), a pixel electrode, etc. on one of a pair of glass substrates; providing a counter electrode etc. on the other one of the glass substrates; thereafter, laminating the two glass substrates via a spacer; then, injecting liquid crystal into a gap between the two glass substrates so as to form a liquid crystal layer; thereafter, laminating polarizing plates onto surfaces of the two glass substrates.
In the above-explained process of manufacturing the liquid crystal device, there is a case where a step of operating various kinds of inspections at predetermined timings to detect inferiority is included. For example, there is a case where, in an inspection performed after the liquid crystal layer is formed, presence or absence of display inferiority is inspected by disposing a pair of polarizing plates for inspection in a manner holding the two glass substrates therebetween, lighting a backlight for inspection, and driving the switching element.
In such an inspection step, in a case where, for example, the liquid crystal layer has a foreign substance that has entered therein, light strikes the foreign substance contained in the liquid crystal layer, reflects diffusely therefrom so as to be detected as a bright point defect that appears bright in spite that black is displayed. The bright point defect causes an extreme lower display quality and a lower yield rate of manufacture.
Accordingly, as a method of repairing the above-explained bright point defect, Patent Document 1, for example, discloses a method as follows: forming a concavity at a surface position of at least one of the pair of substrates, the surface position being on the opposite side from the liquid crystal layer, the surface position being optically overlaid on a portion where the bright point defect has been caused; providing a light blocking material in the concavity; and filling curable resin in the concavity provided with the light blocking material. It is regarded that, with this method, incident light toward the portion where the bright point defect has been caused is blocked with the light blocking material so that the bright point defect is repaired.
In the meantime, in the Patent Document 1, the concavity is cut in the glass substrate by pressing a nib having a diamond head provided thereon against the glass substrate. In the case where the glass substrate is cut in this manner, from a standpoint of preventing damage to the glass substrate, the concavity can be formed only to a certain depth. Accordingly, a space of a certain distance exists between a light-blocking layer and the foreign substance. Then, where such a space exists, there is a case where a phenomenon of light diffraction is induced, the light emitted from the backlight reaches the foreign substance, and the bright point defect is not repaired.
That is, in the case where the foreign substance is contained in the liquid crystal layer held between the glass substrates in the liquid crystal device, incident light toward the foreign substance is completely blocked in an area enclosed with a line connecting the foreign substance with an outer peripheral edge of a bottom portion of the light-blocking layer provided in the glass substrate (i.e. a substantially conic area having the apex at the foreign substance). However, not the entire incident light from the outside of this area travels perpendicularly to the plane of incidence of the glass substrate; there is a case where the light diffracts when passing through the glass substrate, reaches the foreign substance, and causes a trouble that the bright point defect is not repaired.
The present invention was achieved on a basis of the above-explained circumstance, and its purpose is to provide a drill for repairing a point defect in a liquid crystal device, the drill being capable of still more reliably repairing the point defect. Furthermore, its purpose is to provide a method of manufacturing the liquid crystal device, the method including a step capable of suitably repairing the point defect caused in a display area of the liquid crystal device.
In order to solve the above problem, the drill in accordance with the present invention is for repairing the point defect in the liquid crystal device, the drill being characterized by: the drill is for cutting a glass substrate included in the liquid crystal device in order to repair the point defect in the liquid crystal device; and the drill has a point angle from 130 to 180 deg.
With such a drill for repairing the point defect in the liquid crystal device, the point angle from 130 to 180 deg. ensures a sufficient largeness of a light-blockable angular area. As a result of this, light can be prevented from reaching a foreign substance due to light diffraction. Accordingly, the point defect due to the foreign substance can still more reliably be repaired (i.e. light can be blocked).
As one of means for preventing light from reaching the foreign substance due to light diffraction, a configuration as follows is conceivable: providing a light-blocking layer in the concavity formed in the glass substrate; and ensuring the sufficient largeness of the angular area light blockable with the light-blocking layer. Accordingly, as a result of adequate consideration concerning the means for ensuring the largeness of the light-blockable angular area, the inventor of the present invention has found that the light-blockable angular area is larger as a convex angle of a bottom portion of the concavity is greater. In addition, the shape of the concavity is determined by the shape of the drill for cutting the glass substrate, and a greater convex angle of the bottom portion of the concavity can be formed with the greater point angle of the drill. That is, the point angle of the drill for repairing the point defect in the liquid crystal device and the light-blockable angular area have a mutual relation.
Then, after further adequate consideration, where the drill for performing cutting of the glass substrate of the liquid crystal device has the point angle from 130 to 180 deg., the sufficient largeness of the light-blockable angular area can be ensured. As a result of this, light can be prevented from reaching the foreign substance due to light diffraction. On the other hand, where the drill has a point angle of equal to or less than 120 deg., the light-blockable angular area is smaller, and there is a case where light diffraction is caused.
Furthermore, the drill for repairing the point defect in the liquid crystal device in accordance with the present invention may have the point angle from 150 to 180 deg.
While the point angle of equal to or greater than 130 deg. provides a sufficient light-blocked area, the still greater angle of equal to or greater than 150 deg enables light to be blocked still more reliably and the point defect to be suitably repaired.
Furthermore, where the drill has the point angle from 150 to 180 deg., increase in the life of the drill is observed. When the glass substrate is cut using the drill, the drill wears out with each cycle and, by extension, can cause a crack in the glass substrate. Here, where the drill has the point angle from 150 to 180 deg., the drill bears the number of usable cycles equal to or more than ten times the case where the point angle is 130 deg. Thus, where the point angle of the drill for repairing the point defect in the liquid crystal device is from 150 to 180 deg., the life of the drill is increased, which contributes to cost reduction.
Furthermore, the drill for repairing the point defect in the liquid crystal device in accordance with the present invention may have a twist angle from 22 to 26 deg.
Thus, the drill for repairing the point defect in the liquid crystal device has the twist angle from 22 to 26 deg., so that shavings generated accompanying cutting of the glass substrate using the drill can be discharged to the outside of the formed concavity.
That is, the shavings generated accompanying cutting of the glass substrate using the drill usually remain in the formed bottom portion. If light strikes the shavings, the light diffusely reflects and becomes a cause of a minute defect. Therefore, it is required to reliably remove the shavings.
Accordingly, in the present invention, the drill has the twist angle from 22 to 26 deg., which is acute with an axial direction of the drill, so that the generated shavings can be discharged to the outside of the concavity along this twist and not to remain in the bottom portion of the concavity. Thus, a step of removing the shavings can be simplified or can be omitted. Furthermore, the point defect can reliably be repaired. Where similar cutting is performed with the drill having a twist angle from 33 to 37 deg., the shavings twists up along the twist while contacts an inner side face of the concavity. As a result, there is a case where the shavings remains in the bottom portion of the concavity.
Next, in order to solve the above-explained problem, a method of manufacturing the liquid crystal device in accordance with the present invention, the method including a point-defect repairing step for repairing the point defect in a case where the point defect is caused in the liquid crystal device having a liquid crystal layer held between a pair of glass substrates, the method is characterized in that: the point-defect repairing step includes: a concavity forming step for forming a concavity at a position in a face of the glass substrate, the position being capable of blocking light toward the point defect, and the face being on an opposite side from a liquid crystal layer side; and a light-blocking layer forming step for forming a light-blocking layer in the concavity; and, in the concavity forming step, cutting the glass substrate using the drill having a point angle from 130 to 180 deg. so as to form the concavity.
With this manufacturing method, in the concavity forming step, the glass substrate is cut using the drill having the point angle from 130 to 180 deg., so that the convex angle of the bottom portion of the formed concavity can be greater, and, by extension, the sufficient largeness of the light-blockable angular area can be ensured. As a result of this, light can be prevented from reaching the foreign substance due to light diffraction, and the point defect can reliably be repaired. Note that, where the drill has the point angle of equal to or less than 120 deg., the light-blockable angular area is smaller, and there is a case where light diffraction is caused.
Furthermore, the method of manufacturing the liquid crystal device in accordance with the present invention, in the concavity forming step, the drill having a point angle from 150 to 180 deg may be used.
While the point angle of equal to or greater than 130 deg. provides the sufficient light-blocked area, the still greater point angle of equal to or greater than 150 deg. enables light to be still more reliably blocked and the point defect to be suitably repaired.
Furthermore, the drill has the point angle from 150 to 180 deg., so that the life of the drill can be increased. When the glass substrate is cut using the drill in the concavity forming step, the drill wears out with each cycle, and, by extension, can cause the crack in the glass substrate. Here, where the drill has the point angle from 150 to 180 deg., the concavities ten times that of the case where the point angle was 130 deg. can be formed. Thus, contribution to cost reduction in the steps of manufacturing the liquid crystal device can be expected.
Furthermore, in the concavity forming step, the drill having a twist angle from 22 to 26 deg. may be used.
With such a manufacturing method, in the concavity forming step, the shavings generated accompanying cutting of the glass substrate using the drill can be discharged to the outside of the formed concavity, and the removing step can be simplified or can be omitted.
That is, the shavings generated accompanying cutting of the glass substrate using the drill usually remain in the formed bottom portion. If light strikes these shavings, the light diffusely reflects and becomes the cause of the minute defect. Therefore, the step of reliably removing the shavings generated after cutting is required.
Accordingly, by using the drill having the twist angle from 22 to 26 deg., which is arcuate with the axial direction of the drill, the generated shavings can be discharged to the outside of the concavity along this twist and not to remain in the bottom portion of the concavity. Thus, the step of removing the shavings can be simplified or can be omitted. Furthermore, the point defect can reliably be repaired. Where similar cutting is performed using a drill having the twist angle from 33 to 37 deg., the shavings twists up along the twist while contacts the inner side face of the concavity. As a result, there is a case where the shavings remains in the bottom portion of the concavity.
In accordance with the present invention, the drill for repairing the point defect in the liquid crystal device can be provided, the drill being capable of reliably repairing the point defect.
Furthermore, the method of manufacturing the liquid crystal device can be provided, the method including the step capable of suitably repairing the point defect caused in the display area of the liquid crystal device.
10 . . . liquid crystal device; 10a . . . inspection-object liquid crystal panel; 11,12 . . . glass substrate; 21 . . . concavity; 22 . . . light-blocking layer; 40 . . . drill (drill for repairing point defect in liquid crystal device); PA . . . point angle; TA . . . twist angle
An embodiment in accordance with the present invention will be explained with reference to
First, a schematic of a configuration of a liquid crystal device 10 will be explained. As roughly illustrated in
Out of the two glass substrates 11, 12, the glass substrate 11, which is illustrated on the upside in
On the other hand, out of the two glass substrates 11, 12, the glass substrate 12, which is illustrated on the downside in
Next, the method of manufacturing the liquid crystal device 10 will be explained.
Herein explained is mainly a manufacturing step including a point-defect repairing step.
First, the glass substrate 11 is provided, and the TFTs 16, the pixel electrodes 17, etc. are formed on the surface of the glass substrate. On the other hand, separately from the above-explained glass substrate 11, the glass substrate 12 is provided, and the color filter, the counter electrode, etc. are formed on the surface of the glass substrate. Then, via the seal agent 14 provided on the peripheral edge portion of either one of the glass substrates 11, 12, the two glass substrates 11, 12 are laminated in a manner opposed to each other with the faces having the TFTs 16 etc. or the color filters etc. formed thereon inside. Thereafter, liquid crystal is injected into the gap between the two glass substrates 11, 12 so as to form the liquid crystal layer 13. Thereafter, the polarizing plates 15 are laminated to the faces of the two glass substrates 11, 12, the faces being on the opposite sides from the side of the liquid crystal layer 13.
In the above-explained manufacturing step, after the liquid crystal layer 13 is formed, lighting inspection for inspecting presence or absence of display inferiority is performed.
Specifically, as illustrated in
At this time, there is a case where the point defect, which is visually recognized as a bright point, is detected in spite that black is displayed. There is a case where light strikes a foreign substance X that has entered the liquid crystal layer 13, diffusely reflects, and contributes to generation of this point defect. In a case where such a point defect is detected, the point defect is repaired in the point-defect repairing step, which will be illustrated below. Note that it is conceivable that a cause of entrance of the foreign substance X into the liquid crystal layer 13 is a case where the foreign substance X is clinging to the face of the glass substrate 11 or 12, the face facing the liquid crystal layer 13 at a stage before the liquid crystal is injected, a case where the foreign substance X is mixed in the liquid crystal, etc.
The point-defect repairing step includes a step of forming a concavity 21 using a drill 40 (a drill for repairing a point defect in a liquid crystal device) at a position in the face of the glass substrate 11, the face being on the opposite side from the liquid crystal layer 13, the position being optically over laid on the foreign substance X (i.e. the point defect portion). The point-defect repairing step also includes a step of forming a light-blocking layer 22 that blocks light in the concavity 21.
In the step of forming the concavity 21, the concavity 21 having a predetermined depth is formed using a concavity forming device 30 illustrated in
The concavity 21 in the glass substrate 11 is formed using the concavity forming device 30 as follows. First, the inspection-object and repair-object liquid crystal panel 10a is placed at a predetermined position on the stage 31. At this time, the liquid crystal panel 10a is set with the glass substrate 11 upside . Then, the backlight 33 is lightened, and the inspection-object liquid crystal panel 10a is caused to display black. In this state, the display condition is imaged using the CCD camera 35 while the XY driving part 34 is being moved, and the imaging result is image processed so that the position and the size of the foreign substance X is identified. Thereafter, the XY driving part 34 is moved so that the drill 40 is moved to the position matching with the position of the foreign substance X.
Then, the drill 40 is lowered while is revolved at a high speed so that the portion in the surface of the glass substrate 11 is cut, the portion being optically overlaid on the foreign substance X. The concavity 21 is thus formed (see
The concavity 21 is formed as explained above, and, thereafter, in the light-blocking layer forming step, a light blocking material (e.g. epoxy resin having a light blocking property) is filled in the concavity 21 with no space therein and is cured so that the light-blocking layer 22 is formed (see
As explained above, with this embodiment, the drill 40 (the drill for repairing the point defect in the liquid crystal device) is supposed to have the point angle of 130 deg., so that an area light blockable and having a sufficient largeness can be ensured. As a result of this, light can be prevented from reaching the foreign substance due to light diffraction. Accordingly, the point defect due to the foreign substance can be reliably repaired.
That is, with the greater point angle of 130 deg. of the drill 40, the convex angle of a bottom portion of the concavity 21 formed using the drill 40 is also greater. Here, in a case where the concavity 21 has a certain depth, where the bottom portion of the concavity 21 has a greater convex angle, the area light blockable by the light-blocking layer 22 formed in the concavity 21 can also be larger.
Effects of the above explanation will hereinafter be explained in comparison with a case where a comparative drill having a point angle of 100 deg. is used (see
That is, with the point angle of 130 deg. of the drill 40, the sufficient largeness of the light-blockable angular range θ1 can be ensured. As a result of this, light can be prevented from reaching the foreign substance X due to light diffraction. Therefore, the point defect can be reliably repaired.
Furthermore, in this embodiment, with the twist angle of 24 deg. of the drill 40, the twist angle to the axial direction of the drill 40 is acute. Accordingly, shavings generated accompanying cutting of the glass substrate 11 using the drill 40 are naturally discharged to the outside of the concavity 21 along this twist and does not remain in the bottom portion of the concavity 21. As a result of this, a step of removing the shavings can be simplified or can be omitted. Furthermore, the point defect can be reliably repaired.
Hereinafter, concerning the drill 40 of the above-explained embodiment, examples of the point angles PA and the twist angles TA having different values will be shown in Table 1.
Concerning the point-defect repair condition, the grade of repair was determined by performing the lighting inspection again after repair was performed in the point-defect repairing step.
Concerning the shavings discharge condition, the remain of the shavings inside the concavity was visually checked after the concavity was formed in the concavity forming step.
In addition, in order to test the durability of each drill, cutting of the glass substrate was repeated using each of the drills having the same twist angle of 24 deg., and the number of cycles at a time point where a crack was caused in the glass substrate or at a time point where the drill wore out and became incapable of cutting was recorded as the number of usable cycles. Note that, in carrying out the repeated testing of cutting, where the point angle has various values, the cutting resistance or the workload per a unit time varies accordingly. Therefore, first, a condition of the rotating speed for the drill to have a max number of usable cycles was found with respect to each point angle, and the max numbers of usable cycles of the drills under the conditions were compared.
(Table 1)
As understood from the result of Table 1, where the drill had the point angle from 130 to 180 deg., the point defect was able to be reliably repaired. On the other hand, where the drill had the point angle of equal to or less than 120 deg., there was a case where the point defect was found even in the lighting inspection performed again. It is conceivable that this is because, because of the smaller point angle of the drill, the light-blockable angular range was smaller, and light diffraction was caused. Furthermore, where the point angle was from 150 to 180 deg., the number of usable cycles equal to or more than ten times the case where the point angle was equal to or less than 130 deg. was obtained. That is, where the drill has the point angle from 150 to 180 deg., the life of the drill can be increased, which contributes to cost reduction.
Furthermore, where the drill had the twist angle from 22 to 26 deg., the shavings were completely discharged from the concavity. On the other hand, where the twist angle was 35 deg., there was a case where remain of the shavings was found. It is conceivable that, because of the greater twist angle, the shavings twisted up along the twist while contacted an inner side face of the concavity and, as a result, have remained in the bottom portion of the concavity.
While the embodiment in accordance with the present invention is illustrated as above, the present invention is not limited to the embodiment explained above with reference to the drawings. For example, following embodiments are also included in the scope of the present invention.
(1) In the above-explained embodiment, the concavity 21 is formed in the face of the glass substrate 11 out of the pair of glass substrates 11, 12, the face being on the opposite side from the liquid crystal layer 13. The concavity 21 may be formed in the other glass substrate 12 or may be formed in both glass substrates 11, 12.
(2) In the above-explained embodiment, the point defect portion is caused due to the foreign substance that has entered the liquid crystal layer. The point defect portion can be caused also by a scratch made on the surface of the glass substrate. Also in this case, the concavity may be formed at the point defect portion (a portion where the scratch has been made in the glass substrate) so that the point defect is removed and, thereafter, the light blocking layer maybe formed in the concavity so as to block light.
(3) In the above-explained embodiment, the point defect portion is due to the foreign substance that has entered the liquid crystal layer. The point defect portion can be caused also by the switching element or the color electrode that is having a trouble. The present invention is adoptable also in this case.
(4) In the above-explained embodiment, the TFTs are used as the switching element of the liquid crystal device. It is adoptable also to a liquid crystal device using a switching element other than the TFTs (e.g. a thin film diode (TFD)). It is adoptable also to, other than the color-display liquid crystal device, a black-and-white display liquid crystal device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-148328 | Jun 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/051639 | 2/1/2008 | WO | 00 | 12/3/2009 |
