JP2009251338A - Method for manufacturing liquid crystal display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize alignment of liquid crystal molecules by suppressing liquid crystal to absorb ultraviolet light to cause heat generation to high temperature, and to enhance production efficiency of a substrate for liquid crystal display. <P>SOLUTION: In a state wherein a plurality of pixels are formed in a matrix pattern between a pair of substrates and the liquid crystal display substrate in which liquid crystal is encapsulated and an ultraviolet lamp are opposed to each other, the liquid crystal display substrate and lamp are impregnated with a limpid liquid having a resistivity above a given value and a sufficiently high transmittance for the ultraviolet light, and the liquid crystal display substrate is irradiated with a given amount of the ultraviolet light by lighting the lamp with a given amount of the electric field applied to each of the pixels, thereby aligning molecules of the liquid crystal in a predetermined direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal display device in which liquid crystal molecules are aligned in a predetermined direction by irradiating ultraviolet rays in a state where an electric field is applied to a liquid crystal display substrate in which liquid crystals are sealed. Specifically, the liquid crystal absorbs ultraviolet rays. The present invention relates to a method for manufacturing a liquid crystal display device which attempts to stabilize the alignment of liquid crystal molecules by suppressing heat generation to a high temperature and to improve the manufacturing efficiency of a liquid crystal display substrate.

  In a conventional method for manufacturing a liquid crystal display device of this type, a liquid crystal material in which a liquid crystal is mixed with a monomer is sealed between a pair of substrates, and a voltage is applied between the substrates so that the liquid crystal molecules are tilted to emit ultraviolet rays. Irradiation was performed to polymerize the above monomers to polymerize the liquid crystal molecules, thereby defining the alignment direction of the liquid crystal molecules (see, for example, Patent Document 1).

Such a method of manufacturing a liquid crystal display device suppresses the occurrence of defects because liquid crystal molecules can be aligned in a non-contact manner compared to a method in which liquid crystal molecules are aligned in a predetermined direction by rubbing the alignment film. It has the feature that it can do.
JP 2003-228050 A

  However, in such a conventional method of manufacturing a liquid crystal display device, the liquid crystal may absorb ultraviolet rays and generate heat at 80 ° C. or higher, and the liquid crystal loses the switching function of transmission and blocking of light and an appropriate image can be obtained. There was a risk of a problem that the display could not be performed.

  The problem of heat generation of the liquid crystal can be dealt with by performing time-divided UV irradiation at regular intervals, but in this case, there is a problem that the manufacturing efficiency of the liquid crystal display substrate deteriorates. .

  Accordingly, the present invention addresses such problems and suppresses the liquid crystal from absorbing ultraviolet rays and generating heat to a high temperature, thereby stabilizing the alignment of liquid crystal molecules and improving the production efficiency of a liquid crystal display substrate. An object of the present invention is to provide a method of manufacturing a liquid crystal display device which intends to achieve the above.

  In order to achieve the above object, a method for manufacturing a liquid crystal display device according to the present invention includes forming a plurality of pixels in a matrix between a pair of substrates, and applying an electric field to each pixel of the liquid crystal display substrate in which the liquid crystal is sealed. A method for manufacturing a liquid crystal display device in which the liquid crystal display substrate is irradiated with ultraviolet rays in an applied state to align the liquid crystal molecules in a predetermined direction, wherein the liquid crystal display substrate and the ultraviolet lamp are opposed to each other. A first step of immersing the substrate in a transparent liquid having a resistivity equal to or higher than a predetermined value and a sufficiently high transmittance for ultraviolet rays, and applying the predetermined amount of electric field to each of the pixels. A second step of turning on and irradiating the liquid crystal display substrate with a predetermined amount of ultraviolet rays.

  With such a configuration, a plurality of pixels are formed in a matrix between a pair of substrates, and a liquid crystal display substrate sealed with liquid crystal and an ultraviolet lamp are opposed to each other and have an ultraviolet resistance higher than a predetermined value. The substrate is immersed in a transparent liquid having a sufficiently high transmittance, and the liquid crystal display substrate is irradiated with a predetermined amount of ultraviolet light by turning on an ultraviolet lamp in a state where a predetermined amount of electric field is applied to each pixel. The liquid crystal molecules are aligned in a predetermined direction.

  In addition, after performing the second step, the third step of irradiating the liquid crystal display substrate with a predetermined amount of ultraviolet light by turning on the ultraviolet lamp with the application of the electric field to each pixel removed. It is. As a result, after the ultraviolet lamp is turned on with a predetermined amount of electric field applied to each pixel to irradiate the liquid crystal display substrate with a predetermined amount of ultraviolet light, the ultraviolet lamp is removed with the electric field applied to each pixel. Is turned on to irradiate the liquid crystal display substrate with a predetermined amount of ultraviolet rays.

  Furthermore, the liquid is pure water. Thereby, the liquid crystal display substrate is irradiated with a predetermined amount of ultraviolet rays in pure water.

  Furthermore, a plurality of the ultraviolet lamps are arranged in a plane parallel to the surface of the liquid crystal display substrate. Accordingly, the liquid crystal display substrate is irradiated with ultraviolet rays by a plurality of ultraviolet lamps arranged in a plane parallel to the liquid crystal display substrate surface.

  The ultraviolet lamp is a water-cooled flash lamp. Accordingly, the water-cooled flash lamp is immersed in the liquid and irradiated with ultraviolet rays while being cooled by the liquid.

  According to the first aspect of the present invention, the liquid crystal display substrate can be cooled simultaneously with the cooling of the ultraviolet lamp with the liquid, and the liquid crystal can be prevented from absorbing ultraviolet rays and generating heat to a high temperature. Accordingly, the alignment of the liquid crystal molecules can be stabilized, and a liquid crystal display device with high display quality can be stably manufactured. In addition, since it is not necessary to irradiate ultraviolet rays in a time-sharing manner, the manufacturing efficiency of the liquid crystal display substrate can be improved.

  According to the second aspect of the invention, the liquid crystal molecules aligned in a predetermined direction can be fixed, and the liquid crystal molecules can be prevented from returning to the initial state even after the electric field applied to the pixels is removed. it can. Therefore, the alignment of the liquid crystal molecules can be further stabilized.

  Furthermore, according to the invention which concerns on Claim 3, the transparent liquid which has a resistivity more than predetermined and has a sufficiently high transmittance | permeability with respect to an ultraviolet-ray can be obtained easily.

  Furthermore, according to the invention which concerns on Claim 4, a ultraviolet-ray can be uniformly irradiated with respect to the wide liquid crystal display substrate surface. Therefore, the uniformity of the alignment of the liquid crystal molecules can be ensured.

  And according to the invention which concerns on Claim 5, a general purpose lamp can be used and the manufacturing cost of an apparatus can be made cheap.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a plan view showing an embodiment of a liquid crystal alignment processing apparatus used in a method of manufacturing a liquid crystal display device according to the present invention. This liquid crystal alignment processing apparatus irradiates ultraviolet rays in a state where an electric field is applied to a liquid crystal display substrate in which liquid crystal is sealed, and aligns liquid crystal molecules in a predetermined direction. A lighting inspection apparatus 1, a water tank 2, The first ultraviolet lamp 3 and the second ultraviolet lamp 4 are provided.

  The lighting inspection apparatus 1 performs a lighting inspection of the liquid crystal display substrate 5 in which liquid crystal is sealed. In the apparatus main body 6, a movable part 7, a stage 8, a probe unit 9, and an alignment camera 10 are provided. And a backlight 11 and a lighting inspection camera 12. Note that the liquid crystal display substrate 5 used here has a COA (Color filter On Array) configuration in which color filters are continuously formed on top of the TFT, and as shown in FIG. A plurality of electrode groups 16 having a plurality of electrodes 15 arranged side by side in the form of a display area 14 in the form of a matrix and arranged with a plurality of electrodes 15 for supplying drive signals to the plurality of pixels 13 in the vicinity of the three edges 5a, 5b, 5c. It is equipped with.

  The movable portion 7 supports a stage 8 and a probe unit 9 which will be described later, and moves in the X-axis direction in the XY plane in FIG. 1 by a moving mechanism (not shown). In the figure, it moves in the depth direction (Z-axis direction).

  A stage 8 is provided inside the movable portion 7. The stage 8 is configured to place and hold the liquid crystal display substrate 5 conveyed in the direction of arrow A by a loader in FIG. 1 on the upper surface, and display the liquid crystal display substrate 5 placed thereon. A rectangular opening 17 is provided at the center corresponding to the region 14 so that light from the backlight 11 described later can pass therethrough. Further, the stage is located on each side of one side (the right side in FIG. 1) of the two sides parallel to the arrow A and the two sides parallel to the arrow A among the two sides orthogonal to the arrow A of the opening 17. A plurality of positioning pins (not shown) are fixedly provided on the upper surface of 8, and two orthogonal edges 5 b and 5 c of the liquid crystal display substrate 5 placed on the stage 8 are fixed by the positioning pins. The liquid crystal display substrate 5 can be positioned at a predetermined position by regulation. Further, in the diagonal direction of the stage 8, a movable pin (not shown) is provided corresponding to the positioning pin, and the edge opposite to the two edges 5 b and 5 c of the liquid crystal display substrate 5 placed thereon. The liquid crystal display substrate 5 can be pressed against the positioning pins by pressing the portions 5a and 5d to be positioned. And the stage 8 is comprised so that the inside of the movable part 7 may be raised / lowered by the raising / lowering mechanism not shown.

  Further, a plurality of probe units 9 are provided on the movable portion 7 on one side of the back side and two sides parallel to the arrow A among the two sides orthogonal to the arrow A in FIG. Is provided. The probe unit 9 is for supplying a bias voltage to a plurality of pixels 13 of the liquid crystal display substrate 5 from a power supply (not shown) provided outside, and has three edges 5 a to 5 c of the liquid crystal display substrate 5. A plurality of probes that are in contact with a plurality of electrodes 15 formed in the vicinity are provided, and the probes are moved up and down to bring the probe tip portion into contact with the electrode 15 of the liquid crystal display substrate 5. The plurality of probe units 9 are configured to rotate integrally around an axis parallel to the Z-axis, thereby enabling alignment of the probe tip portions with respect to the plurality of electrodes 15 of the liquid crystal display substrate 5. ing.

  Further, in the vicinity of the four corners of the stage 8, an alignment camera 10 that is held by the apparatus main body 6 by a support member 18 is provided. This alignment camera 10 photographs both the electrode 15 of the liquid crystal display substrate 5 and the probe tip of the probe unit 9 so that all the probe tips are correctly positioned on the corresponding electrode 15. Thus, a CCD camera or the like enables automatic adjustment of alignment by pattern matching. The support member 18 is configured to slide, for example, in the longitudinal axis direction thereof and retract out of the field of view of the lighting inspection camera 12 described later when the liquid crystal display substrate 5 is inspected for lighting.

  Further, a backlight 11 is provided below the stage 8 corresponding to the opening 17. The backlight 11 is for illuminating the liquid crystal display substrate 5 placed on the stage 8 with white light from the back side thereof to enable lighting inspection of the liquid crystal display substrate 5, for example, cold cathode discharge. Such as a tube.

  A lighting inspection camera 12 is provided above the stage 8 corresponding to the opening 17. This lighting inspection camera 12 is for inspecting whether or not there is a non-lighting portion on the liquid crystal display substrate 5 by photographing the surface of the liquid crystal display substrate 5, and is a CCD camera or the like.

  A water tank 2 is provided on the side of the lighting inspection device 1. The water tank 2 stores a transparent liquid 19 having a resistivity equal to or higher than a predetermined value and having a sufficiently high transmittance with respect to ultraviolet rays. The upper part is opened and the liquid crystal display substrate 5 is liquid 19 from above. So that it can be immersed inside. Further, a circulation pipe of a liquid 19 (not shown) is connected to the side surface of the water tank 2, and the liquid 19 in the water tank 2 is circulated by a pump provided outside, and the temperature of the liquid 19 is kept constant by a chiller provided in the middle. To keep on. If there is a possibility that a part of the liquid 19 is ionized by irradiation with ultraviolet rays and the resistivity of the liquid 19 is lowered, an ion exchanger is connected to the circulation pipe to perform ion exchange, and a resistivity higher than a predetermined value is obtained. Should be maintained.

In this case, as the liquid 19, a pure water containing distilled water and ion-exchanged water having a resistivity (specific resistance) of about 1 × 10 ⁵ Ωcm or more, preferably about 1 × 10 ⁶ Ωcm or more is suitable. Or antifreeze may be sufficient.

  A first ultraviolet (UV) lamp 3 is provided above the water tank 2 so as to face the liquid crystal display substrate 5 that has been conveyed. The first ultraviolet lamp 3 is for irradiating a liquid crystal display substrate 5 to which an electric field is applied to each pixel 13 with ultraviolet rays of 340 nm to 390 nm to align liquid crystal molecules in a predetermined direction. This is a water-cooled xenon flash lamp. A plurality of lines are arranged in parallel to the surface of the liquid crystal display substrate 5 so that the surface of the liquid crystal display substrate 5 can be uniformly irradiated with ultraviolet rays. The first ultraviolet lamp 3 is moved in the Z-axis direction together with the movable part 7 positioned below by a lamp movement mechanism (not shown), and is placed on the stage 8 for the liquid crystal display substrate 5. At the same time, it is immersed in the liquid 19 filled in the water tank 2.

  Above the water tank 2, a second ultraviolet (UV) lamp 4 is provided on the side of the first ultraviolet lamp 3. The second ultraviolet lamp 4 is for fixing the alignment state of the liquid crystal molecules aligned in a predetermined direction by being irradiated with ultraviolet rays from the first ultraviolet lamp 3, and an electric field is applied to each pixel 13. The removed liquid crystal display substrate 5 is irradiated with a predetermined amount of ultraviolet rays (for example, 340 nm to 390 nm). Similarly to the first ultraviolet lamp 3, the second ultraviolet lamp 4 is formed of, for example, an elongated water-cooled xenon flash lamp, which is transferred from the stage 8 by the transport mechanism provided in the water tank 2 and is moved downward. A plurality of lines are arranged in parallel to the surface of the positioned liquid crystal display substrate 5 so that the surface of the liquid crystal display substrate 5 can be uniformly irradiated with ultraviolet rays. Further, the second ultraviolet lamp 4 is moved up and down in the Z-axis direction together with the lifting platform 20 provided below by another moving mechanism (not shown), and is used for a liquid crystal display mounted on the lifting platform 20. The liquid crystal display substrate 5 is levitated from the liquid 19 together with the substrate 5 and can be taken out by the unloader. The first and second ultraviolet lamps 3 and 4 are not limited to water-cooled xenon flash lamps, and may be water-cooled lamps that emit light continuously.

Next, the operation of the thus-configured liquid crystal alignment processing apparatus and a method for manufacturing a liquid crystal display device using this apparatus will be described.
First, in step S1, the liquid crystal display substrate 5 is transported in the direction of arrow A shown in FIG. 1 by a loader (not shown) with the glass substrate side up, and is placed on the stage 8 of the lighting inspection apparatus 1. At this time, in the liquid crystal display substrate 5, the two edges 5 a and 5 d are pushed diagonally by the movable pins, and the opposite two edges 5 b and 5 c are equal to the positioning pins provided on the stage 8. Is abutted on and positioned, and is then attracted and held on the stage 8. Thereby, the positions of the plurality of electrodes 15 provided in the vicinity of the edge of the liquid crystal display substrate 5 and the tip of the probe of the probe unit 9 are roughly adjusted.

  In step S2, the alignment camera 10 is activated. At the same time, the stage 8 moves up to a position where both the electrode 15 of the liquid crystal display substrate 5 and the probe tip of the probe unit 9 can be imaged by the alignment camera 10. At this time, by the pattern matching based on the photographed image, the plurality of probe units 9 are rotated together so that the electrode 15 and the probe tip end coincide with each other. Alignment is made. In this way, when the alignment between the two ends, the probe unit 9 lowers the probe to bring the probe tip into contact with the electrode 15.

  In step S3, a lighting inspection of the liquid crystal display substrate 5 is performed. Specifically, the lighting inspection camera 12 is activated, a bias voltage is supplied to the electrode 15 from an external power supply, and a predetermined electric field is applied to each pixel 13 of the liquid crystal display substrate 5. Further, the backlight 11 is turned on and white light is irradiated on the back surface of the liquid crystal display substrate 5. The alignment camera 10 is retracted out of the field of view of the lighting inspection camera 12 by sliding the support member 18 in the longitudinal axis direction. In this state, the light transmitted through the liquid crystal display substrate 5 is photographed by the lighting inspection camera 12, and the lighting inspection is performed.

  In step S4, the presence / absence of a lighting failure is determined based on a photographed image of the lighting inspection camera 12. Here, if a lighting failure is detected and a “YES” determination is made, the process proceeds to step S5, where the liquid crystal display substrate 5 is determined to be a defective product and is carried out.

On the other hand, if no lighting failure is detected in step S4 and the determination is “NO”, the process proceeds to step S6.
In step S6, the backlight 11 is turned off, and the alignment camera 10 and the lighting inspection camera 12 are turned off. Further, the liquid crystal display substrate 5 is transported horizontally in the X-axis direction shown in FIG. 1 together with the movable portion 7 by the moving mechanism of the movable portion 7, and is positioned below the first ultraviolet lamp 3 on the water tank 2. It is set as a standby for immersion in the liquid 19 in the water tank 2.

  In step S7 (first step), the liquid crystal display substrate 5 and the first ultraviolet lamp 3 are lowered together by each moving mechanism, have a predetermined resistivity or more, and have a sufficiently high transmission with respect to ultraviolet rays. It is immersed in a transparent liquid 19 having a rate (for example, pure water). At this time, the resistivity of the liquid 19 is measured by a liquid resistivity meter, and it is confirmed that the resistivity is not less than a predetermined value. If the resistivity is lower than a predetermined value, it waits for the resistivity to recover through the ion exchanger. In addition, the circulation of the liquid 19 is started, the flow rate with respect to the substrate surface is set to about 1 m / sec, and the liquid 19 is cooled to a temperature of about 24 ° C. Note that when the liquid crystal display substrate 5 and the first ultraviolet lamp 3 are lowered in the Z direction, the second ultraviolet lamp 4 and the lifting platform 20 provided facing the lamp are also lowered together.

  In step S8 (second step), the first ultraviolet lamp 3 is turned on with a predetermined amount of electric field applied to each pixel 13 of the liquid crystal display substrate 5, and a predetermined amount of ultraviolet light is applied to the liquid crystal display substrate 5. Irradiate. Thereby, the liquid crystal molecules are aligned in a predetermined direction. In this case, the liquid crystal normally absorbs ultraviolet rays and generates heat. However, in the present invention, since the liquid crystal display substrate 5 is cooled by the liquid 19, the temperature of the liquid crystal is maintained at about 24 ° C. become. Note that the electric field and ultraviolet irradiation amount are set to appropriate values in advance by experiments.

  In step S9 (third step), the second ultraviolet lamp 4 is turned on with the electric field applied to each pixel 13 of the liquid crystal display substrate 5 removed, and a predetermined amount of ultraviolet light is applied to the liquid crystal display substrate 5. In step S8, the alignment state of the liquid crystal molecules aligned in a predetermined direction is fixed. Specifically, when the alignment process in step S8 is completed, the probe rises and the tip of the probe is separated from the electrode 15 of the liquid crystal display substrate 5. Next, the liquid crystal display substrate 5 is transferred onto the lifting platform 20 by the transport mechanism, and is disposed opposite to the second ultraviolet lamp 4. In this state, the second ultraviolet lamp 4 is turned on, and the liquid crystal display substrate 5 is irradiated with more ultraviolet light than in the case of step S8, and the alignment state of the liquid crystal molecules is fixed. Also in this case, since the liquid crystal display substrate 5 is cooled by the liquid 19, the temperature of the liquid crystal can be suppressed to about 24 ° C. When the liquid crystal display substrate 5 is transferred to the lift 20, the first ultraviolet lamp 3 and the movable part 7 are raised together, and the first ultraviolet lamp 3 is stopped at the raised position and moved. The unit 7 is further moved in the X-axis direction by the moving mechanism and returned to the predetermined position of the lighting inspection apparatus 1.

  In step S10, when the liquid crystal alignment process is completed, the circulation of the liquid 19 is stopped. At the same time, the second ultraviolet lamp 4 and the lifting platform 20 are raised together, and the liquid crystal display substrate 5 is taken out of the liquid 19. Then, the liquid crystal display substrate 5 is unloaded by the unloader, and all the steps of the liquid crystal display device manufacturing method according to the present invention are completed.

  If stable alignment of the liquid crystal molecules is obtained by the ultraviolet irradiation by the first ultraviolet lamp 3 in step S8, the execution of step S9 may be omitted.

  Further, the ultraviolet irradiation of step S8 and step S9 may be performed only by the first ultraviolet lamp 3. In this case, after performing the ultraviolet irradiation of step S8, the ultraviolet irradiation of step S9 is performed using the first ultraviolet lamp 3 in a state where the application of the electric field to each pixel 13 of the liquid crystal display substrate 5 is removed. It is good to do.

  In the above description, the first and second ultraviolet lamps 4 are configured to move up and down, and the case where the first and second ultraviolet lamps 4 are lowered and installed in the liquid 19 at the time of ultraviolet irradiation is described, but the present invention is not limited to this. Each ultraviolet lamp may be fixedly disposed by being submerged in the liquid 19 of the water tank 2. In this case, the liquid crystal display substrate 5 is preferably transported with the glass substrate side down and irradiated with ultraviolet rays from below.

It is a top view which shows embodiment of the liquid crystal aligning apparatus used for the manufacturing method of the liquid crystal display device by this invention. It is a top view which shows one structural example of the board | substrate for liquid display used in the said manufacturing method. 3 is a flowchart illustrating a method for manufacturing a liquid crystal display device according to the present invention. It is sectional drawing explaining the main processes in the said manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lighting inspection apparatus 2 ... Water tank 3 ... 1st ultraviolet lamp 4 ... 2nd ultraviolet lamp 5 ... Substrate for liquid crystal display 8 ... Stage 9 ... Probe unit 10 ... Camera for alignment 11 ... Backlight 12 ... Camera for lighting inspection 13 ... Pixel 15 ... Electrode 19 ... Liquid

Claims (5)

A plurality of pixels are formed in a matrix between a pair of substrates, and the liquid crystal display substrate is irradiated with ultraviolet rays while an electric field is applied to each pixel of the liquid crystal display substrate in which liquid crystal is sealed. A method of manufacturing a liquid crystal display device in which molecules are aligned in a predetermined direction,
A first step of immersing the substrate in a transparent liquid having a resistivity equal to or higher than a predetermined value and a sufficiently high transmittance with respect to ultraviolet rays in a state where the liquid crystal display substrate and the ultraviolet lamp are opposed to each other;
A second step of illuminating the liquid crystal display substrate with a predetermined amount of ultraviolet light by turning on the ultraviolet lamp in a state where a predetermined amount of electric field is applied to each pixel;
A method for manufacturing a liquid crystal display device.   After performing the second step, the third step of illuminating the liquid crystal display substrate with a predetermined amount of ultraviolet light by turning on the ultraviolet lamp in a state where the application of the electric field to each pixel is removed is performed. A method for manufacturing a liquid crystal display device according to claim 1.   The method for manufacturing a liquid crystal display device according to claim 1, wherein the liquid is pure water.   The method for manufacturing a liquid crystal display device according to claim 1, wherein a plurality of the ultraviolet lamps are arranged side by side in a plane parallel to the surface of the liquid crystal display substrate.   The method for manufacturing a liquid crystal display device according to claim 1, wherein the ultraviolet lamp is a water-cooled flash lamp.

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