JP4381030B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for manufacturing a liquid crystal display device having a narrow gap and high gap accuracy using a dispenser driven by a stepping motor.
[0002]
[Prior art]
A liquid crystal display device is manufactured by filling a liquid crystal in a liquid crystal cell in which a pair of substrates are integrated via an annular sealing material. The outline of the conventional vacuum injection method is as follows. First, a pair of alignment-treated substrates with electrodes is prepared. Next, an annular sealing material that is partially discontinuous is formed on one substrate. And many ball | bowl spacers are spread | dispersed in the area | region enclosed with this cyclic | annular sealing material. A liquid crystal cell is constructed by positioning, overlapping and sealing another substrate on this substrate. The liquid crystal cell and the liquid crystal are placed in a vacuum atmosphere, the discontinuous portion (injection port) of the annular sealing material is brought into contact with the liquid crystal, and the liquid crystal cell is returned from the vacuum state to the atmospheric pressure in this state. Is sucked and filled into the liquid crystal cell. Then, the liquid crystal cell is uniformly pressurized to remove excess liquid crystal from the inlet, and the substrate facing distance (gap) of the liquid crystal cell is made uniform. A liquid crystal display device is manufactured by sealing the inlet of the liquid crystal cell having a uniform gap in this way with an ultraviolet curable resin.
[0003]
In this method, liquid crystal is injected into the liquid crystal cell in a vacuum state by utilizing the external atmospheric pressure and the capillary action of the liquid crystal. Therefore, not only the size and gap of the liquid crystal cell but also the alignment and viscosity of the liquid crystal can be used for the injection. There was a problem that it took a long time.
[0004]
On the other hand, a drop injection method [ODF (One Drop Fill) method] is known as a method for shortening the liquid crystal injection time and improving the gap accuracy. This is because a large amount of a small amount of liquid crystal is dropped on one of the pair of substrates on which an annular sealing material is formed, and this substrate and the other substrate are stacked in a vacuum atmosphere and uniformly pressurized, and the sealing material Is applied to a liquid crystal cell that requires a narrow gap and high gap accuracy, because an appropriate amount of liquid crystal can be supplied in a short time and the amount of liquid crystal supplied can be accurately controlled.
[0005]
As dispensers for discharging a small amount of liquid crystal, there are a dispenser that discharges liquid crystal in a syringe by gas pressure, and a dispenser that discharges liquid crystal by a piston inserted in the syringe. What is discharged by gas pressure has a large variation in discharge amount due to the ambient temperature and the viscosity of the liquid crystal, and is difficult to apply to the liquid crystal drop supply. On the other hand, the one using a piston pushes out the liquid crystal in the syringe and discharges it. The discharge amount is determined by the movement amount of the piston and is not easily influenced by the ambient temperature or the viscosity of the liquid crystal. When a stepping motor is used as a moving drive source, for example, when 100 pulses are required to drop a reference amount of liquid crystal, the supply amount can be controlled with an accuracy of 1/100 of the reference amount, so that liquid crystal can be dropped Is preferred.
[0006]
As a method for manufacturing a liquid crystal display device using a dispenser, Patent Document 1 discloses that the weight of liquid crystal supplied onto a substrate is measured, and if the prescribed weight is not reached, a shortage of liquid crystal is added. Has been.
[0007]
Further, Patent Document 2 discloses that a plurality of dispensers having different drop amounts are moved in parallel, and a small drop amount (2 mg) of liquid crystal is arranged at the center of a region surrounded by a large drop amount (5 mg) of liquid crystal. ing. Also disclosed is a liquid crystal dropping device in which a large number of nozzles (diameter 2 mm) are arranged at a predetermined interval (5 mm).
[0008]
Further, in Patent Document 3, a dispenser using a stepping motor is used, and the liquid crystal application surface of a 13-inch XGA type liquid crystal cell is set in the horizontal direction with respect to a position of 5 mm in the vertical and horizontal directions from one corner. When the cell gap is 5 μm, it is divided into 60 points at 5 mm intervals and 46 points at 5 mm intervals in the vertical direction. It is disclosed that no liquid crystal cell can be realized. It is also disclosed that the supply time can be shortened by driving a set of many dispensers with one stepping motor.
[0009]
Similarly to Patent Document 3, Patent Document 4 discloses that a large number of dispensers are arranged in a straight line and moved by a predetermined pitch to drop liquid crystal, and FIG. 5 shows a liquid crystal application region on the substrate. In order to make the gap uniform, the partition area along the periphery of the coating area is set to 1/2 to 1/4 of the amount of liquid crystal supplied to the inner part thereof, and is set at the center of each partition area. Supplying liquid crystals is disclosed.
[0010]
[Patent Document 1]
JP 2001-242473 A (page 4, FIG. 1)
[Patent Document 2]
JP 2001-133799 A (3rd page, 4th column to 4th page, 5th column, FIG. 2, FIG. 4 to FIG. 5)
[Patent Document 3]
JP 2002-258299 A (pages 4 to 5, FIGS. 1 and 4)
[Patent Document 4]
Japanese Patent Laid-Open No. 2002-14360 (5th page, FIG. 5)
[0011]
[Problems to be solved by the invention]
By the way, the IPS liquid crystal display device using birefringence is colored by utilizing the anisotropy of light, and the gap accuracy has an important effect on the display quality because the gap variation greatly affects the display quality. In particular, display unevenness due to gap variation around the cell, display unevenness due to variation in liquid crystal density, glass distortion locally and zero gradation, vacuum foaming at low temperature, downward movement of liquid crystal in high temperature atmosphere, etc. There was a problem that the manufacturing margin was narrow.
[0012]
On the other hand, when a large liquid crystal cell is subjected to stress such as vibration, the substrate bends. As a result, the ball spacer may move at a portion where the gap is enlarged, and the alignment film formed on the substrate may be damaged. In addition, there is a possibility that the dispersed ball spacers may move or aggregate due to the surface tension of the dropped liquid crystal, and the ball spacers may be biased and the gap may become non-uniform.
[0013]
On the other hand, the post spacer, in which a photosensitive resin is coated on the substrate with a uniform thickness and formed in a columnar shape by photolithography, can be formed at a desired position, and since one end is fixed to the substrate, there is no positional deviation and the height is Since the variation is small, it is also used for liquid crystal cells by vacuum injection method, and it is suitable for large and narrow gap liquid crystal cells, but if the post spacer is lower than the gap of the liquid crystal cell, the post spacer is Does not function as a spacer. Further, if it is higher than the gap, it functions as a spacer, but if it is too high, there is a problem that it does not function as a spacer when the gap fluctuates due to plastic deformation.
[0014]
Further, in the dropping injection method, there is a relationship shown in FIG. 7 between the liquid crystal supply amount and the gap. The figure shows the relationship between the measured drop amount per unit area (x) of the liquid crystal and the gap (y) of the liquid crystal cell when the height of the post spacer is a predetermined height (h). That is, when the amount of liquid crystal (x) is small, the gap (y) needs to be reduced by pressurizing the substrate, but the post spacer is greatly compressed, and the compression amount becomes excessive in the region (1) shown, and the post spacer is Because of plastic deformation, the proportional coefficient between the liquid crystal dropping amount (x) and the gap (y) becomes small. In the region (2) where the post spacer is elastically deformed, the amount of liquid crystal dropped and the gap (y) are proportional. In the region (3) where the gap (y) exceeds the height h of the post spacer (3), the gap (x) is determined by the amount of liquid crystal (x), and the post spacer and the cell inner wall are not in contact with each other. The post spacer does not work.
[0015]
Accordingly, the liquid crystal dripping amount must be set in the range (2). However, it is necessary to take into consideration that the post spacer does not undergo plastic deformation even when local pressure is applied, and that the volume change due to the temperature rise of the liquid crystal. It was necessary to set the dripping amount in a narrower range. The range of this region (2) varies depending on the material, height, desired gap, etc. of the post spacer, but as an example, when the height of the post spacer is 5 μm, the area per unit area that becomes the elastic deformation region (2) Liquid crystal dripping amount is 0.43-0.51 μL / cm ² The width is 0.08 μL / cm ² However, the gap is 5.00 μm to 4.30 μm, but the adjacent state to the region (1) or the region (3) is not stable in the elastic state, so the gap needs to be further narrowed. In order to achieve accuracy, it was necessary to further increase the accuracy of the liquid crystal drop supply amount.
[0016]
If a cell gap of 5 μm can be realized by dripping and supplying 5 mg of liquid crystal a predetermined number of times with one shot of 100 pulses, the gap is increased from 4.95 μm to 5.05 μm with an accuracy of 5/100 by increasing or decreasing the number of pulses. However, an IPS liquid crystal display device requires a gap with higher accuracy.
[0017]
On the other hand, in the technique disclosed in Patent Document 1, even though it is possible to set the supply amount of the liquid crystal to a specified weight, it is not known how much of the portion on the substrate is short. It was not expected to make the gap uniform throughout the cell.
[0018]
In addition, the technique disclosed in Patent Document 2 can reduce the supply time because the liquid crystal is supplied using a large number of dispensers. However, when the supply amount of the liquid crystal is different for each dispenser, irregularities are formed on the liquid crystal surface in a naturally diffused state. In particular, the gap of the liquid crystal cell cannot be made uniform, for example, the gap at the periphery of the liquid crystal layer varies. Also, in the dispenser having a large number of nozzles, the problem that the supply amount becomes non-uniform and the gap becomes non-uniform when some of the nozzles are clogged cannot be solved. Maintenance inspection for keeping the operation state of the dispenser stable over a long period of time has been complicated.
[0019]
Further, since the dispenser disclosed in Patent Document 3 is driven by a stepping motor, the supply amount of liquid crystal can be finely adjusted. However, if the liquid crystal application surface is divided into squares having a side length of 5 mm, the liquid crystal supply per compartment is provided. The amount is small, and the variation in the supply amount for each partitioned area is large. In addition, the liquid crystal supplied to the partition point on the peripheral edge of the substrate is adjacent to another liquid crystal in the three directions, but there is no liquid crystal in the remaining one direction. In-plane unevenness could not be eliminated over the entire surface of the liquid crystal cell. In addition, it has been disclosed that the supply time can be shortened by driving a set of many dispensers with a single stepping motor. However, as with the dispenser of Patent Document 2, problems due to partial nozzle clogging and over a long period of time are disclosed. There is a problem that the work for stable operation is complicated.
[0020]
Further, Patent Document 4 discloses that the liquid crystal application region is partitioned into a substantially square shape and the liquid crystal is dropped at the center of each partition region. However, the amount of liquid crystal supplied differs between the central portion and the peripheral portion of the liquid crystal application region. Therefore, the problem that the thickness of the peripheral edge portion is reduced remains.
[0021]
In addition, the liquid crystal display devices disclosed in each patent document all determine the gap of the liquid crystal cell by the spacer particles, and do not set the gap by the supply amount of the liquid crystal, but the narrow gap and high gap accuracy. It could not be applied immediately to the required IPS liquid crystal display device.
[0022]
[Means for Solving the Problems]
The present invention has been proposed in order to solve the above-described problem, and includes a step of preparing a first substrate having an annular sealing material formed on the periphery thereof, and a second substrate constituting a liquid crystal cell together with the first substrate; Using a dispenser in which the amount of liquid crystal supplied is controlled according to the number of pulses applied to the stepping motor, it is determined by the total amount of liquid crystal enclosed determined by the area and interval inside the liquid crystal cell and the total number of drops on the first substrate. A region surrounded by the annular sealing material on the first substrate by setting the number of integer pulses corresponding to the drop amount to be a reference pulse number and increasing or decreasing the reference pulse number so that the total drop amount of liquid crystal approximates the total enclosed amount Dropping the liquid crystal into the substrate, bonding the liquid crystal dropping surface of the first substrate and the second substrate through an annular sealing material in a vacuum atmosphere, and bonding the first and second substrates in the thickness direction. To provide a method of manufacturing a liquid crystal display device comprising the step of setting the pressurizing a predetermined opposing spacing. In this manufacturing method, the amount of liquid crystal dropped can be controlled by dividing the first substrate into a predetermined area and increasing or decreasing the number of reference pulses for each partitioned region. Also, the reference pulse number can be increased or decreased with a predetermined repetition pattern.
[0023]
The present invention also provides a step of preparing a first substrate having an annular sealing material formed on the periphery thereof and a second substrate constituting a liquid crystal cell together with the first substrate, and a pulse supplied by the liquid crystal supply amount to the stepping motor. Using a dispenser controlled in accordance with the number of the liquid crystal, dropping a liquid crystal on a central portion of each square area defined according to the number of vertical and horizontal pixels on the first substrate; and in the vacuum atmosphere, the first substrate A step of bonding the liquid crystal dropping surface of the first substrate and the second substrate through an annular sealing material, and pressurizing the first and second substrates in the thickness direction to set a predetermined facing distance. A manufacturing method is also provided. In this manufacturing method, the dropping amount of the liquid crystal can be set from the area of the square.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A specific embodiment of a method for manufacturing a liquid crystal display device according to the present invention will be described below with reference to FIGS. In the figure, reference numeral 10 denotes a first substrate, in which an alignment film (not shown) is formed in a liquid crystal application planned region, and a plurality of columnar post spacers are formed by selectively etching a photosensitive resin. Reference numeral 12 denotes a planar rectangular annular sealing material surrounding the liquid crystal application scheduled region.
[0025]
In the manufacturing method according to the present invention, the region surrounded by the sealing material 12 is divided into small-area regions, and liquid crystal is supplied to each partitioned region by using a dispenser that drives a piston by a stepping motor to push out the liquid crystal. Gap accuracy can be achieved.
[0026]
An example of this dispenser is shown in FIG. In the figure, 14 is a syringe, and a nozzle 16 is connected to the lower end. 18 is a liquid crystal storage tank that stores liquid crystal, 20 is a tube that connects the lower end of the liquid crystal storage tank 18 and the side wall on the lower end side of the syringe 14 and supplies liquid crystal into the syringe 14, and 22 is a syringe from above the syringe 14. An amount of liquid crystal corresponding to the amount of movement is discharged from the nozzle 16 by moving up and down with a piston inserted into the nozzle 14. Reference numeral 24 denotes a piston drive mechanism that moves the piston 22 up and down. In the illustrated example, a movable plate 34 that fixes a nut 30 and a bush 32 is disposed between fixed plates 28a and 28b that are opposed to each other by spacer rods 26a and 26b. The screw shaft 36 is screwed into the bush 32, the slide rod 38 is inserted into the bush 32, both ends of the screw shaft 36 and the slide rod 38 are fixed to the fixing plates 28a and 28b, respectively, and the screw shaft 36 is used as the rotation shaft of the stepping motor 40. In this connection, the upper end portion of the piston 22 is fixed to the movable plate 34. When the screw shaft 36 is rotated in one direction by the stepping motor 40, the piston 22 moves in one direction by the movable plate 34 interlocked with the movement of the nut 30. When the stepping motor 40 is reversed, the piston 22 moves in the reverse direction. To.
[0027]
The dispenser 42 has a rotation direction and a rotation angle set by a control pulse supplied to the stepping motor 40, and further, the movement amount of the piston 22 is miniaturized by the nut 30 and the screw shaft 36. For example, a dispenser with a rated supply amount of 1 to 10 mg / shot is used in a range of 2 to 8 mg / shot in consideration of stability in mass production.
[0028]
Liquid crystal is supplied onto the substrate 10 shown in FIG. 1 using the dispenser 42 shown in FIG. At this time, the total amount of liquid crystal sealed is determined from the area and gap of the liquid crystal application planned region surrounded by the sealing material 12 after sealing. Actually, the distance between the display area and the annular sealing material 12 varies, and there is a minute unevenness in the cell, the volume of the post spacer, etc., and it is necessary to subtract them. The display area on the substrate 10 where is accurately set is partitioned into small areas, and liquid crystal is supplied to the center of each partitioned area.
[0029]
In the case of a 13.3 type XGA type liquid crystal cell, the aspect ratio is 4: 3, the number of pixels is set to 1024 pixels horizontally, 768 pixels vertically, and the dot size is set to 263.9 μm. This is partitioned while maintaining a 4: 3 aspect ratio. When divided in 256 pixel units, it is 4: 3 (total number of drops n = 12), 8: 6 (n = 48) in 128 pixel units, 16:12 (n = 192) in 64 pixel units, and 32:32 in 32 pixel units. 24 (n = 768),..., But as the pixel unit is reduced, the total number n of drops drastically increases, and it takes time for the dropping process. decide.
[0030]
For example, if the unit is 128 pixels (8: 6), the partition area is a square having a side length of about 33.78 mm, and the total number n of drops is 48. Therefore, even if it drops in 1 second per division, dripping can be completed in 48 seconds. When the total number n of drops is thus determined, the liquid crystal drop amount per shot of the dispenser 42 is determined. The display area is about 270.2 mm wide and about 202.7 mm long. If the length to the annular sealing material 12 after sealing is 0.5 mm, the liquid crystal sealing area is 271.2 × 203.7 mm = 55243 mm. ² ) If the thickness after sealing is 5.0 μm, the total amount of liquid crystal sealed is about 276 mm. ³ (The specific gravity of the liquid crystal is 1.05 and the total weight of the encapsulated is about 290 mg).
[0031]
As a result, the liquid crystal dropping reference amount per section is about 290 mg / 48 = about 6.0 mg. Further, a reference pulse number P to be supplied to the stepping motor 40 with respect to the dropping reference amount 6.0 mg is determined. The dispenser 42 differs in the number of pulses relative to the drop amount depending on the diameter of the piston 22, the moving pitch of the screw shaft 36, etc., but it is assumed here that 100 pulses are required to discharge the drop reference amount of 6.0 mg. And
[0032]
Next, the post spacer formed at a height of 5.5 μm is compressed by 0.5 μm to make the cell gap 5 μm. In the compression range, the post spacer can be kept in an elastically deformed state.
[0033]
As shown in FIG. 3, the display area 44 in which a large number of pixels are formed is partitioned into square partitioned areas 46 indicated by dotted lines. Although the area of each partition area 46 is set to be the same, the area of the partition areas 46b and 46c at the periphery of the display area 44 is the area between the annular seal material 12 and the partition area 46a at the center of the display area 44. Slightly wider because it is added.
[0034]
The area of the partition region 46b that is not a corner at the periphery of the display region 44 is the area of the partition region 46a in the center of the display region (a square area with a side length of 33.78 mm, approximately 1141.09 mm). ² ) The area of the region S1 indicated by the hatched line (33.78 × 0.5 mm) ² Approx. 16.89mm ² ) And the required liquid crystal supply amount is about 6.08 mg. In addition, the area (0.5 × 33.78 × 2 + 0.25 mm) of the region S2 indicated by the checkered stripes in the partition region 46c located at the corner. ² Approx. 34.03mm ² ) And the required liquid crystal supply amount is about 6.17 mg.
[0035]
Therefore, in the case where a drop reference amount of 6.0 mg is supplied to the partition area 46a at the center of the display area 44 by 100 pulses, the peripheral partition area 46b that is not the corner is 6.06 mg by 101 pulses, and the peripheral partition located at the corner. The region 46c is supplied with 6.18 mg of liquid crystal with 103 pulses. In this way, by increasing or decreasing the amount of liquid crystal supplied to regions having different areas with reference to the number of reference pulses, an amount of liquid crystal approximate to an appropriate amount can be supplied.
[0036]
After supplying the liquid crystal onto each partition region 46 in this way, the second substrate 48 is positioned and overlapped on the first substrate 10 in a vacuum atmosphere as shown in FIG. 4, and the cell gap is 5 μm. The liquid crystal cell is configured by applying pressure.
[0037]
As a result, the liquid crystal supplied to the center of each partition region 46 is pressed and enlarged by the second substrate 48 and comes into contact with the adjacent liquid crystal, but the supplied liquid crystal is centered in the partition region 44a at the center of the display region. The liquid crystal is enlarged without moving, and the supplied liquid crystal spreads in front of the partition region and is set to a gap corresponding to the supply amount.
[0038]
Further, since the amount of liquid crystal supplied to the partition regions 44b and 46c at the periphery of the display region is large, when pressed by the second substrate 48, the movement is restricted in contact with the adjacent three-direction liquid crystal, and surplus in the remaining one direction. The liquid crystal moves and is set to the same gap as the central portion of the display area 44, and the gap can be made uniform over the entire surface of the liquid crystal cell. Even in this case, since the increase / decrease amount of the liquid crystal supplied to each partition region is several pulses, it can be diffused without moving the center of gravity. When the liquid crystal is spread in the cell in this way and the temporarily sealed liquid crystal cell is returned to the atmosphere, the liquid crystal in each region is completely in contact with the substrates 10 and 48 and integrated. Thereafter, the annular sealing material 12 is cured to complete the sealing.
[0039]
In the above embodiment, the display area is divided into a plurality of square areas, further divided into a corner area and a non-corner area among the peripheral edges of the square area, and the amount of liquid crystal supplied to each of the divided areas divided into a plurality of sets. The amount of liquid crystal supplied to the square area at the center of the display area is adjusted as the drop reference amount, and the amount of liquid crystal supplied to the other set of partition areas is adjusted by increasing or decreasing the number of pulses for controlling the dispenser. Since the dripping amount is approximated to the total enclosed amount, the gap can be made uniform over the entire surface of the liquid crystal cell, and the elastic state of the post spacer can be maintained over the entire surface of the liquid crystal cell.
[0040]
The diffusion state of the liquid crystal can be observed from the outside of the cell by using a transparent substrate that is not subjected to alignment treatment instead of the substrates 10 and 48. However, the liquid crystal supplied to each partition region according to the above embodiment is arranged in a substantially lattice pattern. It was confirmed that the amount of liquid crystal supplied to each partition region was appropriate and the gap was uniform over the entire cell surface.
[0041]
In the above-described embodiment, the liquid crystal display area is divided into accurate squares and the amount of the peripheral portion is corrected. However, the liquid crystal encapsulated area surrounded by the annular sealing material 12 after enclosing is arranged in the horizontal and vertical directions of the liquid crystal display area. You may partition by a ratio. For example, in the case of a 13-inch XGA type liquid crystal cell, it is divided into approximately squares with a width of 271.2 mm / 8 = 33.9 mm and a length of 203.7 mm / 6 = 33.95 mm. The number of pulses supplied to the dispenser may be averaged, and the number of pulses corresponding to the drop reference amount for each section may be increased or decreased. In this case, the liquid crystal may be dropped at the center of the substantially square partition region.
[0042]
Another embodiment of the present invention will be described with reference to FIGS. In the figure, the same components as those in FIG. The figure is a plan view of the first substrate 10 constituting the liquid crystal cell, and the outer periphery of the display region 44 and the inner periphery of the annular sealing material 12 are in contact with each other for the sake of simplicity.
[0043]
In the case of a 13.3 type XGA type liquid crystal cell, the display area is 270.2 mm × 202.7 mm (54770 mm). ² ) If the gap is set to 4.99 μm, the total amount of liquid crystal sealed is 273.3 mm. ³ The weight multiplied by the specific gravity of 1.05 is about 287 mg.
[0044]
Next, the display area 44 on the substrate 10 is divided into a number of square areas indicated by dotted lines in the figure. In the illustrated example, when the display area 44 of 1024 pixels in width and 768 pixels in height is maintained at a 4: 3 aspect ratio, for example, in 128 pixel units, a square with a side length of about 33.78 mm is obtained, and 8 partitions in the horizontal direction. In the vertical direction, the number of drops n is 48, and the required liquid crystal supply amount per section area is 5.98 mg.
[0045]
A dispenser having a low supply accuracy per pulse and a dispenser that requires 100 pulses to supply 6 mg of liquid crystal has a supply accuracy of 0.06 mg per pulse. However, when this dispenser is used, the required number of pulses is 4783. 33 pulses. Dividing this by the number of sections of 48 results in 99.65 pulses per section area. If the number of reference pulses is 99 pulses, the difference between the number of pulses per section area and the number of reference pulses is 0.65 pulses. In 48 sections, 31.2 pulses (about 31 pulses) remain.
[0046]
Allocate this as evenly as possible to all partition areas. For example, when one pulse is allocated per two sections, there are 24 pulses in all section areas, and therefore the remaining seven pulses may be reassigned to all section areas. In addition, when 1 pulse is allocated to 3 partitions, 16 pulses are obtained in all the divided regions. Therefore, the remaining 15 pulses may be allocated to the 0 pulse region of all the divided regions. When 2 pulses are allocated to 3 partitions, 32 pulses are applied to all the divided regions. Therefore, it is only necessary to subtract one pulse set in any of the partitioned areas. Also, when 2 pulses are allocated per 4 sections, it is the same as when 1 pulse is allocated per 2 sections. When 3 pulses are set per 4 sections, there are 36 pulses in all sections. One pulse may be subtracted from the number of pulses set in the region.
[0047]
As described above, how to allocate the correction pulses can be arbitrarily determined. However, it is desirable that the excess or deficiency be the minimum, and the entire display area 44 may be re-allocated in a balanced manner. In the drawing, a plus or minus signed numerical value described in the square section area 46 indicates the number of pulses to be added to or subtracted from the reference pulse number. If 2 pulses per 3 sections are set in a repetitive pattern of 0, +1, +1 from the upper left to the right of the display area 44, 32 pulses can be set in the entire display area 44, resulting in an excess of 1 pulse. Next, when the total number of vertical and horizontal pulses of the partition area 46 is obtained, it becomes 5, 5, 6, 5, 5, 6 from the top to the bottom in the illustrated example, and all 4 from the left to the right. Then, the maximum row and column are obtained from the vertical and horizontal totals (in the example shown, a total of 6 pulses in a circle), and 1 pulse is subtracted from the rows and columns. When subtracting the pulse, priority is given to the partition area adjacent to 1 assigned earlier, and if one pulse in the partition area surrounded by a thick frame is replaced with 0 pulse as shown in FIG. 6, a correction pulse for each partition area The total number is set. As a result, the total number of pulses for supplying liquid crystal to all the divided areas is 99 × 48 + 31 = 4783 pulses, and the required number of pulses 478.33 can be approximated with an error of 0.33 pulses. In this way, in the entire display area 44 shown in FIG. 6, a liquid crystal having a reference pulse number of 99 pulses and 5.94 mg is supplied to the dispenser “0” area, and a liquid crystal having 100 pulses and 6.0 mg is supplied to the “1” area. Is 5.94 mg × 17 + 6.0 mg × 31 = 286.98 mg, which can be supplied with an error of 0.02 mg with respect to the total liquid crystal encapsulation amount of 287 mg. In this way, the variation in the required supply amount of the liquid crystal converted into the number of pulses is kept within one pulse in the adjacent divided areas, so that a uniform gap can be set over the entire display area.
[0048]
The stepping motor has a minimum drive unit of 1 pulse and can supply only integer pulses. However, by using a dispenser capable of supplying 1 mg of 100 pulses, the liquid crystal can be supplied and controlled in units of 0.01 mg. However, if the supply amount per shot is small, it is necessary to divide and supply several shots to one partition area. However, the liquid crystal supplied in several shots varies in the position of the center of gravity of the liquid crystal supplied for each partition area, and the spreading method becomes uneven when the liquid crystal is expanded in a later process. In addition, there is a problem that maintenance inspection for maintaining a stable supply becomes complicated.
[0049]
In contrast, in the present invention, an appropriate amount can be supplied in one shot, high gap accuracy can be realized, and dispenser management is also easy.
[0050]
In order to reduce the thickness of the liquid crystal cell, the post spacers that maintain the gap must be lowered. However, if the height of the post spacer is lowered, the elastic deformation region is narrowed in proportion to the height. Therefore, in order to set the post spacer to an appropriate elastic deformation region, it is necessary to accurately control the amount of liquid crystal dropped.
[0051]
According to the present invention, since the necessary supply amount of the liquid crystal can be accurately controlled, an appropriate amount of the liquid crystal can be supplied so that the elastic state of the post spacer can be properly maintained.
[0052]
Also in this embodiment, the liquid crystal supplied to each partition region is arranged in a substantially lattice pattern by the transparent cell, the amount of liquid crystal supplied to each partition region is appropriate, and the gap is uniform over the entire cell surface. I was able to confirm.
[0053]
As described above, the present invention can be applied to an IPS liquid crystal display device that requires a narrow gap and high gap accuracy.
[0054]
The present invention is not limited to the above embodiment. For example, the dispenser 42 rotates the screw shaft 36 by the stepping motor 40 to move the piston 22 up and down, but the piston is driven by the stepping motor. Any mechanism dispenser can be used.
[0055]
Further, the step of pressurizing the first and second substrates in the thickness direction and setting them to a predetermined facing distance may be performed before or after sealing the annular sealing material.
[0056]
【The invention's effect】
As described above, according to the present invention, since a necessary supply amount can be controlled with high accuracy higher than the supply accuracy of a dispenser using a stepping motor, an IPS liquid crystal display device that requires a high gap accuracy with a narrow gap. It can also be applied to.
[Brief description of the drawings]
FIG. 1 is a perspective view of a first substrate constituting a liquid crystal cell.
FIG. 2 is a partial cross-sectional side view showing an example of a dispenser for dropping liquid crystal.
FIG. 3 is a plan view showing a liquid crystal supply operation onto a first substrate.
FIG. 4 is a side sectional view showing an operation of manufacturing a liquid crystal cell by stacking first and second substrates.
FIG. 5 is a plan view of a first substrate showing another embodiment of a liquid crystal supply method according to the present invention.
6 is a plan view of a first substrate showing a liquid crystal supply method following the state shown in FIG. 5;
FIG. 7 is a graph showing the relationship between the amount of liquid crystal supplied to the liquid crystal cell and the cell gap.
[Explanation of symbols]
10 First substrate
12 Sealing material
22 piston
40 Stepping motor
42 Dispenser
44 display area
46, 46a, 46b Partition area
48 Second substrate

Claims (2)

Preparing a first substrate having an annular sealing material formed on the periphery thereof, and a second substrate constituting a liquid crystal cell together with the first substrate;
A step of feeding amount of the liquid crystal have use a dispenser which is controlled in accordance with the number of pulses supplied to the stepping motor, liquid crystal is dropped in a region surrounded by a first annular sealing member on the substrate,
Bonding the liquid crystal dropping surface of the first substrate and the second substrate through an annular sealing material in a vacuum atmosphere;
First, look-containing and setting pressurized predetermined opposite interval second substrate in the thickness direction,
Dropping the liquid crystal,
Obtaining a required number of pulses for encapsulating liquid crystal from the total amount of encapsulated liquid crystal determined by the area of the liquid crystal cell and the substrate interval and the supply amount per pulse of the dispenser;
Partitioning the first substrate vertically and horizontally into a predetermined area, and determining a reference pulse number per section so that a total liquid crystal dropping amount approximates a total enclosed amount from the required number of pulses and the number of sections;
Obtaining a multiplication value of the reference pulse number and the number of sections, obtaining a difference between the multiplication value and the required number of pulses, and evenly assigning the difference to all the sections;
A method for manufacturing a liquid crystal display device. The method of manufacturing a liquid crystal display device according to claim 1, wherein the step of equally allocating the difference to all the sections increases or decreases the reference pulse number of the sections arranged vertically and horizontally in a predetermined repeating pattern.

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