JP3706470B2 - Liquid crystal display device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display element in which the amount of spacers provided between two substrates of the liquid crystal display element can be made constant. More particularly, it relates to a manufacturing method of the liquid crystal display device which is a spacer between the substrates with an amount by controlling the amount of the spacer in the chamber at the time of spraying the spacers constant.
[0002]
[Prior art]
The liquid crystal display element is manufactured as follows. That is, a transparent electrode, an alignment film, and the like are provided on an insulating transparent substrate made of two sheets of glass, a sealing agent is provided around the cells of one substrate, and spacers are dispersed on the other substrate. Then, the two substrates are bonded to each other with a transparent electrode and an alignment film facing each other so as to have a constant gap through a spacer, and after dividing into each cell, the gap between the two substrates is filled with a liquid crystal material, It is manufactured by sticking a polarizing plate or the like on both outer surfaces.
[0003]
This spacer spraying method is performed using, for example, a spacer spraying apparatus as shown in FIG. That is, the exhaust pipe 3 is connected to the lower part of the chamber 1 via the exhaust damper 2 so that the suspended matter in the chamber 1 can be exhausted. Further, a spray nozzle 4 is provided at the upper part, and a spray liquid 5 in which a spacer is dispersed in a solvent such as a mixed liquid of alcohol and water can be sprayed into the chamber 1 by the atomized compressed air 6. ing. In this apparatus, the substrate 30 stored in the cassette 31 is lowered onto the conveyor 22 by the loader 21 and is sequentially transported into the chamber 1, and the sprayed liquid 5 is sprayed into the chamber 1 for about 0.1 to 60 seconds. The solvent of the sprayed liquid sprayed in the chamber 1 evaporates and the spacer floating in the chamber 1 settles on the substrate 30. After a certain period of time, the exhaust damper 2 is opened and the floating spacer is evacuated for a certain period of time, then the substrate 30 is discharged from the chamber 1 and conveyed on the conveyor 23, and another cassette 32 is transferred by the unloader 24. Stored inside.
[0004]
[Problems to be solved by the invention]
According to the above-mentioned spacer spraying method, after the spraying to the previous substrate is finished, the floating spacer in the chamber is evacuated, and then a new substrate is put into the chamber and a certain amount of spray liquid is sprayed into the chamber. By doing so, it is carried out so that a fixed amount of spacers can be dispersed. However, even if evacuation for a certain period of time after the spraying to one substrate is completed, the spacer in the chamber does not disappear completely, and the spacer that floats with time sinks, so that the next substrate is loaded. The amount of spacer remaining in the chamber varies with time. When the next substrate is carried into the chamber, if the remaining spacers are not constant, the spacers floating in the chamber will not be constant even if a certain amount of spray liquid is sprayed. In particular, at the start of production, etc., the dummy must be flown until the spacer floating in the chamber becomes constant, but it is unclear how many dummies will flow. In addition, after the cassette is replaced or after interruption due to a line trouble, the substrate supply interval becomes long, so that the number of spacers floating in the chamber is reduced and the amount of spacers to be dispersed is also reduced. As a result, even if the substrate is placed in the chamber and left for a certain period of time, a certain amount of spacers are not scattered on the substrate, resulting in a non-uniform spacing between the substrates of the liquid crystal panel and a deterioration in display quality. .
[0005]
The present invention has been made to solve such a problem, and it is an object of the present invention to provide a method of manufacturing a liquid crystal display element capable of always spraying a constant spacer regardless of the substrate loading interval.
[0007]
[Means for Solving the Problems]
A method for producing a liquid crystal display device according to the present invention is a liquid crystal display in which a transparent electrode and an alignment film are formed on a substrate, two spacers are attached by spreading spacers, and a gap between the two substrates is filled with a liquid crystal material A method of manufacturing an element, wherein the number of spacers floating in a constant volume in a chamber is measured by a particle counter, and a control controller that controls the measured value to fall within a predetermined range is used to determine the number of spacers floating in the chamber. While the density is controlled to be constant, the spacers are dispersed by placing the substrate on the lower part of the chamber and leaving it for a predetermined time. That is, as a result of the study by the present inventors, it has been found that there is a correlation between the amount of the spacer floating in the chamber and the amount of the spacer settling on the substrate, and the amount of the spacer in the chamber is controlled. As a result, a certain amount of spacers are dispersed on the substrate.
[0008]
In another embodiment of the method for producing a liquid crystal display element of the present invention, a transparent electrode and an alignment film are formed on a substrate, spacers are dispersed and two substrates are adhered, and a liquid crystal material is placed in the gap between the two substrates. A method of manufacturing a liquid crystal display element to be filled, wherein a spacer floating in the chamber is measured by a controller that controls the concentration of the solvent in which the spacer is dispersed in the chamber and controls the measured concentration to fall within a predetermined range. The spacers are dispersed by placing the substrate on the lower part of the chamber and allowing it to stand for a predetermined time while controlling the density of the substrate at a constant level.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, a description about the manufacturing method of the liquid crystal display device of the present invention.
[0011]
In a liquid crystal display element, an electrode pattern is formed with a transparent conductive film such as ITO on each of two insulating transparent substrates such as glass and plastic, an alignment film is formed, and then a spacer is formed on one substrate. It is manufactured by spraying and adhering two substrates with a sealing agent, dividing them into cells or a frame, and then filling a gap between the two substrates with a liquid crystal material. As described above, the manufacturing method of the liquid crystal display element of the present invention is based on the knowledge that there is a correlation between the amount of spacer floating in the chamber and the amount of spacer sinking on the substrate. It is characterized in that the number of spacers interposed between two substrates is made uniform by controlling the density of the spacers. The spacer spraying method will be described with reference to an embodiment of the spacer spraying apparatus of the present invention shown in FIG.
[0012]
In the spacer spraying device shown in FIG. 1, an exhaust pipe 3 is connected to a lower portion of a chamber 1 via an exhaust butterfly valve 2 so that the residue in the chamber 1 can be exhausted. . The exhaust valve 2 can be opened and closed by a solenoid valve 2 a, and the solenoid valve 2 a is controlled using power air 2 b by a control signal from the controller 9. The chamber 1 is, for example, a 1.5 m square and is formed in a stainless steel box shape having a height of about 2 m, and the exhaust pipe 3 has a diameter of about 10 cm, for example, and a thickness of 1 to 1.3 m / sec. Exhaust at a moderate speed.
[0013]
A spray nozzle 4 is provided in the upper part of the chamber 1, and the spray liquid 5 is sent into the spray nozzle 4 via a pump 51. In the example shown in FIG. 1, a pipe is provided so that the spray liquid 5 in the spray nozzle 4 can be circulated with the spray liquid 5 in the container 52, and a rotor (Teflon) is provided in the container 52 by a magnet stirrer 53. The sprayed liquid 5 is agitated via a magnet 54 coated with the sprayed nozzle 54 so that the sprayed liquid 5 in the spray nozzle 4 does not become non-uniform over time. In addition to the pipe for sending the spray liquid 5, the atomizing gas 6 made of N ₂ or the like for atomizing the spray liquid 5 is introduced into the spray nozzle 4 through the gas passage. An electromagnetic valve 6 a whose opening and closing is controlled by a control signal from the controller 9 is also provided in this gas passage. A ventilation hole 7c is further provided in the upper part of the chamber 1, and a ventilation hole damper 7 for opening and closing the ventilation hole 7c is provided. The ventilation hole damper 7 can be opened and closed by an electromagnetic valve 7 a using power air 7 b and is opened and closed based on a control signal from the controller 9.
[0014]
Further, a sensor unit 8a of a detecting means 8 for detecting a spacer density capable of measuring the density of the spacer in the chamber made of, for example, a particle counter is inserted into the chamber 1 so that the density of the spacer in the chamber 1 can be measured. It has become. Then, the count number is sent to the controller 9, and the controller 9 checks whether or not the measured value is within a predetermined range. If the measured value is smaller than the predetermined range, the exhaust valve 2 and the vent hole damper 7 are checked. And a control signal is sent to the solenoid valves 2a, 7a, 6a so as to open the atomizing gas passage, and the spacer can be sprayed from the spray nozzle 4. Conversely, when the number of measurements by the particle counter 8 is larger than the predetermined range, the exhaust valves 2 and the vent hole dampers 7 are opened, and the solenoid valves 2a, 7a and 6a are controlled so as to close the atomizing gas passages. Send a signal. This series of control is controlled by a microcomputer as will be described later.
[0015]
In the chamber 1, the heater 10 is set so that the temperature in the chamber 1 is constant, for example, about 60 ° C., in order to prevent a temperature drop due to heat of vaporization when the spray liquid 5 is sprayed and to facilitate evaporation of the solvent of the spray liquid. Is provided. In the example shown in FIG. 1, it is provided inside the chamber 1, but may be provided outside the chamber 1. In FIG. 1, 11 is a loading door for loading the substrate 30 into the chamber 1, and 12 is a discharge door for unloading the substrate 30 from the chamber 1. The substrates 30 are stored in the cassette 31 and placed on the loader 21, where the substrates 30 are placed one by one on the conveyor 22 and carried to the bottom 1a of the chamber 1. And is stored in another cassette 32 by the unloader 24.
[0016]
Next, a specific example of a method of spraying spacers on a substrate on which an electrode pattern or an alignment film is formed using this spacer spraying device will be described. In the above-described apparatus, the atomizing gas is set to 4 kgf / cm ² , for example, and the power air for driving the solenoid valves 2a and 7a is set to 3 kgf / cm ² . In addition, a silica spherical spacer having a diameter of 5.6 μmφ is used as a spacer, and a spray liquid in which 0.6 g of spacer is dispersed in 100 cc of a solution in which ethyl alcohol and pure water are mixed in a ratio of 1: 1 is prepared. Set to seconds. The product name Particle Counter KC-25 manufactured by Rion Co., Ltd. was used as the spacer density detection means, and the upper limit value of the number counted by this detection means was set to 25500 pieces / liter and the lower limit value was set to 23500 pieces / liter.
[0017]
In this state, in order to clear the interior of the chamber 1 in the initial state, the vent hole damper 7 and the exhaust valve 2 are opened for 30 seconds to exhaust the spacer and the solvent ethyl alcohol gas in the chamber 1. Then, the substrate 30 taken out from the cassette 31 is conveyed by the conveyor 22 to open the loading door 11, the substrate 30 is set on the bottom 1 a in the chamber 1, and the loading door 11 is closed. Thereafter, the spray liquid is sprayed into the chamber 1 for 3 seconds. The spraying of the spray liquid is performed according to the flowchart shown in FIG.
[0018]
That is, the timer counts (S1), and it is checked whether the counter has timed up (S2). If the counter has timed up (for example, a set value of 3 seconds) (NO), the spraying operation is completed, and if not timed up (YES), the spacer density is lower than the lower limit of the set value (for example, 23500 / liter). It is checked whether it is above (S3). Next, if the spacer density is lower than the lower limit value (NO), the ventilation hole damper is closed (S4), the exhaust valve is closed (S5), and the spray nozzle is sprayed (S6). Return. If the spacer density is above the lower limit value (YES), it is checked whether the spacer density is below the upper limit value (for example, 25500 pieces / liter) (S7). If it is below the upper limit (YES), return to step S2, and if it is above the upper limit (NO), open the vent hole damper (S8), further open the exhaust valve (S9), and further turn the spray nozzle Close (S10) and return to step S2. This is repeated until the counter times up, and when the time is up, the spraying operation is finished.
[0019]
After that, the ventilation hole damper and the exhaust valve are closed and left for 30 seconds, and the spacer floating in the chamber is naturally dropped onto the substrate. Next, the exhaust valve 2 is opened, the exhaust is performed for a predetermined time of, for example, about 1 to 3 seconds, the discharge door 12 is opened, the substrate 30 is discharged from the chamber 1, the discharge door 12 is closed, and the same is repeated.
[0020]
The amount of spacers on the actual substrate of the liquid crystal display device manufactured by this method is measured along with the amount of spacers floating in the chamber detected by the above-mentioned detection means, with the number of the order for each substrate sequentially performed on the horizontal axis. The results are shown in FIG. In the conventional method in which the spacer density in the chamber is not managed by the method of the present invention, the amount of the spacer floating in the chamber by the above-described detection means and the amount of the spacer that actually settles on the substrate are shown in FIG. Shown in b). In FIG. 3, the vertical axis of white circles is the number of spacers per liter in the chamber, the vertical axis of black circles is the density of spacers scattered on the substrate (1 piece / mm ² ), and the horizontal axis is the number of substrates in processing order. , P is the upper limit (25500) of the set value of the spacer in the chamber, and Q is the lower limit (23500) of the set value. As apparent from FIG. 3, according to the present invention (FIG. 3 (a)), the amount of spacers dispersed on the substrate is very uniform and in the range of 30 to 38 / mm ² . In the conventional method (FIG. 3B), it can be seen that the amount of spraying varies periodically and is 20 to 40 pieces / mm ² , which varies greatly with the spacer density in the chamber. This periodic change is considered to coincide with the number of substrates accommodated in the cassette, and the spraying interval becomes longer due to the time required to replace the cassette.
[0021]
According to the present invention, the spacers are dispersed on the substrate while the amount of the spacers in the chamber is always kept constant. On the other hand, as is clear from FIG. 3B, there is a correlation between the amount of spacers in the chamber and the amount of spacers actually scattered on the substrate. Therefore, as shown in FIG. 3A, by controlling the amount of spacers in the chamber to be a constant amount, the amount of spacers scattered on the substrate is also constant. As a result, the amount of spacers for each product is constant, the distance between the substrates of the liquid crystal panel is always constant, and a liquid crystal display element with stable quality can be obtained.
[0022]
In the example described above, a spherical spherical spacer made of silica was used as the spacer, but similar results were obtained with plastic beads.
[0023]
In the above example, the number of spacers floating in the chamber is detected by the particle counter and the spacer density is controlled so that the number falls within a certain range. However, the concentration of the solvent in the chamber 1 for dispersing the spacers is controlled. It can also be controlled while measuring. That is, as described above, the spacer is dispersed by, for example, dispersing it in a mixed solution of ethyl alcohol and water and spraying the sprayed liquid into the chamber. This solvent, such as ethyl alcohol, evaporates when sprayed and exists as vapor in the chamber. Since this amount is also proportional to the amount of the dispersion to be sprayed, the density of the spacer floating in the chamber can be similarly controlled by measuring the concentration of the vapor of ethyl alcohol.
[0024]
That is, as the detection means 8 capable of measuring the density of the spacers in the chamber described above, for example, a combustible gas detector manufactured by Shin Cosmos Electric Co., Ltd., trade name Cosmo Protector XP-311A is used to detect ethyl alcohol gas. Can do. In this case, the liquid crystal display device manufacturing method and spacer spraying method are performed by monitoring the concentration of ethyl alcohol gas in the chamber and setting the upper limit value to 0.19 vol% and the lower limit value to 0.175 vol%, for example. The control is the same as the above example except that the control is performed so as to fall within the range, and the description thereof is omitted. FIG. 4 shows a flowchart when the concentration of the ethyl alcohol gas is set in this way and the spray liquid is sprayed. In FIG. 4, the same steps as those in FIG. 2 are denoted by the same step numbers and the description thereof is omitted. This example is different only in that it is checked in step S13 whether the concentration of ethyl alcohol gas is above the lower limit, and in step S17, it is checked whether the ethyl alcohol gas concentration is below the upper limit. The control method in each case is the same as in the above example.
[0025]
FIG. 5 shows the result of measuring the number of spacers per unit area dispersed on the substrate and the concentration of ethyl alcohol gas in the chamber for each substrate in the same manner as described above when the spacers are dispersed by controlling by the method of this example. FIG. 5 (b) shows the number of spacers and the concentration of ethyl alcohol gas in the chamber in the case of a conventional spraying method using the same measurement method. In FIG. 5, the vertical axis of the white circle is the concentration (vol%) of ethyl alcohol gas in the chamber, the vertical axis of the black circle is the density of the spacers scattered on the substrate (pieces / mm ² ), and the horizontal axis is the substrate in processing order. , P is the upper limit (0.19 vol%) of the set value of the ethyl alcohol gas concentration, and Q is the lower limit (0.175%). Also in this case, according to the present invention, the number of spacers on the substrate is as uniform as 30 to 38 / mm ² , whereas in the conventional method, the number of spacers varies from 20 to 40 / mm ^2. The 5B also shows that there is a correlation between the number of spacers actually scattered on the substrate and the concentration of ethyl alcohol gas in the chamber.
[0026]
In this example, the ethyl alcohol gas concentration was detected and the amount controlled, but the solvent is not limited to ethyl alcohol. For example, when chlorofluorocarbon is used, measurement should be made using a detector such as chlorofluorocarbon. Thus, the same control can be performed. When other alcohols such as propanol are mixed and the detection means detects both, the total value of both may be measured and controlled by the total value. Further, when the solvent is a mixture of two or more, any one of them may be detected. In addition, when controlling by this gas concentration, it is preferable to fully control the temperature in the chamber by the heater 10 described above. This is because the evaporation amount of the solvent varies depending on the temperature, and the gas concentration changes. In this case, similar results were obtained even when plastic beads were used as the spacer.
[0027]
FIG. 6 is a schematic diagram for controlling the spacer density while measuring the decrease in the weight of the spray liquid 5 in which the spacers for spraying in a chamber (not shown) are dispersed. That is, while the weight of the container 52 containing the dispersion liquid 5 is detected by the detection means 8 made of, for example, an electronic balance, the data is supplied to the controller 9 and sprayed in a state where the amount of reduction reaches a predetermined set amount. The spray from the nozzle 4 is stopped. In this case, spraying of the spray liquid is performed intermittently, for example, for a short time of about 0.2 seconds, and the weight change of the spray liquid is detected by the detection means 8 each time. And the detection result is sent to the controller 9, and spraying is terminated when a predetermined spray amount is reached. As described above, since the spray liquid is agitated by the magnetic stirrer, the density of the spacer in the spray liquid is always constant, and if the amount of spray liquid to be sprayed is constant, the spray liquid is sprayed into the chamber. The amount of spacers is always constant.
[0028]
According to this example, the amount of sprayed liquid to be sprayed can always be constant. For this reason, there was a variation in the spray amount of about 10% even for a certain period of time spraying due to the difference in spray nozzles (nozzle tip diameter, atomizing gas pressure, etc.) (spray by solenoid valve). The time can be controlled in units of 1/100 seconds), but the spray amount can be reliably controlled to be constant. That is, as shown in the image diagram in FIG. 7, even if the spray amount per hour (slope in the figure) varies depending on the spray nozzle, the spraying time is adjusted (time t ₁ to t ₂ ) so that the constant spray liquid is always constant. A quantity T is sprayed. If the spacer density in the chamber is constant, a predetermined number of spacers are dispersed as described above, and the gap between the insulating transparent substrates can be made constant. In this case, if the density of the spacers in the chamber before spraying the spray liquid is not constant, it will not be constant even if a certain amount of spray liquid is sprayed. It is necessary to make the spacer density constant in the chamber, such as repeating the steps of leaving and evacuating.
[0029]
【The invention's effect】
According to the present invention, since the dispersion amount of the spacers on the substrate is always constant, the distance between the substrates of the liquid crystal panel is always constant, and a stable quality liquid crystal display element with excellent display quality can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view of an embodiment of a spacer spraying device of the present invention.
FIG. 2 is a flowchart when spraying a spray liquid into a chamber with the apparatus of FIG. 1;
FIG. 3 is a diagram showing a change in a spray amount and a spacer density in a chamber when a spacer is sprayed using the apparatus of FIG. 1;
FIG. 4 is a flowchart when spraying a spray liquid according to another embodiment of the present invention.
FIG. 5 is a diagram showing a dispersion amount of spacers and a solvent concentration in a chamber according to the embodiment of FIG. 4;
FIG. 6 is an explanatory diagram of still another embodiment of the present invention.
FIG. 7 is an explanatory view of the stabilization of the spray amount of the spray liquid according to the embodiment of FIG.
FIG. 8 is an explanatory diagram of an example of a conventional spacer spraying device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chamber 2 Exhaust damper 4 Spray nozzle 5 Spray liquid 6 Atomization gas 7 Ventilation hole damper 8 Detection means 9 Control controller 30 Substrate

Claims (2)

A method of manufacturing a liquid crystal display element in which a transparent electrode and an alignment film are formed on a substrate, spacers are dispersed and two substrates are adhered, and a liquid crystal material is filled in a gap between the two substrates. The number of spacers floating in a constant volume in the chamber is measured, and the density of the spacers floating in the chamber is controlled to be constant by a controller that controls so that the measured value falls within a predetermined range. A method of manufacturing a liquid crystal display element, wherein the spacer is dispersed by placing the substrate on a lower part of the substrate and leaving the substrate for a predetermined time. A method of manufacturing a liquid crystal display device in which a transparent electrode and an alignment film are formed on a substrate, spacers are dispersed and two substrates are adhered, and a liquid crystal material is filled in a gap between the two substrates. The concentration of the solvent in the chamber is measured, and the density of the spacer floating in the chamber is controlled to be constant by a controller that controls the measured concentration so that it falls within a predetermined range. A method of manufacturing a liquid crystal display element, wherein the spacer is dispersed by placing the substrate on the substrate and leaving the substrate for a predetermined time.

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