JP2005070634A - Method for manufacturing liquid crystal display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a display defect due to a too large or too small an amount of charged liquid crystal of a liquid crystal display panel manufactured by a liquid crystal drop injecting method. <P>SOLUTION: A substrate 1, on the side where spacers 4 are formed before the liquid crystal display panel, is assembled and an auxiliary substrate 28 for measurement are put one over the other to artificially form a state similar to the gap between the couple of substrates of the liquid crystal display panel having been assembled, and a measurement unit 31 measures the gap between the substrate 1 and auxiliary substrate 28 for measurement, and the optimum amount of injected liquid crystal is calculated from the measured value and the amount of dropped liquid crystal for the liquid crystal drop injection system is calculated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid crystal display panel, and in particular, calculates an optimum value of the amount of liquid crystal when a liquid crystal sealed between a pair of substrates is injected using a dropping injection method, and the calculated optimal value It is characterized in that the occurrence of display defects due to the excess or deficiency of the enclosed liquid crystal amount is suppressed by dropping and injecting the liquid crystal amount based on the above.

  Liquid crystal display devices are widely used in various monitors, display devices for electronic devices, television receivers, and the like. A liquid crystal display device basically includes a liquid crystal display panel in which liquid crystal is sealed between a pair of substrates, a drive circuit for driving the liquid crystal display panel, and the like.

  FIG. 1 is a cross-sectional view schematically illustrating a structural example of a liquid crystal display panel. Here, an active matrix liquid crystal display panel using a thin film transistor as an active element for selecting each pixel on one of a pair of substrates (hereinafter also referred to as two substrates) will be described as an example. However, the present invention is not limited to this. The present invention can be applied to other types of liquid crystal display panels as well.

In Figure 1, a color liquid crystal display panel 9, forming a three-color thin film transistor (T hin F ilm T ransistor) the formed substrate (TFT substrate) 1a and red (R), blue (B), green (G) and has a sandwiched structure of the liquid crystal 5 between the filter (C olor F ilter) substrate (CF substrate) 1b. As a method for manufacturing such a liquid crystal display panel 9, two methods, a vacuum injection method and a drop injection method, have been proposed. In FIG. 1, the spacer 4 is shown as a so-called columnar spacer that is fixedly formed directly on the CF substrate 1b side. However, a spacer in which bead-like spacers are dispersed on one substrate is also known. Since columnar spacers are often used in the dropping injection method, the manufacturing method of the present invention described below will be described assuming that columnar spacers are used.

  In the vacuum injection method, after assembling the TFT substrate 1a and the CF substrate 1b, the liquid crystal 5 is injected into the space formed between the TFT substrate 1a and the CF substrate 1b via the spacer 4. is there. On the other hand, in the dropping injection method, the liquid crystal 5 is first dropped on the TFT substrate 1a or the CF substrate 1b after a specified amount is dropped, and the other substrate is overlapped to simultaneously assemble the liquid crystal display panel 9 and inject the liquid crystal 5. How to do it. Usually, the distance between the TFT substrate 1a and the CF substrate 1b of the liquid crystal display panel 9, that is, the cell gap is as very small as 3 μm to 5 μm.

  In order to completely fill the liquid crystal in the space of 3 μm to 5 μm by the vacuum injection method, first, the TFT substrate 1 a and the CF substrate 1 b are bonded together, and the periphery is bonded with the sealant 7. At this time, a liquid crystal injection port is provided in a part of the sealing material 7. Next, the vacuuming operation of the bonding space between the TFT substrate 1a and the CF substrate 1b is performed using a vacuum chamber or the like. Thereafter, the liquid crystal is brought into contact with the liquid crystal injection port, and the liquid crystal is injected into the space using the capillary phenomenon and the pressure difference inside and outside the bonding gap (space) between the TFT substrate 1a and the CF substrate 1b.

  However, in this method, a very long time is required for evacuating the cell gap space of 3 μm to 5 μm and injecting the liquid crystal. In particular, the liquid crystal injection time is expected to increase as the liquid crystal display panel becomes larger and the gap becomes narrower. In addition, since a step of closing the injection port after the liquid crystal injection is completed is necessary, the liquid crystal injection step is one of the causes of an increase in manufacturing cost.

  On the other hand, in the case of the dropping injection method, since the panel assembly for bonding the TFT substrate 1a and the CF substrate 1b and the liquid crystal injection are performed simultaneously, the bonding gap between the TFT substrate 1a and the CF substrate 1b is 3 μm to 3 μm. There is no need for a vacuuming operation to make the 5 μm space into a decompressed atmosphere. Further, the work for sealing the liquid crystal injection port is eliminated. Furthermore, since the liquid crystal is dropped with a dispenser or the like, the filling time of the liquid crystal is also fast. Therefore, in the case of the dropping injection method, it is possible to greatly reduce the time required for filling the liquid crystal into the bonding gap between the TFT substrate 1a and the CF substrate 1b as compared with the vacuum injection method.

  Here, a manufacturing method of a liquid crystal display panel by a vacuum injection method and a dropping injection method will be described in the order of processes.

[I] Manufacturing method of liquid crystal display panel by vacuum injection method (1) First, display region (TFT substrate 1a and CF substrate 1b) on one of a pair (TFT substrate 1a and CF substrate 1b) constituting the liquid crystal display panel An opening (liquid crystal injection port) for injecting liquid crystal is provided in part and an adhesive sealant such as epoxy resin is applied.
(2) Scattering of spacers for keeping the distance between the two substrates at several 3 μm to 5 μm is performed.
As shown in FIG. 1, when using a substrate in which a spacer is previously formed on one or both of the two substrates, it is not necessary to spray the spacer.
(3) After aligning the two substrates, they are bonded together.
(4) Depending on the curing conditions of the sealing material, the sealing material is cured by ultraviolet irradiation or heat treatment.
The above operation completes an empty liquid crystal display panel having a predetermined space between two substrates and containing no liquid crystal.

(5) When the liquid crystal display panel is multi-faced using the large substrate 1, cutting is performed for each panel size.
(6) In order to inject liquid crystal into the space between the two substrates that have been bonded together, the two bonded substrates are set in a vacuum chamber. Thereafter, the internal space of the two substrates is evacuated by making the inside of the vacuum chamber a reduced pressure atmosphere.
(7) The liquid crystal is brought into contact with the liquid crystal injection port provided in the sealing material, and the pressure in the vacuum chamber is increased to atmospheric pressure or higher than atmospheric pressure. As a result, the liquid crystal is injected into the space by the capillary phenomenon and the pressure difference between the inside and outside of the internal space of the two substrates.
(8) After the operation of wiping off the liquid crystal adhering to the liquid crystal inlet, the liquid crystal inlet is sealed using an ultraviolet curable adhesive or the like.

[II] Manufacturing Method of Liquid Crystal Display Panel by Drop Injection Method FIG. 2 is an explanatory diagram of a manufacturing method of a liquid crystal display panel by the dropping injection method. The spacer can be dispersed or formed on either or both of the two substrates (TFT substrate 1a and CF substrate 1b), and the sealant can be applied on either or both, but the explanation is simple. Therefore, a description will be given assuming that spacers are dispersed or formed on the CF substrate 1b and a sealing material is applied to the TFT substrate 1a.

    (1) The spacers 4 are dispersed to keep the distance between the two substrates 1 at 3 to 5 μm. When spacers are previously formed on one or both of the substrates, it is not necessary to spray the spacers 4. Hereinafter, an example in which the columnar spacer 4 is previously formed in the CF substrate 1b according to the drawing will be described.

(2) Using the dispenser 70, the sealing material 7 is applied to the TFT substrate 1a in a frame shape so as to surround the display region 2 (FIG. 2A).
(3) A prescribed amount of liquid crystal 5 is dropped using a dispenser 50 at a position inside the sealing material 7 (FIG. 2B).
(4) After aligning the two substrates (TFT substrate 1a and CF substrate 1b), bonding is performed in a reduced pressure atmosphere (FIG. 2C).
(5) The two substrates that have been bonded together are taken out into an atmospheric pressure atmosphere and the sealing material 7 is cured, so that ultraviolet light is irradiated using an ultraviolet lamp 18 in accordance with the curing conditions of the sealing material 7, Alternatively, a process such as heating the bonded substrates is performed (FIG. 2D).
(6) When a plurality of liquid crystal display panels 9 are collectively manufactured using a large substrate, cutting is performed for each panel size (FIG. 2 (e)).
The liquid crystal display panel 9 is completed through the above steps.

  The above-described dropping injection method is proposed in Patent Document 1, for example. In the case of this dropping injection method, as described above, there is no need to vacuum the space of 3 μm to 5 μm, and there is no need to seal the liquid crystal injection port. Furthermore, since the filling time of the liquid crystal is fast, the time required for filling the liquid crystal into the bonding space between the two substrates (TFT substrate 1a and CF substrate 1b) can be greatly shortened compared to the vacuum injection method. It is.

  However, in the case of this dropping injection method, the distance (cell gap) between the TFT substrate and the CF substrate which is important as the display quality of the liquid crystal display panel 9 is determined by the total amount of liquid crystal dropped on the spacer 4 or one substrate. .

  FIG. 3 is a cross-sectional view schematically illustrating a state of a completed liquid crystal display panel due to an excess or deficiency in the amount of encapsulated liquid crystal. For a liquid crystal display panel manufactured by a vacuum injection method and a normal liquid crystal display panel 9 with good display quality, FIG. 3A shows a case where an appropriate amount of liquid crystal is sealed. In this case, for example, the TFT substrate 1a and the spacer 4 on the CF substrate 1b on which the spacer is preliminarily assembled are in contact with each other. Liquid crystal is sealed in a space between the TFT substrate 1a and the CF substrate 1b defined by the regular gap G1.

  On the other hand, when the amount of liquid crystal is small, as shown in FIG. 3B, the distance G2 between the two substrates, the TFT substrate 1a and the CF substrate 1b, is defined by the spacer 4, so does not change. However, since the amount of liquid crystal is smaller than the volume formed by the two substrates 1a and 1b and the sealing material 7, the liquid crystal unfilled portion 8 in which the liquid crystal is not filled in a part of the space between the two substrates is generated. .

  Conversely, when the amount of liquid crystal is large, as shown in FIG. 3C, when the volume of the space formed by the two substrates 1a and 1b and the sealing material 7 is equal to the total amount of the dropped liquid crystal, Since the volume of the space is reduced by the volume of the spacer 4, the spacer 4 on the CF substrate 1b on which the TFT substrate 1a and the spacer are preliminarily formed is assembled without being in contact with the TFT substrate 1a. The gap G3 between the substrates is larger than the regular gap G1. For this reason, an external force is applied to the substrate, or the liquid crystal 5 inside the liquid crystal display panel 9 moves due to the influence of gravity, so that the cell gap changes, resulting in a display defect.

  Therefore, in the dropping injection method, the total amount of liquid crystal to be dropped is calculated in accordance with the height of the spacer 4 previously formed on one or both of the TFT substrate and the CF substrate (here, the CF substrate 1b). It is necessary to drop a volume of liquid crystal formed by the substrates 1a and 1b, the sealing material 7 and the spacer 4 with high accuracy.

  There are the following methods for forming the spacer on the substrate. A resist film is formed by applying a photosensitive resin material (also referred to as a photoresist material) to the substrate surface and pre-baking. Next, the resist film is exposed through a photomask having a predetermined opening pattern corresponding to the distribution and size of the spacers. The exposed resist film is patterned by photolithography to remove unnecessary portions of the resist film excluding the spacer portion, thereby producing spacers in a predetermined arrangement.

  Hereinafter, a method for manufacturing the columnar spacer will be further described with reference to FIG. FIG. 4 is a process diagram for forming columnar spacers on the substrate constituting the liquid crystal display panel. In FIG. 4, the substrate 1 indicates either a TFT substrate or a CF substrate.

(1) A photosensitive resin 20 serving as a spacer is applied on the substrate 1 while adjusting the thickness to a predetermined thickness by spin coating, slit coating, printing, or the like (FIG. 4A).
(2) Using a photomask 21 in which the spacer portion has a convex shape on the substrate 1, the photosensitive resin film 20 is exposed through the photomask 21 using an exposure light source 22 (FIG. 4B). ).
(3) A development process is performed to remove the photosensitive resin 20 applied to the portion that is not used as a spacer (FIG. 4C).
(4) The developer attached to the substrate is washed away, and the substrate 1 is dried.
Through the above steps, a spacer is formed on the substrate 1 in a convex shape (FIG. 4D).

  In addition to the above method, a photosensitive resin film or a thermosetting resin is applied directly on the substrate using a printing method or a dispensing method so that the spacer has a convex shape, and then cured by applying a predetermined post-treatment. There is also a method of forming a shape.

  The height of the spacer is determined by the coating thickness of the photoresist material or the like, but in general, the photoresist material is formed with the intention of making it almost uniform and the same thickness each time by spin coating or the like. However, due to variations in the composition, viscosity, and spin conditions of the material to be applied for this formation, the absolute value of the actually applied film thickness varies and is not necessarily constant. Therefore, it is difficult for the spacers manufactured by the above method to have the same height variation between the substrates because of the manufacturing method.

  When a liquid crystal display panel is manufactured by using a drop injection method, liquid crystal for a volume of a space formed by a TFT substrate, a CF substrate, and a sealing material 7 bonded through a spacer is used before the TFT substrate and the CF substrate are assembled. If you need to be dropped in advance either substrate, it is necessary to adjust the total amount of liquid crystal is dropped grasp the volume of the space in advance. This space is determined by the height of the spacer. Therefore, it is necessary to know the height of the spacer accurately.

As a method of measuring the height of the spacer, a method of measuring the height using a laser displacement meter or a stylus step meter, or calculating a spacer height by obtaining a surface shape including the spacer using an optical interferometry method There are ways to do it.
JP-A-62-89025

  FIG. 5 is an explanatory diagram of a spacer height measurement method using a laser displacement meter. In this measurement method, the sensor head 24 of the semiconductor laser shown in FIG. 5A or the substrate 1 having the spacer 4 to be measured is moved as shown in FIG. The distance between the upper surface and the lower surface of the spacer 4 is obtained. FIG. 5C shows an output waveform example of the sensor head 24, which is output as the spacer height corresponding to the scanning position of the sensor head 24. The difference in value between the upper surface and the lower surface shown in the output waveform is the height of the spacer 4. When such a laser displacement meter is used, as shown in FIG. 5 (b), it is necessary for the laser beam 25 for measurement to scan the center of the spacer 4 with certainty. Requires mechanism.

  Further, depending on the material and shape of the spacer 4, the laser beam 25 emitted from the sensor head 24 may not be reliably reflected by the substrate surface or the spacer, and an error may occur in the measurement result. Furthermore, since it is necessary to move the sensor head 24 or the substrate 1 in order to obtain the height of the spacer 4, it is necessary to keep the accuracy of movement of the moving stage high. Since vibration greatly affects the measurement accuracy, anti-vibration measures are also important.

  Similarly, in the case of a stylus type level difference measuring machine, a highly accurate positioning mechanism is required for the stylus to reliably scan the center of the spacer. In addition, since the stylus step meter is generally a contact-type measurement method, it is necessary to keep the stylus moving speed low, and the measurement method using the laser displacement meter described above or the optical interference method described later is used. It takes longer to measure.

  In the case of the measurement method using the optical interferometry, a highly accurate positioning mechanism is not necessary, but an optical system and a data analysis system for measurement are expensive. Further, when the measurement object is a thin transparent film, for example, there is a risk of measuring the interference waveform on the lower surface of the transparent film such as an alignment film, which may result in different measurement results.

  In any of the above methods, the principle is to calculate one cell height after assembling the TFT substrate and the CF substrate from the measured data by measuring one height among the spacers built in the TFT substrate or CF substrate. Therefore, the measured spacer needs to represent the height of the entire spacer formed on the substrate. Further, in order to obtain the cell gap more reliably, it is necessary to measure a plurality of spacer heights, and use an average value of these values as a representative value of the overall spacer height.

  The problem to be solved by the present invention is that in the process of manufacturing a liquid crystal display panel by a liquid crystal dropping injection method or the like, it is possible to measure the spacer height or the amount of encapsulated liquid crystal that determines the cell gap of the liquid crystal display panel at high speed and with high accuracy It is to manufacture a liquid crystal display panel at low cost.

  Another object of the present invention is to measure the height of the spacer formed on the substrate with a height measurement system, and to control the amount of liquid crystal dropped by using the measurement data, thereby producing a high-quality liquid crystal display. It is in manufacturing panels.

  In the method for manufacturing a liquid crystal display panel of the present invention, a measuring apparatus for measuring the amount of liquid crystal sealed in the liquid crystal display panel has the following configuration. That is, among a pair of substrates that sandwich the liquid crystal, a stage on which one substrate on which a spacer is previously formed is placed, a measurement auxiliary substrate that replaces the counter substrate (the other substrate) that is paired with the substrate, Positioning mechanism for positioning and fixing the auxiliary substrate for measurement, pressurizing mechanism for applying a constant force to the auxiliary substrate for measurement, and superposition of the one substrate on which the spacer is formed and the auxiliary substrate for measurement It is comprised by the measurement part which measures the space | interval between both the board | substrates comprised by. An optical interference method using a reflection optical system is suitable for the measurement unit, but other measurement devices may be used.

  Before assembling the liquid crystal display panel, a pseudo empty cell gap that does not contain liquid crystal is formed using the substrate on which the spacer to be actually used is built and the auxiliary substrate for measurement, and the substrate on which this spacer is built The distance between the measuring substrate and the auxiliary substrate for measurement (empty cell gap) is measured with the liquid crystal quantity measuring device to obtain the actual target cell gap of the target liquid crystal display panel, and the optimum value of the liquid crystal quantity, that is, the liquid crystal quantity to be sealed is calculated. Determine the amount of liquid crystal to be injected.

  When the pixels arranged in the display area of the liquid crystal display panel according to the present invention each constitute one color pixel with each of the red, green, and blue sub-pixels, the measurement of the empty cell gap is performed for one color pixel. The average value obtained by simultaneously measuring the red, green, and blue sub-pixel portions as a whole, or the maximum value or the minimum value thereof can be used as the empty cell gap value. In addition, the cell gap of each part of the red, green, and blue sub-pixels can be measured separately, and the average value thereof, or the maximum value or the minimum value thereof can be set as the empty cell gap value.

  As a method for individually measuring the cell gaps of the red, green, and blue sub-pixels, the measurement range is made smaller than the size of each sub-pixel by increasing the magnification of the optical system of the measurement apparatus. Further, without increasing the magnification of the optical system, data for each light wavelength of each color can be specified from data in a range including a plurality of sub-pixels to obtain the cell gap of the sub-pixel.

  The amount of liquid crystal to be dropped is calculated based on the measured empty cell gap. After that, the liquid crystal is dropped in the amount of the liquid crystal calculated above on the other substrate facing the one substrate on which the spacer is formed, and the one substrate is bonded and sealed with a sealing material. To do. A liquid crystal display device is obtained by incorporating a drive circuit, a lighting device, and the like into the manufactured liquid crystal display panel. Note that a method of dropping liquid crystal on a substrate in which a spacer is formed is also possible.

  According to the present invention, an empty cell gap between a measurement auxiliary substrate and a substrate in which a spacer is formed is measured in advance before liquid crystal injection, and the TFT substrate and the CF substrate are formed based on this measurement value. It is possible to measure the optimum amount of liquid crystal sealed in the liquid crystal display panel at high speed and with high accuracy, so that it is possible to obtain a high quality liquid crystal display panel free from display defects due to excessive or insufficient liquid crystal filling amount. . In addition, according to the present invention, it is possible to easily measure the empty cell gap and to reduce the liquid crystal display as a whole as compared with a three-dimensional surface shape measuring device using a white interferometer for measuring the height of the spacer. Panels can be manufactured.

  When manufacturing a liquid crystal display panel by the dropping injection method, it is important to grasp the amount of liquid crystal dropped on one substrate in advance and to accurately drop the liquid crystal display panel. 6A and 6B are schematic views of a liquid crystal display panel for explaining dimensions required for calculating the liquid crystal filling amount. FIG. 6A is a plan view, and FIG. 6B is an A-line in FIG. It is sectional drawing which follows an A 'line. In FIG. 6, reference numeral 1a denotes a TFT substrate, 1b denotes a CF substrate, 4 denotes a spacer (columnar spacer), and 7 denotes a sealing material (seal). AR is a display area (pixel area, corresponding to reference numeral 2 in FIG. 2). The amount of liquid crystal sealed in the empty cell of the liquid crystal display panel bonded with a pair of substrates is determined by the following calculation.

Enclosed liquid crystal volume = W x B x H W: Dimensions in the horizontal seal
B: Dimensions in the vertical seal
H: Cell gap Cell gap: H = h + α + β h: Spacer height
α: Spacer deformation
β: Cell gap correction value

  As described above, the seal portion internal dimensions W and B are internal dimensions of the seal portion. This dimension can be obtained as a value obtained by subtracting the seal width at the completion of the cell gap extraction from the application dimension of the sealing material 7. The dimension H is a cell gap, and this cell gap H needs to coincide with the spacer height h. Since the spacer height h often varies with respect to the design value for each substrate due to its manufacturing method, the spacer height h used for calculating the amount of encapsulated liquid crystal does not use the design value. It is desirable to measure the spacer height h for each substrate and calculate the amount of encapsulated liquid crystal using that value.

  FIG. 7 is an explanatory view of an empty cell gap measuring method for calculating the amount of liquid crystal, illustrating an embodiment of a method for manufacturing a liquid crystal display panel according to the present invention. FIG. 8 is an explanatory diagram of the configuration of the empty cell gap measuring apparatus. In FIG. 7, the substrate 1 (TFT substrate or CF substrate) on which the pre-spacer 4 is built is placed on a stage 27, and a measurement auxiliary substrate 28 is placed on the placed substrate 1. The measurement auxiliary substrate 28 may be sized to be laminated on a part of the substrate 1. In FIG. 7, the position on the substrate 1 is indicated by a dotted line.

  The empty cell gap measuring device shown in FIG. 8 includes a stage 27 and a transparent or translucent auxiliary substrate 28 for measurement, which is a substitute for the other substrate facing the one substrate 1 in which a spacer is formed on the substrate, A positioning mechanism 29 for positioning and fixing the measurement auxiliary substrate 28, a pressurizing mechanism 30 for applying a constant force to the measurement auxiliary substrate 28, a substrate 1 on which a spacer is formed, and the measurement auxiliary substrate 4 And a measurement unit 31 for measuring an interval constituted by

  In this embodiment, in order to determine the amount of liquid crystal to be sealed in the bonding interval (space) constituted by the assembled TFT substrate and CF substrate, the height of the spacer previously formed on the substrate is measured. Rather than calculating the space after assembling the TFT substrate and the CF substrate and calculating the amount of liquid crystal sealed in this space, before assembling the liquid crystal display panel using the empty cell gap measuring device shown in FIG. A portion equivalent to an empty panel not containing liquid crystal is formed by either the TFT substrate or the CF substrate on which the spacers to be actually used are formed and the auxiliary substrate 4 for measurement. And the cell gap of the target liquid crystal display panel is measured by measuring the space | interval (empty cell gap) of the board | substrate of this empty panel, and the final encapsulated liquid crystal quantity is calculated from this measurement result. The calculated amount of encapsulated liquid crystal is defined as the amount of liquid crystal dropped when a liquid crystal display panel is manufactured by the dropping injection method.

The procedure for measuring the empty cell gap in this embodiment using the empty cell gap measuring apparatus shown in FIG. 8 will be described below.
(1) The TFT substrate or the CF substrate on which the spacer 4 to be measured is previously formed is carried onto the stage 27 of the measuring apparatus, and positioning and fixing are performed.
(2) The measurement auxiliary substrate positioning mechanism 29 aligns the transparent or translucent measurement auxiliary substrate 28 on the substrate 1 on which the spacer is formed, and then superimposes them.
(3) The measuring auxiliary substrate 28 is pressurized by the pressurizing mechanism 30 at a predetermined pressure.
(4) The measurement unit 31 measures the empty cell gap formed between the measurement auxiliary substrate 28 and the substrate 1.

  The measurement auxiliary substrate 28 is preferably a transparent glass plate that does not affect the measurement. However, when the substrate 1 on which the spacer 4 is formed is a TFT substrate, a CF substrate as a product is used as the measurement auxiliary substrate 28. It may be used. When the substrate 1 in which the spacer is formed is a CF substrate, a TFT substrate as a product may be used as the measurement auxiliary substrate substrate 28.

  The empty cell gap measuring apparatus used in this example is a product “RETS series” manufactured by Otsuka Electronics Co., Ltd. This measuring device is a device that calculates the thickness of the air layer by frequency-analyzing data obtained by an optical interference method using a reflective optical system. The frequency analysis method is a method of calculating a film thickness by analyzing an interference frequency in an interference waveform of a spectral reflectance spectrum. This method can detect a plurality of frequencies and calculate a film thickness even in the case of a multilayer substrate such as a liquid crystal display panel. By using this analysis method, the empty cell gap of a liquid crystal display panel without liquid crystal injection using a substrate with a color filter or the empty cell gap of a liquid crystal display panel using a substrate composed of a plurality of films on the order of microns can be obtained. There is an advantage that it can be measured in a short time.

  FIG. 9 is a schematic cross-sectional view illustrating an example of a method for measuring an empty cell gap when the substrate in which the spacer is formed is a CF substrate, and FIG. 10 is an empty cell gap in the case where the substrate in which the spacer is formed is a CF substrate. It is a schematic cross section explaining another example of the measurement method. 9 and 10, the CF substrate 1b includes one color pixel composed of three sub-pixels including a red sub-pixel 14-R, a green sub-pixel 14-G, and a blue sub-pixel 14-B. The spacer 4 is formed on the black matrix 13.

  FIG. 9 shows simultaneously measuring one color pixel composed of three sub-pixels including a red sub-pixel 14-R, a green sub-pixel 14-G, and a blue sub-pixel 14-B as an empty cell gap measurement range. This is the case. FIG. 10 shows an empty cell gap measurement range of one color pixel composed of three sub-pixels including a red sub-pixel 14-R, a green sub-pixel 14-G, and a blue sub-pixel 14-B. This is a case where measurement is performed separately for each sub-pixel. When simultaneously measuring the measurement range 16 including the three sub-pixels of the red sub-pixel 14-R, the green sub-pixel 14-G, and the blue sub-pixel 14-B, the output cell gap value has a plurality of cell gap values. This is the average value of the sub-pixels. The output value of the cell gap value may be the maximum value or the minimum value. The maximum value of the cell gap output value is the value at which the distance between the measurement auxiliary substrate 28 and each sub pixel is the largest (in FIG. 10, the cell gap of the green sub pixel 14-G), and the minimum value is the smallest. The value (in FIG. 10, the cell gap of the red sub-pixel 14-R) is meant.

  As shown in FIG. 10, there is an inter-pixel step 17 due to a difference in film thickness between the sub-pixels, and three colors of red sub-pixel 14-R, green sub-pixel 14-G, and blue sub-pixel 14-B. When the sizes of the plurality of sub-pixels are not the same, when the plurality of sub-pixels of three colors are measured at the same time as in FIG. 9 and the amount of encapsulated liquid crystal is calculated using the average value, the calculation result becomes inappropriate. There is. In such a case, the cell gap is measured separately for each of the red sub-pixel 14-R, the green sub-pixel 14-G, and the blue sub-pixel 14-B. The method of calculating is desirable. In order to measure the cell gap for each of the red sub-pixel 14-R, the green sub-pixel 14-G, and the blue sub-pixel 14-B, the magnification of the optical system of the measuring device is increased to increase the measurement area. A method of measuring with a width of 15 or less of each sub-pixel and data including a plurality of sub-pixels with a low magnification of the optical system are taken in the same manner as in FIG. Each sub-pixel (color) is identified from the optical wavelength (for example, red sub-pixel: 600 nm to 720 nm, blue sub-pixel: 420 nm to 480 nm, green sub-pixel: 520 nm to 590 nm), and There is a method for calculating the cell gap.

  When the measurement spot is set to be equal to or smaller than the width of each sub-pixel using the microscopic optical system, it is necessary to align the optical axis of the measurement unit 31 in FIG. 8 with the measurement target substrate. For this purpose, the stage 27 to which the substrate 1 to be measured is attached has an alignment mechanism having two-dimensional degrees of freedom in XY or three-dimensional degrees of freedom in XYZ. However, in the case where measurement is performed by taking in data including a plurality of sub-pixels using a macro optical system with a measurement spot of about φ5 mm, for example, the stage 27 is provided with a mechanism for alignment. There is no problem even if it is not.

  Next, an example of the whole process of the manufacturing method of the liquid crystal display panel of the present invention using the dropping injection method will be described. FIG. 11 is a process diagram illustrating a method for manufacturing a liquid crystal display panel according to the present invention. In FIG. 11, first, before assembling the TFT substrate and the CF substrate, the height of the spacers of the substrates (substrates with spacers) out of these substrates is measured by the method described above (P-1). ).

  Next, the liquid crystal enclosure space volume is calculated from the measurement result (h) of the spacer height and the dimensions (W, B) in the sealing material of the liquid crystal display panel manufactured using the substrate (P-2). When the cell gap (H) and the spacer height (h) of the liquid crystal display panel to be manufactured are changed (for example, when a panel having a cell gap smaller by several μm than the spacer height is produced), the spacer deformation amount (α ) Is added to the measured spacer height (h), and the result of addition is multiplied by the dimensions (W, B) in the sealing material to calculate the sealed liquid crystal capacity. In most cases, the amount of encapsulated liquid crystal is different for each substrate with a spacer. Therefore, if the storage liquid is stored in a one-to-one correspondence with the management number of the substrate, it is effective for management in the subsequent process. In actual panel fabrication, display quality may be improved when the substrate is assembled by slightly deforming the spacers. For example, when the spacer height (h) is 5 μm and the spacer is to be deformed by 0.2 μm, the spacer deformation amount (α) is set to −0.2 μm. Therefore, the target cell gap at this time is 4.8 μm.

  The substrate used for calculating the encapsulated liquid crystal capacity is put into the assembly process with the counter substrate. A sealing material is applied to the substrate without spacer which is the counter substrate (P-3). A liquid crystal is dropped on the substrate without spacers coated with the sealing material based on the liquid crystal injection amount calculated in (P-2) (P-4). When the liquid crystal is dropped by the multi-point dropping method, the liquid crystal dropping amount per drop is calculated, and the liquid crystal for the amount of encapsulated liquid crystal obtained by the calculation is dropped on the substrate. After that, stacking with a substrate with spacers and setting gaps are performed (P-5), the sealing material is cured and cured (P-6), and cut into a predetermined panel size, or an excess portion is cut ( P-7).

  In addition, after the liquid crystal display panel is completed, the cell gap of the panel in which the liquid crystal is sealed is measured (P-8), and it is inspected whether the target cell gap H is reached. If the target cell gap H is not achieved due to in-plane variation, drop amount fluctuation of the liquid crystal drop dispenser, etc., the value of the cell gap correction value (β) is changed, and the amount of liquid crystal sealed at the next panel production By feeding back to the calculation, it is possible to manufacture a liquid crystal display panel with a more accurate cell gap. The value of the cell gap correction value (β) will be described with a specific example. When the target cell gap (H) is set to 4.8 μm and the amount of encapsulated liquid crystal is calculated and the panel is manufactured, When the cell gap of the liquid crystal panel is 5.1 μm, which is 0.3 μm larger than the target cell gap, the target cell gap−the measured cell gap value of −0.3 μm is fed back to the next panel fabrication. Thus, the method is more suitable for the actual manufacturing method / process, and the panel can be manufactured with higher accuracy.

  According to the present invention, the empty cell gap in the space formed in the bonding gap between the pair of substrates of the liquid crystal display panel is measured in advance using the substrate in which the spacer is formed and the auxiliary substrate for measurement, and the measured void is measured. Since the optimum amount of liquid crystal is calculated based on the volume of the cell gap, the amount of liquid crystal sealed in a state close to the final form of the completed liquid crystal display panel can be calculated at high speed and with high accuracy. As a result, a liquid crystal display panel having the target cell gap can be manufactured with high accuracy.

  In the description of the embodiment of the present invention, the empty cell gap is measured by combining the measurement auxiliary substrate with the substrate in which the spacer is formed, but the same applies to the liquid crystal display panel using the substrate on which beads are dispersed. It is also possible to calculate the optimum liquid crystal amount by combining an auxiliary substrate for measurement with a bead-spreading substrate to calculate the optimum amount of liquid crystal, and the same effect as in the case of a liquid crystal display panel using a substrate with a spacer can be obtained. .

It is sectional drawing which illustrates the structural example of a liquid crystal display panel typically. It is explanatory drawing of the manufacturing method of the liquid crystal display panel by a dripping injection system. It is sectional drawing which illustrates typically the state of the completed liquid crystal display panel by the excess and deficiency of the amount of sealing liquid crystals. It is a process figure which forms a columnar spacer in the board | substrate which comprises a liquid crystal display panel. It is explanatory drawing of the spacer height measuring system using a laser displacement meter. It is a schematic diagram of the liquid crystal display panel for demonstrating the dimension required for calculation of the liquid crystal enclosure amount. It is explanatory drawing of the empty cell gap measuring method for liquid crystal amount calculation explaining one Example of the manufacturing method of the liquid crystal display panel by this invention. It is explanatory drawing of an empty cell gap measuring apparatus structure. It is a schematic cross section explaining an example of a method for measuring an empty cell gap when a substrate in which a spacer is formed is a CF substrate. It is a schematic cross section explaining the other example of the measuring method of an empty cell gap when the board | substrate with which the spacer was built is a CF board | substrate. It is a process figure explaining the manufacturing method of the liquid crystal display panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 4 Spacer 5 Liquid crystal 7 Sealing material 9 Liquid crystal display panel 20 Photosensitive resin 21 Photomask 24 Sensor head 27 Stage 28 Measurement auxiliary substrate 29 Measurement auxiliary substrate positioning mechanism 30 Pressure mechanism 31 Measurement unit.

Claims (8)

A method of manufacturing a liquid crystal display panel in which a liquid crystal is sandwiched between a substrate and a substrate bonded to one substrate having a spacer,
A dummy cell gap is formed by superimposing a measurement auxiliary substrate on the one substrate, and an interval between the empty cell gaps is measured.
Based on this measurement result, the amount of liquid crystal that fills the gap between the one substrate and the other is calculated,
A liquid crystal display panel manufacturing method, comprising: dropping the calculated liquid crystal amount onto the one substrate; and bonding the other substrate. 2. The method of manufacturing a liquid crystal display panel according to claim 1, wherein an interval between the empty cell gaps is measured while pressing the auxiliary substrate for measurement superimposed on the one substrate. 2. The measuring apparatus according to claim 1, wherein an interval of an empty cell gap formed by the one substrate and the auxiliary substrate for measurement is measured by an optical interference method using a reflection optical system. 3. A method for producing a liquid crystal display panel according to 2. A plurality of sub-pixels having a color pixel composed of three sub-pixels of red, green, and blue on the one substrate, wherein the measurement range of the measuring device includes the sub-pixels of three colors of red, green, and blue And
4. The measurement output of the empty cell gap interval by the measuring device is an average value, a maximum value, a minimum value, or all of the plurality of sub-pixels. The manufacturing method of the liquid crystal display panel of description. The one substrate has a color pixel composed of three sub-pixels of red, green, and blue, and a measurement range of the measurement device is equal to or less than a width of each of the red, green, and blue sub-pixels,
4. The method of manufacturing a liquid crystal display panel according to claim 3, wherein the measurement device measures the empty cell gap of each of the red, green, and blue sub-pixels separately. Since the measuring device measures separately for each of the red, green, and blue sub-pixels, the magnification of the reflective optical system is increased so that the measurement range is less than the width of the sub-pixels of the three colors of red, green, and blue 6. The method of manufacturing a liquid crystal display panel according to claim 5, wherein the liquid crystal display panel is manufactured. The measurement range of the measurement device is a plurality of sub-pixels including the three sub-pixels of red, green, and blue,
4. The measurement output of the measurement device is measured separately for each of the red, green, and blue sub-pixels by specifying each of the red, green, and blue sub-pixels for each optical wavelength. The manufacturing method of the liquid crystal display panel of description. The optical wavelength of the red sub-pixel is 600 nm to 720 nm, the optical wavelength of the green sub-pixel is 520 nm to 590 nm, and the optical wavelength of the blue sub-pixel is 420 nm to 480 nm. Liquid crystal display panel manufacturing method.

Images