JP2007256975A - Method of manufacturing liquid crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of uniforming substrate intervals within substrate planes and stably manufacturing a liquid crystal superior in display quality. <P>SOLUTION: The method of manufacturing the liquid crystal device includes steps of; dropping a spacer dispersion solution to a prescribed position on a substrate by using an inkjet device; arranging spacers by evaporating a solvent in the dropped solution so that the arrangement density of spacers is 50 to 300 pieces/nm<SP>2</SP>and 0.2 to 3 spacers exist per drop point of drops of the inkjet device on average; and sticking the substrate having spacers arranged thereon and remaining substrates to each other. An aperture diameter of a drop injection nozzle of the inkjet device is set to ≥10 to ≤100μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal device, and more particularly to a technique for arranging a spacer between a pair of substrates.

  As a conventional liquid crystal device, there is a configuration in which a lower substrate and an upper substrate are attached to each other at a peripheral portion of each substrate through a sealing material, and a liquid crystal layer is sealed between the pair of substrates. In this case, a technique is known in which a spacer made of a resin ball, a glass ball, a columnar body made of a resin, or the like is disposed between a pair of substrates in order to keep the substrate spacing uniform within the substrate surface.

  Such a liquid crystal device is usually manufactured through the following steps. First, after laminating and forming electrodes, alignment films, etc. on each of the lower substrate and the upper substrate, an uncured sealing material is printed in a form in which an opening serving as a liquid crystal injection port is formed on the peripheral portion of the lower substrate, for example. An empty liquid crystal cell is manufactured by spreading a spacer on the surface of the substrate or the other substrate and then sticking the lower substrate and the upper substrate through a sealing material. Then, the uncured sealing material is cured, and further, liquid crystal is injected into the liquid crystal cell from the liquid crystal injection port previously formed in the sealing material using a vacuum injection method, and then the injection port is sealed with the sealing material. Seal. Finally, an optical film such as a phase difference plate or a polarizing plate is bonded to the outer surfaces of the lower substrate and the upper substrate to manufacture a liquid crystal device.

  Among the above manufacturing processes, for the spacer spraying process, for example, a method of spraying a spacer dispersion liquid in which a spacer is dispersed in a predetermined solvent while spraying the spacer uniformly has been conventionally employed. On the other hand, a technique has been proposed in which a spacer is arranged in a specific region in a liquid crystal cell using an ink jet method (droplet discharge method) (for example, Patent Document 1). In addition, the spacer serves to keep the substrate spacing uniform, but when it is arranged in the pixel region, it causes adverse effects on the display such as light leakage and liquid crystal alignment failure. Therefore, a spacer is provided in a non-pixel region using a liquid crystal display device (for example, Patent Document 2) or a manufacturing method (for example, Patent Document 3) in which spacers are selectively disposed only in a non-pixel region in a liquid crystal cell, or an inkjet method. An arrangement method (for example, Patent Document 4) has been proposed. Furthermore, a specific spacer fixed point arrangement device using an ink jet method has also been proposed (for example, Patent Document 5).

JP 2001-188235 A JP 54-107754 A JP-A-2-308224 JP-A-9-105946 JP 2002-72218 A

As described above, a method of arranging a spacer in a non-pixel region that does not directly contribute to display is conventionally known. In addition, it is necessary to arrange the spacers more than a predetermined number in the liquid crystal cell from the viewpoint of keeping the substrate spacing uniform. On the other hand, considering the adverse effect on the display, the number of spacers should be the minimum necessary number. Is preferred.
Looking at the conventional technology from this point of view, none of the technologies described in the above publications has been studied at all regarding the optimal number of spacers (arrangement density). Therefore, the optimum spacer to further improve display quality by suppressing display unevenness due to cell thickness (substrate distance) unevenness in the substrate surface, light loss due to the presence of spacers, and contrast deterioration due to poor alignment, etc. The standard of the number of arrangement (arrangement density) of was required.

  At the same time, it has been desired to provide a method that can stably control the number of spacers arranged by the ink jet method. In other words, the ink jet method originally ejects only ink (liquid), but in order to disperse a dispersion containing a solid material such as a spacer only in a certain region, the opening diameter of the nozzle of the ink jet device is reduced. Need to optimize. However, there has been no index for the optimum nozzle opening diameter for such a spacer dispersion.

  The present invention has been made in view of the above circumstances, and when placing a spacer at a fixed point in a substrate surface using a droplet discharge device such as an ink jet device, the number of spacers arranged (arrangement density) is optimal. It is an object of the present invention to provide a method for stably manufacturing a liquid crystal device excellent in display quality by making it easier.

In order to solve the above problems, a method of manufacturing a liquid crystal device according to the present invention includes a liquid crystal and a spacer in a space in which a pair of substrates are opposed to each other with a sealant interposed between the pair of substrates and the sealant. Is a liquid crystal device manufacturing method in which a spacer dispersion liquid in which a spacer is dispersed in a predetermined solvent is applied to a predetermined substrate on one of a pair of substrates using a droplet discharge device. The step of dropping at the position of the substrate and evaporating the solvent in the droplets dropped on the substrate, the spacer arrangement density is 50 to 300 pieces / mm ² , and one drop of the droplet discharge device A step of arranging spacers so that there is an average of 0.2 to 3 spacers per dropping point, and a step of bonding the substrate on which the spacers are arranged to the remaining substrate; Drop ejection The opening diameter of the nozzle 10μm or more, characterized by a 100μm or less. The opening diameter of the droplet discharge nozzle is more preferably 10 μm or more and 30 μm or less.

As a result of intensive studies on the “optimum arrangement number (arrangement density) of spacers” described in the section of [Problems to be Solved by the Invention], the present inventors have obtained the following results. That is, the arrangement density of the spacers is 50 to 300 pieces / mm ² , and the spacers are present in an average of 0.2 to 3 pieces per point where the spacers are present alone or in aggregate, or in the state where these simple substances and aggregates are mixed. If the arrangement is such that the spacer is present, the deterioration of display quality due to the spacer can be sufficiently suppressed, and the display quality can be improved.

  In the method for manufacturing a liquid crystal device of the present invention, a spacer dispersion liquid in which spacers are dispersed in a predetermined solvent is dropped on a substrate using a droplet discharge device, and a random number of droplets per solution is obtained. The spacer is included. And after dripping, a solvent remains on a board | substrate by evaporating a solvent. At this time, since the droplet discharge device is used, the spacers are not irregularly arranged on the substrate, but are arranged in a dotted manner along a plurality of parallel virtual lines extending in one direction. Will be.

The basis for each of the above numerical ranges will be described in detail in the section of [Examples]. When the spacer arrangement density is less than 50 / mm ² , the substrate thickness is not sufficiently maintained by the spacer, and the cell thickness Unevenness becomes noticeable and the display quality is significantly reduced. Further, when the arrangement density of the spacers is larger than 300 / mm ² , bubbles are generated in the liquid crystal at a low temperature. This becomes a defect called a vacuum bubble. The reason for this is that the liquid crystal has a higher coefficient of thermal expansion than the spacer, so in the low temperature state, there will be local occurrence of a vacuum in the liquid crystal layer. This is because a portion in a vacuum state remains.

  Also, if the average number of spacers per point of droplets ejected by the droplet ejection device is less than 0.2, the number of locations where no spacers exist in one point increases so that the spacer arrangement varies. And the unevenness of the cell thickness becomes remarkable, so that the display quality is remarkably lowered. On the other hand, if the average per point is more than three, too many spacers are present in the form of agglomerates, causing cell thickness unevenness and a lot of light leakage, resulting in remarkable display quality. descend.

  Further, when the opening diameter of the droplet discharge nozzle is smaller than 10 μm, a spacer having a diameter of about 2 to 10 μm, which is generally used, is clogged in the nozzle, or the number of spacers to be blown are stably placed in one droplet. I ca n’t launch it. On the other hand, if the nozzle opening diameter is larger than 100 μm, the liquid droplet is not a clean circle but has a tailed shape, or the liquid volume is too large to intersect with an adjacent liquid droplet. Therefore, the probability that the spacer is not arranged at a desired position is increased.

It is desirable that the opening diameter of the droplet discharge nozzle be at least twice the diameter of the spacer.
This is because if the opening diameter of the nozzle is smaller than twice the diameter of the spacer, the spacer is clogged with the nozzle or the number of spacers arranged at a fixed point varies greatly.

The spacer is desirably arranged in the non-pixel region.
If the spacer is present in the display area, it will cause liquid crystal alignment failure and light leakage, and the display quality will be greatly reduced. By placing it in a non-pixel area that does not directly contribute to display, the display quality will be dramatically increased. Can be improved. Further, if a light shielding layer is provided corresponding to the non-pixel region, display defects such as light leakage can be prevented more reliably.

Further, at least the surface of the spacer may be colored.
For example, when the liquid crystal device is used as a liquid crystal display device, when black display (dark display) is performed, light may escape from the arranged spacers, and the portion may become white display (bright display). However, by coloring the spacer as described above, it is possible to reliably perform black display (dark display) by using the spacer colored in particular black.

Moreover, you may perform the process which controls the orientation of a liquid crystal on the surface of a spacer.
That is, the alignment of the liquid crystal may be disturbed near the surface of the spacer, and the contrast may be lowered. Thus, by providing the alignment regulating means on the surface of the spacer, the liquid crystal is aligned even near the spacer surface. It becomes possible. As a result, it is possible to provide a liquid crystal device that prevents the occurrence of light leakage and thus hardly causes problems such as a decrease in contrast. In addition, as an orientation control means, what gave the long-chain alkyl group to the spacer surface using a silane coupling agent etc. can be illustrated, for example.

Further, a fixing layer for fixing the spacer itself on the substrate may be provided on the surface of the spacer. As an example of the material of the fixing layer, a thermosetting resin can be used.
By forming a thermosetting resin on the surface of the spacer in this way, for example, by arranging the spacer at a predetermined position between the substrates and then performing heat treatment, the spacer can be stably fixed to the substrate. It is possible to prevent the occurrence of problems such as the spacer floating and being displaced from a predetermined position.

In the step of dripping the spacer dispersion liquid onto the substrate, it is desirable to drop the liquid droplets at a dimensional interval larger than the diameter of the liquid droplets when dropped onto the substrate.
The principle that the spacer can be arranged at a fixed point by the droplet discharge method is that the solvent is evaporated after the droplet including the spacer is dropped at a predetermined position on the substrate. At this time, the solvent is gradually increased from the peripheral portion of the droplet. This is because the spacers are gathered in the central part as the center of the liquid droplets becomes smaller due to evaporation and the spacers are arranged near the central part of the liquid droplets. Therefore, it is important that the droplets dropped on the substrate exist individually and, therefore, the droplets are dropped at a dimensional interval larger than the droplet diameter when dropped on the substrate. It is desirable to do. This is because if a plurality of droplets are connected, the position of the spacer becomes uncertain and is not necessarily positioned at the center of each droplet.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[Liquid Crystal Device]
First, a liquid crystal device obtained by the liquid crystal device manufacturing method of the present embodiment will be described.
The liquid crystal device described below is an active matrix type transmissive liquid crystal device using a TFT (Thin Film Transistor) element as a switching element. FIG. 1 is an equivalent circuit diagram of switching elements, signal lines, and the like in a plurality of pixels arranged in a matrix of the transmissive liquid crystal device of this embodiment. FIG. 2 is a plan view of a principal part showing the structure of a plurality of pixel groups adjacent to each other on a TFT array substrate on which data lines, scanning lines, pixel electrodes and the like are formed. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2, and FIG. 4 is an overall plan view showing the planar structure of the entire transmissive liquid crystal device of the present embodiment. Note that FIG. 3 illustrates the case where the upper side in the drawing is the light incident side and the lower side in the drawing is the viewing side (observer side). Moreover, in each figure, in order to make each layer and each member the size which can be recognized on drawing, the scale is varied for every layer and each member.

  In the liquid crystal device according to the present embodiment, as shown in FIG. 1, a plurality of pixels arranged in a matrix include a pixel electrode 9 and a TFT element which is a switching element for controlling energization to the pixel electrode 9. 30, and the data line 6 a to which the image signal is supplied is electrically connected to the source of the TFT element 30. Image signals S1, S2,..., Sn to be written to the data line 6a are supplied line-sequentially in this order, or are supplied for each group to a plurality of adjacent data lines 6a.

  In addition, the scanning line 3a is electrically connected to the gate of the TFT element 30, and scanning signals G1, G2,..., Gm are applied to the plurality of scanning lines 3a in a pulse-sequential manner at predetermined timing. The Further, the pixel electrode 9 is electrically connected to the drain of the TFT element 30, and the image signal S1, S2,... Supplied from the data line 6a is turned on by turning on the TFT element 30 as a switching element for a certain period. , Sn is written at a predetermined timing.

  A predetermined level of image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9 is held for a certain period with the common electrode described later. The liquid crystal modulates light by changing the orientation and order of the molecular assembly according to the applied voltage level, thereby enabling gradation display. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9 and the common electrode.

  Next, the planar structure of the main part of the liquid crystal device of the present embodiment will be described with reference to FIG. As shown in FIG. 2, a rectangular pixel electrode 9 made of a transparent conductive material such as indium tin oxide (hereinafter abbreviated as ITO) is outlined on a TFT array substrate by a dotted line portion 9A. ) Are provided in a matrix, and a data line 6a, a scanning line 3a, and a capacitor line 3b are provided along the vertical and horizontal boundaries of the pixel electrode 9, respectively. In the present embodiment, each pixel electrode 9 and a region where the data line 6a, the scanning line 3a, the capacitor line 3b, etc., which are arranged so as to surround each pixel electrode 9 are formed are pixels and arranged in a matrix. Further, the display can be performed for each pixel.

  The data line 6a is electrically connected to a source region (described later) through a contact hole 5 in the semiconductor layer 1a made of, for example, a polysilicon film constituting the TFT element 30, and the pixel electrode 9 is connected to the semiconductor layer 1a. Among these, it is electrically connected to a drain region described later via a contact hole 8. In addition, the scanning line 3a is disposed so as to face a channel region (a region with a diagonal line rising to the left in the figure), which will be described later, in the semiconductor layer 1a, and the scanning line 3a serves as a gate electrode at a portion facing the channel region. Function.

The capacitor line 3b is formed from a main line portion extending in a substantially straight line along the scanning line 3a (that is, a first region formed along the scanning line 3a in a plan view) and a portion intersecting the data line 6a. And a protruding portion (that is, a second region extending along the data line 6 a when viewed in a plan view) protruding toward the previous stage (upward in the drawing) along the data line 6 a.
In FIG. 2, a plurality of first light shielding films 11 a are provided in a region indicated by a diagonal line rising to the right.

  Next, a cross-sectional structure of the liquid crystal device of the present embodiment will be described with reference to FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG. 2 as described above, and is a cross-sectional view showing a configuration of a region where the TFT element 30 is formed. In the liquid crystal device of the present embodiment, the liquid crystal layer 50 is sandwiched between the TFT array substrate 10 and the counter substrate 20 disposed to face the TFT array substrate 10.

  The liquid crystal layer 50 is composed of a smectic liquid crystal that is a ferroelectric liquid crystal, and has a quick response of liquid crystal driving to a voltage change. The TFT array substrate 10 includes a substrate body 10A made of a translucent material such as quartz, a TFT element 30, a scanning line 3a, a capacitor line 3b, a data line 6a, a pixel electrode 9, It is composed of an alignment film 40 and the like. The counter substrate 20 includes a substrate body 20A made of a translucent material such as glass or quartz, a common electrode 21 formed on the surface of the liquid crystal layer 50, an alignment film 60, and the like. Each of the substrates 10 and 20 is maintained at a predetermined substrate interval via the spacer 15. In FIG. 3, the spacer 15 that exists alone above the data line 6 a is illustrated, but in this embodiment, the spacer 15 is arranged in the non-pixel region in this way. The “non-pixel region” refers to a region where wiring such as the data line 6a, the scanning line 3a, the capacitor line 3b, and the TFT element 30 are formed and does not substantially contribute to display.

  In the TFT array substrate 10, a pixel electrode 9 is provided on the surface of the substrate body 10 </ b> A on the liquid crystal layer 50 side, and a pixel switching TFT element 30 that controls switching of each pixel electrode 9 is positioned adjacent to each pixel electrode 9. Is provided. The TFT element 30 has an LDD (Lightly Doped Drain) structure, and includes a scanning line 3a, a channel region 1a ′ of the semiconductor layer 1a in which a channel is formed by an electric field from the scanning line 3a, the scanning line 3a and the semiconductor layer. A gate insulating film 2 that insulates 1a, a data line 6a, a low concentration source region 1b and a low concentration drain region 1c of the semiconductor layer 1a, and a high concentration source region 1d and a high concentration drain region 1e of the semiconductor layer 1a are provided.

  On the substrate main body 10A including the scanning line 3a and the gate insulating film 2, a second interlayer insulating material in which a contact hole 5 leading to the high concentration source region 1d and a contact hole 8 leading to the high concentration drain region 1e are opened. A film 4 is formed. That is, the data line 6 a is electrically connected to the high concentration source region 1 d through the contact hole 5 that penetrates the second interlayer insulating film 4.

  Further, on the data line 6a and the second interlayer insulating film 4, a third interlayer insulating film 7 having a contact hole 8 leading to the high concentration drain region 1e is formed. That is, the high concentration drain region 1 e is electrically connected to the pixel electrode 9 through the contact hole 8 that penetrates the second interlayer insulating film 4 and the third interlayer insulating film 7.

  In the present embodiment, the gate insulating film 2 is extended from a position facing the scanning line 3a and used as a dielectric film, the semiconductor film 1a is extended to form the first storage capacitor electrode 1f, and further opposed thereto. A storage capacitor 70 is configured by using a part of the capacitor line 3b as a second storage capacitor electrode.

  Further, on the surface of the TFT array substrate 10 on the liquid crystal layer 50 side of the substrate main body 10A, the region where the pixel switching TFT elements 30 are formed is transmitted through the TFT array substrate 10, and the lower surface (TFT) of the TFT array substrate 10 is illustrated. The return light that is reflected at the interface between the array substrate 10 and air and returns to the liquid crystal layer 50 side is prevented from entering at least the channel region 1a ′ and the low concentration source / drain regions 1b and 1c of the semiconductor layer 1a. For this purpose, a first light shielding film 11a is provided.

  Further, a first interlayer insulation for electrically insulating the semiconductor layer 1a constituting the pixel switching TFT element 30 from the first light shielding film 11a is provided between the first light shielding film 11a and the pixel switching TFT element 30. A film 12 is formed. Further, as shown in FIG. 2, in addition to providing the first light-shielding film 11a on the TFT array substrate 10, the first light-shielding film 11a is electrically connected to the capacitor line 3b at the preceding stage or the subsequent stage through the contact hole 13. Configured to connect to.

  Further, on the liquid crystal layer 50 side outermost surface of the TFT array substrate 10, that is, on the pixel electrode 9 and the third interlayer insulating film 7, an alignment film 40 for controlling the alignment of liquid crystal molecules in the liquid crystal layer 50 when no voltage is applied. Is formed. Accordingly, in the region including the TFT element 30, a plurality of irregularities or steps are formed on the outermost surface on the liquid crystal layer 50 side of the TFT array substrate 10, that is, the sandwiching surface of the liquid crystal layer 50. .

  On the other hand, the counter substrate 20 has a surface on the liquid crystal layer 50 side of the substrate body 20A, which is a region facing the formation region of the data line 6a, the scanning line 3a, and the pixel switching TFT element 30, that is, an opening region of each pixel unit. The second light-shielding film 23 for preventing incident light from entering the channel region 1a ′, the low-concentration source region 1b, and the low-concentration drain region 1c of the semiconductor layer 1a of the pixel switching TFT element 30 in the other regions. Is provided. Further, a common electrode 21 made of ITO or the like is formed on the entire surface of the substrate body 20A on which the second light-shielding film 23 is formed on the liquid crystal layer 50 side, and on the liquid crystal layer 50 side when no voltage is applied. An alignment film 60 for controlling the alignment of the liquid crystal molecules in the liquid crystal layer 50 is formed.

  FIG. 4 is a schematic plan view showing an example of the overall configuration of the liquid crystal device 100 according to the present embodiment. Between the TFT array substrate 10 and the counter substrate 20, a closed annular sealing material 93 is used. A liquid crystal layer 50 is formed so as to be sealed. That is, in the liquid crystal device 100 of the present embodiment, the sealing material 93 does not include an injection port for injecting liquid crystal, and has a frame shape closed in the in-plane region of the substrates 10 and 20. Without being exposed to the outer edges of the substrates 10 and 20, it is formed in a closed frame shape that does not have an opening toward the outer edges of the substrates 10 and 20.

In the present embodiment, as described above, the spacer 15 is disposed in the non-pixel region between the pair of substrates 10 and 20 that sandwich the liquid crystal layer 50, and in the region inside the sealing material 93 shown in FIG. The arrangement density is 50 to 300 pieces / mm ² , and there are 0.2 to 3 spacers on average per point where the spacers exist in the form of simple substances or aggregates.

  FIGS. 5 and 6 are diagrams showing the arrangement of the spacers 15 on the substrate surface. FIGS. 5A and 5B show an average of 0.2 spacers per droplet. Images (that is, two spacers exist for 10 droplets), FIGS. 6A and 6B are images where three spacers exist on average per point (that is, , There are 30 spacers for 10 droplets). 5 (a) and 6 (a) are the states immediately after the dropping, and FIGS. 5 (b) and 6 (b) are the states after the solvent is evaporated. The hatched circle 17 is placed on the substrate. A dropped liquid droplet is shown, and a circle with a symbol 15 indicates a spacer.

As shown in these drawings, since the spacer 15 is arranged using an ink jet apparatus described later, the spacer 15 is not arranged irregularly at all, and at least in one direction in the non-pixel area 18 outside the pixel area 19. Are arranged so as to be substantially along a plurality of virtual lines K extending in parallel to each other. As is clear from FIGS. 5 (a) and 5 (b), an average of 0.2 spacers per droplet means that for any 10 droplets, That is, there are two droplets containing one spacer, and the remaining eight droplets do not contain a spacer. Further, as is apparent from FIGS. 6A and 6B, the number of spacers 15 included in each droplet 17 cannot be controlled. For example, even if the average number is three, all droplets This does not include three spacers 15 each.
Accordingly, the spacer 15 in one point of the droplet exists as a single substance or an aggregate, or in a state where these simple substances and the aggregate are mixed.

In the liquid crystal device of the present embodiment, the arrangement of the spacers 15 is optimized, the arrangement density is 50 to 300 / mm ² , and the average is 0.2 to 3 per droplet. Since the spacers 15 are disposed, problems such as light loss and contrast reduction due to the spacers 15 are sufficiently suppressed, and display quality can be improved.

For example, when the arrangement density of the spacers 15 is smaller than 50 / mm ² , the substrate interval is not sufficiently held by the spacers 15 and the cell thickness unevenness becomes remarkable, so that the display quality is remarkably lowered. On the other hand, when the arrangement density of the spacers 15 is larger than 300 / mm ² , a defect called a vacuum bubble occurs at a low temperature. If the average number of droplets per point is less than 0.2, the number of points where the spacers 15 do not exist in one point increases so much that the arrangement of the spacers 15 varies, and the cell thickness unevenness becomes remarkable. As a result, display quality is significantly reduced. Conversely, if the average number per point is more than 3, for example, as shown in FIG. 7, too many spacers 15 are present in the form of aggregates, and the huge spacer aggregate 15A becomes a non-pixel region. In some cases, the pixel region 19 protrudes from the pixel region 19. As a result, not only the cell thickness unevenness is caused, but also the degree of light leakage and orientation failure becomes serious, and the display quality is remarkably lowered.

In this embodiment mode, the configuration is based on the assumption of black and white display. However, a color filter layer may be formed to perform color display. That is, a color filter layer including a colored layer and a light-shielding layer (black matrix) is provided on the inner surface of the upper substrate (counter substrate) 20, and a protective layer for protecting the color filter layer is sequentially formed, and further on the protective layer. The common electrode 21 can be formed. The display area includes colored layers of different colors, for example, red (R), green (G), and blue (B). Therefore, pixels are configured by the display areas of the respective colors, and color display is performed for each pixel. It becomes possible.
Further, although an active matrix type liquid crystal device is illustrated in this embodiment mode, for example, a configuration according to the present invention can also be adopted for a simple matrix type liquid crystal device.

  Next, the structure of the spacer 15 used in the liquid crystal device of the present embodiment will be described. The spacer 15 can be composed of a spherical member made of, for example, silicon dioxide or polystyrene. The diameter of the spacer 15 is set in accordance with the thickness of the liquid crystal layer 50 (cell thickness, that is, the substrate interval) sealed in the liquid crystal device, and is selected from a range of 2 to 10 μm, for example.

  As the spacer 15, as shown in FIG. 8, a spacer having a surface provided with a thermosetting resin layer 150 can be employed. In this case, the spacer 15 is securely fixed to the lower substrate (TFT array substrate) 10 and the upper substrate (counter substrate) 20 by curing the thermosetting resin. For example, in the manufacturing process of the liquid crystal device, the spacer 15 is spread on a substrate (counter substrate 20) different from the substrate on which the liquid crystal is dropped (for example, the TFT array substrate 10), and then heat treatment is performed to cure the thermosetting resin. As a result, the spacer 15 can be fixed to the counter substrate 20.

  Further, as shown in FIG. 9, for example, a surface treatment layer 151 provided with a long-chain alkyl group can be provided on the surface of the spacer 15. As a means for providing the surface treatment layer 151 provided with a long-chain alkyl group, for example, surface treatment is performed using a silane coupling agent. As shown in FIG. 11A, when the spacer 15 not provided with the surface treatment layer 151 is used, the alignment of liquid crystal molecules is disturbed near the surface of the spacer 15, and light leakage may occur in that portion. On the other hand, as shown in FIG. 11B, when the spacer 15a provided with the surface treatment layer 151 is used, the liquid crystal molecules are aligned in a predetermined direction near the surface of the spacer 15a (in the case of the present embodiment). Vertical alignment), and light leakage hardly occurs in that portion.

  Furthermore, the spacer can be colored, and the spacer 15b shown in FIG. 10 shows an example of a spacer colored in black. For example, as shown in FIG. 12A, when the non-colored spacer 15 is used, a white dot display is generated corresponding to the spacer during black display (dark display). There is a case. On the other hand, as shown in FIG. 12 (b), by using the colored spacer 15b as shown in FIG. 10, the white dot display corresponding to the spacer does not occur during black display (dark display). Become. In addition, a black dot display corresponding to the spacer occurs during white display (bright display), but the effect on contrast reduction is small compared to the generation of white dot display during black display (dark display). Become.

[Method of manufacturing liquid crystal device]
Next, an example of the method for manufacturing the liquid crystal device described in this embodiment will be described with reference to FIGS. 3 and 13 to 17.
First, as shown in step S1 of FIG. 13, a light shielding film 11a, a first interlayer insulating film 12, a semiconductor layer 1a, a channel region 1a ′, a low-concentration source region 1b, Low concentration drain region 1c, high concentration source region 1d, high concentration drain region 1e, storage capacitor electrode 1f, scanning line 3a, capacitor line 3b, second interlayer insulating film 4, data line 6a, third interlayer insulating film 7, contact Holes 8, pixel electrodes 9, and alignment film 40 are formed, and a lower substrate (TFT array substrate) 10 is formed. Further, the light shielding film 23, the counter electrode 21, and the alignment film 60 are also formed on the upper substrate body 20 </ b> A to form the upper substrate (counter substrate) 20.

Next, in step S <b> 2 of FIG. 13, a predetermined amount of liquid crystal corresponding to the cell thickness of the liquid crystal device is dropped on the lower substrate (TFT array substrate) 10. Subsequently, in step S3 of FIG. 13, the sealing material 93 is printed on the upper substrate 20, and in step S4, the spacer 15 is also disposed on the upper substrate 20 by using an inkjet device (droplet discharge device). In this case, the sealing material 93 is formed in a closed frame shape having no liquid crystal inlet as shown in FIG. In addition, as described above, the spacer dispersion charged in the ink jet apparatus so that the arrangement density of the spacers 15 is 50 to 300 / mm ² and the average number of the spacers 15 is 0.2 to 3 per droplet. Prepare the spacer concentration of the solution.

  In addition, it is necessary to set the conditions of the ink jet apparatus so that the droplets 17 are dropped at a size interval larger than the diameter of the droplets 17 spreading on the substrate when dropped on the upper substrate 20. The spacer 15 can be placed at a fixed point by the ink jet method in addition to dropping the droplet 17 containing the spacer 15 accurately at a predetermined position on the substrate from the head of the ink jet device, after the droplet 17 is dropped. The solvent is evaporated. At this time, the solvent gradually evaporates from the peripheral portion of the droplet 17 and the central portion of the droplet 17 becomes smaller. This is because the spacer 15 is arranged in the vicinity of the center portion of 17. Therefore, it is important that the droplets 17 dropped on the substrate are present independently of each other. For this reason, the droplets are dropped at a dimensional interval larger than the diameter of the droplet 17 when dropped on the substrate. Desirably, 17 is dropped. If the droplets 17 are dropped at a dimensional interval smaller than the diameter of the droplets 17 and the adjacent droplets 17 are connected to each other as shown in FIG. 15A, for example, the spacers are used when the solvent is evaporated. This is because the position 15 is not necessarily located at the center of each droplet 17, and some are arranged in the pixel region 19 as shown in FIG.

  An example of the structure of the head 26 of the ink jet apparatus used here is shown in FIGS. As shown in FIG. 16, the inkjet head 26 includes, for example, a stainless nozzle plate 31 and a diaphragm 32, and both are joined via a partition member (reservoir plate) 33. A plurality of spaces 34 and a liquid pool 35 are formed by the partition member 33 between the nozzle plate 31 and the diaphragm 32. Each space 34 and the inside of the liquid reservoir 35 are filled with the spacer dispersion liquid, and each space 34 and the liquid reservoir 35 communicate with each other via the supply port 36. Further, the nozzle plate 31 is provided with nozzle holes 37 for ejecting the spacer dispersion liquid from the space 34. On the other hand, a hole 38 for supplying the spacer dispersion liquid to the liquid reservoir 35 is formed in the vibration plate 32.

  As shown in FIG. 17, a piezoelectric element 39 is bonded to the surface of the diaphragm 32 opposite to the surface facing the space 34. The piezoelectric element 39 is located between the pair of electrodes 41 and bends so that when energized, the piezoelectric element 39 protrudes outward. At the same time, the diaphragm 32 to which the piezoelectric element 39 is bonded is also integrally formed outward. Bend. As a result, the volume of the space 34 increases. Accordingly, the spacer dispersion liquid corresponding to the increased volume in the space 34 flows from the liquid reservoir 35 through the supply port 36. Next, when energization to the piezoelectric element 39 is released, both the piezoelectric element 39 and the diaphragm 32 return to their original shapes. As a result, the space 34 also returns to its original volume, so that the pressure of the spacer dispersion liquid in the space 34 rises, and the spacer dispersion liquid droplets 27 are ejected from the nozzle holes 37 toward the substrate.

Here, in the case of the present embodiment, as shown in FIG. 18, the opening diameter R of the nozzle hole 37 is 10 μm or more and 100 μm or less, and R> 2r is satisfied with respect to the diameter r of the spacer 15. Has been. The reason is that when the opening diameter R is smaller than 10 μm, the specific amount of the spacer dispersion liquid 16 (viscosity: 1 to 30 mPas) including the spacer 15 cannot be stably discharged, the dropping amount itself varies, The average number of spacers varies. On the other hand, when the opening diameter R is larger than 100 μm, the droplet is not a clean circle but has a tail-like shape, and the probability that the spacer 15 is not arranged at a desired position increases because the shape is not stable. If the opening diameter R is smaller than twice the diameter r of the spacer 15, the probability that the spacer 15 is clogged with the nozzle hole 37 increases, and the variation in the number of the spacers 15 arranged at fixed points increases.
In this embodiment, one piezoelectric element 39 and a space 34 are provided for each nozzle, but the same effect can be expected in a head of an ink jet apparatus in which a plurality of nozzles are arranged in one piezoelectric element. it can.

  Then, in step S5 of FIG. 13, the lower substrate 10 and the upper substrate 20 are bonded together, and an optical film such as a retardation plate or a polarizing plate (not shown) is bonded to the outside of the lower substrate 10 and the upper substrate 20, A liquid crystal device having the cell structure shown in FIG. 3 is manufactured.

  On the other hand, as an example of a different manufacturing method, the liquid crystal device of the above embodiment can be obtained by a process as shown in FIG. First, as shown in step S11 of FIG. 14, the alignment film 40 and the like are formed on the lower substrate body 10A made of glass or the like as in step S1 of FIG. 13 described above, and the lower substrate (TFT array substrate) 10 is formed. Create Further, the alignment film 60 and the like are formed also on the upper substrate body 20A, and the upper substrate (counter substrate) 20 is formed.

Next, in step S12 in FIG. 14, a sealing material 93 having a closed frame shape having no liquid crystal injection port is printed on the lower substrate (TFT array substrate) 10 as described above. Further, in step S13 in FIG. A predetermined amount of liquid crystal is dropped inside the frame-shaped sealing material 93. Subsequently, in step S <b> 14 of FIG. 14, the spacer 15 is disposed on the upper substrate 20 using an inkjet device. Also in this case, the spacer dispersion spacer to be charged in the ink jet apparatus so that the arrangement density of the spacers 15 is 50 to 300 / mm ² and the average number of spacers 15 per droplet is 0.2 to 3 spacers 15. Adjust the concentration.

  Then, in step S15 of FIG. 14, the lower substrate 10 and the upper substrate 20 are bonded together, and an optical film such as a retardation plate or a polarizing plate (not shown) is bonded to the outside of the lower substrate 10 and the upper substrate 20, A liquid crystal device having the cell structure shown in 3 is manufactured.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example of a manufacturing method in which a sealing material having a closed shape without a liquid crystal injection port is provided and liquid crystal is dropped on one substrate and the other substrate is bonded is given. Instead, a method may be employed in which a sealing material having a liquid crystal injection opening partly opened is provided and liquid crystal is injected by a vacuum injection method or the like after two substrates are bonded together. In the above embodiment, an example of an active matrix transmissive liquid crystal device using a TFT element is given as the liquid crystal device to be manufactured. However, the present invention is not limited to this, and the present invention can be applied to various liquid crystal devices. Of course.

Next, the present inventors evaluated the characteristics of the liquid crystal device of the present invention. The results are reported below.
[Example 1]
Using the spacer arrangement method using the inkjet device described in the above embodiment, a liquid crystal cell having a substrate size of 400 mm × 500 mm, a substrate interval of 6 μm, and a different spacer arrangement density was actually manufactured. Of “uniformity” and “presence or absence of low-temperature bubbles”. The spacers were adjusted so that the average number of spacers per droplet was 2, and the arrangement density was changed to 6, 50, 100, 150, 300, 400 / mm ² . The evaluation results are shown in [Table 1] below.

  In Table 1, “uniformity of substrate interval” was “◯” when no display unevenness due to cell thickness unevenness was observed by visual inspection, and “X” when display unevenness was observed. The “presence / absence of low-temperature bubbles” was defined as “◯” when bubbles were not observed by visual inspection, and “x” when bubbles were observed.

As is clear from Table 1, when the spacer arrangement density is 10 pieces / mm ² , display unevenness due to cell thickness unevenness occurs, and when the spacer arrangement density is 400 pieces / mm ² , low temperature bubbles are generated. Both became bad. On the other hand, if the arrangement density of the spacers is 50 to 300 / mm ² , it is possible to obtain a liquid crystal cell excellent in display quality without causing display unevenness due to cell thickness unevenness and without generating low-temperature bubbles. all right. Note that the present inventor has already confirmed that even in the conventional spacer spraying method that does not use an ink jet device, the occurrence of display defects can be suppressed when the spacer arrangement density is 50 to 300 / mm ^2. The experimental results are consistent with the results.

[Example 2]
Next, using the same liquid crystal cell as in Example 1, the liquid crystal cell in which the arrangement density of spacers was limited to a range of 50 to 300 / mm ² and the average number of spacers per droplet was changed was actually used. And evaluated “whether or not display quality is reduced due to cell thickness unevenness” and “whether or not display quality is deteriorated due to light leakage due to spacer aggregates and cell thickness unevenness”. The average number of spacers per droplet was changed to seven types of 0.08, 0.2, 0.5, 1, 3, 4, and 5. The evaluation results are shown in [Table 2] below.

In Table 2, “Presence / absence of deterioration in display quality due to cell thickness unevenness” means “◯” where no display unevenness that is considered to be due to cell thickness unevenness due to too few spacers is observed by visual inspection. The case where display unevenness was recognized was defined as “x”.
In addition, “Presence / absence of deterioration in display quality due to light loss due to spacer aggregates and cell thickness unevenness” is not observed in visual inspection due to light loss due to spacer aggregates or deterioration in display thickness due to cell thickness unevenness. The thing was set as "(circle)" and the recognized thing was set as "x". In addition, when there are too few spacers, the nonuniformity of a hazy feeling is visually recognized, and when there are too many spacers, it can be distinguished by agglomerating the spacers and visually observing white spotted light.

As can be seen from Table 2, when the average number of spacers per droplet is 0.08, droplets are dropped by the inkjet device even if the arrangement density of 50 to 300 / mm ² is satisfied. Among all the dropping points, over 90% of the points where no spacers are arranged and there are too many such points. As a result, the arrangement of the spacers is uneven and cell thickness unevenness occurs. In addition, when the average number of spacers per droplet exceeds 3, the number of giant spacer aggregates tends to increase, and the display due to light leakage and cell thickness unevenness that are apparently caused by spacer aggregates. Degradation occurs.

  Table 3 shows the dropping interval (vertical axis of the table, in other words, the area on the substrate where one droplet is present) and the average spacer per droplet when dropping the spacer dispersion liquid with the ink jet device. The arrangement density (in the column) of the spacers determined by the number of (the horizontal axis of the table). For example, “40 × 40” on the vertical axis in Table 3 means that the dropping interval in the X-axis scanning direction is 40 μm and the dropping interval in the Y-axis scanning direction is 40 μm in the inkjet apparatus. If the combination of “dropping interval” and “average number of spacers per droplet” in the range surrounded by the thick line in Table 3 is set, the arrangement of the spacers in the liquid crystal device of the present invention can be realized.

[Example 3]
Next, using the same liquid crystal cell as in Examples 1 and 2, the arrangement density of spacers is 50 to 300 / mm ² , the average number of spacers per droplet is 2, and the spacer diameter is limited to 4 μm. Then, the liquid crystal cell was actually manufactured by changing the opening diameter of the droplet discharge nozzle of the ink jet apparatus. Then, three items of “stability of the average number of spacers per point”, “stability of droplet shape”, and “stability of liquid amount per droplet” were evaluated. The opening diameter of the nozzle was changed to five types of 6, 10, 30, 100, and 150 μm. The evaluation results are shown in [Table 4] below.

  In Table 4, “Stability of the average number of spacers per point” is “x” when there is no stability by visual inspection and there is a large variation in the number of spacers, and there is a slight variation in the number of spacers. “△”, and “○” means that the number of spacers is sufficiently stable. “Droplet shape stability” was confirmed by visual inspection to have a drop-shaped drop, “x” for a drop that was not stable, and a stable drop. The thing was made into "(circle)". “Stability of liquid volume per drop” is “X” when the liquid volume is not stable due to clogging of the nozzle by visual inspection, and “△” when the liquid volume varies slightly. A sample having a sufficiently stable liquid amount was designated as “◯”.

  As can be seen from Table 4, when the nozzle opening diameter was 6 μm, the nozzle clogged when the spacer diameter was 4 μm, and both the amount of liquid and the number of spacers were unstable due to this. On the other hand, when the opening diameter of the nozzle is 150 μm, the liquid volume itself increases, so both the liquid volume and the number of spacers become slightly unstable, and the shape of the liquid droplets often looks like a tailed shape. Was not stable at all. On the other hand, when the nozzle opening diameter was in the range of 10 to 100 μm, the three items of the liquid amount, the number of spacers, and the shape of the droplet were almost stable. However, when the opening diameter of the nozzle was 100 μm, there was a slight variation in the liquid amount and the number of spacers, and when the opening diameter of the nozzle was 10 μm and 30 μm, it was completely stable.

To summarize the above results, from the results of Examples 1 and 2, it is possible to suppress both display defects due to too few spacers and display defects due to too many spacers, and in order to maintain good display quality, spacers It was confirmed that the arrangement density was preferably 50 to 300 / mm ² , and the average number of spacers per droplet was 0.2 to 3. Furthermore, in order to stably realize such an arrangement of spacers, based on the results of Example 3, the nozzle opening diameter of the inkjet apparatus to be used is set to a range of 10 to 100 μm (more preferably 10 to 30 μm). It was confirmed that

  As described above, according to the present invention, in the technique of arranging a spacer at a predetermined position in a liquid crystal cell using an ink jet device, the arrangement density of spacers, the number of spacers present per droplet, and use By optimizing the opening diameter of the nozzle of the droplet discharge device, it is possible to effectively suppress display defects caused by cell thickness unevenness and light leakage due to spacers, and to stabilize a liquid crystal device with high display quality. Can be manufactured.

FIG. 2 is an equivalent circuit diagram of switching elements, signal lines, and the like in the liquid crystal device according to the embodiment of the present invention. 2 is a plan view showing the structure of a plurality of pixel groups adjacent to each other on a TFT array substrate in the liquid crystal device. FIG. 2 is a cross-sectional view showing a structure in a non-pixel region of the liquid crystal device. FIG. FIG. 2 is an overall plan view schematically showing an overall configuration of the liquid crystal device. FIG. 5A is a plan view illustrating an example of a state in which 0.2 spacers exist on average per droplet in the spacer arrangement process of the liquid crystal device, and FIG. 5 (b) shows a state after the solvent is evaporated. FIG. 6A is a plan view showing an example of a state where three spacers exist on average per droplet in the spacer arrangement step of the liquid crystal device, and FIG. b) shows the state after evaporation of the solvent. FIG. 6 is a plan view showing a state in which spacer aggregates are formed in the spacer arrangement step of the liquid crystal device. It is a schematic diagram which shows the structure of a spacer similarly. It is a schematic diagram which shows the structure at the time of providing a surface treatment layer in a spacer similarly. It is a schematic diagram which shows the structure at the time of coloring a spacer. It is explanatory drawing shown about the effect at the time of using the spacer of FIG. It is explanatory drawing shown about the effect at the time of using the spacer of FIG. It is process explanatory drawing (flowchart) which shows an example of the manufacturing method of a liquid crystal device equally. It is process explanatory drawing (flowchart) which shows the modification of a manufacturing method equally. FIG. 6 is a schematic diagram showing a state in which droplets are dropped at a dimensional interval smaller than the droplet diameter in the spacer arrangement step. It is a perspective view which shows the structure of the head of the inkjet apparatus used at a spacer arrangement | positioning process similarly. FIG. It is sectional drawing which shows the part of the nozzle hole of a head similarly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Lower substrate (TFT array substrate), 15 ... Spacer, 20 ... Upper substrate (counter substrate), 50 ... Liquid crystal layer, 93 ... Sealing material.

Claims (8)

A method of manufacturing a liquid crystal device in which a pair of substrates are arranged to face each other with a sealing material, and a liquid crystal and a spacer are enclosed in a space surrounded by the pair of substrates and the sealing material,
Dropping a spacer dispersion liquid in which the spacer is dispersed in a predetermined solvent at a predetermined position on one of the pair of substrates using a droplet discharge device;
By evaporating the solvent in the droplets dropped on the substrate, the arrangement density of the spacers is 50 to 300 / mm ² , and the average per drop point of the droplet discharge device Placing the spacers such that there are 0.2-3 spacers;
And a step of bonding the substrate on which the spacer is disposed and the remaining substrate, and an opening diameter of a droplet discharge nozzle in the droplet discharge device is set to 10 μm or more and 100 μm or less. Method.   The method for manufacturing a liquid crystal device according to claim 1, wherein an opening diameter of the droplet discharge nozzle is 10 μm or more and 30 μm or less.   The method for manufacturing a liquid crystal device according to claim 1, wherein an opening diameter of the droplet discharge nozzle is set to be twice or more a diameter of the spacer.   The method for manufacturing a liquid crystal device according to claim 1, wherein the spacer is disposed in a non-pixel region.   5. The method for manufacturing a liquid crystal device according to claim 1, wherein at least a surface of the spacer is colored.   The method for manufacturing a liquid crystal device according to claim 1, wherein the surface of the spacer is subjected to a treatment for regulating the alignment of liquid crystal.   The method for manufacturing a liquid crystal device according to claim 1, wherein a fixing layer for fixing the spacer itself on the substrate is provided on a surface of the spacer.   8. The step of dripping the spacer dispersion liquid on the substrate, the liquid droplets are dropped at a dimensional interval larger than the diameter of the liquid droplets when dropped on the substrate. A method for producing a liquid crystal device according to item.

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