JP3931378B2 - Manufacturing method of display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a display device suitable for use in a camera finder or the like using, for example, a polymer dispersed liquid crystal that is a liquid crystal substance that acquires predetermined physical properties by light irradiation.
[0002]
[Prior art]
Conventionally, when a liquid crystal display device is configured in a camera finder or the like, it has been usual to inject liquid crystal uniformly into a gap formed between a pair of glass plates on which electrodes are deposited. This type of display device can display arbitrarily depending on the state of the two electrode surfaces provided so as to be in contact with the liquid crystal surface, and is displayed only when the electrodes on both surfaces are in an active or AC antiphase. The
[0003]
On the other hand, polymer-dispersed liquid crystal has recently attracted attention as a display material. The polymer dispersed liquid crystal is made of a polymer / liquid crystal composite material using nematic liquid crystal, is a field effect type, is a light scattering type, and does not require a polarizing plate. When an electric field is not applied, it is in a cloudy state and does not allow external light to be scattered and transmitted, and when an electric field is applied, the light transmittance increases and becomes extremely high, as an electric field-dependent scatterer exhibiting high light transmittance. It has properties ("Compatech", 1990.7, pages 39-43).
[0004]
As described above, the polymer-dispersed liquid crystal is in a white turbid state when not energized, and becomes transparent when energized. Otherwise, the current must be energized, and the logic is reversed from that of a normal liquid crystal, and it is difficult to perform the desired display with the conventional liquid crystal display system. For example, in this type of liquid crystal, when a certain part is made cloudy, there is a problem that all parts of the electrode leading to that part are clouded. In order to solve this problem, the portion where the liquid crystal is arranged must be patterned to create a state where there is no liquid crystal in the passage of the display electrode.
[0005]
For the reasons described above, it is necessary to dispose liquid crystals partially and selectively between glass plates. For this purpose, it is necessary to drop the liquid crystal on a section formed by making a predetermined pattern of a transparent material. Thus, the glass plate on which the liquid crystal is partially and selectively arranged is sealed with another glass plate and irradiated with ultraviolet rays to form a display device.
[0006]
[Problems to be solved by the invention]
However, it is very difficult to accurately drop the liquid crystal onto a predetermined partition portion without excess or deficiency. In particular, since it must be dripped so as not to overflow after sealing and not to create a space, it is very difficult to select work and materials. Since the drop amount tolerance depends only on the elastic change of the partitioned pattern portion, the drop amount tolerance is very small in a minute drop region where display is performed. For this reason, it is very difficult to carry out manufacturing within this allowable error range.
[0007]
In order to avoid the above-mentioned problem, a method of injecting liquid crystal using capillary action after creating an injection path to the dropping region in advance on the pattern and combining the two glass plates is also conceivable. However, in this case, the liquid crystal remains in the injection path, the quality of the display device cannot be maintained, and there is a problem that the manufacturing process becomes complicated.
[0008]
An object of the present invention is to provide a manufacturing method capable of easily manufacturing a display device in which a polymer diffusion type liquid crystal is arranged only in a desired pattern region.
[0009]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, only a necessary portion of the liquid crystal material between the translucent members is changed to a liquid crystal layer that has acquired a predetermined physical property by light irradiation, and unnecessary liquid crystal material is removed later. I thought about how to do it. That is, the method for manufacturing a display device according to the present invention includes a step of forming a translucent electrode on each of a pair of translucent members, and a liquid crystal substance that acquires predetermined physical properties by light irradiation between the translucent members. The liquid crystal substance is formed on the liquid crystal layer having the predetermined physical property corresponding to the predetermined pattern by performing the intervening step and performing light irradiation corresponding to the predetermined pattern from the light source to the translucent member. And a step of replacing an unnecessary liquid crystal substance other than the one having acquired the predetermined physical properties with another replacement liquid .
[0010]
According to the present invention, the light irradiation corresponding to the predetermined pattern is performed after interposing the liquid crystal material before acquiring the predetermined physical property between the pair of transparent members facing the transparent electrode surface. Accordingly, in order to form a liquid crystal layer and has acquired a predetermined property has a predetermined pattern, as in the prior art, operations such as dropping a liquid crystal in a portion of the partition pattern is Ri Do not required, the manufacturing process In addition to being shortened, it is not necessary to provide an injection path up to the pattern portion, and the injection path does not remain. Therefore, a high-quality display device including a liquid crystal layer having a predetermined pattern can be easily manufactured. In addition, by removing unnecessary liquid crystal material after that, the liquid crystal material in an unstable state that does not acquire the predetermined physical properties can be eliminated, and the liquid crystal layer formed in a predetermined pattern can be isolated from the outside air, and stable. A high- quality display device can be provided.
[0011]
Further, a mask having a predetermined pattern formed on the surface of the translucent member is covered, and the light irradiation is performed through the mask, thereby forming a liquid crystal layer having the predetermined pattern and having the predetermined physical properties. Can do.
[0012]
Further, the light irradiation is performed through a mask having a predetermined pattern and an optical system, and the predetermined pattern is formed on the liquid crystal material between the light-transmissive members, thereby having a predetermined pattern and a predetermined physical property. The acquired liquid crystal layer can be formed. In the method of directly covering the mask as described above, when the thickness of the translucent member is increased, the accuracy of the pattern may not be obtained unless the light is a parallel light beam. When the light irradiation is performed through the liquid crystal, a predetermined pattern image is accurately formed on the liquid crystal substance, so that a highly accurate pattern display unit can be configured.
[0013]
Further, at least one of the translucent electrodes can be formed in a shape corresponding to the pattern. Thereby, a plurality of display pattern portions can be provided and each display pattern portion can be controlled independently.
[0014]
Further, the unnecessary liquid crystal material other than that won predetermined physical properties when removed from between the light-transmitting member, and immersing the one end side of the light transmissive member to the replacement liquid, the unnecessary liquid from the other end It can be removed by discharging and replacing the material. In this case, by disposing a suction member on the other end side, unnecessary liquid crystal substance can be discharged and a replacement liquid can be introduced and replaced by capillary action.
[0015]
Moreover, it is preferable that the said substitution liquid is a liquid crystal or a photocurable adhesive agent.
[0016]
Further, when the unnecessary liquid crystal substance is removed, it can be efficiently removed by performing vacuum suction from the other end side of the translucent member. Further, a suction member may be arranged on the other end side.
[0017]
When the liquid crystal material is composed of a mixture of a nematic liquid crystal and a photocurable monomer, the liquid crystal layer that has acquired predetermined physical properties by the light irradiation becomes a polymer dispersed liquid crystal.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a plan view showing a viewfinder display of the camera viewfinder display device according to the present embodiment. As shown in FIG. 1, display pattern portions 31, 32, 33, 34, and 35 are formed in five regions in the frame 30 of the camera finder, and each planar shape is formed in a pair of U-shapes. , Constitutes a parenthesis shape.
[0019]
The display pattern units 31 to 35 are displayed in a superimposed manner with the subject background in the camera finder. This means that when one of the display pattern portions is displayed, AF (autofocus) in that area becomes active. Of course, the display content may represent other content, and may be, for example, letters / numbers such as a, b, c, 1, 2 or a pit map.
[0020]
The display pattern portions 31 to 35 are made of polymer dispersed liquid crystal. This polymer dispersed liquid crystal is usually formed from a mixture (liquid crystal material) of a nematic liquid crystal and a monomer of an ultraviolet curable resin. The polymer-dispersed liquid crystal is designed so that the refractive index of the aligned liquid crystal, that is, the uniaxial refractive index ellipsoid of the nematic liquid crystal is substantially equal to the refractive index of the cured resin. When the nematic liquid crystal is unoriented and in a random state, the nematic liquid crystal scatters this light beam by the refractive index changing randomly with the adhesive polymer with respect to the incident light beam. When oriented, the refractive index becomes uniform and the light beam passes as it is. By this phenomenon, the polymer dispersed liquid crystal acquires a two-phase state of white turbidity and a transparent body, and can function as a display device. In this case, in order to make the liquid crystal function, the mixture (liquid crystal material) is irradiated with ultraviolet rays, the monomer of the ultraviolet curable resin is cured as a polymer, and a polymer network is formed around the nematic liquid crystal. Is required.
[0021]
According to the display device using polymer dispersed liquid crystal, a polarizing plate required for normal liquid crystal is not required, so that the transmittance of external light can be increased, and a high-quality display device that is bright and easy to see and has good distinguishability. realizable.
[0022]
FIG. 2 is a schematic cross-sectional view of the display device shown in FIG. Between the translucent electrode 51 partially formed on the glass plate 1 and the translucent electrode 56 formed on the entire surface of the glass plate 2, a polymer constituting the display pattern portion 31 corresponding to the electrode 51. A dispersive liquid crystal layer is located, and a liquid crystal layer (or ultraviolet curable adhesive layer) 38 is located between the glass plates 1 and 2 so as to surround it. When the voltage is not applied between the electrodes 51 and 56, the polymer dispersed liquid crystal layer 31 is in a cloudy state, and the light incident on the polymer dispersed liquid crystal layer 31 is scattered and the incident light is not transmitted. 31 is displayed darkly. On the other hand, when a voltage is applied between the electrodes 51 and 56, the polymer-dispersed liquid crystal 31 becomes translucent and incident light is transmitted, and its refractive index is almost the same as that of the surrounding liquid crystal layer 38. The pattern part 31 cannot be visually recognized. In this way, the display pattern portion 31 can be displayed / hidden.
[0023]
A method for manufacturing the finder display device shown in FIGS. 1 and 2 will be described. First, an ITO film (indium / titanium oxide) which is a light-transmitting conductive film having a divided pattern shape as shown in FIG. 3 is formed on the glass plate 1 which is a light-transmitting member having a parallel plane by vapor deposition or the like. The photoelectrodes 51, 52, 53, 54, and 55 are used. FIG. 3 also shows the positions of the pattern portions 31 to 35 to be formed later in order to clarify the positions of the translucent electrodes 51 to 55.
[0024]
The translucent electrodes 51 to 55 correspond to the planar shapes of the display pattern units 31 to 35 in order to switch the polymer diffusion type liquid crystal disposed in the pattern units 31 to 35 shown in FIG. It is formed. As shown in FIG. 3, each of the translucent electrodes 51 to 55 is formed to be elongated from the left side of the drawing toward the display position of each display pattern, and each of the display pattern portions 31 to 35 having a parenthesis shape. It is formed so as to cover the whole in a rectangular shape. Moreover, as shown in FIG. 3, the translucent electrode 56 is formed in the glass plate 2 which is the other translucent member over the whole surface. Note that the electrodes of the glass plate 2 may also be formed in the same shape as the electrodes 51 to 55.
[0025]
Next, a spacer is uniformly spread | dispersed on the surface in which the translucent electrode of the glass plate was formed. This spraying is performed by dissolving a powder made of resinous spheres having a certain diameter in a solvent such as alcohol and spraying the solvent onto a translucent member.
[0026]
Next, as shown in FIG. 4, a pair of glass plates 1 and 2 are put together, and the entire periphery of the end portion thereof is surrounded by a sealing material 9 to secure a space 8 in which liquid crystal enters. The sealing material 9 is provided with two holes (only one hole 9a is shown in the figure), and the liquid crystal can permeate through this hole. The spacing of the space 8 between the glass plates 1 and 2 is determined by the above-mentioned spacer, and thereby the liquid crystal film thickness can be controlled.
[0027]
The outer shape of the display device is completed through the above-described series of steps. Next, the above-described liquid crystal material is injected into the space 8 of the display device. Prior to injecting the liquid crystal material, one of the two holes is temporarily closed. The substance to be closed preferably has a property that airtightness is maintained at the time of closing, but the blocking can be easily released. When one of the holes (9a) becomes a liquid crystal injection port, the outer shape of the display device is surrounded and evacuated, and the space 8 between the glass plates 1 and 2 is evacuated. When the inside is in a sufficiently vacuum state, the holes 9a of the glass plates 1 and 2 are immersed in a container containing a liquid crystal material so that the holes 9a are covered with the liquid crystal material by surface tension. The liquid crystal material penetrates into the space 8 in the display device by capillary action. In addition, here, when the atmosphere surrounding the display device is returned to the atmosphere, the liquid crystal material quickly permeates into the space 8 of the display device due to the atmospheric pressure. In this way, the liquid crystal material can be filled in the space 8 between the glass plates 1 and 2.
[0028]
Since the liquid crystal material is filled in the space 8 between the glass plates 1 and 2, it is irradiated with ultraviolet rays. Since only the region to be patterned has activity as a liquid crystal display material, only the region is irradiated with ultraviolet rays by a photomask. An ultraviolet irradiation apparatus for this purpose will be described with reference to FIGS.
[0029]
FIG. 5 is a diagram schematically showing the entire ultraviolet irradiation apparatus used in the present embodiment. This ultraviolet irradiation device includes a light source, an optical system, and a photomask. The ultraviolet light from the ultraviolet lamp 11 is converted into parallel light by the illumination condenser lens 12 to illuminate the diffusion plate 15. The diffused light illuminates the photomask 13 on which a predetermined pattern is drawn, and the pattern portion of the illuminated photomask 13 is projected onto the liquid crystal material surface filled in the space 8 between the glass plates 1 and 2 by the projection lens 14. It is configured to form an image.
[0030]
FIG. 6 is a plan view of the photomask 13 of FIG. 5, which is a negative image of the display pattern portions 31 to 35 shown in FIG. The photomask 13 is made of an ultraviolet opaque member, and a plurality of regions corresponding to the display pattern portions 31 to 35 in FIG. 1 are cut out.
[0031]
The ultraviolet irradiation device corresponding to the photomask 13 shown in FIG. 6 is irradiated to the predetermined region of the liquid crystal material surface interposed in the space 8 between the glass plates 1 and 2 by the ultraviolet irradiation device of FIG. The display pattern portions 31 to 35 in FIG. 1 are formed by curing the ultraviolet curable resin contained in the liquid crystal material.
[0032]
When the glass plate is thin, a photomask may be superimposed on the glass plate for irradiation. When the glass plate is thick, it is desirable to accurately project the photomask image onto the liquid crystal surface using an optical system as shown in FIG. 5, and the display pattern portion can be accurately formed.
[0033]
If the activation of the liquid crystal is completed as described above, it can be said that the display function is sufficiently satisfied unless the aging stability of the display device is considered, but a large number of uncured monomers remain between the glass plates 1 and 2. The stability as a liquid crystal is not good, and a weak ultraviolet ray may form an unexpected polymer network or the pattern display portion may become cloudy. Therefore, in order to obtain a display device having sufficient stability as a product, it is necessary to remove unnecessary uncured liquid crystal material from between the glass plates 1 and 2. For this purpose, the uncured liquid crystal material remaining between the glass plates 1 and 2 of the display device is replaced with a stable substance.
[0034]
The substitution material depends on the type and composition of the polymer dispersed liquid crystal material, but if the polymer network surrounding the liquid crystal is sufficiently solid and will not be swept away, a liquid UV curable adhesive is desirable. If the ratio of nematic liquid crystal is high and the retention of the network is poor, a liquid crystal material consisting only of nematic liquid crystal is desirable.
[0035]
The above replacement process will be described with reference to FIG. In the replacement, first, the other hole of the sealing material that has been blocked is opened, and a passage through which the substitution substance (substitution liquid) enters and a passage through which the substitution target liquid (uncured liquid crystal material) is discharged are secured.
[0036]
Next, the glass plates 1 and 2 are put into the container 21 from the end face side with the other hole and immersed in the replacement liquid 23 such as liquid crystal, and the suction member 22 is inserted into the hole 9a of the seal member 9 shown in FIG. Place. Since this sucking member 22 sucks the liquid crystal material of the liquid to be replaced in the space 8 between the glass plates 1 and 2, the replacing liquid 23 in the container 21 starts to penetrate into the space 8 by capillary action. If the liquid is allowed to stand for a certain period of time, the liquid to be replaced is sucked into the suction member 22 like a chromatograph, and the replacement liquid 23 penetrates between the glass plates 1 and 2 from the lower part, and is eventually completely replaced. .
[0037]
By this process, the uncured liquid crystal material that is an unstable active material is completely absorbed, and the replacement liquid 23 such as a liquid crystal that is a stable material remains between the glass plates 1 and 2. As a safe and durable.
[0038]
The sucking member 22 can be made of a material that can cause capillary action, such as blotting paper, fine fiber cloth, etc., but is not limited thereto. In addition, as described above, the substitution liquid may be an ultraviolet curable adhesive, but in this case, after the substitution, a step of curing the adhesive by irradiating ultraviolet rays is required.
[0039]
Next, a modification of the replacement process will be described with reference to FIG. In the example of FIG. 8, the upper ends of the glass plates 1 and 2 including the hole 9 a of the seal material 9 of FIG. 4 are covered and sealed with a vacuum suction box 24, and this sealed space 24 a is sealed with a vacuum device 25. Except for the vacuum, the configuration is the same as in the case of FIG. When the vacuum device 25 is operated and the atmosphere in the sealed space 24a of the vacuum suction box 25 is exhausted and depressurized, the atmospheric pressure p is applied to the liquid surface of the replacement liquid 23 in the container 21, and the replacement liquid 25 is sealed as shown in FIG. It flows into the glass plates 1 and 2 from the other hole of the material 9 and starts to push up the liquid to be replaced. As a result, the uncured liquid crystal material that is the liquid to be replaced between the glass plates 1 and 2 is extruded from the hole 9a in FIG. 4, and the replacement liquid 23 in the container 21 penetrates into the space 8 due to the atmospheric pressure p and capillary action. When the liquid to be replaced is completely discharged, the space 8 between the glass plates 1 and 2 is filled with the replacement liquid such as liquid crystal.
[0040]
According to the replacement step shown in FIG. 8, the replacement liquid can shorten the time required for replacement compared with the case of replacement only by a normal capillary phenomenon, and can further increase the production efficiency.
[0041]
Thereafter, when the replacement liquid is a UV curable adhesive, further irradiation with ultraviolet rays is performed, and the holes 9a and the like of the sealing material 9 provided on the entire periphery of the end surfaces of the glass plates 1 and 2 are sealed with an adhesive or the like. The device is completed.
[0042]
In order to obtain a display device that performs arbitrary display using polymer-dispersed liquid crystal, a manufacturing method in which liquid crystal is arranged only in a desired pattern region is required due to the characteristics of polymer-dispersed liquid crystal. The method of dropping the liquid crystal on the partitioned pattern portion and the post-injection method are difficult to work, and the liquid crystal injection path remains on the display. On the other hand, according to the manufacturing method of the display device according to the present embodiment, a display device in which a polymer dispersed liquid crystal is arranged in a predetermined pattern region can be easily manufactured by a simpler process than the conventional method. . Therefore, it is possible to provide a high-quality display device that is bright and easy to see and has high discriminability using a polymer-dispersed liquid crystal at a low cost.
[0043]
The display device according to the present invention is not limited to a finder display device such as a camera, but can be applied to other display devices that do not receive external light. For example, a predetermined display can be performed by backlight illumination.
[0044]
【The invention's effect】
According to the present invention, by the light irradiation to place the liquid crystal material to obtain the physical properties of only to a Jo Tokoro desired region, a stable high-quality display device can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a plan view showing a viewfinder display of a camera viewfinder display device according to an embodiment of the present invention.
2 is a schematic cross-sectional view showing a cross-sectional configuration of the display device of FIG.
3 is a plan view showing a translucent electrode formed in a divided manner in the display device of FIG. 1;
4 is a perspective view showing a state in which a pair of glass plates are combined with a seal member in order to manufacture the display device of FIG. 2; FIG.
5 is a diagram showing a configuration of an ultraviolet irradiation device for forming an image of a predetermined pattern on a liquid crystal material surface between translucent members in order to manufacture the display device of FIG. 2;
6 is a plan view showing an example of a photomask used in the ultraviolet irradiation apparatus of FIG. 5. FIG.
7 is a diagram for explaining an uncured liquid crystal material replacement step for replacing the uncured liquid crystal material in the pair of glass plates of FIG. 4 with a replacement liquid. FIG.
8 is a diagram showing a modification of the replacement process of the uncured liquid crystal material of FIG.
[Explanation of symbols]
1, 2 glass plates (a pair of translucent members)
8 Space between a pair of glass plates 9 Seal member 9a Seal member hole 11 UV lamp 13 Photomask 12, 14 Optical system 21 Container 22 Suction member 23 Replacement liquid 24 Vacuum suction box 24a Sealed space 25 Vacuum device 30 Finder frame 31 , 32, 33, 34, 35 Display pattern (polymer dispersed liquid crystal layer)
51, 52, 53, 54, 55 Divisional translucent electrode 56 Whole surface translucent electrode 38 Liquid crystal layer (UV curable adhesive layer)

Claims (9)

Forming a translucent electrode on each of the pair of translucent members;
A step of interposing a liquid crystal material that acquires predetermined physical properties by light irradiation between the translucent members;
Performing light irradiation corresponding to a predetermined pattern from a light source to the translucent member, thereby forming the liquid crystal material in a liquid crystal layer that has acquired the predetermined physical property corresponding to the predetermined pattern;
And a step of replacing the unnecessary liquid crystal substance other than that having acquired the predetermined physical properties with another replacement liquid.   The manufacturing method of Claim 1 which covers the mask which formed the predetermined pattern on the surface of the said translucent member, and performs the said light irradiation through this mask.   The manufacturing method according to claim 1, wherein the light irradiation is performed through a mask having a predetermined pattern and an optical system, and the predetermined pattern is imaged on the liquid crystal material between the translucent members.   The manufacturing method according to claim 1, wherein at least one of the translucent electrodes is formed in a shape corresponding to the pattern.   The manufacturing method according to claim 1, 2, 3, or 4, wherein one end side of the translucent member is immersed in the replacement liquid, and the unnecessary liquid crystal substance is discharged from the other end side to replace the replacement liquid.   The manufacturing method according to claim 1, wherein the replacement liquid is a liquid crystal or a photocurable adhesive.   The manufacturing method according to claim 5 or 6, wherein vacuum suction is performed from the other end side of the translucent member when the unnecessary liquid crystal substance is removed. The manufacturing method of Claim 5 or 6 which arrange | positions a suction member in the other end side of the said translucent member in the case of the removal of the said unnecessary liquid crystal substance.   The method according to claim 1, wherein the liquid crystal substance is a mixture of a nematic liquid crystal and a photocurable monomer, and the liquid crystal layer that has acquired predetermined physical properties by light irradiation is a polymer-dispersed liquid crystal.

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