JP3629893B2 - Method for manufacturing reflective display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective display element.To the manufacturing methodRelated.
[0002]
[Prior art]
A reflective display element such as a reflective liquid crystal display element does not require a dedicated light source such as a backlight unlike a transmissive display element such as a transmissive liquid crystal display element. Since it can be configured, it is suitable for a display device such as a small information device or a portable information terminal.
[0003]
As a reflective display element capable of color display, conventionally, a polarizing plate is arranged on both sides of a TN liquid crystal or STN liquid crystal cell to form an optical shutter, and incident light as external light is colored with a color filter, A device that transmits through a shutter and reflects it with a reflector is known. However, since this reflective display element uses a polarizing plate and a color filter, there are disadvantages that the loss of light is large, the reflected light of the output is weak, and the luminance is low.
[0004]
Therefore, as a reflective display element that does not use a polarizing plate or a color filter, at least one of the two substrates having electrodes formed thereon is changed in refractive index by an electric field and has two different refractive indexes. It has been considered that a medium layer is alternately formed over a plurality of layers, and a reflection layer is formed that reflects light having a specific wavelength in visible light by a periodic change in refractive index.
[0005]
For example, in JP-A-4-355424 and JP-A-5-134266, as shown in FIG. 14C, a polymer is interposed between the electrodes 12 and 14 of the substrates 11 and 13 on which the electrodes 12 and 14 are formed. A multilayer film in which layers 17 and liquid crystal layers 18 are alternately stacked is shown.
[0006]
In this display element, due to the difference in the periodic refractive index between the liquid crystal layer 18 whose refractive index changes according to the voltage applied between the electrodes 12 and 14 and the polymer layer 17 that does not cause a change in refractive index, Based on the principle of the interference filter, light of a specific wavelength in incident light is reflected and light in other wavelength regions is transmitted.
[0007]
For example, by making the refractive index of liquid crystal with respect to normal light equal to the refractive index of the polymer, in the state where no voltage is applied between the electrodes 12 and 14, the liquid crystal is directed in a random direction, so that the polymer layer A difference in refractive index occurs between the liquid crystal layer 18 and the liquid crystal layer 18, causing a periodic change in refractive index between the electrodes 12 and 14. As shown in FIG. The light 56 having a specific wavelength is reflected. The reflection wavelength is determined by the period of change in the refractive index, that is, the thickness of the polymer layer 17 and the liquid crystal layer 18.
[0008]
On the other hand, when a sufficient voltage is applied between the electrodes 12 and 14, the liquid crystal is aligned in a direction perpendicular to the substrates 11 and 13, so that the refractive index of the polymer layer 17 and the liquid crystal layer 18 are equal. Thus, the periodic change in the refractive index between the electrodes 12 and 14 disappears, and all the incident light 55 is transmitted through the display element.
[0009]
As a manufacturing method of this reflection type display element, conventionally, a mixed liquid of liquid crystal and a photopolymerizable monomer is injected between the electrodes 12 and 14, and the mixed liquid is irradiated with laser light of the same phase with a predetermined wavelength. It is conceivable to form a liquid crystal layer 18 by polymerizing a photopolymerizable monomer to form a polymer layer 17 by this interference and depositing liquid crystal in a region other than the polymer layer 17.
[0010]
For example, SPIE Vol. 2152/303 ('94) “Development of photopolymer-liquid crystal composite materials for dynamic holographic applications” includes a mixture of electrodes 12 and 14 as shown in FIGS. 14A and 14B. Then, the laser beams 51 and 52 are irradiated from both sides of the substrates 13 and 11 as shown in FIG. 5A, or the laser beams 53 and 54 are irradiated from the substrate 13 side as shown in FIG. By doing so, it is shown that a multilayer film in which the polymer layers 17 and the liquid crystal layers 18 are alternately stacked is obtained as shown in FIG.
[0011]
[Problems to be solved by the invention]
In the reflective display element as shown in FIG. 14C, a polarizing plate, a color filter, and the like are not used, so that light loss is small. Further, as the periodic structure of the liquid crystal layer 18 and the polymer layer 17 is more uniform and the period of change in refractive index is more uniform, the intensity of the reflected light 56 is increased by multiple reflection, and a high luminance display can be obtained.
[0012]
As described above, in the conventional manufacturing method in which the mixed liquid of the liquid crystal and the photopolymerizable monomer is irradiated with laser light to form a multilayer film, the liquid crystal layer 18 and the polymer layer 17 have a relatively uniform thickness. The refractive index change period becomes relatively uniform, and a high reflectance is obtained.
[0013]
However, if the period of the refractive index change in the multilayer film is uniform, the reflected light intensity increases, but the reflected wavelength band becomes extremely narrow as shown by the broken line 8 in FIG. The corners are remarkably small, and there is a disadvantage that they are not suitable for practical use as a display device.
[0014]
Therefore, in the present invention, the reflection wavelength band is widened and the viewing angle is increased by providing a change in the refractive index change period in the multilayer film within a certain range.
[0015]
[Means for Solving the Problems]
The manufacturing method of the reflective display element of the present invention is roughly classified into the following first and second manufacturing methods.
[0017]
In the first manufacturing method of the present invention,
On the electrode side of the first substrate on which the electrodes are formed, a first medium layer and a second medium layer are alternately stacked one by one to form a multilayer film,
Next, an adhesive is applied to one or more sides excluding at least one side of the periphery of the multilayer film, and the electrode side of the second substrate on which the electrode is formed is adhered on the multilayer film,
Next, the material forming the second medium layer is eluted from the side of the multilayer film where the adhesive is not applied, and a material whose refractive index is changed by an electric field is injected into the elution part.
Next, the side of the multilayer film where the adhesive is not applied isBy glueSeal.
[0018]
In the second manufacturing method of the present invention,
On the electrode side of the first substrate on which the electrode is formed, the first medium layer and the second medium layer are alternately stacked one by one to form a multilayer film, and on the electrode side of the second substrate on which the electrode is formed, A multilayer film is formed by alternately laminating the first medium layer and the second medium layer one by one,
Next, an adhesive is applied to one or more sides excluding at least one side of the periphery of the multilayer film on the first substrate and the second substrate, and the first substrate and the second substrate are bonded to each other. Glue,
Next, the material forming the second medium layer is eluted from the side of the multilayer film where the adhesive is not applied, and a material whose refractive index is changed by an electric field is injected into the elution part.
Next, the side of the multilayer film where the adhesive is not applied isBy glueSeal.
[0019]
In the first or second manufacturing method, the first medium layer is formed of a photocurable resin, the second medium layer is initially formed of a thermosetting resin, and the thermosetting resin is eluted. In addition, a method of irradiating the multilayer film with light can be employed. In addition, liquid crystal can be used as a material whose refractive index changes. Further, by injecting the liquid crystal into the elution part from the same direction, the liquid crystal can be aligned in one direction by so-called flow alignment.
[0020]
[Action]
Take the above method,In the first or second manufacturing method of the present invention, the first medium layer and the second medium layer are initially formed in layers alternately by printing, transferring, or the like, respectively, of a photocurable resin and a thermosetting resin. As a result, each is formed with a uniform thickness.
[0021]
However, when the material such as the thermosetting resin is eluted by the elution condition when the material such as the thermosetting resin forming the second medium layer is eluted, the material such as the thermosetting resin A part of the material remains without being eluted, and a part of the material such as the photocurable resin forming the first medium layer is eluted, and the first medium layer made of the remaining material and the elution of the material The thickness of the elution part that has become a cavity is nonuniform within a certain range in each layer in the thickness direction of the multilayer film and in each part in the surface direction.
[0022]
Therefore, when a material such as liquid crystal whose refractive index changes due to an electric field is injected into the elution portion, the first medium layer made of the material remaining at the time of elution and the second medium made of a material whose refractive index changes due to the electric field such as liquid crystal. The period of the periodic structure with the medium layer, that is, the period of change in the refractive index of the multilayer film changes within a certain range in each layer in the thickness direction of the multilayer film and in each part in the surface direction. Therefore, the obtained display element has a wide reflection wavelength band and a wide viewing angle.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiments as Manufacturing Method and Display Element]
1-5 shows each process of one Embodiment of the manufacturing method of this invention.
[0024]
In this embodiment, first, as shown in FIG. 1A, a photocurable resin is printed on the electrode 12 of the substrate 11 on which the electrode 12 is formed on one side, leveled, and then dried. The first medium layer 21a is formed.
[0025]
The substrate 11 and the electrode 12 are light transmissive, and examples of the photocurable resin include UVR6105 (resin component) and UVI6990 (polymerization) which are cationic photocurable resins manufactured by Union Carbide Japan Co., Ltd. An initiator obtained by adding a diluent solvent can be used.
[0026]
As a printing method of the photocurable resin, for example, screen printing is used. In the screen printing, as shown in FIG. 7, the substrate 11 on which the electrode 12 is formed is placed on the pedestal 31, and the screen 32 on which the hole 32 a is formed is arranged to face the substrate 11, and the screen is removed by the scraper 33. Resin paste 34 is applied onto 32, squeegee 35 is used to push resin paste 34 out of hole 32 a of screen 32, and printing is performed on substrate 11. However, if the resin paste 34 is placed in the direction in which the resin paste 34 is pushed out by the squeegee 35, the scraper 33 may not be used.
[0027]
Usually, the film thickness printed by one screen printing is 0. It is several μm to several tens of μm. However, if a screen having a thin emulsion film or a plate-like screen (a thin film or fine line is obtained because the wires are not interwoven) is used as the screen 32, a printed material having a thinner film thickness can be obtained. Further, the printed film thickness varies depending on the form of the paste as the material. The film thickness of the material-soluble metalloorganic paste that does not contain fine particles is 0.2 μm or less, and the resin paste can make the printed film thickness thinner than the metalloorganic paste. Furthermore, if the resin component is diluted with a solvent or the solvent is evaporated, an arbitrary film thickness can be obtained.
[0028]
Here, the film thickness of the resin paste 34 of the photocurable resin is set to about 0.05 to 0.1 μm, and the first medium layer 21a for one layer is formed by one printing.
[0029]
Next, as shown in FIG. 1B, a thermosetting resin is printed on the first medium layer 21a, leveled, and dried to form the second medium layer 22a. As a thermosetting resin, what added the solvent for dilution to Toa Gosei Co., Ltd. S1017 can be used, for example.
[0030]
The thermosetting resin is also printed by screen printing as shown in FIG. 7, and the film thickness of the thermosetting resin paste 34 is set to about 0.05 to 0.1 μm. A two-medium layer 22a is formed.
[0031]
The reason why the thermosetting resin is dried is to evaporate the solvent component, and the thermosetting resin is dried at a temperature lower than the temperature at which the thermosetting resin is cured. After the drying, the surface of the second medium layer 22a is cured to the extent that the film of the second medium layer 22a is not affected by the solvent in the photo-curing resin to be printed next. However, the second medium layer 22a is not cured completely because the thermosetting resin is later eluted and liquid crystal is injected into the elution part.
[0032]
Next, as shown in FIG. 1C, a photocurable resin is printed on the second medium layer 22a, leveled, and then dried to form the first medium layer 21b. Next, as shown in FIG. 1D, a thermosetting resin is printed on the first medium layer 21b, leveled, and then dried to form the second medium layer 22b.
[0033]
In this way, as shown in FIG. 2 (A), the first medium layers 21a, 21b,... 21n and the second medium layers 22a, 22b,. Thus, a multilayer film is obtained.
[0034]
In practice, the total number of the first medium layers 21a, 21b,... 21n and the second medium layers 22a, 22b,. As the number of layers increases, the reflected light intensity of the obtained display element increases, but the number of steps also increases. Therefore, the number of stacked layers is determined in consideration of the reflected light intensity necessary for the display element.
[0035]
Next, in one or more sides excluding at least one side or more on the substrate 11, for example, as shown in FIG. 2B, two sides facing in a direction perpendicular to the paper surface of the figure are removed. The adhesive 25 is applied to the periphery of the multilayer film on the two sides facing in the left-right direction in the figure, and the electrode 14 side of the substrate 13 on which the electrode 14 is formed on one side is adhered on the multilayer film. The substrate 13 and the electrode 14 are also light transmissive.
[0036]
The first medium layers 21a, 21b,... 21n and the second medium layers 22a, 22b,... 22m can each be formed to have a uniform thickness by screen printing, so that the substrate 11 on which the multilayer film is formed on the electrode 12 and the electrode 14 are formed. The gap between the substrates 11 and 13 can be made uniform by simply pasting the formed substrate 13 with the adhesive 25.
[0037]
Next, as shown in FIG. 2C, light 27 such as ultraviolet rays is applied to the cell formed as shown in FIG. 2B, and the photo-curable resin forming the first medium layer 21 is cured. Irradiate with sufficient light. In this case, the photocurable resin is cured, but the thermosetting resin forming the second medium layer 22 is not cured. However, even if a part of the thermosetting resin is cured depending on the type of the thermosetting resin or the irradiation amount of the light 27, if a space for injecting liquid crystal is secured by eluting the remainder of the thermosetting resin, There is no particular problem.
[0038]
The above example is a case where all the multilayer films are formed on one substrate 11 and the two substrates 11 and 13 are bonded to each other. As shown in FIG. Alternatively, a part of the multilayer film may be formed on each other, and the two substrates 11 and 13 may be bonded together.
[0039]
That is, in this example, as shown in FIG. 3A, the first medium layer 21 made of a photocurable resin and the first medium layer made of a thermosetting resin are formed on the electrode 12 of the substrate 11 on which the electrode 12 is formed. The two medium layers 22 are alternately formed one by one by screen printing, and, for example, an adhesive 25A is applied to the periphery of the multilayer film on two sides of the substrate 11 facing in the left-right direction in FIG.
[0040]
At the same time or before and after this, as shown in FIG. 3B, the first medium layer 21 made of a photocurable resin and the heat on the electrode 14 of the substrate 13 on which the electrode 14 is formed, The second medium layers 22 made of a curable resin are alternately formed one layer at a time by screen printing. Similarly, the adhesive 25B is formed around the multilayer film on the two sides of the substrate 13 facing in the left-right direction in FIG. Apply. However, when the uppermost layer on the substrate 11 is the first medium layer 21, the uppermost layer on the substrate 13 is the second medium layer 22.
[0041]
Next, as shown in FIG. 3C, the side of the substrate 13 on which the multilayer film is formed is placed on the side of the substrate 11 on which the multilayer film is formed, and the substrate 11 and the substrate 13 are Bonding is performed using an adhesive 25 composed of adhesives 25A and 25B. Also in this case, since the first medium layer 21 and the second medium layer 22 can be formed to have a uniform thickness by screen printing, the gap between the substrates 11 and 13 can be increased by simply bonding the substrates 11 and 13 together. It can be made uniform.
[0042]
Next, as shown in FIG. 3C, the photocurable resin forming the first medium layer 21 is cured by irradiating the cell formed as described above with light 27 such as ultraviolet rays.
[0043]
After the photocurable resin is cured as shown in FIG. 2C or FIG. 3C, next, as shown in FIG. 4A, the cell is placed in the elution tank 41 containing the eluent 42. In the above example, the eluent 42 is infiltrated into the second medium layer 22 from the two sides facing in the direction perpendicular to the paper surface of FIG. The thermosetting resin that forms the layer 22 and is not cured even when irradiated with light is eluted.
[0044]
As the eluent 42, an organic solvent or a low-concentration alkaline solution can be used. However, instead of immersing in the elution tank 41 containing the eluent 42, the thermosetting resin may be eluted by spraying the eluent on the cells.
[0045]
By eluting the thermosetting resin that forms the second medium layer 22 in this way, the cell is cured between the electrodes 12 and 14 on the substrates 11 and 13 as shown in FIG. The first medium layer 21 made of the photo-curing resin and the elution portion 23 in which the thermosetting resin is eluted to form a cavity in a layer shape are alternately stacked one by one.
[0046]
However, when the light 27 is irradiated as shown in FIG. 2 (C) or FIG. 3 (C), depending on the irradiation amount and the type of the thermosetting resin, a part of the thermosetting resin is cured, and the eluent 42, and the eluent 42 hardly completely penetrates into the second medium layer 22, and the second medium layer is formed in each layer in the thickness direction of the multilayer film and each part in the surface direction. As shown in FIG. 4C, the thickness of the elution portion 23 that becomes a cavity is in the thickness direction of the multilayer film. Each layer and each part in the surface direction are non-uniform within a certain range.
[0047]
Further, the first medium layer 21 which is a non-hollow part or a non-eluting part is also irradiated with light 27 as shown in FIG. 2C or FIG. Depending on the condition, a part of the photo-curing resin is not cured and is eluted by the eluent 42, or a part of the thermosetting resin that has formed the second medium layer 22 as described above is not eluted. As shown in FIG. 4C, the thickness of the multilayer film is assumed to be composed of a polymer in which some thermosetting resin is added to the photocurable resin that is the main material. Each layer in the thickness direction and each part in the surface direction are non-uniform within a certain range.
[0048]
Therefore, the period of the multilayer structure of the first medium layer 21 and the elution part 23 has a certain maximum value T2 and a minimum value in each layer in the thickness direction of the multilayer film and each part in the surface direction, as shown in FIG. It becomes non-uniform within the range of T1.
[0049]
Next, from the side where the cell adhesive 25 is not applied, in the above example, liquid crystal is injected into the elution portion 23 from two sides facing in the direction perpendicular to the paper surface of FIG. As shown in (A), the second medium layer 22 made of liquid crystal is formed between the first medium layers 21 made of polymer, and then the side where the cell adhesive 25 is not applied is sealed with the adhesive. Then, a reflective display element is obtained in which the first medium layer 21 made of polymer and the second medium layer 22 made of liquid crystal are alternately laminated between the electrodes 12 and 14 one by one.
[0050]
When aligning the liquid crystal, it is possible to align the liquid crystal in one direction by so-called fluid alignment by injecting the liquid crystal from the same direction, that is, from one side where the cell adhesive 25 is not applied. it can.
[0051]
In the display element thus obtained, the cycle of the multilayer structure of the first medium layer 21 made of a polymer and the second medium layer 22 made of a liquid crystal has the first medium layer shown in FIG. Similar to the cycle of the multilayer structure of 21 and the elution part 23, as shown in FIG. 5B, the range between a certain maximum value T2 and minimum value T1 in each layer in the thickness direction of the multilayer film and each part in the surface direction. Becomes uneven.
[0052]
Therefore, in the obtained display element, the refractive index change period in the multilayer film changes within the range of T2 to T1, and the reflection wavelength changes correspondingly within the range of λ2 to λ1. As shown by the solid line 9, the reflection wavelength band becomes wider and the viewing angle becomes larger.
[0053]
As is apparent from the above description, the change width (T2-T1) of the period of change in the refractive index, and hence the reflection wavelength bandwidth (λ2-λ1), the irradiation conditions such as the irradiation amount of the light 27, the photocurable resin, and the like. It can be adjusted depending on the elution conditions such as the type of the thermosetting resin, the type of the eluent 42 and the elution time.
[0054]
If the reflection wavelength bandwidth is too wide, the reflected light intensity is significantly reduced and color blurring (color mixing) occurs. Conversely, if the reflection wavelength bandwidth is too narrow, the reflected light intensity increases, but the viewing angle. Becomes significantly smaller. Therefore, the reflection wavelength bandwidth is determined in consideration of the reflected light intensity or color blur and the viewing angle. In practice, when the reflection wavelength bandwidth is about 5 to 10% of the reflection center wavelength, color blurring is reduced and the viewing angle is increased.
[0055]
As described above, the method of irradiating the mixed liquid of the liquid crystal and the photopolymerizable monomer with laser light as in the past is to give the change period of the refractive index change in the multilayer film within the adjusted fixed range. In addition, it is difficult to realize by a method in which materials having different refractive indexes are simply printed or transferred alternately one by one, and can be realized only by the above-described method of the present invention.
[0056]
The first medium layer 21 made of a photocurable resin and the second medium layer 22 made of a thermosetting resin shown in FIG. 1 and FIG. 2 or FIG. 3 are not limited to screen printing, but by other printing methods. It can also be formed, or can be formed by transfer. In the case of transfer, the printed material is once applied to the transfer body and then transferred to the printed material.
[0057]
For example, as shown in FIG. 8, the substrate 11 on which the electrode 12 is formed is placed on a pedestal 31, the transfer material 39 is supplied from the transfer material supply roller 37 to the transfer body 38, and the transfer body 38 is rotated. Then, the transfer 39 is transferred onto the substrate 11. When the transfer body 38 rotates once and the transfer material 39 is exhausted, the transfer material 39 is supplied from the transfer material supply roller 37. However, it is desirable that the transfer to the substrate 11 is completed by one rotation of the transfer body 38. When the transfer member 38 has a small diameter and is transferred by rotating the transfer member 38 several times, the transfer member 38 is adjusted so that the rotation breaks overlap and there is no gap between the breaks.
[0058]
Even in such a transfer, the first medium layer 21 made of a photocurable resin and the second medium layer 22 made of a thermosetting resin can be formed to have uniform thicknesses. C) or FIG. 3C, the cell is irradiated with light 27 such as ultraviolet rays to cure the photocurable resin, and then the second medium is used as shown in FIGS. The thermosetting resin that forms the layer 22 is eluted, and liquid crystal is injected into the elution portion 23 to form a multilayer film of the first medium layer 21 made of polymer and the second medium layer 22 made of liquid crystal. Thus, the period of the multilayer structure becomes non-uniform within a certain range in each layer in the thickness direction and each part in the surface direction of the multilayer film.
[0059]
In the example described above, the adhesive 25 is applied to the two opposite sides of the multilayer film, and the thermosetting resin is eluted from the remaining two sides. The elution of the thermosetting resin is reliably performed in a short time. For this, it is desirable to apply the adhesive 25 only to one side of the multilayer film and to elute the thermosetting resin from the remaining three sides. However, in that case, there is a possibility that the three sides where the adhesive 25 is not applied are crushed by their own weight due to the elution of the thermosetting resin.
[0060]
In order to prevent this, for example, by adjusting the irradiation amount of the light 27, a part of the thermosetting resin forming the second medium layer 22 is cured as described above, or the second medium layer 22 is formed. What is necessary is just to mix some photocurable resin with the thermosetting resin to make, and to cure the photocurable resin.
[0061]
When a photocurable resin is mixed with a thermosetting resin, even if the cell is immersed in the eluent 42 after irradiation with the light 27, the photocurable resin is cross-linked and is not eluted. On the other hand, the thermosetting resin is not cross-linked by light and is dissolved in the eluent 42. In this way, the layer in which the photocurable resin is mixed with the thermosetting resin does not become a complete cavity due to the elution of the thermosetting resin, unlike the layer made only of the thermosetting resin, but in a chain shape. The crosslinked photo-curing resin remains, and there is no risk of the cells being crushed. The amount of the photocurable resin mixed with the thermosetting resin is desirably 0.5 or less with respect to the thermosetting resin.
[0062]
Since the multilayer film has a larger area than the thickness, when the photocurable resin forming the first medium layer 21 is cured and then the thermosetting resin forming the second medium layer 22 is eluted, the plane direction In some cases, the thermosetting resin cannot be sufficiently eluted up to the central part. In this case, when the light 27 is irradiated as shown in FIG. 2C or FIG. 3C, the light 27 may be irradiated through a mask having a predetermined pattern.
[0063]
For example, when the light 27 is irradiated through the stripe-shaped mask, the photocurable resin forming the first medium layer 21 is not cured in the pattern portion 29 of FIG. 9 located in the stripe portion of the mask. Is immersed in the eluent, the eluent easily enters the thermosetting resin forming the second medium layer 22 from the uncured portion of the photocurable resin, and the thermosetting resin is surely eluted. Is done. Therefore, it becomes easy to inject liquid crystal after elution.
[0064]
In this case, for example, if the width of the non-pattern portion, that is, the portion to be cured of the photocurable resin is 50 to 200 μm, and the width of the pattern portion 29, that is, the mask stripe width is 5 to 10 μm, the column of the pixels 1 The pattern portion 29 in between does not affect visually.
[0065]
A negative photo-curing resin as the first medium layer 21 and a positive photo-curing resin as the second medium layer 22 are alternately laminated one by one over a predetermined number to form a cell. , The negative photocurable resin forming the first medium layer 21 is cured, and then the uncured positive photocurable resin forming the second medium layer 22 is eluted, and the elution is performed. Liquid crystal may be injected into the portion 23. Further, in this case, the negative type photocurable resin is mixed with the positive type photocurable resin to form the second medium layer 22, and when the light 27 is irradiated, the negative type photocurable resin is cured. Thus, the cell can be prevented from being crushed when the positive-type photocurable resin is eluted.
[0066]
As the positive-type photocurable resin, for example, naphthoquinonediazide can be used. Naphthoquinonediazide forms a carbosyl group when irradiated with light and becomes soluble in an alkaline solution. Naphthoquinonediazide shows a pale yellow color, but it is eluted in the first place. Even if it remains insufficiently eluted, it is diluted with butyl carbitol acetate, etc., and since the film thickness is thin, it does not feel chromaticity. .
[0067]
FIGS. 10A and 10B show the display element obtained by the above method. Between the electrodes 12 and 14 on the substrates 11 and 13, the first medium layer 21 made of polymer and the second made of liquid crystal. The medium layer 22 has a multilayer film formed alternately, and as described above, the period of change in the refractive index in the multilayer film is changed within a certain range, the reflection wavelength band is widened, and the viewing angle Is enlarged.
[0068]
In this case, the refractive index of the liquid crystal (second medium layer 22) when no voltage is applied between the electrodes 12 and 14 as shown in FIG. 11A is n1, and the electrodes 12 and 14 as shown in FIG. The refractive index of the liquid crystal (second medium layer 22) when a sufficient voltage is applied across 14 is n2. However, n1 <n2. The refractive index n3 of the polymer (first medium layer 21) is, for example, n1 <n2 ≦ n3 in relation to the refractive indexes n1 and n2 of the liquid crystal.
[0069]
According to this, in the state where no voltage is applied between the electrodes 12 and 14 as shown in FIG. 4A, the difference in refractive index between the first medium layer 21 and the second medium layer 22 becomes large, The display element 10 reflects light 57 in a specific wavelength band in incident light (external light) 55 and transmits other light. The reflection center wavelength is determined by the center value of the refractive index change period, that is, the center value of the thicknesses of the first medium layer 21 and the second medium layer 22 for one period (one layer each).
[0070]
On the other hand, when a sufficient voltage is applied between the electrodes 12 and 14 as shown in FIG. 5B, the difference in refractive index between the first medium layer 21 and the second medium layer 22 becomes small. Thus, most of the incident light 55 is transmitted through the display element 10.
[0071]
In the case of n3 ≦ n1 <n2 instead of n1 <n2 ≦ n3, conversely, in the state where no voltage is applied between the electrodes 12 and 14, between the first medium layer 21 and the second medium layer 22 In the state where the difference in refractive index is small and most of the incident light 55 is transmitted through the display element 10 and a sufficient voltage is applied between the electrodes 12 and 14, the first medium layer 21 and the second medium layer 22 Accordingly, the display element 10 reflects the light 57 in the specific wavelength band in the incident light 55.
[0072]
In addition, even if n1 <n3 <n2, if n3 is close to n1 or n2, the state similarly changes depending on whether or not a sufficient voltage is applied between the electrodes 12 and 14.
[0073]
In addition, since the refractive index of the liquid crystal (second medium layer 22) changes according to the voltage applied between the electrodes 12 and 14, the reflection of the light 57 in a specific wavelength band can be achieved by continuously changing the voltage. The rate can be controlled continuously.
[0074]
[Embodiment as a full-color display device]
In the display element according to the present invention, by adjusting the center value of the thickness of the first medium layer 21 and the second medium layer 22 for one period, the reflection wavelength band can be set to the red, green, or blue wavelength region. it can. Therefore, a reflective full-color display device having a wide viewing angle can be realized by providing three display elements having reflection wavelength bands in the red, green, and blue wavelength regions, respectively.
[0075]
FIG. 11 shows an example of the reflection-type full-color display device. Display elements 10R, 10G, and 10B having the reflection wavelength bands in the red, green, and blue wavelength regions according to the present invention are arranged in one direction in the same plane. One pixel 1 is formed side by side. In this example, a black or gray layer 15 is formed on the side opposite to the incident side of external light.
[0076]
In the full-color display device of this example, when any one of the display elements 10R, 10G, and 10B of a certain pixel is in the reflective state, red, green, or blue is displayed in that pixel, and any two are in the reflective state. When displayed, cyan, magenta or yellow is displayed, and when all are reflected, white is displayed.
[0077]
Further, when all of the display elements 10R, 10G, and 10B are in the transmissive state, black is displayed. Even when the display elements 10R, 10G, and 10B are all in a transmissive state, a part of incident light is birefringent due to the above-described substrates 11 and 13, the electrodes 12 and 14, the first medium layer 21, and the second medium layer. As a result, the intensity of the transmitted light with respect to the incident light is significantly reduced, so that black is displayed even if the layer 15 is gray.
[0078]
The area of the display element of each color display color may not be uniform. For example, the area occupied by one pixel of a display element having a low reflected light intensity can be increased to compensate for low perceived luminance.
[0079]
FIG. 12 shows an example of this case, in which one pixel 1 is divided into four, and a display element 10R that reflects red color light in one region is arranged in one region located diagonally to this. A display element 10G that reflects green color light and a display element 10B that reflects blue color light are formed in the remaining two regions, respectively.
[0080]
FIG. 13 shows still another example of the reflection type full-color display device, in which display elements 10B, 10R, and 10G that reflect blue, red, and green light are laminated in this order from the side opposite to the incident side of external light. To do. A black or gray layer 15 is formed on the back surface of the display element 10B. By laminating the display elements in the above order, a clear full-color display can be achieved, but it is not always necessary to stack in this order.
[0081]
In the examples of FIGS. 11, 12, and 13, the contrast can be increased by forming the black or gray layer 15, but the layer 15 is not necessarily formed.
[0082]
【The invention's effect】
As mentioned above, the present inventionProduction methodAccording toA reflective display element having a wide reflection wavelength band and a wide viewing angle can be obtained reliably and easily, and the viewing angle and reflected light intensity can be arbitrarily adjusted.
[Brief description of the drawings]
FIG. 1 is a diagram showing a part of steps of a first example of a manufacturing method according to the present invention.
FIG. 2 is a diagram showing a part of the subsequent steps of the first example of the manufacturing method of the present invention.
FIG. 3 is a diagram showing a part of steps of a second example of the manufacturing method of the present invention.
FIG. 4 is a diagram showing a part of subsequent steps common to the first and second examples of the manufacturing method of the present invention.
FIG. 5 is a diagram showing a further subsequent step common to the first and second examples of the manufacturing method of the present invention.
FIG. 6 is a graph showing the wavelength-reflected light intensity characteristics of the display element of the present invention and a conventional display element.
FIG. 7 is a diagram schematically showing a method of forming a medium layer by screen printing.
FIG. 8 is a diagram schematically showing a method of forming a medium layer by transfer.
FIG. 9 is a diagram showing a part of steps of another example of the manufacturing method of the present invention.
FIG. 10 is a diagram for explaining the operation of the display element of the present invention.
FIG. 11 is a diagram showing an example of a display device according to the present invention.
FIG. 12 is a diagram showing another example of the display device of the present invention.
FIG. 13 is a diagram showing still another example of the display device of the present invention.
FIG. 14 is a diagram showing an example of a conventional manufacturing method and a display element obtained thereby.
[Explanation of symbols]
10, 10R, 10G, 10B Display element
11, 13 substrate
12,14 electrodes
15 Black or gray layer
21, 21a, 21b, 21n First medium layer
22, 22a, 22b, 22m Second medium layer
23 Elution part
25, 25A, 25B Adhesive
27 Irradiation light
29 Pattern section
41 Elution tank
42 Eluent

Claims (5)

On the electrode side of the first substrate on which the electrodes are formed, a first medium layer and a second medium layer are alternately stacked one by one to form a multilayer film,
Next, an adhesive is applied to one or more sides excluding at least one side of the periphery of the multilayer film, and the electrode side of the second substrate on which the electrode is formed is adhered on the multilayer film,
Next, the material forming the second medium layer is eluted from the side of the multilayer film where the adhesive is not applied, and a material whose refractive index is changed by an electric field is injected into the elution part.
Next, a method for manufacturing a reflective display element, wherein a side of the multilayer film where the adhesive is not applied is sealed with an adhesive. On the electrode side of the first substrate on which the electrode is formed, the first medium layer and the second medium layer are alternately stacked one by one to form a multilayer film, and on the electrode side of the second substrate on which the electrode is formed, A multilayer film is formed by alternately laminating the first medium layer and the second medium layer one by one,
Next, an adhesive is applied to one or more sides excluding at least one side of the periphery of the multilayer film on the first substrate and the second substrate, and the first substrate and the second substrate are bonded to each other. Glue,
Next, the material forming the second medium layer is eluted from the side of the multilayer film where the adhesive is not applied, and a material whose refractive index is changed by an electric field is injected into the elution part.
Next, a method for manufacturing a reflective display element, wherein a side of the multilayer film where the adhesive is not applied is sealed with an adhesive. In the manufacturing method of Claim 1 or 2 ,
The first medium layer is formed of a photocurable resin, the second medium layer is initially formed of a thermosetting resin, and the multilayer film is irradiated with light before the thermosetting resin is eluted. A method for producing a reflective display element, characterized in that: In the manufacturing method of Claim 1, 2, or 3 ,
A method for producing a reflective display element, characterized in that liquid crystal is used as the material whose refractive index changes. In the manufacturing method of Claim 4 ,
A method of manufacturing a reflective display element, wherein the liquid crystal is injected into the elution portion from the same direction.

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