JP2009020435A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of maintaining image display even when external force is removed and of achieving energy saving. <P>SOLUTION: The image display device 10 is equipped with display devices 22 which reflect visible light of specific wavelength in such a state where a plurality of display devices are arranged to be planar, and a shape deforming part 30 which elastically deforms the display device 22. Each display device 22 has colloidal particles 23a arranged at regular spacings and filler 23b lying between the colloidal particles 23a and elastically deformed. The shape deforming part 30 is disposed to apply pressing force to the display device 22 and equipped with a shape holding member 31 formed of material reversibly plastically deformed by the external force. The shape holding member 31 is plastically deformed when it is driven by a deforming driving part 32, elastically deform the display element 22 to change reflection wavelength, whereby display content is varied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image display device that displays an image by reflecting visible light of a specific wavelength by a periodic structure made of colloidal particles.

  As this type of image display device, for example, the technique of Patent Document 1 is known. In this device, a colloidal crystal filled with a polymer gel is configured as each pixel, and by applying a voltage to each pixel, the polymer gel absorbs and releases the solvent, and the colloidal crystal undergoes a volume change due to expansion and contraction. Let Thus, the desired display is obtained by changing the interval between the colloidal crystals and reflecting the light having the wavelength determined by Bragg's law in the visible light. However, this image display device has a problem that power consumption is large because deformation of the colloidal crystal cannot be maintained unless voltage is continuously applied.

JP 2007-11112 A

  An object of the present invention is to provide an image display device that can maintain image display even when an external force is removed, and can realize energy saving, in view of the problems of the conventional technology.

The present invention made to solve the above problems
In an image display device having a plurality of arrayed display elements that reflect visible light of a specific wavelength and a shape deformation unit that elastically deforms the display elements,
Each of the display elements has colloidal particles arranged at regular intervals, and a filler that is interposed between the colloidal particles and is elastically deformable. By changing the intervals, each display element has a specific wavelength. Configured to reflect visible light,
The shape deforming portion has a shape holding member that receives an external force and changes the distance between the display elements by a plurality of displacements and plastically deforms the displacement so as to maintain the displacements;
It is characterized by.

In the image display device of the present invention, a plurality of display elements that change image display by reflecting visible light having a specific wavelength are arranged. In the display element, colloidal particles are arranged at regular intervals, and a filler is interposed therebetween. When visible light is applied to the display element, the reflectance increases at a specific reflection wavelength λpeak. That is, the reflection wavelength λpeak is expressed by the equation (1) based on Bragg's law and Snell's law, using the distance d between the crystal planes (111) formed by the colloidal particles as a parameter.
λpeak = 2d (111) (neff ² −sin ² θ) ^0.5 -(1)
λpeak: reflection wavelength θ: incident angle d (111): interval neff: effective refractive index That is, the wavelength included in the visible light incident can be selectively reflected by the difference in the interval d. Here, the effective refractive index neff is determined by the equation (2) by the refractive index of the colloidal particles, the refractive index of the filler, and the ratio thereof.
neff = (1−φ) ns + φ · nsphere− (2)
nsphere: Refractive index of colloidal particles ns: Refractive index of filler φ: Occupancy ratio of colloidal particles per volume

  Thus, the display element can change the reflection wavelength λpeak by changing the interval of the colloidal particles. In the present invention, by arranging a plurality of display elements that selectively reflect visible light of a specific wavelength, and further using a shape holding member that undergoes plastic deformation under external force, by changing the interval between the display elements, Various image displays can be obtained. Since the shape holding member changes the display element by a plurality of displacements and plastically deforms so as to maintain the displacement, the shape holding member maintains the distance between the display elements even when an external force is removed. That is, once the shape holding member is plastically deformed, the display color of the display element can be maintained, and it is not necessary to continuously apply an external force for maintaining the display color, and energy saving can be achieved.

The shape holding member is not particularly limited as long as it is a material that is plastically deformed and maintains its shape when subjected to a predetermined deformation or more by an external force. Room temperature plastic elastomer, thermoplastic polymer, shape memory polymer, surface polymer A soft metal such as coated aluminum (Al) can be used.
Further, as means for applying an external force to the shape holding member, a configuration in which mechanical force is applied to the shape holding member, or a configuration including a deformation drive unit that applies an external force to the shape holding member by an electric signal can be taken. Moreover, these means can take the structure which can be attached or detached with respect to a shape maintenance member, or the structure assembled | attached integrally.

  As a preferred mode of the deformation driving unit, it is arranged corresponding to each of the display elements, a driving force for plastically deforming the shape holding member is applied so as to change the interval of the display elements, and the deformation driving unit is returned to the original position. It is possible to adopt a configuration provided with a drive element for plastic deformation. According to this configuration, it is easy to return the plastic deformation of the shape holding member to the original state, and the change of the image display is simplified.

The colloidal particle is not particularly limited as long as it can transmit light reflected by Bragg, and has a substantially spherical shape. For example, silicon dioxide (SiO ₂ ), borosilicate glass, calcium aluminate, lithium niobate, calcite , Titanium oxide (TiO ₂ ), strontium titanate, aluminum oxide, lithium fluoride, magnesium fluoride, yttrium oxide, calcium fluoride, barium fluoride, zinc selenide, thallium bromoiodide, diamond and the like can be used. Also, ferroelectrics such as lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT), polyethylene, polyethylene terephthalic acid, vinyl chloride, acrylic, vinyl oxide, polystyrene, polypropylene, polymethyl methacrylate, etc. Silicon and germanium can be used. Also, a mixture of two or more of polystyrene, polymethyl methacrylate, SiO ₂ and TiO ₂ , a core-shell structure in which the core is covered with one or more of these one as a core, and the like can be used. Further, the regularity in the arrangement of the colloidal particles is not particularly limited, but examples thereof include face-centered cubes, body-centered cubes, simple cubes, and the like, and particularly, face-centered cubic structures, that is, hexagonal close-packed packed structures. Can do. Further, although the interval between the colloidal particles depends on the expansion coefficient due to the filler, it is necessary that the reflection wavelength such as Bragg's law is in the infrared region when expanded.

Hereinafter, the best mode for carrying out the invention will be described according to embodiments.
(1) Schematic Configuration of Image Display Device 10 FIG. 1 is a plan view showing an image display device 10 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line 2-2 of FIG. In FIG. 2, an image display device 10 is arranged between a support substrate 11, a display panel 12 arranged in parallel to the support substrate 11 with a predetermined gap, and between the support substrate 11 and the display panel 12, and displays a number of displays. The display mechanism 20 formed from the elements 22, the shape deforming section 30 for applying stress for deforming the display elements 22 of the display mechanism 20, and the control device 40 that outputs a drive signal to the shape deforming section 30 (FIG. 1). ) And a frame 50 arranged to surround the side surface of the display mechanism 20. In the configuration of the image display device 10, the control device 40 outputs a drive signal to the shape deforming unit 30 to change the shape of each display element 22 of the display mechanism 20 and set the reflection wavelength of the display element 22. Various displays can be performed. Hereinafter, the configuration of each unit of the image display apparatus 10 will be described.

(2) Configuration of Each Part of Image Display Device 10 The support substrate 11 is a member for supporting the display mechanism 20, and is formed from a printed circuit board or the like. The display panel 12 includes a transparent substrate 12a formed of a glass plate or a transparent resin that can transmit visible light, and a masking 12b formed on the outer surface of the transparent substrate 12a. As shown in FIG. 1, the masking 12b is formed with square windows 12c arranged two-dimensionally. The windows 12c are 5 mm × 5 mm per one, and are arranged in 8 × 8.

FIG. 3 is an explanatory diagram in which a part of the display mechanism 20 is enlarged. The display mechanism 20 includes a display element 22 in which a plurality of cells are arranged in a two-dimensional matrix, and a pressure plate 25 attached to the lower surface of the display element 22. The display element 22 includes a colloidal particle 23a and a filler 23b filled between the colloidal particles 23a. The colloidal particles 23a are arranged at positions similar to the lattice positions of the close-packed structure, but the filler 23b is present between the adjacent colloidal particles 23a, and the colloidal particles 23a are not in contact with each other. For example, SiO ₂ particles having a particle size of 80 nm are used as the colloid particles 23a. The filler 23b includes a first resin material [polyethylene glycol # 600 diacrylate (product name: Shin-Nakamura Chemical Co., Ltd .; NK ester A-600)] and a second resin material [methoxy polyethylene glycol # 400 acrylate (product). Name: Shin-Nakamura Chemical Co., Ltd .; NK ester AM-90G)], and the ratio is 1: 4 to 1:19. Further, the colloidal particles 23a are prepared in a blending ratio of 6% by weight with respect to 15% by weight of the filler 23b. Under such conditions, the colloidal crystal is not deformed and the distance d (111) in the crystal plane (111) of the colloidal particles is arranged at 230 nm, and the peak value of the reflected wavelength is displayed in red as shown in FIG. Can be displayed in red. In the above, an example of a colloidal crystal has been shown. However, a colloid that reflects infrared light and transmits visible light without being deformed by appropriately selecting the material and particle size of the colloidal particles and the material of the filler. Crystals may be formed. Such a colloidal crystal becomes transparent when not deformed, and can display a pressure plate disposed on the lower surface of the colloidal crystal.
The pressure plate 25 is a transparent resin plate disposed in close contact with and integrated with the lower surface of the display element 22, and receives the stress from the shape deforming portion 30 (FIG. 2) to cause the display element 22 to have a uniform force. Compress. Further, on the lower surface of the pressure plate 25, a colored portion 26 to which black is applied is integrally formed with the pressure plate 25.

FIG. 5 is an enlarged sectional view showing the shape deforming portion 30. The shape deforming unit 30 includes a shape holding member 31, a deformation driving unit 32 disposed so as to sandwich the shape holding member 31, and wiring for sending an electrical signal from the control device 40 (FIG. 1) to the deformation driving unit 32 ( (Not shown). The shape holding member 31 may be a room temperature plastic elastomer that holds the shape of the display element 22 by plastic deformation (for example, an elastomer described in Japanese Patent Application Laid-Open No. 2004-078873). FIG. 6 is an explanatory view showing the vicinity of the deformation driving unit 32. The deformation drive unit 32 includes a first drive member 33 supported by the support substrate 11 and a second drive member 34 that sandwiches the shape holding member 31 together with the first drive member 33. The drive element 32b which has the press part 32a which became convex shape in the location of the corresponding pressurizing plate 25 is comprised. The first drive member 33 is configured by sandwiching a dielectric elastomer 33b such as acrylic rubber or silicon rubber between the two electrodes 33a and 33a. Due to the configuration of the first drive member 33, when a voltage is applied between the electrodes 33a and 33a, a positive charge is stored in one electrode, and a negative charge is stored in the opposite electrode. Attracting force is generated, and the dielectric elastomer 33b is crushed by this force to expand in the surface direction. Thereby, the uneven shape of the deformation driving unit 32 is increased, the shape holding member 31 is deformed, and the display element 22 is elastically deformed via the pressure plate 25. The second drive member 34 is configured in the same manner as the first drive member 33, that is, the dielectric elastomer 34b is sandwiched between the electrodes 34a and 34a, and moves away from the pressure plate 25 by application to the electrodes 34a and 34a. Then, the shape retaining member 31 is deformed so as to remove the elastic compressive force of the display element 22.
The control device 40 controls each display element 22 independently by sending a signal to a grid-like wiring corresponding to each drive element 32 b of the deformation drive unit 32.

(3) Display Operation of Image Display Device 10 FIG. 7 is an explanatory diagram for explaining the operation of the image display device 10. In the image display device 10, the control device 40 changes the display by sending a signal to the shape deforming unit 30 to maintain and change the shape of each display element 22. That is, when the control device 40 (FIG. 1) outputs a 0V level signal (a signal corresponding to the first displacement) to the drive element 32b of the shape deforming unit 30, the display element 22 is deformed by the drive element 32b. Not performed (state shown in FIG. 7A). The display element 22 in this state is a transparent body that allows visible light to pass. Since the peak value, which is a condition that satisfies Bragg's law, has an interval that does not appear in the visible light region, visible light passes through the pressure plate 25. It is transmitted and further absorbed by the colored portion 26, and the black color of the colored portion 26 is displayed as it is.

  When the control device 40 outputs another level signal (a signal corresponding to the second displacement) to the drive element 32 b of the shape deforming unit 30, the dielectric elastomer 33 b of the first drive member 33 of the deformation drive unit 32. The shape holding member 31 is plastically deformed following the convex shape of the dielectric elastomer 33b. The shape holding member 31 compresses the display element 22 via the pressure plate 25 and elastically deforms it with the displacement L1 (state shown in FIG. 7B). As a result, the display element 22 changes the interval of the colloidal particles 23a, changes the reflection wavelength corresponding to the interval, and reflects the visible light having the reflection wavelength determined by the interval to display the corresponding color. Then, as shown in FIG. 7C, the control device 40 outputs a signal of 0 V level to the drive element 32b of the shape deforming unit 30, that is, excluding the voltage applied to the drive element 32b, the deformed drive unit 32. Even if one of them returns to its original state, the shape retaining member 31 maintains its displacement L1, so that the display element 22 remains elastically deformed. Therefore, the display on the display element 22 does not change.

  In such display control, the display of the display element 22 can be variously changed by changing the level of the signal output from the control device 40. That is, as shown in FIGS. 7B and 7C, when the displacement L1 of the display element 22 is small and the interval is large, the peak value of the reflected wavelength appears in red, and as shown in FIG. 8A. In addition, when the displacement L2 of the display element 22 is increased, a peak value appears in the green reflection wavelength, and when the displacement L3 of the display element 22 is further increased as shown in FIG. A peak value appears in the reflection wavelength. For example, when the thickness of the display element 22 is 0.01 mm, the display element 22 becomes transparent and displays the black color of the colored portion 26, and when the thickness is 0.005 mm, 0.007 mm, and 0.009 mm, Blue, green and red are displayed respectively, and when it is 0.003 mm, it becomes transparent again. In addition, white display by the display element 22 can be performed by creating a reflection wavelength of three primary colors by combining three adjacent display elements.

(4) Manufacturing Method of Image Display Device 10 Next, a manufacturing method of the display mechanism 20 will be described. The display mechanism 20 can use a well-known method, for example, can be manufactured by the following steps. First, a solvent for forming the filler is prepared. The solvent is obtained by mixing the first resin material and the second resin material to prepare a 15% by weight aqueous solution. The mixing ratio of the first resin material to the second resin material is 1: 9. The first resin material is added to promote ultraviolet curing of the second resin material by radical polymerization. Subsequently, SiO ₂ particles having a particle size of 80 nm as a solute are added to the solvent in an amount of 6% by weight based on the final colloidal dispersion. Next, the solution is subjected to ultrasonic stirring, and an ultraviolet curing initiator (trade name: manufactured by Ciba Specialty Chemicals Co., Ltd .; Darocur 1173) is added at 2% by weight with respect to the resin. Thereby, a colloidal dispersion is obtained.

  Next, 0.01 to 1 mm of the colloidal dispersion liquid is applied onto the transparent substrate 12a, and a mask excluding the region where the display element 22 is formed is applied, and ultraviolet rays are irradiated toward the mask. When the film is cured by the ultraviolet rays, the display element 22 in which the colloidal particles are held by the filler is formed. At this time, the colloidal particles are arranged autonomously and regularly. Then, the display element 22 is formed by removing the film which is not irradiated with the ultraviolet rays while being masked by the solvent. Further, in order to create the pressure plate 25 and the colored portion 26, as in the case where the display element 22 is formed, the films are stacked, and a film is formed only in a predetermined region by applying a mask. Thereby, the display mechanism 20 can be formed.

(5) Functions and effects of the image display device 10 (5) -1 Since the display element 22 of the image display device 10 uses colloidal particles, in principle, visible light can be reflected with 100% efficiency. Therefore, a bright image display can be obtained.
(5) -2 The shape deforming unit 30 can cause the display element 22 to display an arbitrary color by changing the reflection wavelength by arbitrarily setting a displacement when the display element 22 is compressed.
(5) -3 The display element 22 displays the black color that could not be displayed by the conventional technique by reflecting the visible light that has been displaced so as to transmit visible light and reflected by the colored portion 26. Can do.
(5) -4 The image display apparatus 10 can display white by creating a reflection wavelength of three primary colors by combining three adjacent display elements 22 into one set.
(5) -5 The display panel 12 is provided with a masking 12b corresponding to the display element 22, and the masking 12b hides the part extended in the surface direction of the display element 22, so that the display element in the hidden part is hidden. 22 color mixing and bleeding can be reduced, and a clear display can be obtained.
(5) -6 The pressure plate 25 transmits the pressing force from the shape deforming portion 30 to the display element 22 uniformly and presses the display element 22 so that the distance between the display elements 22 is uniform. A change in wavelength can be reduced and a clear image can be obtained.
(5) -7 Since the shape holding member 31 of the shape deforming portion 30 is plastically deformed by receiving an external force, the distance between the display elements 22 is maintained even when the external force is removed. Therefore, once the shape holding member 31 is plastically deformed, the display color of the display element can be maintained, and it is not necessary to continue to apply an external force for maintaining the display color, thereby saving energy.

(6) The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(6) -1 FIG. 9 is a cross-sectional view showing an image display device 10B according to another embodiment. The present embodiment is characterized in the configuration of the deformation driving unit 32B that reversibly plastically deforms the shape holding member 31B by a force and heat in one direction. That is, the shape deforming portion 30B includes a shape holding member 31B made of a shape memory polymer that stores a predetermined shape by temperature, a deformation driving portion 32B having a convex pressing portion 32Ba that contacts the shape holding member 31B, and a shape. And a heater (not shown) for heating the pressing portion 32Ba of the holding member 31B. The deformation driving unit 32B is deformed by a voltage by a dielectric elastomer. With the configuration of the shape deforming portion 30B according to the present embodiment, the shape holding member 31B is plastically deformed via the coloring portion 26B and the pressure plate 25B by applying a voltage to the deformation driving portion 32B to deform the pressing portion 32Ba, On the other hand, the pressing portion 32Ba is heated with a heater to return to the original shape. Thereby, the color display of each display element 22B can be changed.

(6) -2 As a mode of the deformation driving unit, various configurations can be adopted as long as the shape holding member 31 generates a driving force capable of plastic deformation, and examples thereof include magnetic force, compressed air, liquid crystal elastomer, and dielectric. Various configurations such as an elastomer, a piezo element, an ionic dielectric polymer actuator, a conductive actuator, and a polymer gel may be used.

1 is a plan view showing an image display device 10 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. It is explanatory drawing which expanded a part of display mechanism. It is explanatory drawing explaining the relationship between the wavelength of the display mechanism 20, and a reflectance. It is sectional drawing which expands and shows the shape deformation | transformation part. FIG. 6 is an explanatory diagram showing the vicinity of a deformation driving unit 32. FIG. 6 is an explanatory diagram for explaining the operation of the image display apparatus 10. FIG. 6 is an explanatory diagram for explaining the operation of the image display apparatus 10. It is sectional drawing using the shape deformation | transformation part 30B concerning another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image display apparatus 10B ... Image display apparatus 11 ... Support substrate 12 ... Display panel 12a ... Transparent substrate 12b ... Masking 12c ... Window 20 ... Display mechanism 22 ... Display element 22B ... Display element 23a ... Colloidal particle 23b ... Filler 25 ... Pressure plate 25B ... Pressure plate 26 ... Colored portion 26B ... Colored portion 30 ... Shape deforming portion 30B ... Shape deforming portion 31 ... Shape retaining member 31B ... Shape retaining member 32 ... Deformation driving portion 32B ... Deformation driving portion 32a ... Pressing portion 32b ... Drive element 32Ba ... Pressing portion 33 ... First drive member 33a ... Electrode 33b ... Dielectric elastomer 34 ... Second drive member 34a ... Electrode 34b ... Dielectric elastomer 40 ... Control device 50 ... Frame

Claims (4)

In an image display device having a plurality of arrayed display elements (22) that reflect visible light of a specific wavelength and a shape deformation section (30) that elastically deforms the display elements (22),
Each of the display elements (22) includes colloidal particles (23a) arranged at regular intervals, and a filler (23b) interposed between the colloidal particles (23a) and elastically deformable. By changing the above interval, it is configured to reflect visible light of a specific wavelength,
The shape deforming part (30) has a shape holding member (31) that receives an external force and changes the interval of the display element (22) by a plurality of displacements and plastically deforms the displacements so as to maintain the displacements. ,
An image display device characterized by the above. The image display device according to claim 1,
The shape deforming unit (30) is an image display device including a deformation driving unit (32) that applies the external force to the shape holding member (31). The image display device according to claim 2,
The deformation drive unit (32) includes a drive element (32b) arranged corresponding to the display element (22), and the drive element (32b) is applied to the shape holding member (31) by an electric signal. An image display device configured to reversibly plastically deform. The image display device according to any one of claims 1 to 3,
An image display device comprising a pressure plate (25) interposed between the display element (22) and the drive element (32b) and uniformly pressing the interval between the display elements (22).

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