JP2013088558A - Optical filter, display cell and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter that uses metal microparticles and can be adjusted in absorption, transmission, and diffuse wavelength, and a display cell using the optical filter, and a display device with the display cell.SOLUTION: An optical filter 1 includes a filter part 4 where plural metal microparticles 42 having two or more shape anisotropic axes are aligned in the same direction on the surface of or inside a transparent dielectric 41 transmitting light in visible region, and direction adjustment means 3 for relatively changing the polarization direction of transmission light that transmits the filter part and the directions of shape anisotropic axes of the metal microparticles 42.

Description

  The present invention relates to an optical filter, a display cell, and a display device.

  It is known that a metal fine particle has a phenomenon of absorbing a specific wavelength in incident light by resonance (surface plasmon resonance) of incident light and electron vibration in the metal fine particle. Since ancient times, this phenomenon has been used to mix specific metal fine particles into glass and have been used as stained glass. Recently, application to optical filters and paints has also been attempted.

  The surface plasmon resonance spectrum of the metal fine particle depends on the type of metal constituting the metal fine particle, the size and shape of the particle, and the surrounding refractive index. As an optical filter using this characteristic, Japanese Patent No. 4348720 discloses a film form in which nanorod-shaped metal fine particles are formed, and the metal nanorods are mixed and dispersed in a resin, from visible light to near infrared light. An optical filter that selectively absorbs light having a wavelength between visible light and near infrared light by adjusting the lengths of the short axis and long axis of the nanorods is disclosed.

  Japanese Patent Application Laid-Open No. 2005-126310 discloses an optical filter in which a noble metal is formed in a nanorod shape, exhibits properties derived from the short axis and long axis of the nanorod, and can impart near-infrared shielding and design properties to glass or the like. Is disclosed.

  For example, in a liquid crystal display panel capable of color display, each pixel transmits red light (light in the R wavelength range), green light (light in the G wavelength range), and blue light (light in the B wavelength range). Is configured to do. The above-described optical filter is often used as a member that transmits each light. That is, the color filter described in Japanese Patent No. 4348720 or the color filter described in Japanese Patent Application Laid-Open No. 2005-126310 is formed with a color filter having a light absorption spectrum that transmits each light of RGB, and the color filter of each color is appropriately set. The color of the pixel is determined by spreading over the pixel and adjusting the light incident on the color filter.

Japanese Patent No. 4348720 JP 2005-126310 A

  However, the color filter disclosed in Japanese Patent No. 4348720 is a color filter having an absorption wavelength due to the long axis of rod-shaped fine particles. In Japanese Patent Laid-Open No. 2005-126310, absorption due to the short axis and long axis of the nanorod. It is a color filter having a wavelength, and the absorption, transmission and scattering wavelengths of the color filter once manufactured cannot be adjusted or changed, and multiple types of color filters having different absorption, transmission and scattering wavelengths are required in advance. .

  In addition, when each of the RGB color filters is used, the color filter displays any one of the RGB colors, so that the light of other colors is blocked, resulting in poor light use efficiency.

  Therefore, an object of the present invention is to provide an optical filter that uses metal fine particles and can adjust the wavelength of absorption, transmission, or diffusion. It is another object of the present invention to provide a display cell using such an optical filter and a display device including the display cell.

  In order to achieve the above object, in the present invention, a plurality of fine metal particles having two or more anisotropic axes are arranged on the surface or inside of a transparent dielectric that transmits light in the visible range. Provided is an optical filter comprising: a filter unit; and a direction adjusting unit that relatively changes the polarization direction of transmitted light that passes through the filter unit and the direction of the anisotropic axis of the metal fine particles. To do.

  According to this configuration, the surface plasmon resonance that occurs in any direction of the metal fine particles is utilized by an easy method of relatively changing the polarization direction of transmitted light and the direction of shape anisotropy of the metal fine particles. Can be adjusted. Alternatively, it is possible to select whether light having a surface plasmon resonance wavelength is absorbed or scattered. In addition to the two colors corresponding to the major and minor axes, this optical filter shifts the surface plasmon resonance wavelength when a polarization direction intermediate between the major and minor axes is incident. It is possible to make the color to make into 2-4 colors.

  As a result, the number of optical filters can be reduced, the aperture ratio can be increased, and the light utilization efficiency can be reduced compared to the conventional color filters that extract light of each RGB wavelength for full color display. Can be increased. Further, even when three optical filters are used as usual, the range of color expression can be widened if there are four color options that can be displayed on one sheet.

  In the above configuration, the direction adjusting means may rotate the polarization direction of the transmitted light in a direction parallel or perpendicular to the shape anisotropic axis of the metal fine particles. According to this configuration, the surface plasmon resonance wavelength of the metal fine particles can be adjusted by an existing simple method such as a liquid crystal element.

  In the above configuration, the transparent dielectric rotatably supports the plurality of metal fine particles, and the direction adjusting means aligns the plurality of metal fine particles on or inside the transparent dielectric. It may be rotated. According to this configuration, since no means for rotating the polarization direction is required, it is possible to suppress a decrease in light transmittance. Thereby, energy consumption can be reduced.

  In the above configuration, incident light whose polarization direction is not parallel to or perpendicular to any of the two anisotropic axes of the metal fine particles may be incident on the filter unit. According to this configuration, since it is possible to select whether to absorb or scatter light having a surface plasmon resonance wavelength, more colors can be expressed with one optical filter. Can be widened.

  The said structure WHEREIN: You may provide the 2nd direction adjustment means to change relatively the polarization direction of the incident light which injects into the said filter part, and the direction of the shape anisotropic axis | shaft of the said metal microparticle. According to this configuration, since it is possible to select whether to absorb or scatter light having a surface plasmon resonance wavelength with high light utilization efficiency, more colors can be expressed with one optical filter. Therefore, the range of color expression can be widened.

  In the above configuration, the transparent dielectric material rotatably supports the plurality of metal fine particles, and either one of the direction adjusting unit or the second direction adjusting unit converts the plurality of metal fine particles into the transparent dielectric. It may be rotated on the body or inside with the orientations aligned. According to this configuration, since no means for rotating the polarization direction is required, it is possible to suppress a decrease in light transmittance. Thereby, energy consumption can be reduced.

  In the above-described configuration, the plurality of metal fine particles have three shape anisotropic axes, and the direction adjusting unit moves the plurality of metal fine particles on or inside the transparent dielectric also in a direction perpendicular to the surface of the transparent dielectric. It may be rotated. According to this configuration, since the metal fine particles have three surface plasmon resonance wavelengths, an optical filter capable of full color display with one optical filter is obtained. Therefore, since the number of optical filters can be reduced, light utilization efficiency can be increased.

  In the above configuration, the plurality of metal fine particles are arranged in the light irradiation direction, and the arrangement interval is five times or more the length of the metal fine particles in the irradiation direction. According to this configuration, the peak shift due to the interaction of the metal fine particles can be prevented, so that the shape of the metal fine particles can be designed considering only the absorption peak of the metal fine particles alone.

  The present invention provides a display cell comprising any one of the optical filters described above, a light source that emits light in the visible range, and a light intensity adjusting unit that adjusts the intensity of light incident on the optical filter.

  According to this configuration, a transmissive display device that can express two colors and their mixed colors with one optical filter is obtained. Therefore, the number of filters necessary for full color display can be reduced to two or less, so that the aperture ratio is high and the light utilization efficiency can be increased.

  Furthermore, in addition to the two colors corresponding to the major axis and the minor axis, when a polarization direction intermediate between the major axis and the minor axis is incident, the surface plasmon resonance wavelength shifts, so that a full color is displayed using three resonance wavelengths. It is also possible. Further, when the metal fine particles are rotated three-dimensionally, one surface of the optical filter has three surface plasmon resonance wavelengths, so that a full color display can be performed with one optical filter. Therefore, since the number of optical filters can be reduced, light utilization efficiency can be increased.

  The said structure WHEREIN: Two said optical filters may be provided, and both of said two optical filters may be provided with the filter part containing the wavelength from which the surface plasmon resonance wavelength of the said metal microparticle becomes a complementary color of red.

  According to this configuration, by expressing red, which has low human eye sensitivity, with two optical filters, the aperture ratio for red is increased, so it is not necessary to increase the incident light intensity and reduce energy consumption. Is possible.

  The present invention provides a display device comprising a plurality of any of the display cells described above, wherein the plurality of display cells are two-dimensionally arranged.

  In the above configuration, the display device includes a data input unit to which image data is input, a direction adjustment unit drive circuit that controls the direction adjustment unit, a light intensity adjustment unit drive circuit that controls the light intensity adjustment unit, and The direction adjustment is performed so as to determine a color and intensity to be displayed in each display cell based on image data, and to drive the direction adjustment unit and the light intensity adjustment unit of each display cell based on the color and intensity. A calculation unit for giving an instruction to the unit driving circuit and the light intensity adjusting unit driving circuit may be provided.

  An object of the present invention is to provide an optical filter that uses metal fine particles and that can adjust the absorption, transmission, and diffusion wavelengths. In addition, a display cell using such an optical filter and a display device including the display cell can be provided.

It is a perspective view which shows an example of the optical filter concerning this invention. It is a figure which shows the relationship between the peak wavelength of an absorption spectrum, and the polarization direction of the incident light with respect to a silver metal microparticle. It is a figure which shows the relationship between the peak wavelength of an absorption spectrum, and the polarization direction of the incident light with respect to a silver metal microparticle. It is a figure which shows the relationship between the peak wavelength of an absorption spectrum, and the polarization direction of the incident light with respect to a silver metal microparticle. It is a figure which shows the polarization dependence of the electric field immediately after the metal microparticles arranged on the plane. It is a figure which shows the relationship between a transmission spectrum and the number of layers of silver metal fine particles. It is a figure which shows the relationship between a transmission spectrum and the space | interval of the layer of silver metal fine particles. It is a figure which shows the relationship between a transmission spectrum and the polarization direction of the transmitted light with respect to silver metal microparticles. It is a perspective view which shows the other example of the optical filter concerning this invention. It is the schematic which shows an example of the display apparatus concerning this invention.

  Embodiments of the present invention will be described below with reference to the drawings. First, the structure and manufacturing method of the optical filter according to the present invention will be described.

(First embodiment)
FIG. 1 is a schematic perspective view of an example of an optical filter according to the present invention. In the drawings described below, unless otherwise specified, as shown in FIG. 1 and the like, the left-right direction of the paper surface is the X direction, the depth direction of the paper surface is the Y direction, and the vertical direction of the paper surface is the Z direction.

  As shown in FIG. 1, the first optical filter 1 is a filter that transmits light in a specific wavelength range among incident light (absorbs light in a specific wavelength range). The first optical filter 1 includes a polarizing plate 2, a direction adjusting unit 3 (direction adjusting means), and a filter unit 4. From the light incident side (light source side), the filter unit 4, the direction adjusting unit 3, and the polarizing plate. Arranged in the order of 2.

  The filter unit 4 includes a transparent dielectric 41 and metal fine particles 42. The transparent dielectric 41 is a substrate for dispersing the metal fine particles 42, and is a substrate that is transparent to certain light (here, light in the visible light region). As the transparent dielectric 41, an organic film such as a glass substrate or a polyethylene terephthalate (PET) film can be used.

  The metal fine particle 42 is a metal that causes surface plasmon resonance, and for example, gold, silver, copper, aluminum, platinum, palladium, and the like are often used. As shown in FIG. 1, the metal fine particles 42 have an elliptic sphere shape whose length in the Y direction is longer than the length in the X direction. The lengths in the X direction, the Y direction, and the Z direction are about several nm to 100 nm. As will be described in detail later, the wavelength of the light transmitted through the filter unit 4 is absorbed (scattered) depending on the length of the metal fine particles 42 and the relative ratio (hereinafter referred to as aspect ratio) and the polarization direction of the incident light. Is determined. The metal fine particles 42 shown in FIG. 1 have rounded corners such as an elliptical sphere shape. However, the present invention is not limited to this. For example, the corners are not rounded like a rectangular parallelepiped, a cylinder, or an elliptical column. It may be a thing. The metal fine particles should just be formed so that length may differ in at least two different directions.

  As shown in FIG. 1, the metal fine particles 42 are dispersed on the surface of the transparent dielectric 41. The metal fine particles 42 all have the same shape and size, and are arranged in equal intervals with the same orientation. The metal fine particles 42 may be dispersed inside the transparent dielectric 41, and may not be equally spaced as long as the orientation directions are the same. Examples of the method for arranging the metal fine particles 42 on the transparent dielectric material 41 include a flow method, a Langmuir Blodget method, a bubble inflation method, an electric field arrangement, and a roll-to-roll method.

  In the filter unit 4 shown in FIG. 1, the metal fine particles 42 are arranged two-dimensionally (X direction and Y direction), but may be arranged three-dimensionally. Further, the amount of the metal fine particles 42 (amount per unit area or unit volume) is preferably large. However, if the metal fine particles 42 come into contact with each other or are too close, the optical characteristics may be different from those of the single particles. is there. It is known that the distance between the metal fine particles 42 is preferably open to some extent in order to suppress changes in optical characteristics. Details will be described later.

  The filter part 4 is produced as follows. A metal film is formed on the surface of a solid transparent dielectric material 41 such as glass, plastic, polymer, etc., and then the portions that become the metal fine particles 42 are masked, and the surrounding portions are removed by a photolithography process or the like. Moreover, when using a photocurable resin as the transparent dielectric 41, after aligning the metal microparticles 42 in a desired direction, the photocurable resin may be cured and the metal microparticles 42 may be fixed. Note that the creation method is not limited to this.

  The direction adjusting unit 3 relatively changes the polarization direction of transmitted light. The direction adjusting unit 3 is an optical element including a liquid crystal, and the liquid crystal is filled between a pair of flat plate electrode substrates arranged in parallel at a predetermined interval. The direction adjusting unit 3 is disposed between the polarizing plate 2 and the filter unit 4. The direction adjusting unit 3 can rotate the incident linearly polarized light when an electric signal for driving is sent from the outside (a voltage is applied to the liquid crystal). The electrode sandwiching the liquid crystal of the direction adjusting unit 3 is preferably transparent if possible, and examples thereof include a transparent electrode using indium tin oxide (ITO) or indium zinc oxide (IZO).

  Moreover, the direction adjustment part 3 is not limited to the thing using a liquid crystal, For example, the thing using a Faraday element and a 1/2 wavelength plate may be used. A Faraday element is an element that adjusts the polarization direction of light that is transmitted by a magnetic field. Like a liquid crystal, an incident electric polarization signal can be input to an electrode to rotate incident linearly polarized light. Further, if the half-wave plate is used, the user can rotate the incident linearly polarized light by manually rotating or automatically rotating by an external signal. In addition, the structure which rotates a polarizing plate as the direction adjustment part 3 may be sufficient. In this case, the direction adjustment unit 3 may also serve as the polarizing plate 2.

  When liquid crystal is used as the direction adjustment unit 3, the transparent dielectric 41 of the filter unit 4 can also be used as one electrode substrate of the direction adjustment unit 3. In the case of this configuration, for example, it is manufactured by the following method. Metal fine particles 42 are dispersed on one surface of the glass, which is the transparent dielectric 41, and an ITO film is formed on the other surface as a transparent electrode by high-frequency sputtering, and then an electrode pattern is formed by photolithography. Thereafter, after an alignment film is applied and rubbed, the other electrode substrate is placed in parallel with the transparent dielectric 41, and liquid crystal is filled between the other electrode substrate and the transparent dielectric 41 and sealed. By the above method, it is possible to produce the direction adjustment part 3 and the filter part 4 integrally.

  The polarizing plate 2 extracts only specific linearly polarized light from the transmitted light, and has the same configuration as the well-known polarizing plate. The transmitted light passes through the polarizing plate 2 so that light having a specific polarization direction is extracted. In the first optical filter 1 shown in FIG. 1, the polarizing plate 2 is arranged so as to extract light whose polarization direction is the X direction (X polarization).

  Here, a description will be given of a mechanism for absorbing (scattering) a specific wavelength by the filter unit 4 based on a specific simulation result. The filter unit 4 absorbs (scatters) a specific wavelength (which may be referred to as a surface plasmon resonance wavelength or simply a resonance wavelength) using surface plasmon resonance that occurs when light enters the metal fine particle 42.

  In order to describe the surface plasmon resonance wavelength of the filter unit 4, first, the wavelength absorbed by the surface plasmon resonance when incident light is incident on metal fine particles existing in the air will be described with reference to the drawings. 2A to 2C are diagrams showing a near-field component of a scattering cross section when light having a predetermined polarization direction is incident on silver fine particles as metal fine particles. The results shown in FIGS. 2A to 2C are obtained by performing a simulation in which light is incident on silver fine particles having different shape models.

  The relationship between the shape model of the silver fine particles used in the simulations of FIGS. 2A to 2C and the incident light is as follows. FIG. 2A shows the polarization direction of light traveling in the Z direction and the Y direction when silver metal particles having a size in the X direction of 5 nm, a size in the Y direction of 20 nm, and a size in the Z direction of 100 nm are present in the air. The result is the direction. FIG. 2B shows the polarization direction of light traveling in the Z direction and the Y direction when silver metal particles having a size in the X direction of 20 nm, a size in the Y direction of 100 nm, and a size in the Z direction of 5 nm are present in the air. It is a result when it is set as a direction. FIG. 2C illustrates the polarization direction of light traveling in the Z direction and the Y direction when silver metal particles having a size in the X direction of 5 nm, a size in the Y direction of 100 nm, and a size in the Z direction of 20 nm are present in the air. It is a result when it is set as a direction.

  That is, FIGS. 2A to 2C show results when the silver fine particles having the same shape (aspect ratio) and size and the polarization direction of the incident light are relatively rotated. It is calculated that incident light is Rayleigh scattered by silver fine particles. The near-field component of the scattering cross section corresponds to the generation of near-field light by the light irradiated to the metal fine particles (silver fine particles), that is, the intensity of surface plasmon resonance. When viewed from a far field, the near-field light is absorbed, and therefore, light excluding this wavelength, that is, light of a complementary color of the wavelength of the near-field light by the surface plasmon resonance (surface plasmon resonance wavelength) can be seen. Therefore, FIGS. 2A to 2C can be regarded as absorption spectra with respect to incident light.

  That is, FIGS. 2A to 2C show changes in the absorption wavelength when the incident direction and the polarization direction of incident light with respect to silver fine particles are changed. In the configuration of FIG. 2A, it can be seen that when X-polarized light is incident, a wavelength near 330 nm is absorbed, and when Y-polarized light is incident, a wavelength near 430 nm is absorbed. Similarly, in the configuration of FIG. 2B, it is understood that when X-polarized light is incident, a wavelength around 430 nm is absorbed, and when Y-polarized light is incident, a wavelength near 940 nm is absorbed. Further, in the configuration of FIG. 2C, it can be seen that when X-polarized light is incident, a wavelength around 330 nm is absorbed, and when Y-polarized light is incident, a wavelength near 940 nm is absorbed.

  From the above, the wavelength of absorbed light (the wavelength of transmitted light) can be determined by adjusting the relative angle between the polarization direction of incident light and the anisotropic axis of the metal fine particles. For example, in the configuration of FIG. 2C, it is assumed that light having both polarization components of the X polarization component and the Y polarization component is incident because the polarization direction is random, circular polarization, 45 degree polarization, or the like. . At this time, the X-polarized component of the incident light absorbs a wavelength around 330 nm. Further, the Y-polarized component of the incident light absorbs a wavelength around 940 nm.

  Next, the resonance spectrum of the two-dimensionally arranged silver metal fine particles will be described. FIG. 3 shows the results of FDTD simulation, and the model is as follows. Elliptical columnar silver metal fine particles having a size in the X direction of 30 nm, a size in the Y direction of 60 nm, and a size in the Z direction of 10 nm were two-dimensionally arranged in the XY plane with a period of 100 nm. Incident light is a plane wave propagating in the Z direction, and its polarization direction is inclined 45 degrees with respect to the X axis. And FIG. 3 is a figure which shows the intensity | strength of a X component, a Y component, and a 45 degree component among the electric fields immediately after the area | region which arranged the metal microparticles two-dimensionally.

  The electric field strength is an electric field strength enhanced mainly by surface plasmon resonance excited by metal fine particles (silver fine particles). Most of the electric field strength appears as near-field light existing in the vicinity of the metal fine particles, and part of it propagates to the far field as scattered light. When viewed from a far field, the near-field light is absorbed, and therefore, light having a wavelength other than the wavelength of the near-field light, that is, a complementary color of the surface plasmon resonance wavelength can be seen. In the far field, complementary color light having a surface plasmon resonance wavelength is observed. Therefore, FIG. 3 shows a case where light whose polarization directions are the X direction, the Y direction, and the 45 degree direction is extracted from the light transmitted through the metal fine particles. It can be understood as an absorption spectrum for each component. In the following description, it is assumed that a polarizing plate is arranged behind the light traveling direction of the two-dimensionally arranged metal fine particles, and the polarizing plate is moved to extract light in the X, Y, and 45 degrees directions.

  Based on the above, FIG. 3 will be described. In FIG. 3, when the polarization direction of the transmitted light taken out by the polarizing plate is 0 degree (X-polarized light), it has an absorption peak only at a wavelength around 460 nm, that is, transmitted through a region in which metal fine particles are two-dimensionally arranged. The X-polarized component of the light thus absorbed has a wavelength around 460 nm absorbed in the far field. On the other hand, when the polarization direction of the transmitted light taken out by the polarizing plate is 90 degrees (Y-polarized light), it has a peak only at a wavelength around 650 nm, that is, the light transmitted through the region in which the metal fine particles are two-dimensionally arranged. Among them, the Y-polarized component absorbs a wavelength around 650 nm in the far field. When the polarization direction of the transmitted light extracted by the polarizing plate is 0 degree (X-polarized light) / 90 degrees (Y-polarized light), the effect of absorption depending on the minor axis / major axis of the metal fine particle out of the two generated peaks Can only take out.

  And when the polarization direction of the transmitted light taken out by the polarizing plate is 45 degrees, it absorbs at both wavelengths of 460 nm (absorption peak when the polarization direction is 0 degree) and 650 nm (absorption peak when the polarization direction is 90 degrees). When the polarization direction of the transmitted light extracted by the polarizing plate has a peak of 45 degrees, light having both wavelength components absorbed is emitted. Thus, by having an angle that is not parallel to the polarization direction of the transmitted light extracted by the polarizing plate and either of the two anisotropic axes of the metal fine particles, an absorption peak depending on the short axis / long axis of the metal fine particles is obtained. can do.

  Further, as shown in FIG. 3, the electric field intensity at 460 nm when the polarization direction of the transmitted light extracted by the polarizing plate is 45 degrees is about half that when the polarization direction is 0 degrees. Similarly, the electric field intensity at 650 nm when the polarization direction of the transmitted light extracted by the polarizing plate is 45 degrees is about half that when the polarization direction is 90 degrees. Accordingly, it is possible to change the absorption intensity of the absorption peak depending on the ratio between the polarization direction of the transmitted light extracted by the polarizing plate and the angle between the two anisotropic axes of the metal fine particles. That is, by adjusting the relative angle between the shape anisotropy of the metal fine particles and the polarization direction of the light transmitted through the polarizing plate, the absorption intensity of the absorption peak corresponding to each of the two directions of the shape anisotropy of the metal fine particles Can be changed.

  From the above, the position of the absorption peak of the optical filter can be set to a desired position by appropriately adjusting the shape and arrangement of the metal fine particles in the filter part and the polarization direction of the transmitted light extracted by the polarizing plate. it can. That is, the optical filter can be an optical filter having a desired absorption spectrum. In the simulation of FIG. 3, the incident light is 45-degree polarized light, but the same effect can be obtained even when both X and Y polarization components such as random polarization and circular polarization are included. .

  In the first optical filter 1 of the present invention, the filter unit 4 has a configuration in which metal fine particles 42 are diffused in a transparent dielectric 41, and the metal fine particles 42 are two-dimensionally arranged. In the first optical filter 1, the direction adjustment unit 3 adjusts the polarization direction of the transmitted light transmitted through the filter unit 4. And the light which permeate | transmitted the direction adjustment part 3 permeate | transmits the polarizing plate 2, and takes out specific linearly polarized light (light of a specific polarization direction). Accordingly, the polarization direction of the transmitted light transmitted from the filter unit 4 can be adjusted.

  The operation of the first optical filter 1 having this configuration is as follows. As described above, surface plasmon resonance corresponding to the size in the X direction of the metal fine particles 42 is generated by the component of X polarization in the incident light, and light in a wavelength region due to the size in the X direction is absorbed (FIG. 1). In FIG. 3, since the metal fine particle 42 has a short axis in the X direction, when the metal fine particle used in the simulation of FIG. 3 is used, the wavelength of the absorption peak is 460 nm.

  In addition, surface plasmon resonance corresponding to the size in the Y direction of the metal fine particles 42 is generated by the Y-polarized light component in the incident light, and light in a wavelength region due to the size in the Y direction is absorbed (in FIG. 1). Since the metal fine particle 42 has a short axis in the Y direction, when the metal fine particle used in the simulation of FIG. 3 is used, the wavelength of the absorption peak is 650 nm in the short axis direction).

  In the first optical filter 1 shown in FIG. 1, assuming that the polarization direction of the polarizing plate 2 is the X direction (X polarization), when the direction adjustment unit 3 does not rotate the polarization direction of the light transmitted through the filter unit 4, Light outside the wavelength region (460 nm) corresponding to the size of the metal fine particles 42 in the X direction is transmitted. That is, light having an absorption peak in the wavelength region corresponding to the size in the X direction of the metal fine particles 42 (X-direction component) is transmitted.

  On the other hand, when the direction adjusting unit 3 rotates the polarization direction of the light transmitted through the filter unit 90 by 90 degrees, light other than the wavelength region (650 nm) corresponding to the size in the Y direction of the metal fine particles 42 is transmitted. That is, light having an absorption peak in the wavelength region corresponding to the size in the Y direction of the metal fine particles 42 (Y-direction component) is transmitted.

Further, when the direction adjustment unit 3 is adjusted and the polarization direction of the light transmitted through the filter unit 4 is rotated between 0 degrees and 90 degrees, light having the X direction component and the Y direction component is transmitted. That is, surface light plasmon resonance in the X direction and surface plasmon resonance in the Y direction of the metal fine particles 42 are generated in the light transmitted through the filter unit 4, and transmitted light extracted by the polarizing plate 2 is light transmitted through the filter unit 4. The X-direction component and the Y-direction component are superposed at the ratio of the intensity projected onto the polarization direction set by the direction adjustment unit 3. For example, the X direction component increases as the polarization direction of the transmitted light is closer to 0 degrees, and the Y direction component increases as it is closer to 90 degrees.

  Therefore, in the first optical filter 1, the direction adjustment unit 3 rotates the polarization direction of the light transmitted through the filter unit 4 and adjusts the polarization direction of the transmitted light taken out by the polarizing plate 2. The absorption spectrum can be adjusted. As a result, it is possible to reproduce various colors with the single first optical filter 1.

  Next, the absorption spectrum when the light is incident on the two-dimensionally arranged silver metal fine particles and the transmitted light is observed in the far field will be described. FIG. 4A is a diagram showing the relationship between the number of layers and the electric field strength in the far field when two-dimensionally arranged silver metal fine particles are stacked in the light irradiation direction, and FIG. It is a figure which shows the relationship between the space | interval space | interval and the electric field strength in a far field when arrange | positioning the metal fine particle of this to overlap in the irradiation direction of light.

  In FIG. 4A, a broken line is an absorption spectrum in the same configuration (that is, one layer) as in FIG. 3, and a dotted line is an absorption spectrum in a configuration in which five layers of metal fine particles having the same shape as in FIG. The solid line shows the absorption spectrum in the case where eight layers of metal fine particles having the same shape as in FIG. 3 are stacked with an interval of 100 nm. The results of the 5th layer and the 8th layer are displayed with the vertical axis shifted so as not to overlap with other graphs.

  As shown in FIG. 4A, in any of the 1-layer, 5-layer, and 8-layers, the electric field strength decreases in the vicinity of the same wavelength as the absorption peak when the polarization direction is 0 ° in FIG. That is, the electric field strength immediately after the metal fine particles shown in FIG. 3 is an electric field enhanced by surface plasmon resonance, and light of a complementary color having the surface plasmon resonance wavelength is observed in the far field. Further, even when a plurality of layers are stacked, the absorption spectrum corresponds to the absorption spectrum when the polarization direction is 0 ° in FIG. As shown in FIG. 7A, when the number of layers on which the metal fine particles are superimposed increases, the amount of light absorbed at the surface plasmon wavelength increases, which makes it possible to increase the contrast.

  In FIG. 4B, the broken line is the absorption spectrum in the case of the same configuration (ie, one layer) as in FIG. 3, and the dotted line is the absorption spectrum in the case of the configuration in which metal fine particles having the same shape as in FIG. Yes, the chain line is the absorption spectrum when the metal fine particles having the same shape as in FIG. 3 are stacked on eight layers at intervals of 50 nm, and the one-dot chain line is the metal spectrum of the same shape as FIG. 3 stacked on eight layers at intervals of 60 nm. It is an absorption spectrum in the case of the configuration, and the solid line shows the absorption spectrum in the case of a configuration in which metal fine particles having the same shape as in FIG. The results for the 8th layer are displayed with the vertical axis shifted so as not to overlap with other graphs.

  As shown in FIG. 4B, the absorption peak is shifted in the configuration with an interval of 30 nm as compared with the single-layer configuration. On the other hand, in the configuration where the interval is 50 nm or more, the absorption peak returns to almost the same position as the configuration of one layer. This is thought to be due to the fact that the interaction between the neighboring particles occurs due to the narrow spacing between the layers, and the wavelength of the absorption peak is shifted. And by extending the interval to 50 nm or more, it is considered that the interaction between adjacent particles does not occur (difficult to occur), and the wavelength of the absorption peak returns to almost the same wavelength as in the case of one layer.

  The sufficient interval at which the interaction does not occur depends on the length of the metal fine particles in the light irradiation direction. That is, in this simulation, the length of the metal fine particles in the Z direction is 10 nm. As described above, 50 nm, which is a sufficient interval at which interaction between adjacent particles is difficult to occur, is the length of the metal fine particles in the Z direction. About 5 times the Therefore, the interval in the light irradiation direction when the metal fine particles are arranged is preferably 5 times or more the length in the irradiation direction of the metal fine particles. In this way, by setting the interval between adjacent metal fine particles to an interval where no interaction occurs, peak shift due to the interaction of metal fine particles can be prevented, so only the absorption peak of the metal fine particle alone is considered, The shape of the metal fine particles can be designed.

  From the above, the first optical filter 1 of the present invention has absorption peaks at two surface plasmon resonance wavelengths corresponding to the major axis and the minor axis (the Y direction and the X direction in FIG. 1) of the metal fine particles 42, respectively. It can be configured. Thereby, the 1st optical filter of this invention makes the 1st optical filter which expresses red and blue and the 1st optical filter which expresses green (and red) by selecting the metal particulates 42 appropriately. In other words, full color display is possible with the two first optical filters. Compared to a conventional optical filter with a fixed absorption wavelength (for example, a color filter that is separately applied to RGB), it is possible to increase the light use efficiency by reducing the number of optical filters.

  As described above, the case in which the direction adjustment unit 3 adjusts the relative relationship between the metal fine particles 42 and the polarization direction of the transmitted light extracted by the polarizing plate 2 by rotating the polarization direction of the light transmitted through the filter unit 4 has been described. It is not limited to this. For example, the direction adjusting unit may be configured to rotate the metal fine particles 42. In this case, it is preferable that the transparent dielectric 41 is a gel or a liquid so that the metal fine particles 42 can be easily rotated. A similar optical filter can be obtained by rotating the metal fine particles 42 and adjusting the relative relationship with the polarization direction of transmitted light taken out by the polarizing plate 2.

  It is known that by applying a voltage to the metal fine particles 42, the long axes of the metal fine particles 42 are arranged in the direction between the voltages. Therefore, as a method of rotating the metal fine particles 42, the direction adjusting unit 3 is configured to generate an electric field in the filter unit 4 (for example, an electrode), and the metal fine particles 42 are caused to act by applying an electric field to the metal fine particles 42. Can be mentioned.

  By utilizing this feature, two pairs of electrodes are provided and the voltage applied between the electrodes is adjusted, so that the metal fine particles 42 can be rotated three-dimensionally. By rotating the metal fine particles in a three-dimensional manner, one optical filter has three surface plasmon resonance wavelengths. Therefore, an optical filter capable of full color display can be obtained with one optical filter. Therefore, it is possible to further increase the light utilization rate as compared with the conventional color filter.

  Next, the case where the incident light is linearly polarized light will be considered in detail. FIG. 5 is a diagram showing the FDTD simulation result of the transmission spectrum in the far field. The X component is a broken line, the Y component is a solid line, the component in the major axis direction of the metal fine particle 42 is a dotted line, and the component in the minor axis direction is a thick line. The polarization direction of incident light is the X direction, and the metal fine particles 42 are installed in a direction inclined by 45 degrees. The shape of the metal fine particles 42 is the same as in the simulation of FIG. 3, and eight layers are stacked at an interval of 200 nm.

  As a result, the X component of the light transmitted through the filter unit 4 absorbs light having the surface plasmon resonance wavelength (650 nm) in the major axis direction and the surface plasmon resonance wavelength (460 nm) in the minor axis direction of the metal fine particles 42. It can be seen that light of a wavelength is transmitted. On the other hand, it can be seen that the Y component is transmitted by scattering light having a surface plasmon resonance wavelength in the major axis and minor axis directions.

  Since light having a polarization direction inclined by 45 degrees is incident on the metal fine particles 42, surface plasmon resonance occurs in both the long axis direction and the short axis direction of the metal fine particles 42. When the X component of the light transmitted through the filter unit 4 is extracted, the light having the same polarization direction as that of the incident light is transmitted, so that light having a wavelength at which surface plasmon resonance does not occur is transmitted as it is, and light having the surface plasmon resonance wavelength is absorbed. . On the other hand, when the Y component of the light transmitted through the filter unit 4 is taken out, the light having a wavelength that does not cause surface plasmon resonance cannot be transmitted because the polarization direction is orthogonal to the incident light, and light having the surface plasmon resonance wavelength is scattered. Looks like.

  By using this phenomenon, the first optical filter can express colors as follows.

  If the polarization direction of the incident light is tilted so as not to be parallel / perpendicular to the direction of the metal fine particles 42, the polarization direction of the transmitted light extracted by the polarizing plate 2 by the adjustment of the direction adjusting unit 3 is the polarization direction of the incident light. By making them parallel, absorption of surface plasmon resonance in the major axis and minor axis directions is observed, and a complementary color of the surface plasmon resonance wavelength in the major axis and minor axis directions can be expressed. In FIG. 5, the surface plasmon resonance wavelength in the major axis direction is about 650 nm (red), the surface plasmon resonance wavelength in the minor axis direction is about 460 nm (blue), and the complementary color green can be expressed.

  On the other hand, scattering by surface plasmon resonance in the major axis and minor axis directions is observed by making the polarization direction of transmitted light extracted by the polarizing plate 2 by adjusting the direction adjusting unit 3 perpendicular to the polarization direction of incident light. The color of the surface plasmon resonance wavelength in the major axis and minor axis directions, that is, purple can be expressed.

  Further, by adjusting the direction adjusting unit 3 and setting the polarization direction of transmitted light taken out by the polarizing plate 2 to be the major axis direction of the metal fine particles 42, absorption of surface plasmon resonance in the major axis direction is observed, and the surface in the major axis direction is observed. Blue-green, which is a complementary color of the plasmon resonance wavelength, can be expressed. On the other hand, absorption of surface plasmon resonance in the short axis direction is observed by adjusting the direction adjusting unit 3 and setting the polarization direction of the transmitted light extracted by the polarizing plate 2 to the short axis direction of the metal fine particles 42, and the surface in the short axis direction is observed. Yellow, which is a complementary color of the plasmon resonance wavelength, can be expressed.

  Therefore, if the polarization direction of the incident light is tilted with respect to the direction of the metal fine particles 42 and the direction adjusting unit 3 is operated to adjust the polarization direction of the transmitted light extracted by the polarizing plate 2 by 45 degrees, blue-green, purple, Blue and yellow can be expressed.

  As can be seen in FIG. 5, when the direction adjustment unit 3 is adjusted and the polarization direction of the transmitted light taken out by the polarizing plate 2 is the major axis / minor axis direction of the metal fine particles 42, and when it is inclined 45 °, The peak position is different. This is considered to be due to the influence of surface plasmon resonance in directions other than the complete major axis / minor axis direction by tilting the polarization direction of incident light by 45 °. That is, the absorption wavelength can be adjusted using this phenomenon.

  In the above description, the direction adjusting unit 3 is described as rotating the polarization direction of the transmitted light extracted by the polarizing plate 2, but the direction of the metal fine particles 42 may be adjusted. However, in this case, the relative angle with the incident light must also be adjusted. For example, if the polarization direction of incident light and the direction of the metal fine particles 42 are parallel or perpendicular, the four colors cannot be expressed as described above. Even if the polarization direction of the incident light and the direction of the metal fine particles 42 are in a state other than parallel or perpendicular, the contribution ratio of the surface plasmon absorption in the major axis direction and the surface plasmon absorption in the minor axis direction changes.

(Second Embodiment)
Next, another example of the optical filter according to the present invention will be described with reference to the drawings. FIG. 6 is a perspective view showing another example of the optical filter according to the present invention. As shown in FIG. 6, the second optical filter 11 includes a second direction adjustment unit 31 on the surface of the filter unit 4 opposite to the direction adjustment unit 3. The other parts are the same as those of the first optical filter 1 shown in FIG. 1, and the same reference numerals are given to the parts having substantially the same light. That is, the second optical filter 11 is different from the first optical filter 1 in that the second direction adjusting unit 31 is used to adjust the polarization direction of incident light.

  Similarly to the direction adjustment unit 3, the second direction adjustment unit 31 may be an optical element including a liquid crystal, or may be one using a Faraday element or a half-wave plate. In this case, it is assumed that the incident light is linearly polarized light. Further, the polarizing plate may be rotated. In this case, the incident light may not be linearly polarized light.

  For example, the second direction adjustment unit 31 is adjusted so that the polarization direction of the incident light is parallel to the major axis direction of the metal fine particles 42, the direction adjustment unit 3 is adjusted, and the polarization direction of the transmitted light is changed to the major axis of the metal fine particles 42. By making the direction parallel to the direction, absorption due to surface plasmon resonance in the major axis direction of the metal fine particles 42 is observed. As a result, the second optical filter 11 emits light of a complementary color having a surface plasmon resonance wavelength in the major axis direction of the metal fine particles 42.

    According to the second optical filter 11 having this configuration, the polarization direction of the incident light and the major axis direction of the metal fine particles 42 are not parallel / perpendicular (for example, the polarization direction of the incident light is 45 degrees with respect to the major axis direction of the metal. The light use efficiency is higher than when the first optical filter that is inclined is allowed to transmit light of the same wavelength. On the other hand, by adjusting the direction adjustment unit 3 and making the polarization direction of the transmitted light perpendicular to the polarization direction of the incident light by the adjustment of the second direction adjustment unit 31, the light from the light source is not transmitted and black can be expressed. Become.

  Further, the second direction adjustment unit 31 is adjusted so that the polarization direction of the incident light is perpendicular to the major axis direction of the metal fine particles 42 (parallel to the minor axis direction), the direction adjustment unit 3 is adjusted, and the polarization direction of the transmitted light is changed. By making it parallel to the polarization direction of incident light, the absorption of surface plasmon resonance in the minor axis direction of the metal fine particles 42 is observed, and the complementary color of the surface plasmon resonance wavelength in the minor axis direction can be expressed.

  According to the second optical filter 11 having this configuration, the polarization direction of the incident light and the major axis direction of the metal fine particles 42 are not parallel / perpendicular (for example, the polarization direction of the incident light is 45 degrees with respect to the major axis direction of the metal. The light utilization efficiency is higher than when the light having the same wavelength is transmitted through the first optical filter that is inclined. On the other hand, by adjusting the direction adjusting unit 3 so that the polarization direction of the transmitted light is perpendicular to the polarization direction of the incident light, the light from the light source is not transmitted and black can be expressed.

  In the second optical filter 11, even when the polarization direction of the light emitted from the light source is different from that determined in advance (by design or the like), the second direction adjustment unit 31 adjusts the polarization direction of the incident light in advance. The polarization direction can be determined. There are few restrictions on the light source to obtain an optical filter with the desired absorption spectrum. Furthermore, the second optical filter 11 can have a desired absorption spectrum even if a light source whose light direction is not adjusted is used.

In the above description, the second direction adjustment unit 31 adjusts the polarization direction of incident light. However, the second direction adjustment unit 31 may be configured to adjust the direction of the metal fine particles 42. In this case, the direction adjusting unit 3 must adjust the polarization direction of the transmitted light extracted by the polarizing plate 2 in consideration of the direction of the metal fine particles 42.

  In the optical filter of the present invention (the first optical filter 1 and the second optical filter 11), the transmitted light is changed to have an absorption spectrum in a desired wavelength range by adjusting the polarization direction of the transmitted light. Can do. Thereby, various colors (for example, 2 to 4 colors) can be reproduced with one optical filter.

(Third embodiment)
Next, a display device according to the present invention will be described with reference to the drawings. FIG. 7 is a schematic layout diagram of an example of a display device according to the present invention. The display device 100 shown in FIG. 7 is assumed to be composed of a single display cell 10 for convenience of explanation, but actually, a plurality of display cells 10 are vertically and horizontally arranged in a matrix (for example, 1080 vertical × horizontal). 1920). In the following description, the display cell 10 will be mainly described. In the present embodiment, the first optical filter is used. However, the present invention is not limited to this, and a second optical filter may be used.

  The display device 100 is a transmissive display device, and is observed from the first optical filter 1a, 1b side (polarizing plate 2 side) by an observer. As shown in FIG. 7, the display device 100 includes a display cell 10, a calculation unit 91, a display data input unit 92, a direction adjustment unit drive circuit 93, and a light intensity adjustment unit drive circuit 94.

  The display cell 10 is divided into two subcells 10a and 10b arranged in the X direction, and includes first optical filters 1a and 1b, a light source 5, and light intensity adjusting units 6a and 6b. The optical filters 1a and 1b are arranged side by side in the X direction. The subcell 10a and the subcell 10b can be displayed differently (displayed in different colors).

  The light source 5 only needs to emit visible light. When performing full color display, the light source 5 preferably emits white light. Examples of the light source 5 include a fluorescent lamp, an incandescent bulb, an LED, and a laser light source. In addition, you may provide the diffuser plate, light guide plate, etc. which irradiate the light of the light source 5 to the whole surface. When the light source 5 emits linearly polarized light such as a laser light source, for example, the laser light source is installed so that the polarization direction is not parallel to either the major axis or the minor axis of the metal fine particles, thereby displaying a full color display. It can be made to correspond. Further, even if a quarter wave plate or the like is disposed between the light source 5 and the optical filters 1a and 1b, and circularly polarized light is converted and then incident on the filter units 4a and 4b, it is possible to support full color display. .

  The light intensity adjusters 6a and 6b adjust the intensity of light incident on the metal fine particles 42a and 42b (in other words, the degree of light transmission). The light intensity adjusting units 6a and 6b are to combine the optical filters 1a and 1b so that the desired color can be seen. When the incident light is linearly polarized light, it is assumed that the polarizing plate and the liquid crystal element are combined. it can. That is, the polarizing direction of the light intensity adjusting units 6a and 6b may be rotated with the liquid crystal and the polarizing plates of the light intensity adjusting units 6a and 6b may be irradiated. At this time, the light transmitted through the light intensity adjusting units 6a and 6b has a certain polarization direction, and the light intensity adjusting units 6a and 6b are configured such that the polarization direction of the transmitted light is the metal fine particles 42a of the filter units 4a and 4b. , 42b are arranged so as to form a predetermined angle with the major and minor axes.

  In addition, when the incident light is randomly polarized light or circularly polarized light, an electrochromic material that changes color by applying an electric charge may be used as the light intensity adjusting units 6a and 6b. By applying a voltage to the light intensity adjusting units 6a and 6b using an electrochromic material, the intensity (transmission degree) of the transmitted light can be changed. In the present embodiment, the light intensity adjusting units 6a and 6b are installed between the light source 5 and the filter units 4a and 4b, but may be installed anywhere after the light source 5.

  The optical filter 1a includes a polarizing plate 2, a direction adjustment unit 3a, and a filter unit 4a. Similarly, the optical filter 1b includes a polarizing plate 2, a direction adjustment unit 3b, and a filter unit 4b. The polarizing plate 2 is a common member for the optical filters 1a and 1b. Hereinafter, the direction adjusting units 3a and 3b are liquid crystal elements and will be described as adjusting the polarization direction of incident light. However, the polarization direction of incident light and the anisotropic direction of the metal fine particles 42a and 42b are relative to each other. However, the present invention is not limited to this as long as it can be changed.

  In the optical filters 1a and 1b, the polarizing plate 2, the direction adjusting means 3a and 3b, and the filter portions 4a and 4b (transparent dielectrics 41a and 41b and metal fine particles 42a and 42b) are the same as those of the optical filter 1 described above. The shapes of the metal fine particles 42a and 42b are different between the optical filter 1a and the optical filter 1b. For example, if the sub-cell 10a displays colors from red to blue and the sub-cell 10b displays green, the display cell 10 can express the three primary colors, that is, full color.

  Since human eyes have low sensitivity to red, when displaying red only by the subcell 10a, it is necessary to increase the intensity of incident light. If it is possible to display red in both the subcell 10a and the subcell 10b, the aperture ratio at the time of displaying red increases, so that it is not necessary to increase the incident light intensity. From the above, in the display cell 10, the subcell 10a displays red and blue, and the subcell 10b displays red and green. The optical filter 1a develops red and blue, and the optical filter 1b develops red and green.

  In the display cell 10 shown in FIG. 7, since the subcell 10a displays red and blue, the filter unit 4a includes metal fine particles 42a having absorption peaks in two wavelength regions of 490 to 500 nm and 580 to 595 nm. . Since the subcell 10b displays green and red, the filter unit 4b includes metal fine particles 42b having absorption peaks at 750 to 800 nm and 490 to 500 nm.

  The direction adjustment unit drive circuit 93 sends an electric signal to the direction adjustment units 3a and 3b based on the data given from the calculation unit 91, and selects a desired polarization direction from the light transmitted through the filter units 4a and 4b. It is for making it happen. The light intensity adjustment unit drive circuit 94 sends an electrical signal to the light intensity adjustment units 6a and 6b based on the data given from the calculation unit 91, and controls the light intensity transmitted through the light intensity adjustment layers 6a and 6b. It is. When the light source 5 is configured to be independent for each of the subcells 10a and 10b, the light intensity adjusting unit driving circuit 94 may be configured to send an electric signal to the light source 5 and adjust the light emission intensity. . At this time, the light intensity adjusting units 6a and 6b can be omitted, and the light transmittance of the subcells 10a and 10b can be increased.

  Since the direction adjusting units 3a and 3b are liquid crystal elements, electrodes arranged opposite to each other are provided. The light intensity adjusting units 6a and 6b are also provided with electrodes with a liquid crystal element interposed therebetween. These electrodes are preferably transparent if possible. For example, a transparent electrode such as indium tin oxide (ITO) or indium zinc oxide (IZO) can be used. Further, the direction adjusting unit 3a and the light intensity adjusting unit 6a, and the direction adjusting unit 3b and the light intensity adjusting unit 6b may be provided with a common electrode (for example, a ground electrode) at the center.

  The display data input unit 92 is a part to which image and video data sent from a disk device such as a DVD device or a BD device, a PC, or the like and displayed on the display device 100 is input. The input image and video data can include data including color data and luminance data for each display cell 10. In order to display the image and video data given from the display data input unit 92 on the main display cell 10, the calculation unit 91 calculates the intensity of incident light and the polarization direction of transmitted light with respect to each cell, and calculates the result. A processing circuit for outputting to the light intensity adjusting units 6a and 6b and the direction adjusting units 3a and 3b is included.

  Next, the operation of the display device 100 will be described. First, image / video data is input to the display data input unit 92. The calculation unit 91 determines the color and intensity in each display cell 10 based on the image / video data, and calculates the intensity of incident light and the polarization direction of transmitted light selected from the filter units 4a and 4b from the color information. To do. Then, the calculation unit 91 transmits a signal including information on the polarization direction of transmitted light to the direction adjustment unit driving circuit 93 and a signal including information on intensity to the light intensity adjustment unit driving circuit 94.

  The direction adjustment unit drive circuit 93 sends a drive signal to the direction adjustment units 3 a and 3 b based on the signal from the calculation unit 91. Further, the light intensity adjustment unit drive circuit 94 sends a drive signal to the light intensity adjustment units 6 a and 6 b based on the signal from the calculation unit 91. In addition, the drive signal sent to the direction adjustment parts 3a and 3b is an independent signal, and applies the voltage for driving a liquid crystal to an electrode substrate. Similarly, the drive signals sent to the light intensity adjusters 6a and 6b are also independent signals, and a voltage for driving the liquid crystal is applied to the electrode substrate.

  By receiving a drive signal from the light intensity adjusting unit driving circuit 94, the light intensity adjusting units 6a and 6b adjust the transmittance of light from the light source 5 and adjust the intensity of incident light incident on the direction adjusting units 3a and 3b. To do. Incident light whose intensity has been adjusted by the light intensity adjusting units 6a and 6b enters the filter units 4a and 4b. On the other hand, the direction adjustment units 3a and 3b rotate and adjust the polarization direction of the light transmitted through the filter units 4a and 4b by receiving the drive signal from the direction adjustment unit drive circuit. The light incident on the filter portions 4 a and 4 b is absorbed at a wavelength determined by the shape anisotropy of the metal fine particles 42 a and 42 b and the polarization direction of the transmitted light extracted by the polarizing plate 2. In this way, a desired color display is performed in the subcells 10a and 10b, that is, the display cell 10.

  Below, the case where the display cell 10 concerning this invention displays each of red, green, blue, and these intermediate colors, white, and black is demonstrated.

  When displaying red, it is as follows. The direction adjustment unit driving circuit 93 controls the polarization direction of light transmitted through the direction adjustment units 3a and 3b from the filter units 4a and 4b so that red is displayed. Then, the light intensity adjusting unit driving circuit 94 controls the light intensity adjusting units 6a and 6b to set the intensity of the incident light to the direction adjusting units 3a and 3b to an optimum intensity. By controlling each part of the display cell 10 in this way, red is displayed in both the subcells 10a and 10b. Thereby, the display cell 10 is displayed in red (red display in the far field).

  When displaying green, it is as follows. The direction adjustment unit drive circuit 93 controls the polarization direction of the light transmitted from the filter unit 4b through the direction adjustment unit 3b so that green is displayed. Then, the light intensity adjusting unit driving circuit 94 controls the light intensity adjusting unit 6b to set the intensity of incident light to the direction adjusting unit 3b to an optimum intensity. Further, the light intensity adjusting unit driving circuit 94 controls the light intensity adjusting unit 6a to block the incident light to the filter unit 4a (the incident light intensity is made zero). By controlling each part of the display cell 10 in this way, no display is made in the subcell 10a (black display), and green is displayed in the subcell 10b. Thereby, the display cell 10 is displayed in green (displayed in green in the far field).

  When displaying blue, it is as follows. The direction adjustment unit drive circuit 93 controls the polarization direction of light transmitted through the direction adjustment unit 3a from the filter unit 4a so that blue is displayed. Then, the light intensity adjusting unit driving circuit 94 controls the light intensity adjusting unit 6a to make the intensity of incident light to the direction adjusting unit 3a optimal. Further, the light intensity adjusting unit driving circuit 94 controls the light intensity adjusting unit 6b to block the incident light to the filter unit 4b (the intensity of the incident light is zero). By controlling each part of the display cell 10 in this way, blue is displayed in the subcell 10a and no display is displayed in the subcell 10b (black display). Thereby, the display cell 10 becomes blue display (it becomes blue display in a far field).

  A neutral color can be displayed by appropriately adjusting the relative intensities of red, blue, and green. Further, by displaying red and blue in the subcell 10a and green or red and green in the subcell 10b, the display cell 10 becomes white display.

  Furthermore, when performing black display, the light intensity adjusting units 6a and 6b may be adjusted by the light intensity adjusting unit driving circuit 94 so that light does not enter the filter units 4a and 4b.

  As described above, the display device 100 uses the optical filters 1a and 1b of the present invention, and adjusts the relative anisotropy between the shape anisotropy of the metal fine particles 42a and 42b and the polarization direction of the transmitted light, thereby obtaining one subcell. Can express two colors and their mixed colors. Therefore, the number of filters necessary for full color display can be reduced to 2 or less.

  When the conventional RGB color filter is used, the display cell includes a red (R) display subcell, a green (G) display subcell, and a blue (B) display subcell. For example, when performing red (R) display, the green (G) display subcell and the blue (B) display subcell are darkly displayed, and the two pixels are not lit. That is, when red (R), green (G), and blue (B) display is performed, a 66% non-lighting area is generated in the conventional display cell.

  As described above, in the display cell 10 according to the present invention, since the color direction is tunable by controlling the polarization direction, the subcells 10a and 10b are lit when red is displayed, so that no astigmatic area is generated. . Further, since the subcell 10a is not lit when displaying in green, and the subcell 10b is not lit when displaying in blue, the non-lighting area is reduced from 66% to 50%, the light use efficiency is high, and bright display is possible or the same. It is possible to reduce energy consumption when displaying.

  Furthermore, the optical filter of the present invention shifts the peak of surface plasmon resonance by entering a polarization direction intermediate between the long axis and the short axis in addition to the two resonance wavelengths corresponding to the long axis and the short axis, and the third resonance. Wavelength can be added. By using such an optical filter, it is possible to express all RGB colors (light having a wavelength corresponding to RGB) necessary for full color with one optical filter, and the display cell is one optical filter, that is, Full color display is possible with one subcell. In this case, since there is no non-lighting area, it is possible to further increase the light use efficiency. In addition, the direction adjusting unit driving circuit 93 and the light intensity adjusting unit driving circuit 94 can be simplified.

  Note that the filter units 4a and 4b are not limited to the above, and when the filter unit 4a has an absorption peak in two wavelength regions of 490 to 500 nm and 580 to 595 nm, the filter 4b has at least a green color. The filter 4b may have an absorption peak at 750 to 800 nm. With this configuration, the subcell 10a can display colors from blue to red, the subcell 10b can display green, and the display cell 10 can perform full color display. Furthermore, the subcell 10b can display yellow as a complementary color by making another absorption peak of the filter part 4b into 435-480 nm. Since the subcell 10a can display red and blue and the subcell 10b can display green and yellow, the display cell 10 can express high-definition colors using the four primary colors RGBY. At this time, if blue is displayed in the subcell 10a and yellow is displayed in the subcell 10b, pseudo white can be displayed. When the filter unit 4b has an absorption peak at 750 to 800 nm and another absorption peak other than the visible region (less than 400 nm or 800 nm or more), white color can be displayed in the subcell 10b.

  As described above, the first optical filter 1 is used as the display device 100, and the filter units 4a and 4b express two colors and mixed colors, respectively, so that the display cell 10 (subcells 10a and 10b) has red, green, Although the case where each of blue, these intermediate colors, white, and black is displayed was demonstrated, it is not limited to this.

  For example, by adjusting the polarization direction of the light transmitted through the filter units 4a and 4b, the filter units 4a and 4b can express three colors, four colors, and a mixed color thereof, respectively. And since the color which can be expressed by combination increases by using the 1st optical filter 1 and / or the 2nd optical filter 11 provided with the filter parts 4a and 4b of such a structure, the color of the display apparatus 100 Reproducibility can be improved.

  In addition, since the second optical filter 11 has an effect of increasing the contrast as described above, the display device 100 having high color reproducibility and high contrast can be obtained by using the second optical filter 11 in the display device. can do.

  Further, the display cell 10 may be configured to include three subcells. In the normal RGB three-pixel configuration, the triangular range surrounded by the three RGB peak wavelengths in the chromaticity diagram is the color expression region. However, if this optical filter is used, wavelengths other than R, G, and B can be used. Since points can be taken, the shape of the reproduction area triangle on the chromaticity diagram can be changed. That is, the color expression range can be widened.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

  The optical filter according to the present invention can be used as a color filter for a display device that performs full-color display.

1, 1a, 1b Optical filter 2 Polarizing plate 3, 31, 3a, 3b Direction adjustment part 4, 4a, 4b Filter part 41, 41a, 42b Transparent dielectric 42, 42a, 42b Metal fine particle 5 Light source 6a, 6b Light intensity adjustment Unit 91 Calculation unit 92 Display data input unit 93 Direction adjustment unit drive circuit 94 Light intensity adjustment unit drive circuit 10 Display cell 100 Display device

Claims (14)

A filter unit in which a plurality of metal fine particles having two or more anisotropic axes are arranged on the surface or inside of a transparent dielectric that transmits light in the visible range; and
An optical filter, comprising: a direction adjusting unit that relatively changes a polarization direction of transmitted light transmitted through the filter unit and a direction of a shape anisotropic axis of the metal fine particles.   The optical filter according to claim 1, wherein the direction adjusting unit rotates the polarization direction of the transmitted light in a direction parallel to or perpendicular to the shape anisotropic axis of the metal fine particles. The transparent dielectric material rotatably supports the metal fine particles,
2. The optical filter according to claim 1, wherein the direction adjusting unit rotates the plurality of metal fine particles on the transparent dielectric or inside thereof in a state in which the directions are aligned. The plurality of metal fine particles have three anisotropic axes,
The optical filter according to claim 3, wherein the direction adjusting unit rotates the plurality of metal fine particles also on or inside the transparent dielectric in the direction perpendicular to the surface of the transparent dielectric.   2. The optical filter according to claim 1, wherein incident light whose polarization direction is not parallel or perpendicular to any of the two anisotropic axes of the metal fine particles is incident on the filter unit.   The optical filter according to claim 3, further comprising a second direction adjusting unit that relatively changes a polarization direction of incident light incident on the filter unit and a direction of a shape anisotropic axis of the metal fine particles. The transparent dielectric material rotatably supports the metal fine particles,
The optical filter according to claim 6, wherein either one of the direction adjustment unit or the second direction adjustment unit rotates the plurality of metal fine particles on the transparent dielectric or inside thereof in a state in which the directions are aligned. The plurality of metal fine particles have three anisotropic axes,
The optical filter according to claim 7, wherein the direction adjusting unit rotates the plurality of metal fine particles in the direction perpendicular to the surface of the transparent dielectric on or inside the transparent dielectric.   The plurality of metal fine particles are also arranged in the light irradiation direction, and the arrangement interval in the light irradiation direction is at least five times the length of the metal fine particles in the light irradiation direction. The optical filter according to any one of the above. The optical filter according to any one of claims 1 to 9,
A light source that emits light in the visible range;
A display cell comprising: a light intensity adjusting unit that adjusts the intensity of light incident on the optical filter. Two optical filters are provided,
The display cell according to claim 10, wherein both of the two optical filters include a filter unit including a wavelength at which a surface plasmon resonance wavelength of the metal fine particle is a complementary color of red. A data input unit for inputting image data;
A direction adjusting unit driving circuit for controlling the direction adjusting means;
A light intensity adjusting unit driving circuit for controlling the light intensity adjusting unit;
Determining the color and intensity to be displayed in each display cell based on the image data, and driving the direction adjusting means and the light intensity adjusting unit of the display cell based on the color and intensity; The display cell according to claim 10 or 11, further comprising a calculation unit that gives instructions to the adjustment unit drive circuit and the light intensity adjustment unit drive circuit. A plurality of display cells according to claim 10 or claim 11 are provided,
A display device in which the plurality of display cells are two-dimensionally arranged. A data input unit for inputting image data;
A direction adjusting unit driving circuit for controlling the direction adjusting means;
A light intensity adjusting unit driving circuit for controlling the light intensity adjusting unit;
Determining the color and intensity to be displayed in each display cell based on the image data, and driving the direction adjusting means and the light intensity adjusting unit of each display cell based on the color and intensity; The display device according to claim 13, further comprising: an adjustment unit driving circuit and a calculation unit that gives instructions to the light intensity adjustment unit driving circuit.

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