JP4986645B2 - Optical device - Google Patents

Description

  The present invention relates to an optical device, and more particularly to an optical device using electrochromic technology.

  The fluid fine particle display (MFPD) has a structure in which fine particles are dispersed in a dielectric fluid such as liquid crystal and sandwiched between upper and lower substrates with electrodes, and the movement of fine particles is controlled in the in-plane direction by electrophoresis. Thus, the display performs display according to the position distribution of the fine particles in the plane. MFPD is disclosed in Patent Document 1, for example. The MFPD can perform a bright reflective display like paper and has a display memory property.

  9A and 9B are schematic cross-sectional views illustrating examples of MFPD. A fluidized bed 104 made of liquid crystal in which fine particles 103 are dispersed is formed between the upper transparent substrate 101 and the lower transparent substrate 102 facing each other. An opaque electrode 105 is formed on the lower surface of the upper transparent substrate 101. The opaque electrode 105 defines an opening window in plan view. A light absorption layer 106 is formed on the upper surface of the lower transparent substrate 102, and a transparent electrode 107 is formed on the upper surface of the light absorption layer 106.

  In a state where no voltage is applied between the transparent electrode 107 and the opaque electrode 105, the fine particles 103 are dispersed throughout the fluidized bed 104 as shown in FIG. 9A. The fine particles 103 reflect the external light 108 incident from above. Thereby, the inside of the opening window looks bright.

  By applying a predetermined voltage between the transparent electrode 107 and the opaque electrode 105, the fine particles 103 are collected below the opaque electrode 105 as shown in FIG. 9B. Thereby, the fluidized bed 104 in the opening window becomes transparent. External light 108 passes through the fluidized bed 104 and is absorbed by the light absorbing layer 106. Thereby, the inside of the opening window looks dark.

  Here, a relatively bright display is simply called “white display”, and a relatively dark display is simply called “black display”. The display device described with reference to FIGS. 9A and 9B is a reflective display device, and white display is realized by scattering reflection by the fine particles 103 in the fluidized bed 104 (FIG. 9A). )), Black display is realized by light absorption by the light absorption layer 106 (FIG. 9B).

  Note that when a light absorption layer is removed and fine particles that absorb light are used, a transmissive display device can be obtained. Black display is realized with the fine particles dispersed in the fluidized bed, and white display is realized with the fine particles collected under the opaque electrode.

  As a display, an electrochromic display using an electrochromic material that changes a transparent state and a colored state by applying a voltage is also known.

  A reflective electrochromic display has a structure in which a reflective member is disposed under an electrochromic film. When the electrochromic film is in a transparent state and external light is reflected by the reflecting member, white display is realized. When the electrochromic film is in a colored state and external light is absorbed by the electrochromic film, black display is realized.

  The transmissive electrochromic display has a structure in which a transparent member is disposed under an electrochromic film. When the electrochromic film is in a transparent state, light is transmitted through the transparent member and the electrochromic film, thereby realizing white display. When the electrochromic film is in a colored state and light is absorbed by the electrochromic film, black display is realized.

JP 2003-98556 A

  There is a demand to use one display device under various environments. For example, it is desirable to have a display device that can be used as a reflective display device in a bright place and can be used as a transmissive display device using a backlight in a dark place. However, in the conventional MFPD and electrochromic display, one display device does not serve as both a reflective display device and a transmissive display device.

  An object of the present invention is to provide an optical device applicable to a display device that serves as both a reflective display device and a transmissive display device.

  Another object of the present invention is to provide a novel optical device.

  An electrochromic film is formed on one electrode, a first electrode pair that applies a voltage to the electrochromic film, an electrolyte layer that is disposed between the first electrode pair and includes fine particles, and the electrolyte layer An optical device is provided that has a second electrode pair that moves the fine particles in the in-plane direction of the electrochromic film by collecting an electric field in the vicinity of the one electrode to collect the fine particles.

  The coloring state of the electrochromic film is controlled by the first electrode pair. Further, the position distribution of the fine particles in the electrolyte layer is controlled by the second electrode pair. By changing the position distribution of the fine particles in the electrolyte layer, the reflectance (or transmittance) of the electrolyte layer can be changed.

  Consider using the optical device of the present invention as a display device that performs display using changes in the coloring state of an electrochromic film, for example. If display is performed in a state where the reflectivity of the electrolyte layer is high, a reflective display device can be realized. On the other hand, when display is performed in a state where the reflectance of the electrolyte layer is low (transmittance is high), a transmissive display device can be realized. It can also be applied to lighting devices and the like.

  With reference to FIG. 1, the structure and manufacturing method of the optical apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a schematic sectional view of an optical device according to the first embodiment. The case where the optical device of the embodiment is used as a display device will be continued.

  First, an upper substrate 1 having a transparent electrode 2 and an opaque electrode 3 formed on the surface and a lower substrate 5 having a transparent electrode 4 formed on the surface are prepared.

  The upper substrate 1 and the lower substrate 5 are made of a transparent material such as blue plate glass or white plate glass, and have a thickness of, for example, 0.7 mmt. The transparent electrodes 2 and 4 are made of indium tin oxide (ITO), for example, and have a thickness of, for example, 80 nm. The opaque electrode 3 is made of a metal such as aluminum or molybdenum and has a thickness of 80 nm, for example.

  In plan view, the opaque electrode 3 defines an opening window, and the transparent electrode 2 is formed in the opening window. The inside of the opening window defined by the opaque electrode 3 corresponds to the display area for one pixel.

Next, an electrochromic film 6 is formed on the surface of the transparent electrode 2 on the upper substrate 1. In this embodiment, the electrochromic film 6 is formed by vacuum deposition of tungsten trioxide (WO ₃ ). The formed electrochromic film 6 is subjected to heat treatment at 350 ° C. for 30 minutes.

The material of the electrochromic film 6 is not limited to WO ₃ as long as the material can be switched between a transparent state and a colored state of the film by an applied voltage. For example, molybdenum oxide, tungsten oxide-molybdenum composite film, vanadium oxide, iridium oxide, manganese dioxide, nickel oxide, or an organic material such as a viologen-based compound or a styryl-based compound can be used.

  Further, the method of forming the electrochromic film 6 is not limited to vacuum deposition. For example, sputtering (radio frequency (RF) magnetron sputtering etc.), plating, Langmuir Blodget (LB) method, various printing methods (screen printing, spin coating, die coating, etc.) can also be used.

  As the film structure of the electrochromic film 6, a dense structure is not preferable, and an amorphous structure having many gaps is preferable. In order to positively provide a gap, particles having a minute particle diameter may be dispersed in the electrochromic film 6. An electron donating film may be formed on the surface of the transparent electrode 4 on the lower substrate 5.

  Next, the main seal layer 7 is formed on the lower substrate 5. As a material for the main seal layer 7, a main seal agent containing 2 wt% to 5 wt% of a gap control agent is used. In this example, a plastic ball having a diameter of 75 μm is used as a gap control agent, and 5 wt% of this is added to a sealing agent ES-7500 manufactured by Mitsui Chemicals to make a main sealing agent. As a method for forming the main seal layer 7, for example, screen printing or a dispenser is used. The diameter of the gap control agent corresponds to the thickness of the electrolyte layer 8. It is preferable to select the gap control agent so that the thickness of the electrolyte layer 8 is in the range of 50 μm to 200 μm.

  Next, the surface on which the transparent electrode 2 and the opaque electrode 3 are formed is opposed to the surface on which the transparent electrode 4 is formed, and the transparent electrode 2 and the transparent electrode 4 are aligned in plan view (for example, both electrodes The upper substrate 1 and the lower substrate 5 are overlapped with each other via the main seal layer 7. In this way, an empty cell is formed. In a state where the cells are formed, the transparent electrode 4 on the lower substrate 5 is also disposed in the opening window in plan view.

  Next, the electrolyte layer 8 is formed by vacuum-injecting the electrolyte into the empty cell. As an electrolytic solution for forming the electrolyte layer 8, a liquid crystal in which a charge transfer complex (CTC) is added to liquid crystal and fine particles 9 are further dispersed is used. After the electrolyte layer 8 is formed, an end sealant is applied to the electrolyte inlet and the cell is sealed.

  In this embodiment, RDP-00333 manufactured by Dainippon Ink is used as the liquid crystal, and n-butyl-isoquinolinium-iodide (BIQI) is used as the CTC. The amount of CTC added in the electrolyte is, for example, 0.038 wt%. CTC has not only a function as an electrolyte but also an effect of improving the moving speed of the fine particles 9 as described later. In addition, various liquid salts and solvents (such as acetonitrile) can be used as the electrolyte. The liquid crystal material is not particularly limited, but a material having a large absolute value of dielectric anisotropy Δε is preferable. When Δε is close to zero, the movement becomes dull.

As the fine particles 9, various metal oxides such as TiO ₂ , SiO ₂ , and ZnO, organic substances such as styrene balls, colored substances thereof, hollow bodies thereof, and the like are used. In this embodiment, fine particles that are often used as a gap control material for liquid crystal display elements are used as the fine particles 9. The fine particles 9 of this example are a non-colored mixed system of TiO ₂ and organic matter.

  The fine particles 9 of the present example are spherical particles having a diameter of 6 μm, and the variation in the particle size (diameter) is within ± several%. The particle size can be measured by a technique such as laser diffraction, sedimentation, image analysis, or light scattering. The particle diameter of the fine particles 9 is not limited to 6 μm, but is preferably in the range of 0.5 μm to 100 μm, and more preferably in the range of 2 μm to 20 μm.

  The addition amount of the fine particles 9 in the electrolytic solution is preferably in the range of 1 wt% to 50 wt%, and more preferably in the range of 10 wt% to 30 wt%. In this embodiment, it is 20 wt%.

  The transparent electrode 2 on the upper substrate 1 and the transparent electrode 4 on the lower substrate 5 are connected to the DC power source 10. When the switch 11 is turned on, a predetermined voltage is applied between the transparent electrode 2 and the transparent electrode 4.

  The opaque electrode 3 on the upper substrate 1 and the transparent electrode 4 on the lower substrate 5 are connected to the DC power source 20. When the switch 21 is turned on, a predetermined voltage is applied between the opaque electrode 3 and the transparent electrode 4.

  A backlight 30 is disposed below the lower substrate 5 (on the side opposite to the upper substrate 1 with respect to the lower substrate 5). In this embodiment, a backlight 30 that emits white light is used. The control device 40 controls voltage application between the transparent electrode 2 and the transparent electrode 4, voltage application between the opaque electrode 3 and the transparent electrode 4, and lighting and extinguishing of the backlight 30.

  Next, control of the coloring state of the electrochromic film 6 will be described. A voltage can be applied to the electrochromic film 6 by applying a voltage between the transparent electrode 2 on the upper substrate 1 and the transparent electrode 4 on the lower substrate 5 shown in FIG.

  The electrochromic film 6 is almost transparent when no voltage is applied. By applying a negative voltage to the electrochromic film 6, positive charges are injected from the electrolyte layer 8 into the electrochromic film 6. Thereby, the electrochromic film 6 is colored blue. As the voltage applied to the electrochromic film 6 is lowered (the absolute value of the negative voltage is increased), the coloring becomes deeper. The negative voltage necessary for sufficiently coloring the electrochromic film 6 is, for example, −1V.

  FIG. 2 is a transmission spectrum of the electrochromic film in a voltage non-application state and a voltage application state (−1 V). The horizontal axis indicates the wavelength in nm, and the vertical axis indicates the transmittance in%. A curve C1 is a spectrum when no voltage is applied, and a curve C2 is a spectrum when no voltage is applied. The transmission characteristics of the pixel portion of the cell of the example are shown.

  When no voltage is applied, the transmittance is almost constant at 80% in the wavelength range of 400 nm to 800 nm. On the other hand, when -1V is applied, the transmittance is about 80% in the wavelength range of 400 nm to 450 nm. However, when the wavelength exceeds 450 nm, the transmittance decreases, and the transmittance is about 45% at the wavelength of 600 nm. Become. In the wavelength range of 600 nm to 800 nm, the transmittance is about 45%. That is, the electrochromic film is transparent when no voltage is applied, and is colored blue when the voltage is applied.

  Thus, the transparent state and the colored state (blue state) of the electrochromic film can be switched by voltage control between the transparent electrode on the upper substrate and the transparent electrode on the lower substrate.

  Next, control of the reflectance (or transmittance) of the electrolyte layer 8 will be described. Fine particles 9 are dispersed throughout the electrolyte layer 8 without applying a voltage between the opaque electrode 3 on the upper substrate 1 and the transparent electrode 4 on the lower substrate 5 shown in FIG. The electrolyte layer 8 in which the fine particles 9 are dispersed as a whole has a high reflectance and exhibits a white color.

  When a sufficiently high positive voltage is applied to the opaque electrode 3 on the upper substrate 1, an in-plane direction (upper transparent electrode 2 and lower transparent electrode 4) is generated by an electric field generated in the electrolyte layer 8 (by electrophoresis). With respect to the direction perpendicular to the opposing direction), the flow of the electrolyte solution occurs and the fine particles 9 move, and the fine particles 9 gather below the opaque electrode 3 (collect at the edge of the opening window). As a result, fine particles are not distributed in the opening window (at least in the center of the opening window), and the electrolyte layer 8 in the opening window becomes transparent. The positive voltage necessary for collecting the fine particles 9 in the vicinity of the opaque electrode 3 is, for example, 40V. The movement of the fine particles is mainly controlled by the electric field strength. For example, when the distance between the electrodes is 75 μm and the applied voltage is 40 V, the electric field is about 0.5 V / μm (5000 V / cm).

  The fine particles 9 gathered in the vicinity of the opaque electrode 3 remain in the vicinity of the opaque electrode 3 even if the application of the positive voltage to the opaque electrode 3 is canceled. That is, even if the application of the positive voltage to the opaque electrode 3 is canceled, the transparent state in the opening window is maintained.

  Again, in order to disperse the fine particles 9 throughout the electrolyte layer 8 (or in the opening window), a sufficiently high positive voltage (for example, 40 V) is applied to the transparent electrode 4 on the lower substrate 5 to The fine particles 9 are returned above 4. Thereafter, even if the application of the positive voltage to the transparent electrode 4 is canceled, the dispersed state of the fine particles 9 is maintained.

  3A to 3D are photomicrographs showing how fine particles move due to voltage application. FIG. 3A is a photograph corresponding to a state in which no voltage is applied, in which white fine particles are uniformly distributed in the electrolyte layer. The fine particles start moving when voltage is applied. FIGS. 3B to 3D are photographs showing the distribution of fine particles in order of the elapsed time from the start of voltage application. As time passes, the fine particles are in the vicinity of the opaque electrode that defines the opening window. Gathered in.

  FIG. 4A shows the reflectivity (indicated by white circles) of the electrolyte layer in the aperture window when the fine particles are dispersed throughout the electrolyte layer (fine particle dispersed state), and the fine particles gathered under the opaque electrode. It is a graph which shows the viewing angle dependence of the transmittance | permeability (it shows with a black circle) of the electrolyte layer in an opening window in a state (fine particle movement state). The horizontal axis indicates the viewing angle in degrees, and the left vertical axis and the right vertical axis indicate the reflectance and transmittance in%, respectively. The measurement is performed on an apparatus having the same electrode structure as that of the apparatus shown in FIG. 1 and having no electrochromic film formed thereon. Therefore, it corresponds to the measurement of optical characteristics when the electrochromic film is in a transparent state (non-colored state).

  FIG. 4B is a schematic cross-sectional view of the electrolyte layer 8 for explaining the reflectance measurement method. The reflectance of the electrolyte layer 8 was measured with respect to the light LI that isotropically incident on the surface of the electrolyte layer 8 from the diffusion light source. The viewing angle θ (reflection measurement angle θ) is defined by an angle formed between the normal direction of the surface of the electrolyte layer 8 and the reflected light LR to be measured. For each viewing angle, the reflectance of the standard white plate is 100%.

  As shown in FIG. 4A, in the state where the fine particles are dispersed throughout the electrolyte layer, the reflectance is approximately constant at about 50% in the range of viewing angle of about 0 ° to 60 °. The reflectivity of newspaper is about 40%. In this way, a brighter reflectance than newspaper can be stably obtained over a wide viewing angle range.

  Further, in a state where the fine particles are gathered under the opaque electrode, the transmittance is approximately constant at about 90% in the viewing angle range of about 0 ° to 20 °. The transmittance slightly decreases at a viewing angle of 20 ° or more, but is 80% or more even at a viewing angle of 60 °.

  As described above, the electrolyte layer in which the position distribution of the fine particles is controlled functions as a reflection plate that exhibits natural scattering reflection in a wide viewing angle range, and also functions as a very bright transmission plate in a wide viewing angle range.

  As described above, by switching the voltage between the opaque electrode on the upper substrate and the transparent electrode on the lower substrate, the reflection state (white state) and the transparent state of the electrolyte layer in the opening window are switched. Can do.

  Next, with reference to FIGS. 5A to 5D, a method of using the display device according to the embodiment will be described. An example of using as a reflective display device in a bright place and further as a transmissive display device using a backlight in a dark place will be described. The display state in the opening window is observed from above.

  5A and 5B are schematic cross-sectional views of a display device in a state where it is used as a reflective display device. 5A and 5B, the electrolyte layer 8 is in a reflective state, and the backlight 30 is in an extinguished state. External light 50 enters the upper substrate 1 from above and is reflected upward by the electrolyte layer 8.

  In FIG. 5A, the electrochromic film 6 is in a transparent state. Since the electrolyte layer 8 under the electrochromic film 6 is in a reflective state (white state), the inside of the opening window looks white in FIG. In this way, white display in the reflective display device is realized.

  In FIG. 5B, the electrochromic film 6 is in a colored state (blue state). Light that has passed through the electrochromic film 6 from above, reflected by the electrolyte layer 8, and again transmitted through the electrochromic film 6 and emitted upward appears blue. In this way, blue display in the reflective display device is realized.

  FIG. 5C and FIG. 5D are schematic cross-sectional views of a display device in a state where it is used as a transmissive display device. 5C and 5D, the electrolyte layer 8 is in a transmissive state and the backlight 30 is in a lit state. Light emitted from the backlight 30 enters the lower substrate 5 from below and exits upward from the upper substrate 1.

  In FIG. 5C, the electrochromic film 6 is in a transparent state. Since the electrolyte layer 8 is also in a transparent state, the inside of the opening window appears white (the color of light emitted from the backlight 30). In this way, white display in the transmissive display device is realized.

  In FIG. 5D, the electrochromic film 6 is in a colored state (blue state). The electrolyte layer 8 is in a transparent state. The light transmitted through the electrochromic film 6 from below appears blue. In this way, blue display in the transmissive display device is realized.

  For example, it is possible to use the backlight 30 in a dark place with the electrolyte layer 8 in a reflective state (white state) (the backlight 30 is turned on in FIGS. 5A and 5B). Or when the electrolyte layer 8 is in a white state in FIGS. 5C and 5D). At this time, since the electrolyte layer 8 functions as a transmission / scattering member, a display state different from the case of FIGS. 5C and 5D in which the electrolyte layer 8 is a transparent member is obtained.

  When used as a reflective display device, black display can also be realized by making the electrolyte layer 8 transparent with the backlight 30 turned off (FIG. 5A or FIG. 5B). Thus, when the electrolyte layer 8 is in a transparent state, or corresponds to a state in which the backlight 30 is turned off in FIG. 5C or FIG. 5D).

  As described above, the display device of the embodiment can generate various display states by combining the change in the coloring state of the electrochromic film and the change in the reflectance of the electrolyte layer. Furthermore, it is also possible to generate more various display states by combining changes in lighting and extinguishing of the backlight.

  Next, with reference to FIG. 6 (A), FIG. 6 (B), and FIG. 7, the effect of improving the moving speed of the fine particles of CTC will be described. FIG. 6A shows the molecular structure of BIQI (n-butyl-isoquinolinium-iodide), which is a CTC used in this example.

  FIG. 6B is a graph showing the results of measuring the applied voltage dependence of the moving speed of the fine particles while changing the amount of CTC added. The horizontal axis indicates the applied voltage in V units, and the vertical axis indicates the movement speed of the fine particles in arbitrary units. Curves C3 to C6 show the results when the CTC addition amount is 0 wt%, 0.005 wt%, 0.007 wt%, and 0.038 wt%, respectively.

  When CTC is not added (addition amount 0 wt%), the moving speed of the fine particles is almost independent of the applied voltage. By adding CTC, the moving speed of CTC can be increased as the applied voltage is increased. Moreover, the moving speed at a predetermined applied voltage increases as the amount of CTC added increases. This is remarkable when the applied voltage is about 20 V or more. At about 20V, the microparticles begin to move.

  FIG. 7 is a graph showing the results of an experiment for examining how the response time until the inside of the aperture window becomes transparent when switching from the fine particle dispersion state to the fine particle movement state changes due to the addition of CTC. A comparison was made between a system in which fine particles are dispersed only in liquid crystal and a system in which fine particles are dispersed in liquid crystal added with CTC. The measurement is performed on an apparatus having the same electrode structure as that of the apparatus shown in FIG. 1 and having no electrochromic film formed thereon.

  The horizontal axis of the graph indicates time in seconds, and the vertical axis indicates transmittance in%. A curve C7 is a result when only the liquid crystal is used, and a curve C8 is a result when CTC is added to the liquid crystal. In the case of only the liquid crystal, the transmittance reaches nearly 90% and is saturated in about 100 msec. On the other hand, when CTC is added, the transmittance reaches nearly 90% and is saturated in about 50 msec.

  As described above, by using the electrolyte layer to which CTC is added, the moving speed of the fine particles is improved, and the switching between the reflective state and the transparent state of the electrolyte layer becomes faster. That is, the switching between the reflective display device and the transmissive display device becomes faster.

  A display device that can be switched at high speed has the following advantages when applied to, for example, an in-vehicle display. When used as an in-vehicle display, when the headlight is not lit (when used in a bright place), it is used as a reflective display device. When the headlight is lit (when used in a dark place), the backlight is turned on and transmitted. A mode of use as a mold display device is conceivable.

  For example, it is desired that the reflective display device and the transmissive display device can be switched instantaneously when passing through the tunnel. Even when such instantaneous switching is required, the response time of 50 msec can be said to be sufficiently fast.

  Although the basic display technology for one pixel has been described in the above embodiment, a multi-pixel display device can be manufactured by applying the display device of the embodiment. Either a simple character display (static drive display) or a display device that performs dot matrix display having an electrode arrangement in which an active element is arranged in each pixel can be manufactured.

  As described above, when the display device of the embodiment is used as a reflection type display device, the display is performed with a colored electrochromic film on the electrolyte layer serving as a diffuse reflection member, so that it is bright and natural from any point of view. A reflective display can be obtained. In addition, since the electrolyte layer serving as the diffuse reflection member and the electrochromic film for display are in close contact, there is no parallax during reflective display.

  When used as a transmissive display device, a backlight technology can be used as an auxiliary light source in a dark place, so that a cheaper and brighter display can be obtained compared to the case of using a frontlight technology. Further, when used as a transmission type, the electrolyte layer can be made transparent, so that the luminance of the backlight does not have to be so high. For this reason, power consumption can be suppressed. This is particularly beneficial in portable devices.

  In the front light technology, since the light guide plate is disposed in front of the display unit, disadvantages such as a reduction in display quality (decrease in reflectivity and a decrease in contrast due to surface reflection) and an increase in cost may occur. .

  In the conventional reflective MFPD, the light absorption layer is made semi-transmissive, or in the conventional reflective electrochromic display, the reflective member is made semi-transmissive so that the backlight technology is adopted. It would be possible to perform type indication. However, since the light absorbing layer or the reflecting member is semi-transmissive, it is necessary to increase the luminance of the backlight.

  The case where the optical device according to the embodiment is used as a display device has been described above. However, the optical device according to the embodiment can be used other than the display device. For example, it can be used as a lighting device. For example, consider the case of use for light distribution control of general illumination. The description will be continued with reference to FIGS. 5 (A) to 5 (D) again.

  5A and 5B, the electrolyte layer 8 is in a white state and the backlight 30 is in an extinguished state. External light 50 enters the upper substrate 1 from above and is reflected upward by the electrolyte layer 8.

  In FIG. 5A, the electrochromic film 6 is in a transparent state, and this lighting device functions as a white wallpaper. In FIG. 5B, the electrochromic film 6 is in a blue state, and this lighting device functions as a blue wallpaper.

  5 (C) and 5 (D), the electrolyte layer 8 is in a transparent state, and the backlight 30 is in a lighting state. In FIG. 5C, the electrochromic film 6 is in a transparent state, and a white spot light source (when the backlight 30 is white light) is realized. Note that if the emission color of the backlight 30 is changed, a spot light source of a different color can be obtained. In FIG. 5D, the electrochromic film 6 is in a blue state, and a blue spot light source is realized.

  Note that the electrolyte layer 8 can be in a white state and the backlight 30 can be turned on (when the backlight 30 is turned on in FIGS. 5A and 5B, or FIG. 5C). And corresponding to the case where the electrolyte layer 8 is in a white state in FIG. 5D). If the electrochromic film 6 is in a transparent state, a white diffused light source is realized, and if the electrochromic film 6 is in a blue state, a blue diffused light source is realized.

  As described above, the optical device according to the embodiment can be used as, for example, a display device that can switch between a reflective type and a transmissive type, or an illumination device that can switch between a spot type and a diffusive type. A display device that is easy to see in various environments is realized, and an illumination device that generates various light distribution states is realized.

  In the above embodiment, an electrochromic film that is colored blue is used. However, if an electrochromic film material that is colored in another color is used, a display device, a lighting device, or the like using another color can be manufactured.

In the above example, an electrochromic film made of WO ₃ was used, and the electrochromic film was colored by applying a negative voltage. For example, when an electrochromic film made of a viologen-based material is used, the electrochromic film is colored by applying a positive voltage.

  For example, let us consider a state where fine particles are gathered in the vicinity of an opaque electrode and the inside of the opening window is transparent. In this state, in order to color the electrochromic film, a voltage is applied between the transparent electrode on the upper substrate on which the electrochromic film is formed and the transparent electrode on the lower substrate. At this time, one of the transparent electrodes on the upper and lower substrates has a positive voltage with respect to the other. If this voltage for coloring the electrochromic film is too large, the fine particles may move from the vicinity of the opaque electrode into the opening window. In order to suppress such problems, it is desirable that the magnitude (absolute value) of the voltage for coloring the electrochromic film is sufficiently smaller than the magnitude (absolute value) of the voltage for moving the fine particles.

  As described above, the magnitude of the voltage for coloring the electrochromic film is, for example, 1 V, and the magnitude of the voltage for moving the fine particles is, for example, 40 V (for example, the fine particles begin to move at about 20 V). In this example, the transparent state and the colored state of the electrochromic film can be switched so as to hardly affect the position distribution of the fine particles. The magnitude of the voltage for moving the fine particles will preferably be at least 10 times the magnitude of the voltage for coloring the electrochromic film (for example, 20V at which the fine particles start moving in the above example is the electrochromic film) 20 times the coloring voltage of 1V).

  In the above embodiment, glass substrates are used as the upper and lower substrates. However, for example, plastic substrates may be used as necessary. A film substrate may also be used.

  In the apparatus of the example, of the electrode pair that controls the coloring state of the electrochromic film, the electrode that does not form the electrochromic film (the electrode on the lower substrate) and the electrode pair that controls the movement of the fine particles Of these, the electrodes in the opening window (electrodes on the lower substrate) are made common, but these electrodes are not made common and a configuration in which they are formed separately is also possible. Note that the structure having a common electrode has an advantage that, for example, the number of terminal electrodes can be reduced and the number of connection points can be reduced.

  Next, an optical device according to a second embodiment will be described. FIG. 8 is a schematic cross-sectional view showing the optical device of the second embodiment. Hereinafter, differences from the apparatus of the first embodiment will be described.

  In the optical device of the second embodiment, an insulating film 50 is formed to cover the transparent electrode 4 on the lower substrate 5, and an electrode 51 having a shape that defines an opening window in plan view is formed on the insulating film 50. Has been. An electrode pair consisting of the transparent electrode 4 on the lower substrate 5 and the electrode 51 on the insulating film 50 is used for the movement control of the fine particles, and the transparent electrode 4 on the lower substrate 5 and the transparent on the upper substrate 1 are transparent. An electrode pair including the electrode 2 is used for controlling the coloring state of the electrochromic film 6.

  A light shielding film 52 is formed on the upper substrate 1 so as to define an opening window in plan view. The light shielding film 52 hides the fine particles so that the fine particles are not seen from above in a state where the fine particles are collected in the vicinity of the electrode 51 (at the edge of the opening window). In the electrode structure of the first embodiment, the opaque electrode 3 on the upper substrate 1 can be formed so as to function as a light shielding film.

  Examples of products that can be used for the optical device according to the embodiment will be described below. The optical apparatus according to the embodiment is a reflective or transmissive display, such as a display surface of an information device (personal computer, portable information terminal, mobile phone, etc.) that saves power and does not require frequent rewriting, and a projection display in general. Can be used for information display surfaces of magnetically or electrically recorded cards, can be used for children's toys, etc., and can be used for general substitutes (electronic paper) for paper and printed materials (magazines, newspapers, posters, etc.) Can be used for automotive (in-vehicle) displays, aircraft displays, clock displays, digital still cameras (strobe lights, optical systems, viewfinder displays, etc.) , Trucks, buses, etc.) lamps and interior lighting, motorcycle (motorcycles, bicycles, etc.) lamps (light distribution control unit), general lighting (indoor Akira, street light, can be used for the light distribution control unit of the flashlight, etc.).

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

FIG. 1 is a schematic sectional view of an optical device according to the first embodiment. FIG. 2 is a transmission spectrum of the electrochromic film. 3A to 3D are photomicrographs showing how fine particles move due to voltage application. FIG. 4A is a graph showing the viewing angle dependence of the reflectance and transmittance of the electrolyte layer in the opening window, and FIG. 4B is a graph of the electrolyte layer for explaining the reflectance measurement method. It is a schematic sectional drawing. FIGS. 5A and 5B are schematic cross-sectional views of the optical device of the embodiment in a state where it is used as, for example, a reflective display device, and FIGS. FIG. 1 is a schematic cross-sectional view of an optical device according to an embodiment in a state where it is used, for example, as a transmissive display device. 6A is an example of the molecular structure of CTC, and FIG. 6B is a graph showing the applied voltage dependence of the moving speed of the fine particles. FIG. 7 is a graph showing the response time until the inside of the aperture window becomes transparent when the particle dispersion state is switched to the particle movement state. FIG. 8 is a schematic cross-sectional view of the optical device according to the second embodiment. 9A and 9B are schematic cross-sectional views illustrating examples of MFPD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper substrate 2 Transparent electrode 3 Opaque electrode 4 Transparent electrode 5 Lower substrate 6 Electrochromic film 7 Main seal layer 8 Electrolyte layer 9 Fine particle 10, 20 DC power source 11, 21 Switch 30 Backlight 40 Controller 50 External light

Claims (5)

An electrochromic film is formed on one electrode, and a first electrode pair for applying a voltage to the electrochromic film;
An electrolyte layer disposed between the first electrode pair and containing fine particles;
An optical apparatus comprising: a second electrode pair that moves the fine particles in an in-plane direction of the electrochromic film by generating an electric field in the electrolyte layer and collects the fine particles in the vicinity of one of the electrodes.   Furthermore, it has voltage application means for applying a first voltage between the first electrode pair and applying a second voltage between the second electrode pair, and the magnitude of the second voltage. The optical device according to claim 1, wherein is 10 times or more the magnitude of the first voltage. further,
A first substrate;
A second substrate disposed opposite to the first substrate,
One of the first electrode pairs, a first electrode on which the electrochromic film is formed, and one second electrode of the second electrode pair are formed on the first substrate, The other electrode of the first electrode pair and the other electrode of the second electrode pair are a common third electrode, and the third electrode is formed on the second substrate. The optical device according to claim 1.   The optical device according to any one of claims 1 to 3, wherein a particle diameter of the fine particles is in a range of 0.5 µm to 100 µm.   The optical device according to claim 1, wherein a charge transfer complex is added to the electrolyte layer.