JP2014048353A - Suspended particle device, dimmer using the suspended particle device, driving device for driving the suspended particle device and driving method thereof - Google Patents

Abstract

An optical state change when a suspended particle device is stopped is delayed.
Suspended particles having a first substrate and a second substrate, and a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate. The suspension includes light adjustment particles and a dispersion medium, the light adjustment particles are dispersed in the dispersion medium, and the concentration of the light adjustment particles in the suspension is 1 vol% or more and 10 vol% or less. A suspended particle device in which a response time in which the transmittance of the suspended particle device changes is controlled by an alternating voltage applied between the electrode and the second electrode.
[Selection] Figure 8

Description

  The present invention relates to a suspended particle device, a light control device using the suspended particle device, and a driving method thereof.

  As a conventional example, Patent Document 1 discloses the following technique. The light control device of Patent Document 1 includes an energy beam curable polymer medium containing a resin having an ethylenically unsaturated bond and a photopolymerization initiator, and light dispersed in a dispersion medium in a state where the light control particles can flow. A light control material containing droplets of the adjusted suspension, wherein the dispersion medium in the light adjusted suspension is capable of phase separation from the polymer medium and a cured product thereof, and has an ethylenically unsaturated bond. The resin has an ethylenically unsaturated bond concentration of 0.3 to 0.5 mol / kg.

  Patent Document 2 discloses the following technique. The light control device of Patent Document 2 includes a pair of substrates, a viscoelastic body or elastic body including fine particles or fine particle aggregates arranged in a certain direction with respect to the substrate between the substrates, and shearing into the viscoelastic body or elastic body. An all-solid-state light control device comprising a device that exerts stress. The light control method of the all-solid light control device is characterized in that the viscoelastic body or an apparatus that applies a shear stress to the elastic body applies a shear stress to control light transmittance.

  Patent Document 3 discloses the following technique. At least one of them forms a cell with a dispersion system in which fine particles are dispersed between transparent substrates, and the fine particles are moved by an electric field to transmit light in the direction perpendicular to the substrate of the cell or reflect light. In the display device that changes the electric characteristics, the electrode pitch p between the drive electrode and the common electrode provided for applying the electric field is 5 μ to 100 μ, the cell thickness d is 0.2 to 1.5 times the p, By making the electrode area ratio 20% or less, high transmittance, high contrast, low voltage driving monochrome and color display can be made thin, light and high speed, ultra high definition light modulation element, portable device display, electronic It can be applied to various fields such as paper, large monitors, large TVs, and super large public displays.

JP 2008-209953 A Japanese Patent Application Laid-Open No. 5-019306 JP 2008-158040 A

  In Patent Document 2, the dispersion medium for the fine particles is a solid viscoelastic body, and the arrangement state of the fine particles between the substrates is maintained even when no voltage is applied. However, in order to uniformly disperse the fine particles in the dispersion medium, a device for applying a shear stress for breaking the arrangement state of the fine particles is necessary. Therefore, it is difficult to perform a reversible fine particle state and dimming operation by simple electrical control as in Patent Document 1.

  In Patent Document 3, a cell is formed by sandwiching a dispersion system in which charged fine particles are dispersed in a transparent liquid or gas medium between at least one transparent substrate, and the state of fine particle dispersion in the cell is determined. The cell is optically shielded in a direction perpendicular to the substrate, and a voltage is applied between the electrode between the common electrode and the driving electrode made of a thin wire provided between the substrates to move the fine particles horizontally to the substrate. Then, it is deposited on the thin line drive electrode to modulate and maintain the optical shielding state, that is, the transmittance of the cell by modulating the amount of dispersed fine particles. Therefore, when the optical shielding state is modulated, the optical shielding state in the cell is uniform due to the difference in the amount of the particulates in the electrode part where the particulates are deposited in the cell and the other optical modulation part. May be low. Further, when the fine drive electrode is miniaturized to improve the uniformity of the optical shielding state, there may be problems such as high cost of the electrode formation method, disconnection, and malfunction due to electrode nonuniformity. .

  Therefore, the conventional suspended particle device suppresses sudden changes in the optical state due to sudden stoppage of drive voltage application, and uniform and reversible optical modulation operation without the need for modulation and mechanical action of the transmission state. It was difficult to achieve both. An object of the present invention is to delay a change in the optical state of a suspension apparatus when the suspension particle apparatus is capable of performing a uniform and reversible optical modulation operation.

  The features of the present invention for solving the above problems are as follows, for example.

  A suspended particle device having a first substrate and a second substrate, and a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate, The suspension includes light adjusting particles and a dispersion medium. The light adjusting particles are dispersed in the dispersion medium, and the concentration of the light adjusting particles in the suspension is 1 vol% or more and 10 vol% or less. The suspension particle device, the light control device using the suspension particle device, and the suspension particle device are driven in which the response time in which the transmittance of the suspension particle device is changed by the AC voltage applied between the two electrodes is controlled. Driving device and driving method thereof.

  A suspended particle device having a first substrate and a second substrate, and a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate, The suspension includes light adjusting particles and a dispersion medium, the light adjusting particles are dispersed in the dispersion medium, and the concentration of the light adjusting particles in the suspension is 1 vol% or more and 4 vol% or less. Light control device using particle device, driving device for driving suspended particle device, and driving method thereof.

  According to the present invention, it is possible to increase the response time of the optical state change when the suspension particle device is stopped. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing which shows the structure of the suspended particle apparatus of one Embodiment. It is explanatory drawing which shows the structure of the light modulation apparatus using the suspended particle apparatus of one Embodiment. In the suspended particle apparatus of one Embodiment, it is explanatory drawing of a structure and drive waveform of the drive method which controls a light control state. In the suspended particle apparatus of FIG. 1, it is a figure which shows the state of the light adjustment particle | grains in a stop. FIG. 2 is a diagram showing a state of light adjusting particles during driving in the suspended particle device of FIG. 1. In the suspended particle apparatus of one Embodiment, it is explanatory drawing which shows the relationship of the transmittance | permeability with respect to the drive voltage of a sustain period. It is a graph which shows the response time in the stop period of one Embodiment. It is a measurement result of the response time of the drive method and transmittance | permeability fluctuation | variation in the stop period of one Embodiment. It is a measurement result of the response time of the drive method and transmittance | permeability fluctuation | variation in the stop period of one Embodiment. It is a measurement result of the response time of the drive method and transmittance | permeability fluctuation | variation in the stop period of one Embodiment. It is sectional drawing which shows the structure of the suspended particle apparatus of one Embodiment. 6 is a graph illustrating a response time of a dimming operation due to a driving method and a transmittance variation in the suspended particle device of one embodiment. 6 is a graph illustrating a response time of a dimming operation due to a driving method and a transmittance variation in the suspended particle device of one embodiment. It is explanatory drawing of the drive method of the suspended particle apparatus of one Embodiment. It is explanatory drawing of the drive method of the suspended particle apparatus of one Embodiment. It is explanatory drawing of the drive method which comprised the drive method of FIG. 11 periodically. It is explanatory drawing of the drive method which comprised the drive method of FIG. 11 periodically. In the suspension particle device of one embodiment, it is a graph which shows the relation between the drive method in the stop period with respect to the light control particle concentration, and the response time of transmittance variation. In the suspended particle device of one embodiment, it is a graph which shows the relationship of the response time of the transmittance | permeability fluctuation | variation in the transmission drive transition with respect to the light adjustment particle | grain density | concentration and a start period.

  The contents of the present invention will be described in detail below by showing specific examples. The following examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples, but by those skilled in the art within the scope of the technical idea disclosed in this specification. Various changes and modifications are possible. Further, in all the drawings for explaining the embodiments, the same reference numerals are given to those having the same function, and the repeated explanation thereof may be omitted.

  In the specification, numerical ranges indicated using “to” indicate ranges including numerical values described before and after “to” as the minimum value and the maximum value, respectively.

<SPD>
In order to facilitate understanding of this embodiment, the basic structure of the SPD studied by the present inventors will be described. The suspended particle device (SPD) 1 includes a B plate 2, an A plate 3 and a suspension 8. In this embodiment, the “A plate 3” and the “B plate 2” of the two substrates that are arranged opposite to each other and constitute the SPD 1 are the X electrodes 7 of the electrode pair that forms an electric field in the suspension between the substrates. The substrate on which the Y electrode 5 is disposed is the A plate 3 and the substrate on which the Y electrode 5 is disposed is the B plate 2. FIG. 1 is a schematic sectional view of an SPD studied by the present inventors. A suspension 8 is sandwiched between the A plate 3 and the B plate 2. The SPD 1 of this embodiment dimmes incident light in the Z-axis direction with respect to the SPD 1.

  First, a conductive substrate and a method for forming the conductive substrate will be described. The A plate 3 and the B plate 2 are respectively formed with an X electrode 7 and a Y electrode 5 which are transparent electrodes made of indium tin oxide (ITO) on the A substrate 6 and the B substrate 4 which are transparent support base materials made of glass. Is done. That is, the X electrode 7, the Y electrode 5, and the suspension 8 are disposed between the A substrate 6 and the B substrate 4. The X electrode 7 and the Y electrode 5 may be formed only on one of the A substrate 6 and the B substrate 4.

  Examples of the transparent support substrate include resin films such as polyethylene terephthalate (PET), polycarbonate (PC), and cycloolefin polymer (COP) in addition to glass.

  The X electrode 7 and the Y electrode 5 may be formed of a transparent conductor such as a metal oxide such as indium zinc oxide (IZO), tin oxide, or zinc oxide, or a carbon material such as carbon nanotube or graphene. In the present embodiment, the transparent electrode is formed on the entire surface of the support substrate, but the present invention is not limited to this, and the transparent electrode may be arranged in a pattern such as a circle or a parallel line or a character type.

Next, the A plate 3 and the B plate 2 are arranged to face each other, and a sealing agent containing spacer beads or the like is applied to opposite sides of both plate end portions (not shown) to bond the both plates. Thereby, a suspension filling space of the suspension 8 in which the distance between both plates is 25 μm is formed. The space for filling the suspension 8 and the distance between the A plate 3 and the B plate 2 are 4 μm or more and 100 μm or less, and spacer beads are dispersed between the A plate 3 and the B plate 2 to suspend the suspension. The filling space of the liquid 8 may be maintained. Examples of the spacer beads include glass and polymer, and it is desirable that the spacer beads are stable with respect to the adhesive.
When spacer beads are dispersed between the A plate 3 and the B plate 2, the spacer beads preferably have a refractive index close to that of the dispersion medium 10.

  The suspension 8 and its formation method will be described. The suspension 8 includes light adjusting particles 9 and a dispersion medium 10. The light adjusting particles 9 are dispersed in the dispersion medium 10. The suspension 8 may be composed only of the light adjusting particles 9 and the dispersion medium 10 or may contain other materials.

The light adjusting particle 9 is, for example, polyperiodide, has an anisotropy in shape, exhibits optical anisotropy having different absorbance due to the orientation direction, and has a shape in which the aspect ratio is not 1. And is negatively charged. It is desirable that the light adjusting particles 9 cause orientation polarization at the frequency of the alternating voltage during the driving period of the suspended particle device and at a frequency equal to or lower than that frequency. In that case, it is desirable to use a dielectric material having low conductivity as the light adjusting particles 9. Examples of the dielectric material having low conductivity include polymer particles and particles obtained by coating a conductor material with a polymer.
The polymer used for the coating may contain a dye, a pigment or the like in order to correct the color tone of SPD1. As the shape of the light adjusting particles 9, a rod shape, a plate shape, or the like can be considered. By making the light adjusting particles 9 into a rod shape, it is possible to suppress the resistance of the particle rotational motion with respect to the electric field and the increase in haze during transmission. For example, the aspect ratio of the light control particles 9 is preferably about 5 or more and 30 or less. By setting the aspect ratio of the light adjusting particles 9 to 5 or more, optical anisotropy caused by the shape of the light adjusting particles 9 can be expressed.

The size of the light adjusting particles 9 is preferably 1 μm or less, more preferably 0.1 μm or more and 1 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less.
When the size of the light adjusting particles 9 exceeds 1 μm, optical properties and driving characteristics are deteriorated, such as light scattering or orientation movement in the dispersion medium 10 when an electric field is applied. Problems may occur. The size of the light adjusting particles 9 is measured by observation with an electron microscope or the like. The particle concentration of the light adjusting particles 9 with respect to the suspension 8 is preferably 1 to 50 vol%, and the above-mentioned orientation movement due to the optical and driving characteristics design of the SPD 1 such as transmittance change and the viscosity increase of the suspension 8 accompanying the concentration increase. It is more desirable that it is 1-10 vol% from the influence on the.
Examples of the light adjusting particles 9 include carbon-based materials such as carbon black, metal materials such as copper, nickel, iron, cobalt, chromium, titanium, and aluminum, and particles made of inorganic compounds such as silicon nitride, titanium nitride, and aluminum oxide. These are positively or negatively charged. Carbon black, metal, etc. may not be charged with a specific charge, but may be particles coated with a polymer having a property of being charged with a specific charge. As the light adjustment particle | grains 9, you may be comprised with one type among said material, and may be contained two or more types.

The dispersion medium 10 is a liquid copolymer made of an acrylate oligomer. Other examples of the dispersion medium 10 include polysiloxane (silicone oil). The dispersion medium 10 has a viscosity at which the light control particles 9 can float, has high resistance, has no affinity with the A substrate 6, the B substrate 4, the X electrode 7, and the Y electrode 5. It is preferable to use a liquid copolymer having a refractive index close to that of the B substrate 4 and having a dielectric constant different from that of the light adjusting particles 9. Specifically, the resistivity of the dispersion medium 10 is desirably 10 ¹² Ωm or more and 10 ¹⁵ Ωm or less at 298K. If there is a dielectric constant difference between the dispersion medium 10 and the light adjusting particles 9, it can act as a driving force under an alternating electric field in the alignment operation of the light adjusting particles 9 described later. In this embodiment, the relative dielectric constant of the dispersion medium 10 is set to 3.5 or more and 5.0 or less.

  The space for filling the suspension 8 is filled with the suspension 8 by capillary action from the end portions of both plates not bonded with the sealing agent. After the suspension 8 is filled between the A plate 3 and the B plate 2, the end portions of the A plate 3 and the B plate 2 which are not bonded are bonded and sealed with a sealing material. Thereby, the suspension 8 is isolated from the outside air. In this embodiment, the suspension 8 is filled by capillary action, but before the A plate 3 and the B plate 2 are bonded to the suspension 8, a bar coating method, a drop injection method (ODF) under vacuum, or the like is used. Then, the A plate 3 and the B plate 2 may be bonded together and bonded and sealed.

<Light control device>
FIG. 2 is an explanatory diagram illustrating the configuration of the light control device 11 including the SPD 1. The light control device 11 includes an SPD 1 and a driving device 15. Each electrode of the SPD 1 and each electrode output circuit of the driving power source 13 in the driving device 15 are connected via an interconnection element 21.

  The driving device 15 that controls the SPD 1 drives and controls the X electrode output circuit 107 and the Y electrode output circuit 105, and the X electrode output circuit 107 and the Y electrode output circuit 105 for driving the SPD 1 with the X electrode 7 and the Y electrode 5. Drive control circuit 12 and drive power supply 13, signal processing circuit 14 for processing an input signal for controlling the dimming region and dimming state, and a long light-shielding dynamic response based on the dimming driving characteristics of SPD 1 described later The memory circuit 200 that stores the driving conditions to be stored is provided. When one of the X electrode 7 and the Y electrode 5 is set to GND, one of the X electrode output circuit 107 and the Y electrode output circuit 105 is not necessarily required. The light control device 11 may include an external signal input device that inputs an external environment information signal related to incident light, temperature, and the like to the signal processing circuit 14.

  The interconnection element 21 preferably has low resistance and low loss, and is composed of conductive rubber (rubber connector), flexible wiring board (FPC), tape carrier package (TCP), conductive tape, and the like. The interconnection element 21 is connected to the X electrode 7, the Y electrode 5, the X electrode output circuit 107, and the Y electrode output circuit 105 by being sandwiched and fixed with resin or the like. Further, if the conductive part such as a metal paste or a conductive polymer or a supporting base material having high heat resistance such as glass is bonded, the conductive part is bonded with solder or the like, thereby connecting the interconnect element 21 and the X electrode. 7, Y electrode 5, X electrode output circuit 107 and Y electrode output circuit 105 may be connected. Examples of the conductive adhesive include a metal paste such as silver, an anisotropic conductive paste, and an anisotropic conductive film (ACF).

  The circuit elements constituting the X electrode output circuit 107, the Y electrode output circuit 105, and other driving devices 15 may be arranged on a flexible wiring board that is the interconnection element 21.

  The light control device 11 of the present embodiment includes, for example, indoor and outdoor partitions, window glass / skylights for buildings, various flat display elements used in the electronics industry and video equipment, various instrument panels, and existing liquid crystals. Substitutes for display elements, optical shutters, various indoor / outdoor advertisements and information signs, window glass for aircraft / railcars / ships, window glass / back mirror / sunroof for automobiles, glasses, sunglasses, sun visors, image sensors, etc. It can use suitably for the use of. As an application method, it is possible to directly use the light control device 11 of the present embodiment. However, depending on the application, for example, the light control device 11 of the present embodiment is sandwiched between two substrates. Or may be used by being attached to one side of the substrate. As the base material, for example, glass, a polymer film, and the like can be used as in the case of the A substrate 6 and the B substrate 4.

<SPD driving method>
Next, a driving method will be described. FIG. 3 is an explanatory diagram of the driving method studied in this embodiment. (I) of FIG. 3 is a configuration diagram of the driving method studied in this embodiment, and includes a start period, a sustain period (dimming period), and a stop period. (II) of FIG. 3 is a drive waveform of the drive method examined in this embodiment. FIG. 4 shows the state of the light adjusting particles 9 in the SPD 1 under each driving condition. In this embodiment, the start period and the sustain period are used as the driving period of SPD1. 4A shows when the SPD is stopped (light-shielding), and FIG. 4B shows the time when the SPD is driven (during driving and transmission).

The start period corresponds to the dimming start period, that is, the transmission operation in this embodiment. In the start period, an AC waveform of voltage VON (hereinafter also simply referred to as voltage) V _ON is applied to the Y electrode 5 or the X electrode 7, and an AC electric field is formed between the X electrode 7 and the Y electrode 5. In the SPD 1 of the present embodiment, the voltage V _{ON is set} to 150 V because of the pressure resistance of the dispersion medium 10 and the suspension 8. In response to this AC electric field, the light adjusting particles 9 in the suspension 8 are in a disordered state (random) due to Brownian motion, but are applied to the applied voltage V _ON so as to follow the electric field direction due to dielectric polarization or the like. Orient accordingly. The incident light 20 is modulated by the aligned light adjusting particles 9. The state in which the transmittance of the SPD increases is an open state. If the electric field and the particle orientation direction are the same as those of the incident light 20, the incident light 20 can pass through the suspension 8 as shown in FIGS. 4A and 4B, and the transmittance T of the SPD 1. Rises. The frequency f _{ON of the} start period is a condition that allows the light adjusting particles 9 to be oriented in the dispersion medium 10. The concentration, the dielectric constant, the shape of the light adjusting particles 9, the affinity with the dispersion medium 10, etc. It is determined by electrical characteristics such as dielectric constant and impedance of the medium 10, viscosity, etc., and is preferably 1000 Hz or less. The frequency f _{ON of the} start period is desirably 15 Hz or more, but is not limited thereto.

Further, as a method of forming an AC electric field, one of the X electrode 7 and the Y electrode 5 is set to G.N.D, an AC waveform is applied to the other electrode, or the polarity is different in 1/2 cycle. An AC waveform may be applied simultaneously to each of the X electrode 7 and the Y electrode 5. By simultaneously applying AC waveforms having different polarities in ½ cycle to each of the X electrode 7 and the Y electrode 5, a circuit element having low pressure resistance can be used. In FIG. 3, f _ON is constant, but f _ON may be modulated.

The sustain period corresponds to a dimming period, that is, to maintain a predetermined transmission state in this embodiment. In the sustain period, an AC waveform having a voltage V _S (√2V _{S in} FIG. 3) is applied to the Y electrode 5 at a frequency f _S of 16 Hz to 1000 Hz, preferably 50 Hz to 1000 Hz. An alternating electric field is formed between the electrodes of the electrode 5. The time when the transmittance of the SPD that has risen in the start period becomes almost constant is the start of the sustain period. In the sustain period, the SPD transmittance at a predetermined voltage V _S is maximized. The frequency f _{S of the} AC electric field needs to be driven at a frequency higher than that maintained in a state in which the light adjusting particles 9 are oriented in the direction of the electric field between the electrodes, and should be higher than a critical fusion frequency (CFF). Desirably, preferably 16 Hz or more. In FIG. 3, the frequency f _{S in the} sustain period is the same as the frequency f _{ON in the} start period, but f _S and f _ON may be different values. In the SPD 1 of the present embodiment, the maximum value of the voltage V _S is 150 V because of the pressure resistance of the dispersion medium 10 and the suspension 8.
In this embodiment, the voltage V _{S in the} sustain period is the same as the voltage V _{ON in the} start period, but may be a different voltage value. Further, alternating waveforms having different polarities in half cycles may be applied simultaneously to the X electrode 7 and the Y electrode 5.

The stop period corresponds to a dimming stop period, that is, a light shielding operation in this embodiment. In the stop period, the voltage V _OFF applied to the Y electrode 5 and the X electrode 7 is set to 0V, and the AC voltage between the electrodes of the X electrode 7 and the Y electrode 5 is set to 0V, that is, an equipotential. As a result, the light adjusting particles 9 in the suspension 8 change from a predetermined orientation state in the electric field direction by the voltage V _S to a disordered state by Brownian motion, and the light incident on the suspension 8 is absorbed and scattered. Therefore, as shown in FIG. 4A again, the incident light 20 cannot be transmitted through the suspension 8 and is blocked. The time when the drive waveform application between the X electrode 7 and the Y electrode 5 of the SPD 1 is stopped is the start of the stop period.

  As described above, the light adjusting particles 9 reversibly change between a disordered state and an oriented state. This embodiment relates to a dimming stop operation from a transmission state to a light shielding state.

<Dimming drive characteristics with respect to drive voltage>
FIG. 5 shows the drive waveform with respect to the voltage V _S of the drive waveform of the SPD 1 when the drive waveform is the sine wave of FIG. 3 (II), the frequency f _S is 50 Hz, and the concentration of the light control particles 9 in the suspension 8 is 1 to 10 vol%. It is a graph which shows the relationship of the linear transmittance | permeability T of the incident light to the board | substrate of an electric field direction, ie, the voltage dependence of a light control operation.

From FIG. 5, when the voltage V _S rises in the range of the voltage V _S from 0 to 150 V, the transmittance T also increases to around 40 to 50 V as in the S-shaped function. 8 is almost constant when the concentration of the light adjusting particles 9 is 1 to 6 vol%, and slightly decreases when the concentration is higher.

<Drive waveform and dimming stop response>
FIG. 6 shows an SPD 1 in which the concentration of the light control particles 9 in the suspension 8 is 10 vol%, the drive waveform is the sine wave of FIG. 3 (II), f _ON and f _S are 50 Hz, voltages V _ON and V _S Is a graph showing the response time t _OFF of the light-shielding operation in the stop period when the voltage rise is set to 40 V near the maximum transmittance due to the voltage increase. The vertical axis in FIG. 6 represents the transmittance variation ΔT with respect to the transmittance change from the transmittance T at t _OFF = 0 to the minimum transmittance T in the light shielding operation.

In the case of the SPD 1 having reversibility in the light control operation, the main factor of the light shielding operation in the stop period is a change from the orientation state of the light control particles 9 to the disordered state due to the Brownian motion. Therefore, the drive waveform using a normal sine wave as shown in FIG. 5 in this embodiment generally depends on the physical properties of the suspension 8 but the time required for the light shielding operation is generally short. As shown in FIG. 6, when the drive voltage application of the suspended particle device is suddenly stopped with the voltages V _ON and V _{S being} as low as 40 V, the optical state of the suspended particle device is changed to the state before the drive voltage is applied. It changes rapidly.

Therefore, in this embodiment, the drive waveform in the sustain period is controlled to increase the response time t _OFF of the light shielding operation. In this embodiment, the voltage V _S applied between the X electrode 7 and the Y electrode 5 for forming an alternating electric field is set to a predetermined voltage. A method for setting the voltage V _S will be described below.

The voltage V _S is determined based on the dimming driving characteristic measurement result with respect to the driving voltage in FIG. In this embodiment, the voltage V _S is set to a voltage value at which the change in transmittance with respect to the voltage V _s is constant or slightly decreased during the sustain period in FIG. It can be said that the electric field strength is set to 3.2 × 10 ⁶ V / m or more because the AC voltage V _S during the dimming period is 80 V or more and the electrode interval by the spacer beads is 25 μm. By controlling the AC voltage in the light control period in this way, the time for reducing the transmittance of the suspended particle device is made longer than the response time of the light shielding period of the SPD 1 before the AC voltage is controlled. As can be seen from FIG. 15 to be described later, the higher the concentration of the light adjusting particles 9, the shorter t _OFF (ΔT (100% −20%)) at the voltage V _S 60V. Therefore, in order to lengthen the time for reducing the transmittance of the suspended particle device, the concentration of the light control particles 9 in the suspension 8 is 4 to 10 vol%, preferably 6 to 10 vol%.

FIG. 7 shows the response time of the light-shielding operation in the stop period with respect to 40 V in FIG. 6 with f _ON and f _{S set} to 50 Hz, and the voltages V _ON and V _{S set} to 150 V which becomes a substantially constant transmittance state due to voltage increase in the sustain period. t is a graph showing a comparison of _OFF. The vertical axis in FIG. 7 represents the transmittance variation ΔT with respect to the transmittance change from the transmittance T at t _OFF = 0 to the minimum transmittance T in the light shielding operation.

From FIG. 7, in the SPD 1 of this embodiment, the response time t _OFF of the light shielding operation at a voltage of 150 V, which is almost constant or slightly changed without changing the transmittance T with respect to the voltage V _S , is near the maximum transmittance. It is longer than the voltage 40 V, which is the voltage V _S. Accordingly, when driven in the high transmittance state during the sustain period, the response increase time t _OFF of the light shielding operation is reduced above the voltage increase range of the S-shaped function with respect to the voltage V _S , that is, the voltage that becomes the maximum transmittance due to the voltage V _S increase. Can be extended. As a result, by controlling the applied voltage in the sustain period without changing the basic structure of the SPD, the SPD and dimming in which the light shielding operation in the stop period is prolonged for the light shielding operation from the same high transmittance state. A device can be obtained.

As can be seen from FIG. 9 described later, in order to increase the response time t _OFF , V _S is preferably as large as possible, specifically 80 V and 3.2 × 10 ⁶ V / m or more, particularly 100 V and 4.0. × 10 ⁶ V / m or more, more preferably 150 V or 6.0 × 10 ⁶ V / m or more. The voltage V _S during the sustain period need not always be larger than the voltage near the maximum transmittance, and the voltage near the maximum transmittance may be changed to a voltage that can increase the response time t _OFF during the sustain period.

An embodiment of the present invention will be described in detail. The SPD structure in the present embodiment is the same as the SPD structure in the first embodiment, but the drive waveform shape in the sustain period is different. In this embodiment, the shape of the drive waveform applied between the X electrode 7 and the Y electrode 5 for forming an alternating electric field is the rectangular wave (square wave) in FIG. 3 (III), and the voltage V _s is set to a predetermined value. The voltage.

FIG. 8 shows the response time t _OFF of the light shielding operation in the light control stop period after driving at the voltage V _S with the frequency f _{S set} to 50 Hz for the SPD 1 in which the concentration of the light adjusting particles 9 in the suspension 8 is 10 vol%. As a comparison, the graph also shows the result when the drive waveform is a sine wave and the drive voltage is 150 Vrms. The vertical axis represents the transmittance variation ΔT with respect to the transmittance change from the transmittance T at t _OFF = 0 to the minimum transmittance T in the light shielding operation as in FIG. The voltage V _S is 40 to 150 V, which is a voltage range equal to or higher than the voltage near the maximum transmittance in the sustain period, as in FIG.

From Figure 8, in SPD1 of this embodiment, the 40V and 60V is the voltage V _S near the maximum transmittance in Figure 6, the response time t _OFF of the light shielding operation is almost the same, both t _OFF is short.
On the other hand, when the voltage V _S is equal to or higher than the voltage V _S at which the maximum transmittance is obtained in FIG. 6 and the voltage V _S is almost constant or slightly changed without changing the transmittance T with respect to the voltage V _S , the light shielding operation is performed. The response time t _OFF is longer than those at 40 V and 60 V, which are the voltages V _S near the maximum transmittance. Furthermore, when comparing the response time t _OFF of the light-shielding operation at voltage V _S 100 V and 150 V, the direction of high voltage V _S 150 V is longer response time t _OFF of the light-blocking operation. Therefore, when driven in the high transmittance state in the sustain period, depending on the response time t _OFF the voltage V _S of the shielding operation at higher voltages the voltage V _S becomes maximum transmittance, sinusoidal waveform of Example 1 As in the case of, the higher the response time t _OFF becomes. When the response time t _OFF of the light-shielding operation compared with the waveform shape, the 150V square wave with respect to the sine wave of 150Vrms, the response time t _OFF of the light shielding operation is longer.

FIG. 15 shows the response of the light shielding operation to the concentration of the light control particles 9 when the voltage V _S is 60 V and 150 V, and the frequency f _{S of the} sustain period is 50 Hz. The first axis (left side) of the vertical axis is the time t _OFF (ΔT (100% −20%)) until the transmission fluctuation rate ΔT in the light shielding operation decreases from 100% to 20%.

From Figure 15, the higher the concentration of the light control particles 9 _{low, t OFF (ΔT (100%} -20%)) is long in the voltage V _S 60V, prolonged effect when formed into a 150V voltage V _S from 60V Is small. Therefore, if the concentration of the light adjusting particles 9 is 1 to 4 vol%, the response time t _OFF of the light shielding operation can be extended without performing the voltage control as described above. Of course, even if the concentration of the light adjusting particles 9 is 1 to 4 vol%, the voltage control as described above may be performed in order to further increase the response time t _OFF of the light shielding operation.

FIG. 16 shows the relationship between the concentration of the light control particles 9 and the time t _ON required for the transmittance fluctuation ΔT to rise from 0% to 80% in the start period when the voltage V _ON 60V is applied at 50 Hz. As can be seen from FIG. 16, the lower the concentration of the light control particles 9, the shorter the t _{ON at the} voltage V _S 60V. In consideration of speeding up of the response time during the transmission drive of the light control device, the concentration of the light adjusting particles 9 is desirably 2 to 4 vol%.

From the above, the response time t _OFF of the light shielding operation is prolonged by applying a voltage V _S higher than the minimum voltage that is constant at the maximum transmittance or high transmittance during the sustain period, between the X electrode and the Y electrode. . Further, by making the drive waveform a rectangular wave, the response time t _OFF of the light shielding operation becomes longer compared to the sine wave. Thus, by controlling the drive waveform during the sustain period without changing the basic structure of the SPD, the SPD and the light control device in which the light shielding operation during the stop period is prolonged, particularly for the light shielding operation from the high transmittance state. Can be obtained.

  An embodiment of the present invention will be described in detail. The SPD structure in the present embodiment is the same as the SPD structure in the first embodiment, and the drive waveform in the sustain period is a rectangular wave as in the second embodiment.

In this embodiment, the response time t _OFF of the light shielding operation is lengthened by controlling the frequency f _S of the drive waveform in the sustain period.

FIG. 9 shows the measurement result of the response time t _OFF of the light shielding operation in the stop period in this example. In the sustain period, the AC waveform of the drive waveform is a rectangular wave, the frequency f _S is 50 to 1000 Hz, and the voltage V _S Is applied between the X electrode 7 and the Y electrode 5 at 150V.

From FIG. 9, regarding the frequency f _S of the drive waveform in the sustain period, the response time t _{OFF of the} light shielding operation becomes longer as f _S becomes lower. However, when f _S becomes 15 Hz or less of the critical fusion frequency, it is visually recognized as, for example, flicker depending on incident light and transmitted light in the transmission state in the sustain period. Accordingly, the frequency f _S of the drive waveform in the sustain period is lowered and higher than the critical fusion frequency. Specifically, the frequency f _S of the drive waveform in the sustain period is set to 50 to 100 Hz, so that the stable sustain period is achieved. It is possible to shift from a transparent state to a light shielding operation with a long response time t _OFF .

  The configuration of the SPD of this embodiment is basically the same as that of the SPD described in the first embodiment. The difference from the first embodiment is that a light control layer 17 including a resin matrix is sandwiched between the B plate 2 and the A plate 3.

<SPD>
FIG. 10 shows the basic structure of the SPD according to the basic embodiment of the present invention. The suspended particle device (SPD) 1 includes a B plate 2, an A plate 3, and a light control layer 17. The B plate 2 includes a B substrate 4 and a Y electrode 5. The A plate 3 includes an A substrate 6 and an X electrode 7.

  The light control layer 17 includes the suspension 8 and the resin matrix 16. The thickness of the light control layer 17 is preferably 5 μm or more and 1000 μm or less, and more preferably 20 μm or more and 100 μm or less. In the present embodiment, the light control layer 17 has a thickness of 65 μm.

  The suspension 8 includes light adjusting particles 9 and a dispersion medium 10. The suspension 8 is dispersed in the resin matrix 16. The size (average droplet diameter) of the suspension 8 dispersed in the resin matrix 16 is usually 0.5 μm to 100 μm, preferably 0.5 μm to 20 μm, and more preferably 1 μm to 5 μm. .

  The suspension 8 preferably comprises 1 to 70% by weight of the light adjusting particles 9 and 30 to 99% by weight of the dispersion medium 10 and 4 to 50% by weight of the light adjusting particles 9. More preferably, the dispersion medium 10 comprises 50 wt% or more and 96 wt% or less.

  The resin matrix 16 is a polymer that is cured by heating or photosensitivity, holds the A substrate 6, the B substrate 4, and the suspension 8 in film formation, and insulates between the X electrode 7 and the Y electrode 5. Examples of the polymer medium to be cured include a polymer composition containing a polymerization initiator and a polymer compound to be cured. In this embodiment, a liquid polymer composition containing a photopolymerization initiator and a polymer compound silicone resin is used. Examples of the silicone resin include both-end silanol polydimethylsiloxane, both-end silanol polydiphenylsiloxane-dimethylsiloxane copolymer, both-end silanol siloxane polymers such as both-end silanol polydimethyldiphenylsiloxane, trialkylalkoxysilane such as trimethylethoxysilane, ( 3-acryloxypropyl) methyldimethoxysilane and other ethylenically unsaturated bond-containing silane compounds are synthesized by dehydrogenative condensation reaction and dealcoholization reaction in the presence of an organotin catalyst such as 2-ethylhexanetin. The As the form of the silicone resin, a solventless type is preferably used. That is, when a solvent is used for the synthesis of the silicone resin, it is preferable to remove the solvent after the synthesis reaction.

  The refractive index of the resin matrix 16 and the refractive index of the dispersion medium 10 are preferably close. Specifically, the difference between the refractive index of the resin matrix 16 and the refractive index of the dispersion medium 10 is desirably 0.002 or less. Thereby, scattering of the resin matrix 16 and the dispersion medium 10 in the light control layer 17 can be suppressed. As the dispersion medium 10, it is preferable to use a liquid copolymer that is not electrically conductive and has no affinity for the resin matrix 16. Specifically, a (meth) acrylic acid ester oligomer having a fluoro group and / or a hydroxyl group is preferred, and a (meth) acrylic acid ester oligomer having a fluoro group and a hydroxyl group is more preferred. When such a copolymer is used, one monomer unit of either a fluoro group or a hydroxyl group is directed to the light control particle 9, and the remaining monomer unit is used for the suspension 8 to be stably maintained in the resin matrix 16. Because of this, the light adjusting particles 9 are very homogeneously dispersed in the suspension 8, and the light adjusting particles 9 are induced in the suspension 8 to be phase separated during phase separation.

  Next, a method for forming the light control layer 17 will be described. First, the suspension 8 and the polymer compound are mixed to prepare a mixed solution in which the suspension 8 is dispersed in a droplet state in the polymer compound. This mixed solution is applied on the electrode of one of the A substrate 6 and the B substrate 4 with a certain thickness, and the solvent contained in the mixed solution is dried and removed as necessary. After that, the other substrate is stacked and adhered to one substrate so that the electrode on the other substrate is in contact with the applied mixed solution.

  When applying, if necessary, it may be diluted with an appropriate solvent. When a solvent is used, drying is required after coating on the A substrate 6 or the B substrate 4. As the solvent, tetrahydrofuran, toluene, heptane, cyclohexane, ethyl acetate, ethanol, methanol, isoamyl acetate, hexyl acetate, or the like can be used. In order to form a light control film in which the liquid suspension 8 is dispersed in the form of fine droplets in the resin matrix 16, the light control material of this embodiment is mixed with a homogenizer, an ultrasonic homogenizer, or the like. A method of finely dispersing the suspension 8 in the resin matrix 16, a phase separation method by polymerization of the silicone resin component in the resin matrix 16, a phase separation method by solvent volatilization, or a phase separation method by temperature. Can do.

  By irradiating energy rays in this state to cure the polymer composition, a film-like SPD having the light control layer 17 in which the suspension 8 is dispersed in a droplet state in the resin matrix 16 is obtained.

<Dimming drive characteristics with respect to drive voltage>
In the present embodiment, as in the driving method shown in FIG. 3, the response time t _OFF of the light shielding operation is lengthened by controlling the voltage V _S of the driving waveform in the sustain period. FIG. 12 shows the SPD 1 in this embodiment in which the drive waveform is the rectangular wave of FIG. 3 (III), the frequency f _S is 50 Hz, and the concentration of the light control particles 9 in the suspension 8 is 5.3 to 10% by weight. 6 is a graph showing the relationship of the linear transmittance T of incident light to the substrate in the electric field direction with respect to the voltage V _S of the driving waveform of FIG.

From FIG. 12, when the voltage V _S increases in the range of the voltage V _S from 0 to 200 V, the transmittance T also increases to around 100 V as in the S-shaped function as in the first embodiment. Slightly increases or becomes almost constant without change.

<Drive waveform and dimming operation response time>
FIGS. 11A and 11B show the measurement results of the response time t _OFF of the light-shielding operation during the stop period in this example. In the sustain period, the AC waveform that is the drive waveform is a rectangular wave and the frequency f _S is set. The voltage V _S is 50 to 200 V and is applied between the X electrode 7 and the Y electrode 5 at 50 Hz. FIG. 11A shows the concentration of the light adjusting particles 9 in the suspension 8 is 5.3% by weight, and FIG. 11B shows the concentration of the light adjusting particles 9 in the suspension 8 is 10% by weight.

From FIG. 11 (a) and FIG. 11 (b), the voltage V _S of the drive waveform in the sustain period is similar to the SPD 1 of the first embodiment having a different structure, like the S-shaped function in FIG. The response time t _OFF of the light shielding operation hardly changes when the voltage V _{S at} which the voltage rises is 50 V or 100 V, but becomes longer at 200 V, which is a higher voltage V _S. Therefore, in the sustain period, a film-like SPD is applied by applying, between the X electrode and the Y electrode, a voltage V _S that is equal to or higher than the voltage at which the transmittance increases as in the S-shaped function in the dimming characteristics with respect to the drive voltage. In addition, the response time t _OFF of the light shielding operation can be extended for the dimmer.

  FIG. 13 is a configuration diagram of a driving method configured based on the driving waveforms of Examples 1 and 2 for the suspended particle device of one embodiment. The driving method of the present embodiment includes a start period for shifting the suspended particle device to a driving state, a sustain period for maintaining the driving state of the suspended particle device, and a stopping period for releasing the maintenance state of the suspended particle device. The driving cycle is repeated with one period as the driving cycle.

Next, the driving flow will be described. FIG. 14A shows a driving flow in the driving method according to the present embodiment. When the dimming state is continuously set, the response time t of the light shielding operation shown in the first and second embodiments in the periodic sustain period. _The drive condition is that _OFF is extended for a long time, and a transition is made to the next cycle through a stop period which is the final period of the cycle, that is, a start period again. At this time, the AC voltage waveform, which is the drive waveform, is not applied to the suspended particle device during the stop period, but the response time t _OFF of the light shielding operation is long, so that the change in the light control state and the transmission state is also delayed. Accordingly, when continuously adjusting the dimming state, it is possible to provide a time for stopping the application of the AC voltage waveform while suppressing the change in the dimming state and the transmission state from being visually recognized, thereby reducing power consumption. .

In addition, by controlling the driving conditions such as V _S and f _S in the sustain period and the length of the pause period, a continuous transmittance lowering operation according to the high transmittance state in the sustain period and the drive condition in the pause period can be performed. A dimming drive including this can also be realized.

When the dimming drive is stopped and the light is blocked, the driving conditions such as V _S and f _S during the sustain period are controlled, the voltage is kept constant without setting V _OFF to 0 V after the end of the sustain period, or A light-shielding operation period in which the voltage is lowered to 0 V in a multistage manner may be provided as shown in FIG.

1 Suspended particle device (SPD)
2 B plate 3 A plate 4 B substrate 5 Y electrode 6 A substrate 7 X electrode 8 Suspension 9 Light adjustment particle 10 Dispersion medium 11 Light control device 12 Drive control circuit 13 Drive power supply 14 Signal processing circuit 15 Drive device 16 Resin matrix 17 Dimming layer 20 Incident light 21 Interconnect element 105 Y electrode output circuit 107 X electrode output circuit 200 Memory circuit

Claims (16)

A first substrate and a second substrate;
A suspended particle device having a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate,
The suspension includes light adjusting particles and a dispersion medium,
The light adjusting particles are dispersed in the dispersion medium,
The concentration of the light control particles in the suspension is 1 vol% or more and 10 vol% or less,
A suspended particle device in which a response time in which the transmittance of the suspended particle device changes is controlled by an alternating voltage applied between the first electrode and the second electrode. In claim 1,
Resin is included between the first substrate and the second substrate,
A suspended particle device in which the suspension is dispersed in the resin. In any one of Claims 1 thru | or 2.
The light adjusting particles are rod-shaped,
The suspended particle device wherein the light control particles have an aspect ratio of 5 or more and 30 or less. In any one of Claims 1 thru | or 3,
The suspended particle device wherein the alternating voltage during the light control period of the suspended particle device is greater than the voltage at which the transmittance of the suspended particle device is maximum. In any one of Claims 1 thru | or 4,
The suspended particle device in which the alternating voltage during the light control period of the suspended particle device is 3.2 × 10 ⁶ V / m or more. In any one of Claims 1 thru | or 5,
The suspended particle device in which the concentration of the light control particles in the suspension is 4 vol% or more and 10 vol% or less. In any one of Claims 1 thru | or 6.
By controlling the AC voltage during the light control period of the suspended particle device, the response time of the light shielding period of the suspended particle device is the response time of the light shielding period of the suspended particle device when the AC voltage is not controlled. Longer suspended particle device. In any one of Claims 1 thru | or 7,
The waveform of the alternating voltage is a suspended particle device having a rectangular wave. In any one of Claims 1 thru | or 8.
The frequency of the alternating voltage is a suspended particle device having a frequency of 50 Hz to 100 Hz. A first substrate and a second substrate;
A suspended particle device having a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate,
The suspension includes light adjusting particles and a dispersion medium,
The light adjusting particles are dispersed in the dispersion medium,
The suspended particle device wherein the concentration of the light control particles in the suspension is 1 vol% or more and 4 vol% or less. The suspended particle device of any of claims 1 to 10,
A light control device comprising: a driving device that controls the suspended particle device; A first substrate and a second substrate;
A method for driving a suspended particle device comprising: a first electrode, a second electrode and a suspension disposed between the first substrate and the second substrate,
The suspension includes light adjusting particles and a dispersion medium,
The light adjusting particles are dispersed in the dispersion medium,
The concentration of the light control particles in the suspension is 1 vol% or more and 10 vol% or less,
A method for driving a suspended particle device, wherein a response time in which the transmittance of the suspended particle device is changed by an alternating voltage applied between the first electrode and the second electrode is controlled. In claim 12,
The suspension particle device is driven by
A start period for transitioning the suspended particle device to a driven state;
A dimming period for maintaining the driving state of the suspended particle device;
A suspension particle apparatus drive method comprising a period of a suspension period for releasing the maintenance of the drive state of the suspension particle apparatus. In any of claims 12 to 13,
Regarding the AC voltage during the dimming period, when the AC voltage when the response time during the light shielding period of the suspended particle device is increased is V _L , and the AC voltage when the response time is decreased is V _S , V _L and V _S is a driving method of the suspended particle device in the relationship of V _L > V _S. In any of claims 12 to 14,
The suspension particle device driving method in which the response time of the light shielding period of the suspension particle device is controlled by controlling the frequency of the AC voltage waveform applied between the first electrode and the second electrode. . A first substrate and a second substrate;
A suspension particle device driving device comprising: a first electrode disposed between the first substrate and the second substrate; a second electrode; and a suspension,
The suspension includes light adjusting particles and a dispersion medium,
The light adjusting particles are dispersed in the dispersion medium,
The concentration of the light control particles in the suspension is 1 vol% or more and 10 vol% or less,
The suspension particle device drive device in which a response time in which the transmittance of the suspended particle device changes is controlled by an alternating voltage applied between the first electrode and the second electrode.