Electronic Dimming Device

Abstract

An electronic light control device capable of suppressing a change in transmittance during a color retention period. [Solution] The electronic dimming device of the present invention comprises an electrochromic element that is optically transparent and whose transmittance changes depending on the voltage applied during a color-forming operation period, and whose transmittance is maintained by opening an electrochromic circuit during a color-forming retention period after the color-forming operation period; a voltage measuring unit that measures the open-circuit voltage of the electrochromic element; a voltage determination unit that determines a color-forming retention voltage and an application time of the color-forming retention voltage to be applied to the electrochromic element during part of the color-forming retention period based on a comparison result between the open-circuit voltage and a reference value so that the difference between the transmittance during the color-forming retention period and a target value is small; and a voltage application unit that applies the color-forming retention voltage to the electrochromic element for the application time during the color-forming retention period.

Description

[Technical field]

[0001] The present invention relates to electronic dimming devices. [Background technology]

[0002] Patent Document 1 discloses an electrochromic element having a pair of substrates and an electrochromic medium disposed between them. When a voltage is applied to the electrodes provided on the pair of substrates, the transmittance of the compound in the electrochromic medium changes. This makes it possible to adjust the amount of light passing through the electrochromic element.

[0003] Some electrochromic elements have a function (memory function) that maintains the transmittance when the electrodes are electrically disconnected after the transmittance has been changed by applying a voltage. Because such electrochromic elements can maintain the transmittance (coloring can be maintained) even without applying a voltage, they can contribute to the realization of power-saving electronic light control devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-167317 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even when the electrodes are electrically open, the transmittance may change gradually over time, and unintended changes in the transmittance may reduce the quality and usability of the electrochromic element.

[0006] An object of the present invention is to provide an electronic light control device capable of suppressing a change in transmittance during a color retention period. [Means for solving the problem]

[0007] Such an object can be achieved by the present invention described in (1) to (9) below. (1) The device has optical transparency, and its transmittance changes depending on the voltage applied during the color-developing period. During the color-developing period, the electrochromic circuit is opened. Rito Electrochromic device with maintained transmittance The first element and the second element are and, The above First element Open circuit voltage and the open circuit voltage of the second element A voltage measuring unit for measuring Estimating a transmittance of the first element and a transmittance of the second element based on the open circuit voltage of the first element and the open circuit voltage of the second element. During the color retention period The estimated first element Transmittance and The estimated transmittance of the second element During a part of the color retention period, the difference between First element a voltage determination unit that determines a color-developing sustain voltage to be applied to the pixel and a time period during which the color-developing sustain voltage is applied; During the color retention period, First element a voltage application unit that applies the color-developing sustain voltage for the application time to the An electronic dimming device comprising:

[0008] (2) an electrochromic element having optical transparency, a transmittance of which changes depending on a voltage applied during a color-developing operation period, and a transmittance of which is maintained by opening an electrochromic circuit during a color-developing maintenance period following the color-developing operation period; A voltage measuring unit for measuring an open circuit voltage of the electrochromic element; a voltage determination unit that determines a color-developing retention voltage and an application time of the color-developing retention voltage to be applied to the electrochromic element during a part of the color-developing retention period, based on a comparison result between the open-circuit voltage and a reference value, so as to reduce a difference between the transmittance during the color-developing retention period and a target value; a voltage application unit that applies the color-developing maintaining voltage to the electrochromic element for the application time during the color-developing maintaining period; Equipped with The voltage determination unit stores a correlation between the open-circuit voltage and the transmittance of the electrochromic element, and determines the color-developing maintaining voltage and the application time based on the measured open-circuit voltage and the correlation. Electronic dimming device.

[0009] (3) The electrochromic element includes a first element and a second element, The voltage determination unit is The first element has a Based on the correlation, The color-developed holding voltage and the application time to be applied to the first element are determined, and a voltage to be applied to the second element is determined based on the correlation specific to the second element. The above method for determining the color-developing sustain voltage and the application time (2) 2. The electronic dimming device according to claim 1 .

[0010] (4) The electronic light control device according to (3), wherein the voltage determination unit has a function of changing the correlation in accordance with an accumulated drive time.

[0011] (5) The electronic light control device according to (1) above, wherein the color-developing retention voltage is 60% or more and 130% or less of the open-circuit voltage immediately after the color-developing retention period starts.

[0012] (6) The electronic light control device according to any one of (1) to (5) above, wherein the application time is from 1 to 30 continuous seconds.

[0013] (7) The electronic light control device according to any one of (1) to (6) above, wherein the application time is set multiple times within one of the color development retention periods.

[0014] (8) The electronic light control device according to any one of (1) to (7) above, wherein the voltage measurement unit measures the open circuit voltage after a predetermined time has elapsed after the color development retention period has started.

[0015] (9) An electronic light control device according to any one of (1) to (8) above, which is used as glasses. Effect of the Invention

[0016] According to the present invention, an electronic light control device capable of suppressing a change in transmittance during a color retention period is obtained. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing sunglasses (eyeglasses) to which an electronic light adjusting device according to an embodiment is applied. [Diagram 2] FIG. 2 is a perspective view of a first lens shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of a first lens shown in FIG. [Figure 4] FIG. 4 is a partial enlarged view of the EC functional unit shown in FIG. [Diagram 5] 2 is a functional block diagram of a control unit shown in FIG. 1. [Figure 6] 4 is a graph showing an example of a change in voltage measured in a first electrochromic element during a coloring maintenance period and a color disappearance period. [Figure 7] 7 is a graph showing changes in transmittance of the first electrochromic element during a coloring maintenance period and a color disappearance period shown in FIG. 6. [Figure 8] 7 is a graph showing an example of the change in open-circuit voltage when a color-developing maintaining voltage is applied to a first electrochromic element during deterioration during the color-developing maintaining period shown in FIG. 6, and the change in open-circuit voltage when no color-developing maintaining voltage is applied. [Figure 9] 9 is a graph showing an example of a change in transmittance when a color-developing maintaining voltage is applied to a first electrochromic element during deterioration during the color-developing maintaining period shown in FIG. 8, and a change in transmittance when no color-developing maintaining voltage is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic light control device according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

[0019] 1. Configuration of electronic dimming device FIG. 1 is a perspective view showing sunglasses 100 (eyeglasses) to which an electronic light adjusting device according to an embodiment is applied.

[0020] The sunglasses 100 shown in Fig. 1 include a frame 20, a first lens 31, a second lens 32, and a control unit 40. In the following description, when the sunglasses 100 are worn on the head of a user, the user side of the first lens 31 and the second lens 32 is referred to as the "back" and the opposite side is referred to as the "front." In the following description, the term "lens" includes not only optical elements having the function of focusing or diverging light, but also optical elements having the function of simply transmitting light.

[0021] 1.1.Frame A frame 20 shown in FIG. 1 has two rim portions 21, 21, a bridge portion 22, two temple portions 23, 23, and two nose pad portions 24, 24.

[0022] The frame 20 is worn on the user's head and positions the first lens 31 and the second lens 32 near the user's eyes.

[0023] Each rim portion 21 is in a ring shape. A first lens 31 is fitted inside one of the rim portions 21, and a second lens 32 is fitted inside the other rim portion 21.

[0024] The bridge portion 22 is rod-shaped and connects the rim portions 21 to each other. Each temple portion 23 is shaped like a temple, with one end connected to each rim portion 21 and the other end being a free end.

[0025] In addition, a control unit 40 is provided on the temple portion 23. The control unit 40 applies a voltage to the first lens 31 and the second lens 32, and controls the operation thereof.

[0026] The nose pad portion 24 is provided on the edge of each rim portion 21 and is supported on the nose of the user of the sunglasses 100.

[0027] The material of the frame 20 is not particularly limited, but may be, for example, various metal materials, various resin materials, etc. Also, it may be a composite material containing these materials.

[0028] The shape of the frame 20 is not limited to the shape shown in the figure, so long as it can be worn on the head of the user. For example, the rim portion 21 and the temple portion 23 may be omitted. Also, the entire frame 20 may be omitted, and the first lens 31 and the second lens 32 may be used alone.

[0029] Furthermore, the electronic light adjusting device according to the present invention may be applied to glasses other than sunglasses, for example, prescription glasses, fashion glasses, goggles, etc. Furthermore, the electronic light adjusting device according to the present invention may have one or more additional lenses similar to the first lens 31 and the second lens 32.

[0030] 1.2. First lens and second lens Next, the first lens 31 and the second lens 32 will be described.

[0031] 1, the first lens 31 has a first electrochromic element 1. In addition, the second lens 32 has a second electrochromic element 2 separate from the first electrochromic element 1. Note that the configurations of the second lens 32 and the second electrochromic element 2 are similar to the configurations of the first lens 31 and the first electrochromic element 1, and therefore will not be described.

[0032] FIG. 2 is a perspective view of the first lens 31 shown in FIG. The first lens 31 shown in FIG. 2 has a first electrochromic element 1 and a resin layer 35 provided on the back surface thereof.

[0033] The first electrochromic element 1 is optically transparent and has the function of developing color when a voltage is applied. In addition, by switching the voltage application state, it is possible to reversibly switch between color development and decolorization. The power required for the first electrochromic element 1 to operate is supplied from the control unit 40. In addition, the control unit 40 is also responsible for switching the voltage application state.

[0034] For example, when the sunglasses 100 are used, the amount of light passing through the first lens 31 (transmittance) can be controlled by switching the coloring and decoloring of the first electrochromic element 1 or by changing the coloring density. The period during which a voltage is applied to the first electrochromic element 1 to change the coloring density is called the "coloring operation period." When the coloring operation period ends, the application of the voltage is stopped and the electrochromic circuit provided in the first electrochromic element 1 is opened. In the following description, opening the electrochromic circuit is sometimes referred to as "opening the element." Also, shorting the electrochromic circuit is sometimes referred to as "shorting the element."

[0035] After the coloring operation period ends, the color density is maintained due to the memory effect of the first electrochromic element 1. This period is called the "coloring retention period." Thereafter, if necessary, the coloring state can be canceled and the element can be decolored by shorting the first electrochromic element 1. The period during which the element is decolored is called the "decoloring period."

[0036] Although sunglasses 100 have been illustrated as an example of this embodiment, the electronic light control device according to the present invention may also be applied to various types of eyeglasses, such as prescription eyeglasses, fashion eyeglasses, and goggles that protect the eyes from wind, rain, dust, chemicals, etc.

[0037] FIG. 3 is a cross-sectional view of the first lens 31 shown in FIG. The first electrochromic element 1 shown in Figure 3 comprises a first substrate 11, a second substrate 12, a first electrode 13, a second electrode 14, an EC functional section 60, a sealing section 55, a first auxiliary electrode 15, and a second auxiliary electrode 16.

[0038] 1.2.1. First board The first substrate 11 supports other components such as the EC functional section 60. In addition, the first substrate 11 serves as the outermost layer of the first electrochromic element 1, and protects the EC functional section 60 and the like.

[0039] The material for forming the first substrate 11 is not particularly limited as long as it is a transparent resin material, but a material containing a transparent resin having thermoplastic properties is preferable.

[0040] The transparent resin is not particularly limited, but examples thereof include acrylic resins, polystyrene resins, polyethylene resins, polypropylene resins, polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), polycarbonate resins, polyamide resins, cycloolefin resins, vinyl chloride resins, polyacetal resins, etc., and one or a mixture of two or more of these resins is used. Among these, the transparent resin is preferably a polycarbonate resin or a polyamide resin, and more preferably a polycarbonate resin. These resins are excellent in transparency (translucency) and mechanical properties, and further in heat resistance and moldability. Therefore, the transparency and shape accuracy of the first substrate 11, as well as the impact resistance and heat resistance of the first substrate 11 can be improved.

[0041] In particular, the polycarbonate resin is preferably an aromatic polycarbonate resin, which has an aromatic ring in the main chain and contributes to improving the mechanical strength of first substrate 11.

[0042] The first substrate 11 may contain various additives, such as dyes, pigments, antioxidants, fillers, plasticizers, light stabilizers, ultraviolet absorbers, heat absorbers, and flame retardants, as necessary.

[0043] The thickness of the first substrate 11 is preferably 0.1 mm or more and 10.0 mm or less, and more preferably 0.3 mm or more and 5.0 mm or less. If the thickness of the first substrate 11 is within the above range, it is possible to achieve both a thin structure and mechanical strength of the first electrochromic element 1.

[0044] 1.2.2. Second board The second substrate 12 is disposed opposite the first substrate 11 via the EC functional unit 60, and supports other components such as the EC functional unit 60. The second substrate 12 also serves as the outermost layer of the first electrochromic element 1, and protects the EC functional unit 60, etc. In the following description, the space between the first substrate 11 and the second substrate 12 is also referred to as the "inside."

[0045] The material of the second substrate 12 is not particularly limited as long as it is a transparent material, but a material containing a transparent resin having thermoplastic properties is preferable. The transparent resin is the same as the material of the first substrate 11.

[0046] The thickness of the second substrate 12 may be the same as the thickness of the first substrate 11, or may be different.

[0047] The thickness of the second substrate 12 is preferably 0.1 mm to 10.0 mm, more preferably 0.3 mm to 5.0 mm. If the thickness of the second substrate 12 is within the above range, the first electrochromic element 1 can be made thin while maintaining its mechanical strength.

[0048] 1.2.3.EC Functional Department FIG. 4 is a partial enlarged view of the EC function unit 60 shown in FIG.

[0049] The EC functional unit 60 (electrochromic circuit) shown in Figure 4 has a first electrode 13 and a first electrochromic layer 63 stacked in sequence on the inside of the first substrate 11, a second electrode 14 and a second electrochromic layer 64 stacked in sequence on the inside of the second substrate 12, and an electrolyte layer 65 filled between the first electrochromic layer 63 and the second electrochromic layer 64.

[0050] The first electrode 13 and the second electrode 14 are electrically connected to the control unit 40. The control unit 40 controls the potentials of the first electrode 13 and the second electrode 14, and injects and extracts charges into and from the first electrochromic layer 63 and the second electrochromic layer 64. This allows the EC function unit 60 to perform coloring, color retention, and color erasing operations.

[0051] The constituent materials of the first electrode 13 and the second electrode 14 are not particularly limited as long as they are transparent conductive materials, and examples thereof include oxides such as ITO (indium tin oxide), FTO (F-doped tin oxide), ATO (antimony tin oxide), IZO (indium zinc oxide), In2O3, SnO2, Sb-containing SnO2, and Al-containing ZnO, Au, Pt, Ag, Cu, or alloys containing these, and one or more of these may be used in combination.

[0052] The thickness of each of the first electrode 13 and the second electrode 14 is set appropriately according to the required conductivity. For example, when ITO is used as the constituent material of each of the first electrode 13 and the second electrode 14, the thickness is preferably about 50 nm or more and 200 nm or less, and more preferably about 100 nm or more and 150 nm or less.

[0053] The first electrochromic layer 63 contains a material that develops color through an oxidation reaction. The material that develops color through an oxidation reaction is not particularly limited, but examples thereof include polymers obtained by polymerizing a composition containing a radically polymerizable compound having triarylamine, triarylamine derivatives such as triphenylamine, bisacridan compounds, Prussian blue-type complexes, benzidine, nickel oxide, and the like, and one or more of these may be used in combination.

[0054] An example of a Prussian blue-type complex is a material made of Fe(III)4[Fe(II)(CN)6]3.

[0055] Among these, a polymer obtained by polymerizing a composition containing a radically polymerizable compound having triarylamine is preferably used, since it can be operated at a constant voltage, has excellent durability during repeated use, and can provide an electrochromic element with high contrast.

[0056] In addition, the composition containing the radical polymerizable compound having a triarylamine may contain another radical polymerizable compound different from the radical polymerizable compound having a triarylamine, and the polymer obtained by polymerizing such a composition may be composed of a crosslinked product in which these radical polymerizable compounds are crosslinked.

[0057] The thickness of the first electrochromic layer 63 is not particularly limited, but is preferably about 0.1 μm or more and 30 μm or less, and more preferably about 0.4 μm or more and 10 μm or less.

[0058] The second electrochromic layer 64 contains a material that develops color through a reduction reaction. The material that develops color through a reduction reaction is not particularly limited, but examples thereof include inorganic electrochromic compounds, organic electrochromic compounds, conductive polymers, etc., and one or more of these can be used in combination.

[0059] Examples of inorganic electrochromic compounds include tungsten oxide, molybdenum oxide, iridium oxide, titanium oxide, etc., and tungsten oxide is particularly preferred. Tungsten oxide has a low reduction potential, so that the color development / discoloration potential is low, and further, since it is an inorganic material, it has excellent durability.

[0060] Examples of organic electrochromic compounds include low molecular weight organic electrochromic compounds such as azobenzene, anthraquinone, diarylethene, dihydroprene, dipyridine, styryl, styrylspiropyran, spirooxazine, spirothiopyran, thioindigo, tetrathiafulvalene, terephthalic acid, triphenylmethane, triphenylamine, naphthopyran, viologen, pyrazoline, phenazine, phenylenediamine, phenoxazine, phenothiazine, phthalocyanine, fluoran, fulgide, benzopyran, and metallocene, and particularly preferably viologen compounds or dipyridine compounds. These compounds have low color development and fading potential and show good color values.

[0061] Examples of viologen compounds include compounds described in Japanese Patent No. 3955641 and JP-A-2007-171781.

[0062] Examples of the dipyridine compound include compounds described in JP-A-2007-171781 and JP-A-2008-116718.

[0063] Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, and derivatives thereof.

[0064] In addition, a material that develops a color in the same tone as the material that develops a color in the oxidation reaction described above is preferably used as the material that develops a color in the reduction reaction, which improves the maximum color density and, as a result, the contrast during color development.

[0065] On the other hand, when a material that develops color through an oxidation reaction and a material that develops color through a reduction reaction, which have different color tones, are used, it becomes possible to control the color development by mixing colors.

[0066] Either the first electrochromic layer 63 or the second electrochromic layer 64 may be set not to develop color, but by having both develop color, the color density can be increased. This allows the driving voltage applied to the EC function section 60 to be reduced, and the durability of the first electrochromic element 1 to be improved when color development is repeated.

[0067] The thickness of the second electrochromic layer 64 is not particularly limited, but is preferably about 0.2 μm or more and 5.0 μm or less, and more preferably about 1.0 μm or more and 4.0 μm or less.

[0068] The electrolyte layer 65 is filled between the first electrochromic layer 63 and the second electrochromic layer 64, and contains an electrolyte having ion conductivity.

[0069] The electrolyte is not particularly limited, but examples thereof include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, acids, and alkali supporting salts, etc. Specific examples include LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiCF3COO, KCl, NaClO3, NaCl, NaBF4, NaSCN, KBF4, Mg(ClO4)2, Mg(BF4)2, etc., and one or more of these may be used in combination.

[0070] Ionic liquids can also be used as the electrolyte material. Among ionic liquids, organic ionic liquids are easy to handle because they are liquid over a wide temperature range including room temperature.

[0071] As the molecular structure of the organic ionic liquid, the cationic component may be, for example, an imidazole derivative such as N,N-dimethylimidazole salt, N,N-methylethylimidazole salt, or N,N-methylpropylimidazole salt; a pyridinium derivative such as N,N-dimethylpyridinium salt or N,N-methylpropylpyridinium salt; or an aliphatic quaternary ammonium derivative such as trimethylpropylammonium salt, trimethylhexylammonium salt, or triethylhexylammonium salt. In addition, it is preferable to use a fluorine-containing compound as the anionic component, taking into consideration stability in the atmosphere, such as BF4 - , CF3SO3 - , PF4 - , (CF3SO2)2N - , (SO2F)2N - etc.

[0072] Such an electrolyte material may be an ionic liquid containing any combination of cationic and anionic components.

[0073] The ionic liquid may be directly dissolved in any one of the photopolymerizable monomer, oligomer, and liquid crystal material. If the ionic liquid has poor solubility in these materials, it may be dissolved in a small amount of solvent to obtain a solution, and then this solution may be mixed with any one of the photopolymerizable monomer, oligomer, and liquid crystal material to dissolve the ionic liquid.

[0074] Examples of the solvent include propylene carbonate, acetonitrile, γ-butyrolactone, ethylene carbonate, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, polyethylene glycol, alcohols, and the like, or mixed solvents containing two or more of these.

[0075] The electrolyte may be in the form of a low-viscosity liquid, a gel, a polymer cross-linked type, a liquid crystal dispersion type, or the like. Of these, the electrolyte is preferably in the form of a gel or a solid. This can improve the mechanical strength and reliability of the EC functional unit 60.

[0076] The thickness of the electrolyte layer 65 is not particularly limited, but is preferably set to about 10 μm or more and 100 μm or less, and more preferably about 20 μm or more and 80 μm or less.

[0077] Between the first electrode 13 and the second electrode 14, an intermediate layer such as an insulating porous layer or a protective layer may be provided as necessary.

[0078] In this embodiment, the EC function section 60 has the first electrochromic layer 63 and the second electrochromic layer 64, but either one of them may be omitted.

[0079] 1.2.4.Sealing Part 3, the sealing portion 55 is disposed between the first substrate 11 and the second substrate 12, and defines a colored region 70. This allows the EC functional portion 60 to be encapsulated in the colored region 70. The first electrode 13 and the second electrode 14 shown in FIG. 3 extend beyond the sealing portion 55 to the outside of the colored region 70.

[0080] The constituent material of the sealing portion 55 is not particularly limited as long as it is an insulating material having transparency, and examples thereof include resin materials such as acrylic resin and epoxy resin, and inorganic oxides such as silicon oxide (SiO2), silicon oxynitride (SiON), and aluminum oxide (Al2O3).

[0081] The thickness of the sealing portion 55 is adjusted according to the thickness of the EC function portion 60, and is preferably, for example, about 20 μm or more and 100 μm or less, and more preferably about 40 μm or more and 80 μm or less.

[0082] 1.2.5.1st auxiliary electrode The first auxiliary electrode 15 is laminated on the first electrode 13 that extends to the outside of the colored region 70. The first auxiliary electrode 15 is made of a material having a higher conductivity than the first electrode 13. This improves the efficiency of controlling the potential of the first electrode 13.

[0083] The material constituting the first auxiliary electrode 15 is not particularly limited as long as it has a higher conductivity than the first electrode 13. Examples of the material include silver, aluminum, copper, chromium, molybdenum, etc., and one or a combination of two or more of these may be used. The first auxiliary electrode 15 may be provided as necessary, and may be omitted.

[0084] 1.2.6.Second auxiliary electrode The second auxiliary electrode 16 is laminated on the second electrode 14 that extends to the outside of the colored region 70. The second auxiliary electrode 16 is made of a material having a higher conductivity than the second electrode 14. This improves the efficiency of controlling the potential of the second electrode 14.

[0085] The material of the second auxiliary electrode 16 is not particularly limited as long as it has a higher conductivity than the second electrode 14. Examples of the material include silver, aluminum, copper, chromium, molybdenum, etc., and one or a combination of two or more of these may be used. The second auxiliary electrode 16 may be provided as necessary, and may be omitted.

[0086] 1.3.Control Unit The control unit 40 is provided in the temple portion 23 and controls the operation of each of the first electrochromic element 1 and the second electrochromic element 2.

[0087] FIG. 5 is a functional block diagram of the control unit 40 shown in FIG. The control unit 40 shown in FIG. 5 has a voltage measurement unit 42, a voltage determination unit 44, and a voltage application unit 46 as functional units.

[0088] The voltage measuring unit 42 measures the open circuit voltage of the first electrochromic element 1 and the open circuit voltage of the second electrochromic element 2. These open circuit voltages are the voltages (open circuit voltages) between the first electrode 13 and the second electrode 14 measured when the first electrochromic element 1 and the second electrochromic element 2 are each opened.

[0089] The voltage determination section 44 determines the color-developing operation voltage to be applied to the first electrochromic element 1 and the second electrochromic element 2 during the color-developing operation period, and the application time thereof.

[0090] Furthermore, the voltage determination unit 44 determines the color retention voltage to be applied to the first electrochromic element 1 during a portion of the color retention period and its application time based on the result of comparing the open circuit voltage of the first electrochromic element 1 with a reference value. Similarly, the voltage determination unit 44 determines the color retention voltage to be applied to the second electrochromic element 2 during a portion of the color retention period and its application time based on the result of comparing the open circuit voltage of the second electrochromic element 2 with a reference value.

[0091] The function of the voltage determination unit 44 is realized by hardware including a CPU, a memory, and an interface. An example of such hardware is a microcomputer. The CPU is a central processing unit. Examples of the memory include any non-volatile memory element (ROM), any volatile memory element (RAM), and a removable external memory element. Examples of the interface include a digital input / output port such as a Universal Serial Bus (USB). The function of the voltage determination unit 44 is realized by the CPU executing a program that is loaded in advance in the memory. Instead of or in addition to the method in which the CPU executes a program to realize the above function, a method in which hardware such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC) realizes the above function may be used.

[0092] The voltage application section 46 applies the color-developing operation voltage determined above to the first electrochromic element 1 and the second electrochromic element 2 during the color-developing operation period.

[0093] Furthermore, the voltage application section 46 applies the color-developing retention voltage determined above to the first electrochromic element 1 and the second electrochromic element 2 for the application time set as a part of the color-developing retention period. The color-developing retention voltage and its application time applied to the first electrochromic element 1, and the color-developing retention voltage and its application time applied to the second electrochromic element 2 may be the same as or different from each other. Furthermore, the color-developing retention voltage may not be applied to either one of the elements.

[0094] The voltage application unit 46 includes, for example, a DC power supply, a voltage converter, and a switch. The DC power supply is a power supply that generates a predetermined DC voltage, and is composed of, for example, a primary battery, a secondary battery, an external power supply, etc. The voltage converter converts the DC voltage generated by the DC power supply to a target value. The voltage converter may have a function of generating a pulse width modulated voltage from the DC voltage and changing the duty ratio to bring the effective voltage closer to the target value. The switch switches between the coloring operation period, the coloring retention period, and the decoloring period in response to a user's operation.

[0095] 2. Operation of electronic dimming device Next, a description will be given of the operation of the sunglasses 100. In the following description, the operation of the first electrochromic element 1 will be described. The operation of the second electrochromic element 2 is similar to that of the first electrochromic element 1, and therefore a description thereof will be omitted.

[0096] Fig. 6 is a graph showing an example of the change in voltage measured in the first electrochromic element 1 during the coloring retention period T2 and the color disappearance period T3. In Fig. 6, the voltage change in the first electrochromic element 1 when it is normal is V-OK, and the voltage change when it is deteriorated is V-NG. The horizontal axis of Fig. 6 is time, and the vertical axis is voltage.

[0097] Fig. 7 is a graph showing the change in transmittance of the first electrochromic element 1 during the coloring retention period T2 and the color disappearance period T3 shown in Fig. 6. In Fig. 7, the change in transmittance of the first electrochromic element 1 when it is normal is designated TR-OK, and the change in transmittance when it is deteriorated is designated TR-NG. The horizontal axis of Fig. 7 is time, and the vertical axis is transmittance.

[0098] The normal state of the first electrochromic element 1 refers to a state in which no initial abnormality or deterioration over time occurs in the first electrochromic element 1. The deteriorated state of the first electrochromic element 1 refers to a state different from the normal state in which initial abnormality or deterioration over time occurs.

[0099] In the coloring operation period T1 shown in Fig. 6, a predetermined voltage is applied in both normal and deteriorated states. This causes charge to be injected into the first electrochromic element 1, increasing the coloring density. As a result, as shown in the coloring operation period T1 in Fig. 7, coloring operations with low transmittances TR-OK and TR-NG of, for example, about 10% are performed.

[0100] In the example shown in FIG. 6, after the coloring operation period T1 ends, the first electrochromic element 1 is opened and the coloring maintenance period T2 begins.

[0101] In the example shown in FIG. 7, immediately after the start of the color development retention period T2, the transmittances TR-OK and TR-NG immediately after the end of the color development operation period T1 are maintained due to the memory effect.

[0102] Thereafter, in the normal first electrochromic element 1, the memory effect is fully functioning, so that the transmittance TR-OK is maintained at a low value even after time has passed within the color retention period T2. On the other hand, in the deteriorated first electrochromic element 1, the memory effect is not fully functioning, and the transmittance TR-NG increases over time.

[0103] In this way, when the first electrochromic element 1 deteriorates, the transmittance TR-NG increases over time during the color retention period T2. When the transmittance TR-NG increases, the color density decreases unintentionally (the transmittance increases), which reduces the quality and usability of the sunglasses 100.

[0104] The difference in memory effect described above is reflected in the changes in the voltages V-OK and V-NG shown in Figure 6. The voltages V-OK and V-NG during the color retention period T2 are called the "open circuit voltage." Looking at the changes in the voltages V-OK and V-NG during the color retention period T2 (changes in open circuit voltage), under normal conditions, as shown in Figure 6, the voltage V-OK is constant (zero decrease) or the decrease is kept small.

[0105] In contrast, when the device is degraded, the voltage V-NG decreases more significantly as shown in Figure 6. The transmittance TR-NG also increases more significantly as shown in Figure 7. This shows that there is a positive correlation between the decrease in open-circuit voltage and the increase in transmittance.

[0106] As a result of the inventor's investigation, it has been found that it is possible to detect the presence or absence of degradation of the first electrochromic element 1 based on the amount of decrease in the voltage V-NG. It has also been found that by utilizing the above correlation, it is possible to estimate the amount of increase in the transmittance TR-NG based on the amount of decrease in the voltage V-NG.

[0107] In this embodiment, the control unit 40 operates as follows to solve the above problem.

[0108] 2.1. Open circuit voltage measurement First, during the color development maintaining period T2, the voltage measuring section 42 measures the voltages V-OK and V-NG (open circuit voltage).

[0109] The open-circuit voltages may be the voltages V-OK and V-NG measured by the voltage measuring unit 42 when the first electrochromic element 1 is open, that is, during the coloring retention period T2. However, the voltages V-OK and V-NG may not be stable immediately after opening. Therefore, the voltage measuring unit 42 may operate to measure the voltages V-OK and V-NG when a predetermined time t has elapsed after the coloring operation period T1 ends (the coloring retention period T2 begins), as shown in FIG. 6, and set the measured values ​​as the initial open-circuit voltages OCV-OK and OCV-NG. This makes it possible to obtain the open-circuit voltages OCV-OK and OCV-NG with fewer abnormal values.

[0110] The predetermined time t is not particularly limited, but is preferably 1 second or more and 500 seconds or less, and more preferably 5 seconds or more and 300 seconds or less, which makes it possible to obtain measurement values ​​with particularly few abnormal values ​​and with reduced instability due to changes over time.

[0111] If the predetermined time t is below the lower limit, the predetermined time t is too short, and there is a risk that the initial open circuit voltages OCV-OK, OCV-NG may contain abnormal values. On the other hand, if the predetermined time t is above the upper limit, the predetermined time t is too long, and there is a risk that the initial open circuit voltages OCV-OK, OCV-NG may contain abnormal values ​​if the voltage V-NG has dropped significantly.

[0112] Furthermore, the voltage measuring unit 42 may operate to measure the open circuit voltages OCV-OK and OCV-NG multiple times at predetermined time intervals during the color development maintenance period T2, or may operate to measure the open circuit voltages OCV-OK and OCV-NG continuously in time.

[0113] 2.2. Determination of voltage required for color development Next, the voltage determination unit 44 compares the open circuit voltages OCV-OK, OCV-NG with a reference value. For example, the reference value is an allowable upper limit value when the transmittance of the first electrochromic element 1 gradually increases during the coloring retention period T2. The voltage determination unit 44 monitors whether the open circuit voltages OCV-OK, OCV-NG fall below the reference value by repeating the comparison of the open circuit voltages OCV-OK, OCV-NG with the reference value. If the open circuit voltages OCV-OK, OCV-NG fall below the reference value, the voltage determination unit 44 determines a coloring retention voltage to be applied to the first electrochromic element 1 during the coloring retention period T2 so that the transmittance approaches the target value. The coloring retention voltage refers to a voltage that is additionally applied to the first electrochromic element 1 during a part of the coloring retention period T2. By applying this coloring retention voltage from the voltage application unit 46 described later, even if the first electrochromic element 1 is deteriorated, the coloring density can be temporarily restored (increased) and the transmittance TR-NG can be brought closer to the target value.

[0114] Fig. 8 is a graph showing an example of the change in open circuit voltage OCV-K when the coloring retention voltage KV is applied to the first electrochromic element 1 during degradation, and the change in open circuit voltage OCV-NG when the coloring retention voltage KV is not applied, during the coloring retention period T2 shown in Fig. 6. Fig. 8 shows how the open circuit voltage OCV-NG, which had been gradually decreasing, rises to the open circuit voltage OCV-K by applying the coloring retention voltage KV twice, as indicated by the arrows. The horizontal axis of Fig. 8 is time, and the vertical axis is voltage.

[0115] Fig. 9 is a graph showing an example of the change in transmittance TR-K when the color-developing holding voltage KV is applied to the first electrochromic element 1 during the color-developing holding period T2 shown in Fig. 8, and the change in transmittance TR-NG when the color-developing holding voltage KV is not applied. Fig. 9 shows how the gradually increasing transmittance TR-NG decreases to the transmittance TR-K by applying the color-developing holding voltage KV twice, as indicated by the arrows. The horizontal axis of Fig. 9 is time, and the vertical axis is transmittance.

[0116] In the example shown in FIG. 8, the voltage measuring unit 42 constantly or intermittently measures the open circuit voltage OCV-NG, and the voltage determining unit 44 compares the measured open circuit voltage OCV-NG with a reference value DL.

[0117] On the other hand, in the voltage determination unit 44, for example, a reference value DL shown in Fig. 8 is preset. Then, as a result of comparing the open circuit voltage OCV-NG measured by the voltage measurement unit 42 with the reference value DL, the voltage determination unit 44 determines to apply the color-developing maintaining voltage KV when the open circuit voltage OCV-NG falls below the reference value DL.

[0118] The reference value DL is a "threshold value" for determining the application of the color-developing maintenance voltage KV, and is set appropriately depending on the configuration of the first electrochromic element 1, the color-developing operating voltage, the external environment, etc., and is not limited to a particular value, but examples thereof include an arbitrary voltage value, a voltage value calculated based on the color-developing operating voltage applied during the color-developing operating period T1, etc.

[0119] Among these, the arbitrary voltage value may be, for example, a voltage value corresponding to the lower limit of the color density allowable in the first electrochromic element 1, in other words, a voltage value corresponding to the upper limit of the allowable transmittance TR-NG. If this voltage value is set as the reference value DL, it is possible to realize sunglasses 100 that do not give a sense of discomfort to the user and that have low power consumption and deterioration by suppressing the number of times the color-maintaining voltage KV is applied more than necessary.

[0120] Furthermore, as described above, when the reference value DL is set based on the coloring operation voltage applied in the coloring operation period T1, the change in the transmittance in the coloring holding period T2 can be suppressed with the transmittance in the coloring operation period T1 as the reference. As a specific example, when the maximum value (maximum voltage) of the coloring operation voltage applied in the coloring operation period T1 is set to 100%, a voltage value corresponding to 60 to 99% of the maximum value may be set as the reference value DL, and more preferably a voltage value corresponding to 70 to 90% of the maximum value. This suppresses the difference in color density from that in the coloring operation period T1 when the coloring holding voltage KV is applied, thereby realizing sunglasses 100 that do not cause discomfort.

[0121] The voltage determination unit 44 may be configured to apply the color-holding voltage KV when the open circuit voltage OCV-NG falls below the reference value DL, but it is preferable that the voltage value and application time are configured, for example, to set a target value TL for the transmittance TR-NG and determine the color-holding voltage KV that brings the transmittance TR-NG closer to the target value TL.

[0122] 9, a target value TL is preset in the voltage determination unit 44. The target value TL refers to a target to be reached when the color density is increased (transmittance TR-NG is decreased) by applying the color-development maintaining voltage KV. The target value TL may be, for example, the transmittance TR-NG immediately after the color-development maintaining period T2 starts (immediately before the color-development operation period T1 ends), or may be a transmittance estimated based on the open-circuit voltage measured in the second electrochromic element 2.

[0123] In the former case, it is possible to minimize the change in transmittance when the color generation operation period T1 transitions to the color generation retention period T2 in the first electrochromic element 1. This makes it possible to realize sunglasses 100 that suppress the discomfort caused by the change in transmittance.

[0124] In the latter case, it is possible to match the transmittance of the first electrochromic element 1 and the transmittance of the second electrochromic element 2. In the case of various glasses such as the sunglasses 100, suppressing the difference in transmittance that occurs between the first electrochromic element 1 and the second electrochromic element 2 incorporated in the left and right lenses is particularly important in terms of the quality (appearance) and usability of the sunglasses 100.

[0125] The voltage determination unit 44 stores parameters necessary for determining the color-developing maintaining voltage KV, such as the correlation between the amount of decrease in the open-circuit voltage and the amount of increase in the transmittance, the target value TL of the transmittance, the reference value DL, etc. Among these, the correlation may be stored in the form of, for example, a calculation formula or a database.

[0126] The voltage determination unit 44 determines the color-developing maintaining voltage KV based on stored parameters and the like, for example, as follows.

[0127] First, the reference value DL (threshold value) is set as described above. At this time, if necessary, the set reference value DL is referenced to the correlation stored in the voltage determination unit 44 to determine the transmittance TR-NG corresponding to the reference value DL. This makes it possible to estimate the transmittance TR-NG when the open circuit voltage OCV-NG drops to the reference value DL.

[0128] Next, the difference between the stored target transmittance value TL and the estimated transmittance TR-NG is calculated.

[0129] On the other hand, the electrochromic element has a characteristic that the higher the applied voltage, the higher the color density (the lower the transmittance). Such a characteristic is called a "dimming characteristic." The voltage determination unit 44 also stores the dimming characteristic specific to the first electrochromic element 1 in advance.

[0130] The voltage determination unit 44 derives the color-developing maintaining voltage KV required to make the calculated transmittance difference zero (to make the transmittance TR-NG approach the target value TL) in light of the stored light control characteristics of the first electrochromic element 1. In this way, the color-developing maintaining voltage KV can be determined.

[0131] The method of determining the color-developing retention voltage KV is not limited to the above. For example, the color-developing retention voltage KV may be determined based on a database in which the reference value DL and the color-developing retention voltage KV correspond one-to-one without setting the target value TL, or a uniform color-developing retention voltage KV may be determined without considering the reference value DL.

[0132] The application time is determined based on, for example, previously acquired experimental data, simulations, calculations, etc. If the charge transfer speed in the first electrochromic element 1 is fast, the application time can be shortened even if the color development holding voltage KV is the same. On the other hand, if the charge transfer speed is slow, the application time must be lengthened. The application time can be determined taking these factors into consideration.

[0133] The method of determining the application time is not limited to the above. For example, the application time may be determined based on a database in which the color-developing sustain voltage KV and the application time correspond one-to-one, or a uniform application time may be determined without considering the color-developing sustain voltage KV.

[0134] Furthermore, from the viewpoint of minimizing the change in transmittance when transitioning from the coloring operation period T1 to the coloring retention period T2, it is preferable that the coloring retention voltage KV is approximately the same as the open circuit voltage OCV-NG immediately after the coloring retention period T2 begins. Specifically, the coloring retention voltage KV is preferably 60% to 130% of the open circuit voltage OCV-NG immediately after the coloring retention period T2 begins, more preferably 80% to 125%, and even more preferably 90% to 110%. This makes it possible to realize sunglasses 100 with particularly small fluctuations in transmittance TR-NG.

[0135] The duration of each application is not particularly limited since it varies depending on the color-developing holding voltage KV, but as an example, it is preferably 0.01 to 30 seconds continuously, more preferably 0.1 to 25 seconds, and even more preferably 1 to 20 seconds, which makes it easier to stabilize the transmittance TR-K.

[0136] 2.3. Application of voltage to maintain color development Next, the voltage application unit 46 applies the determined coloring retention voltage KV to the first electrochromic element 1 for the determined application time during the coloring retention period T2. As a result, as shown in Fig. 9, the transmittance TR-NG, which is increasing to the right, can be shifted to the low transmittance side as shown by the transmittance TR-KV, and transitioned to the transmittance TR-K. As a result, even with a deteriorated first electrochromic element 1, an unintended increase in the transmittance TR-NG during the coloring retention period T2 is suppressed, and sunglasses 100 with good quality and usability can be realized.

[0137] Furthermore, when the transmittance estimated based on the open circuit voltage measured in the second electrochromic element 2 is adopted as the target value TL, the transmittance of the first electrochromic element 1 and the transmittance of the second electrochromic element 2 can be made uniform by applying the color-developing maintenance voltage KV.

[0138] The voltage application section 46 may be configured to set a plurality of application times of the color retention voltage KV during one color retention period T2, as shown in Fig. 8. This makes it easier to stabilize the transmittance TR-K even when the color retention period T2 is long. The color retention voltage KV is preferably constant, but may be set to change over time.

[0139] As described above, the voltage determination unit 44 stores the correlation between the amount of decrease in open-circuit voltage and the amount of increase in transmittance, but in the case of sunglasses 100 that have two electrochromic elements (first electrochromic element 1 and second electrochromic element 2), it may store a common correlation for these elements or individual correlations.

[0140] In the former case, since the common correlation between the two electrochromic elements is utilized, for example, when the transmittance of the two electrochromic elements is to be made uniform, the coloring holding voltage KV and the application time may be determined so that the open circuit voltages are brought closer to each other. In this case, the transmittance can be made uniform without estimating the transmittance, thereby reducing the processing load of the voltage determination unit 44.

[0141] On the other hand, in the latter case, the coloring holding voltage KV and the application time can be determined based on the correlation specific to each electrochromic element. This can improve the estimation accuracy of the transmittance estimated from the open voltage. As a result, the transmittance of the two electrochromic elements can be precisely matched, and the quality of the sunglasses 100 can be improved.

[0142] Furthermore, the voltage determination unit 44 may have a function of successively changing the above correlation in response to various factors. Examples of the various factors include temperature, accumulated temperature, continuous driving time, accumulated driving time, and the like. These factors may cause the above correlation to be disturbed. Therefore, if the voltage determination unit 44 is configured to acquire these factors and reflect the acquired results in the correlation (change the correlation), the correlation can be corrected even if the above correlation deviates from the actual situation. This makes it possible to suppress a decrease in the estimation accuracy of the transmittance due to the above factors.

[0143] 3. Advantages of the above embodiment The sunglasses 100 to which the electronic light control device according to the embodiment is applied include a first electrochromic element 1, a voltage measurement unit 42, a voltage determination unit 44, and a voltage application unit 46. The first electrochromic element 1 has light transparency, and its transmittance changes depending on the voltage applied during the coloring operation period T1, and the transmittance is maintained by opening the electrochromic circuit during the coloring retention period T2 after the coloring operation period T1 ends. The voltage measurement unit 42 measures the open voltage of the first electrochromic element 1. The voltage determination unit 44 determines the coloring retention voltage KV and the application time of the coloring retention voltage KV to be applied to the first electrochromic element 1 during a part of the coloring retention period T2 based on the comparison result between the open voltage and the reference value DL so that the difference between the transmittance during the coloring retention period T2 and the target value TL is small. The voltage application unit 46 applies the coloring retention voltage KV to the first electrochromic element 1 for the application time during the coloring retention period T2.

[0144] With this configuration, even if the first electrochromic element 1 is deteriorated, the change in transmittance can be suppressed during the coloring retention period T2. This makes it possible to realize sunglasses 100 (electronic light control device) with good quality and ease of use.

[0145] Moreover, sunglasses 100 to which the electronic light control device according to the embodiment is applied include a first electrochromic element 1 (first element) and a second electrochromic element 2 (second element). A voltage measurement unit 42 measures the open-circuit voltage of the first electrochromic element 1 and the open-circuit voltage of the second electrochromic element 2. A voltage determination unit 44 estimates the transmittance of the second electrochromic element 2 based on the open-circuit voltage of the second electrochromic element 2, and determines the color development holding voltage KV and application time of the first electrochromic element 1 with the estimated transmittance of the second electrochromic element 2 as a target value TL.

[0146] With this configuration, it is possible to align the transmittance of the first electrochromic element 1 and the transmittance of the second electrochromic element 2. This makes it possible to suppress the difference in transmittance that occurs between the first electrochromic element 1 and the second electrochromic element 2 incorporated in the left and right lenses, for example, and to realize sunglasses 100 (eyeglasses) with good quality (appearance) and ease of use.

[0147] In addition, in the sunglasses 100 to which the electronic light control device according to the embodiment is applied, the voltage determination unit 44 stores the correlation between the open voltage and the transmittance of the electrochromic element. The voltage determination unit 44 determines the coloring maintenance voltage KV and the application time based on this correlation.

[0148] According to this configuration, the transmittance can be accurately estimated from the open circuit voltage by utilizing the correlation, and the transmittance can be accurately brought close to the target value TL.

[0149] Moreover, in the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied, the voltage determination section 44 has a function of changing the correlation in accordance with the accumulated drive time.

[0150] According to this configuration, even if the correlation deviates from the actual situation, the correlation can be corrected, thereby reducing the deviation of the transmittance due to the accumulated driving time.

[0151] In addition, in the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied, the coloring retention voltage KV is 60% or more and 130% or less of the open circuit voltage immediately after the coloring retention period T2 starts. With this configuration, sunglasses 100 with particularly small fluctuations in transmittance can be realized.

[0152] In addition, in the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied, the application time is continuously from 1 second to 30 seconds. With this configuration, the transmittance can be easily stabilized.

[0153] Moreover, in the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied, a plurality of application times are set within one coloring maintenance period T2.

[0154] With this configuration, even if the color retention period T2 is long, the transmittance can be easily stabilized.

[0155] Furthermore, in the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied, the voltage measuring section 42 measures the open circuit voltage after a predetermined time has elapsed since the color development maintenance period T2 has started. With this configuration, it is possible to obtain an open circuit voltage with fewer abnormal values.

[0156] Moreover, the sunglasses 100 to which the electronic light adjusting device according to the embodiment is applied are used as spectacles.

[0157] According to this configuration, it is possible to realize eyeglasses that are less likely to give the user a sense of discomfort due to an unintended decrease in color density (increase in transmittance).

[0158] Although the electronic light control device of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0159] For example, the electronic dimming device of the present invention may have each part of the above-described embodiment replaced with any component having a similar function, or may have any component added to the above-described embodiment. [Explanation of symbols]

[0160] 1. First electrochromic element 2. Second electrochromic element 11 First board 12 Second board 13 1st electrode 14 2nd electrode 15 1st auxiliary electrode 16 2nd auxiliary electrode 20 Frames 21 Rim 22 Bridge section 23 Temple Section 24 Nose pad section 31 First lens 32 Second lens 35 Resin layer 40 Control section 42 Voltage measurement section 44 Voltage determination unit 46 Voltage application section 55 Sealing part 60 EC function section 63 First electrochromic layer 64 Second electrochromic layer 65 Electrolyte layer 70 colored areas 100 Sunglasses DL reference value KV Color retention voltage OCV-K Open circuit voltage OCV-NG Open circuit voltage OCV-OK Open circuit voltage V-NG Voltage V-OK Voltage t predetermined time T1 Coloring period T2 color retention period T3 Color fading period TL target value TR-K Transmittance TR-KV Transmittance TR-NG Transmittance TR-OK Transmittance

Claims

1. a first element and a second element which are electrochromic elements having optical transparency, a transmittance of which changes depending on a voltage applied during a color-developing operation period, and a transmittance of which is maintained by opening an electrochromic circuit during a color-developing maintenance period following the color-developing operation period; a voltage measurement unit that measures an open circuit voltage of the first element and an open circuit voltage of the second element; a voltage determination unit that estimates a transmittance of the first element and a transmittance of the second element based on the open-circuit voltage of the first element and the open-circuit voltage of the second element, and determines a color-development holding voltage to be applied to the first element during a part of the color-development holding period and an application time of the color-development holding voltage so that a difference between the estimated transmittance of the first element and the estimated transmittance of the second element during the color-development holding period becomes small; a voltage application unit that applies the color-developing maintaining voltage to the first element for the application time during the color-developing maintaining period; An electronic dimming device comprising:

2. an electrochromic element having optical transparency, a transmittance of which changes depending on a voltage applied during a color-developing operation period, and the transmittance of which is maintained by opening an electrochromic circuit during a color-developing maintenance period following the color-developing operation period; A voltage measuring unit for measuring an open circuit voltage of the electrochromic element; a voltage determination unit that determines a color-developing retention voltage and an application time of the color-developing retention voltage to be applied to the electrochromic element during a part of the color-developing retention period, based on a comparison result between the open-circuit voltage and a reference value, so that a difference between the transmittance during the color-developing retention period and a target value becomes small; a voltage application unit that applies the color-developing maintaining voltage to the electrochromic element for the application time during the color-developing maintaining period; Equipped with The electronic light control device is characterized in that the voltage determination unit stores a correlation between the open circuit voltage and the transmittance of the electrochromic element, and determines the color-developing retention voltage and the application time based on the measured open circuit voltage and the correlation.

3. A liquid crystal display comprising a first element and a second element which are electrochromic elements, The electronic dimming device of claim 2, wherein the voltage determination unit determines the color-holding voltage and the application time to be applied to the first element based on the correlation specific to the first element, and determines the color-holding voltage and the application time to be applied to the second element based on the correlation specific to the second element.

4. The electronic light control device according to claim 3 , wherein the voltage determination unit has a function of changing the correlation in accordance with an accumulated driving time.

5. The electronic light control device according to claim 1 , wherein the color-developing retention voltage is 60% or more and 130% or less of the open-circuit voltage immediately after the color-developing retention period is started.

6. The electronic light control device according to claim 1 or 2, wherein the application time is from 1 to 30 seconds.

7. The electronic light control device according to claim 1 , wherein a plurality of application times are set within one of the color-developing retention periods.

8. The electronic light control device according to claim 1 , wherein the voltage measurement unit measures the open-circuit voltage after a predetermined time has elapsed after the color development retention period has started.

9. The electronic light control device according to claim 1 or 2, which is used as glasses.

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