Imaging equipment

Abstract

To provide an image pickup apparatus that can suppress an influence of an achromatic defect by electrically detecting charge imbalance in a solution-type EC element.SOLUTION: An image pickup apparatus includes an electrochromic element. The electrochromic element includes a complementary-type EC layer including a solvent and an anodic redox substance and a cathodic redox substance dissolved in the solvent, and image processing is performed on the basis of a charge imbalance current flowing between a first electrode and a second electrode when a voltage lower than a voltage causing a substantial change in transmittance of the EC layer is applied between the first electrode and the second electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging device using an electrochromic element. [Background technology]

[0002] Variable light transmittance elements, which electrically control the transmittance of light transmittance-reducing elements such as ND filters that reduce the light entering the image sensor in imaging devices, offer greater flexibility in exposure adjustment and enable image expression that was previously impossible with elements with fixed transmittance. There are several types of elements used as variable light transmittance elements, but organic electrochromic elements (hereinafter referred to as "EC") are characterized by their ability to achieve both high coloring / bleaching contrast and high maximum transmittance. These organic EC elements use organic EC compounds, which change their optical properties (absorption wavelength, absorbance) through electrochemical redox reactions. When using organic EC compounds in imaging devices, it is important to minimize the impact of changes in their optical properties over time. Specifically, the challenge is to minimize the impact of poor bleaching, which occurs when a portion of the organic EC compound remains colored even under voltage conditions that would cause the EC element to bleach, resulting in a change in color or a decrease in transmittance. One of the causes of this poor decolorization is a "charge imbalance," which occurs when the balance between electron transfer is disrupted due to factors such as deterioration of the organic EC compounds contained in the EC layer. In order to suppress the effects of defective erasing due to charge imbalance, it is necessary to detect the degree of charge imbalance. The primary detection method is an optical method that detects defective erasing by light absorption. However, this method requires a reference light source and subject, so the conditions under which it can be implemented are limited. In contrast, an effective electrical detection method would be desirable, as it would be easy to use inside imaging equipment. Patent Document 1 describes an immobilized EC element in which an EC compound is immobilized on an electrode, in which defective decoloring is detected by voltage measurement and the defective decoloring is resolved by applying a reverse voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6547415 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology in Patent Document 1 is a method for detecting decolorization failure in an EC element, but it is a method for detecting decolorization failure due to residual charge, not due to charge imbalance. This method utilizes the voltage generated between immobilized electrodes due to residual charge, which is a characteristic of fixed-type EC elements. In solution-type EC elements, which have a simpler configuration in which an EC compound is dissolved in a solvent, this method cannot be used when decolorization failure due to charge imbalance occurs, because no voltage is generated between the electrodes. In view of the above-mentioned problems, an object of the present invention is to provide an imaging device that can electrically detect charge imbalance in a solution-type EC element and suppress the influence of defective decoloring. [Means for solving the problem]

[0005] The present invention provides a liquid crystal display device comprising a first electrode, a second electrode, and an electrochromic layer disposed between the first electrode and the second electrode, the electrochromic layer has a solvent, and an anodic redox material and a cathodic redox material dissolved in the solvent, and at least one of the anodic redox material and the cathodic redox material is an electrochromic compound; When a voltage equal to or lower than a voltage at which a substantial change in transmittance of the electrochromic layer occurs is applied between the first electrode and the second electrode, a current flowing between the first electrode and the second electrode is calculated based on the following: Compensating for defective bleaching of the electrochromic element It is characterized by performing image processing. [Effects of the Invention]

[0006] According to the present invention, an imaging device is provided in which the influence of defective decoloring due to charge imbalance is suppressed by using a method capable of electrically detecting defective decoloring due to charge imbalance in a solution-type EC element. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a schematic configuration of an embodiment of an imaging device of the present invention; [Figure 2] 1 is a cross-sectional view schematically showing the configuration of an example of an EC element used in the present invention. [Figure 3] FIG. 1 is a diagram illustrating the concept of charge balance / imbalance. [Figure 4] FIG. 10 is a diagram showing the relationship between the reaction between an oxidant and a reductant in a charge imbalance and the voltage. [Figure 5] FIG. 1 is a diagram showing an example of the characteristics of steady-state current when a voltage is applied to an EC element in a charge-balanced state and a charge-imbalanced state. [Figure 6] FIG. 10 is a diagram showing an example of the absorbance change-steady-state current profile of an EC element in a charge imbalance state. [Figure 7] FIG. 10 is a diagram showing the absorbance spectrum of the residual color of the EC element after the durability test. [Figure 8] FIG. 10 is a diagram showing the relationship between a change in white balance gain and a charge imbalance current. [Figure 9] FIG. 1 is a diagram showing an equivalent circuit of an EC element. [Figure 10] FIG. 10 is a diagram showing the relationship between a change in white balance gain and charge transfer resistance. DETAILED DESCRIPTION OF THE INVENTION

[0008] The imaging device of the present invention is characterized by having a solution-type EC element, detecting a charge imbalance current flowing between electrodes of the EC element, and performing image processing based on the detected current. The following describes in detail the configuration of an imaging device according to a preferred embodiment of the present invention, with reference to the drawings. However, unless otherwise specified, the configuration, relative arrangement, and the like described in this embodiment are not intended to limit the scope of the present invention.

[0009] FIG. 1 is a diagram showing a schematic configuration of an embodiment of an imaging device of the present invention. In FIG. 1, the imaging device 10 includes an EC element 11 and an imaging element 12. Subject light 17 passing through the EC element 11 enters the imaging element 12 and is converted into an electrical signal. The electrical signal is then processed by a control unit 14, where it is converted into image information such as color and intensity. The EC element 11 functions in conjunction with the control unit 14 of the imaging device 10. The imaging device 10 may also include a photographic optical system including multiple lenses 13 and an aperture 15, an IR filter (not shown), and other components as needed. In this case, the subject light 17 entering the imaging device 10 passes through the photographic optical system including the multiple lenses 13 and the aperture 15, and then through the EC element 11 and the IR filter (not shown) to form an image on the imaging element 12. The imaging device 10 may also include a temperature sensor 16 for acquiring temperature information about the EC element 11, a recording device (not shown), and other components as needed. Each component shown in FIG. 1 will now be described in detail.

[0010] [Electrochromic element] An EC element is a device that takes in light from the outside and passes the light through at least a portion of an EC layer, thereby changing the characteristics of the emitted light, typically the intensity of the light, relative to the incident light in a specific wavelength range.

[0011] 2 is a diagram showing a schematic view in the thickness direction of the configuration of one embodiment of an EC device used in the present invention. The EC device of this embodiment has a first electrode 21, a second electrode 22, and an EC layer 23 disposed between these electrodes 21 and 22. The EC device of this embodiment also has a first substrate 26, a second substrate 27, and a sealant 25. The EC layer 23 has a solvent, an anodic redox material dissolved in the solvent, and a cathodic redox material, at least one of which is an electrochromic compound (EC compound). A configuration in which both of these are EC compounds is preferably used.

[0012] 2 is an example, and the EC element used in the present invention is not limited to this. For example, an anti-reflection film layer may be provided between the substrate and the electrode, or between the electrode and the EC layer.

[0013] The components of the EC element will be described below. <Substrate> The EC element used in the present invention may have substrates (first substrate 26 and second substrate 27). When the EC element is a transmissive type, both substrates 26 and 27 must be transparent. When the EC element is a reflective type, at least the substrates on the light-incident and light-exiting sides must be transparent. The term "transparent" as used herein refers to a light transmittance of 50% to 100%, more preferably 70% to 100%. Furthermore, the term "light" in this specification refers to light in the wavelength range for which the EC element is intended. For example, if the EC element is used as an optical filter for an imaging device in the visible light region, this refers to light in the visible light region. If the EC element is used as an optical filter for an imaging device in the infrared region, this refers to light in the infrared region.

[0014] Specifically, colorless or colored glass or transparent resin can be used for the substrates 26 and 27. Examples of glass include optical glass, quartz glass, white plate glass, blue plate glass, borosilicate glass, alkali-free glass, and chemically strengthened glass. Examples of transparent resin include polyethylene terephthalate, polyethylene naphthalate, polynorbornene, polyamide, polysulfone, polyethersulfone, polyetheretherketone, polyphenylene sulfide, polycarbonate, polyimide, and polymethyl methacrylate. When a non-transparent substrate is used, there are no particular limitations.

[0015] <Electrode> The materials used for the electrodes (first electrode 21, second electrode 22) are preferably materials that are stable in the operating environment of the EC device and can rapidly promote a redox reaction in response to the application of an external voltage. Examples of materials that can be used for the electrodes include transparent conductive materials and metals, which will be described later.

[0016] It is preferable that at least one of the electrodes 21 and 22 is a transparent electrode. Here, "transparent" means that the light transmittance is 50% or more and 100% or less. By using a transparent electrode for at least one of the electrodes 21 and 22, light can be efficiently taken in from outside the EC element, and the light can interact with the EC compound in the EC layer, allowing the optical properties of the EC compound to be reflected in the emitted light.

[0017] The transparent electrode may be a film formed of a transparent conductive material on a substrate, a transparent electrode in which metal wires are partially arranged on a transparent substrate, etc. Here, although the metal wires themselves are not transparent, in the present invention, an electrode in which the metal wires are partially arranged and the light transmittance is set within the above range is called a transparent electrode.

[0018] Examples of transparent conductive materials include transparent conductive oxides and carbon materials such as carbon nanotubes. Examples of transparent conductive oxides include tin-doped indium oxide (ITO), zinc oxide, gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide (AZO), tin oxide, antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), and niobium-doped titanium oxide (TNO). Among these, ITO and FTO are preferred.

[0019] When an electrode is formed from a transparent conductive oxide, the thickness of the electrode is preferably 10 nm to 10 μm. In particular, by using ITO or FTO formed to a thickness in the range of 10 nm to 10 μm as an electrode, both high transparency and chemical stability can be achieved. When an electrode is formed from a transparent conductive oxide, the electrode may have a structure in which sublayers of transparent conductive oxide are stacked, which makes it easier to achieve high conductivity and high transparency.

[0020] The metal constituting the electrode is not particularly limited, but electrochemically stable metals such as silver (Ag), gold (Au), platinum (Pt), and titanium (Ti) are preferably used. Furthermore, a grid-like arrangement pattern of metal wires is preferably used. Electrodes having metal wires are typically flat electrodes, but curved electrodes can also be used if necessary.

[0021] As described above, it is preferable that at least one of the electrodes 21 and 22 is a transparent electrode. However, if one electrode is a transparent electrode, the other electrode can be selected according to the intended use of the EC device. For example, if the EC device is a transmissive EC device, it is preferable that both electrodes 21 and 22 are transparent electrodes. On the other hand, if the EC device is a reflective EC device, it is preferable that one of the electrodes 21 and 22 is a transparent electrode and the other is an electrode that reflects the light captured by the EC device. Furthermore, by forming a reflective layer or a scattering layer between the first electrode 21 and the second electrode 22, the degree of freedom in the optical properties of the other electrode can be improved. For example, if a reflective layer or a scattering layer is introduced between the first electrode 21 and the second electrode 22, the other electrode can be an opaque electrode or an electrode that absorbs the target light.

[0022] The electrodes 21 and 22 can be arranged using any commonly known arrangement method for EC devices. A typical example is a method in which a first electrode 21 formed on a first substrate 26 and a second electrode 22 formed on a second substrate 27 are arranged so that the first electrode 21 and the second electrode 22 face each other across an EC layer 23. In this case, the distance between the first electrode 21 and the second electrode 22 (the inter-electrode distance) is preferably 1 μm or more and 500 μm or less. Increasing the inter-electrode distance allows for a thicker EC layer 23, allowing for a sufficient amount of EC compound to be disposed in the EC layer 23 for effective EC device function. This is advantageous in that it facilitates lowering the transmittance during coloring. On the other hand, reducing the inter-electrode distance is advantageous in that it facilitates increasing the response speed of the EC device. As described above, setting the inter-electrode distance to 1 μm or more and 500 μm or less facilitates achieving low transmittance and fast response during coloring.

[0023] <Sealing material> The sealing material 25 is a member that keeps the distance between the electrodes (the thickness of the EC layer 23) constant. As shown in Fig. 2, the first electrode 21 and the second electrode 22 may be directly bonded with the sealing material 25, or the electrodes 21 and 22 may be formed smaller than the substrates 26 and 27, and the first substrate 26 and the second substrate 27 may be bonded together.

[0024] The sealant 25 is preferably made of a material that is chemically stable, impermeable to gases and liquids, and does not inhibit the redox reaction of the EC compound. For example, inorganic materials such as glass frit, organic materials such as epoxy and acrylic resins, and metals can be used. The sealant 25 may contain a spacer material to maintain the distance between the first electrode 21 and the second electrode 22. In this case, the first electrode 21, the second electrode 22, and the sealant 25 can form a space for disposing the EC layer 23 between the electrodes 21 and 22.

[0025] If the sealing material 25 does not have the function of defining the distance between the first electrode 21 and the second electrode 22, a spacer having the function of defining and maintaining the distance between the two electrodes may be separately disposed to maintain the distance between the two electrodes. The spacer may be made of inorganic materials such as silica beads and glass fiber, or organic materials such as polyimide, polytetrafluoroethylene, polydivinylbenzene, fluororubber, and epoxy resin.

[0026] <Electrochromic layer> The EC layer 23 includes a solvent and at least one of an anodic EC compound and a cathodic EC compound. The EC layer 23 is a layer in which the anodic EC compound and the cathodic EC compound are dissolved in a solvent. The EC layer 23 may further include additives such as a supporting electrolyte and a thickener.

[0027] (solvent) The solvent can be appropriately selected depending on the application, taking into consideration the solubility, vapor pressure, viscosity, potential window, etc. of the solutes, such as the anodic EC compound and the cathodic EC compound, to be used. The solvent is preferably one that can dissolve the anodic EC compound and the cathodic EC compound to be used. Furthermore, the solvent is preferably a polar solvent. Specific examples include organic polar solvents such as ether compounds, nitrile compounds, alcohol compounds, dimethyl sulfoxide, dimethoxyethane, sulfolane, dimethylformamide, dimethylacetamide, and methylpyrrolidinone, as well as water. Among these, solvents containing cyclic ethers, such as propylene carbonate, ethylene carbonate, γ-butyrolactone, valerolactone, and dioxolane, are preferred. These solvents containing cyclic ethers are preferred in terms of the solubility, boiling point, vapor pressure, viscosity, and potential window of the EC compound. Among cyclic ethers, solvents containing propylene carbonate and γ-butyrolactone are particularly preferred. Ionic liquids can also be used as the solvent.

[0028] The solvent may further contain a polymer, gelling agent, or thickener to increase the viscosity of the EC layer 23 or to form a gel. A polymer electrolyte or a gel electrolyte may be used as the solvent or electrolyte. The polymer may be, but is not limited to, polyacrylonitrile, carboxymethyl cellulose, polyvinyl chloride, polyethylene oxide, polypropylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, Nafion (registered trademark), and derivatives thereof. Increasing the viscosity of the EC layer 23 or forming a gel suppresses the migration of the EC compound within the EC layer 23. This further suppresses vertical color separation.

[0029] The EC layer 23 may further contain a supporting electrolyte. The supporting electrolyte is not particularly limited as long as it is an ion-dissociating salt and has good solubility in the solvent. The supporting electrolyte is preferably a substance that is stable at the operating potential of the EC element. The supporting electrolyte may be selected from various cations and anions, and a combination of both may be used. Examples of cations include metal ions such as alkali metal ions and alkaline earth metal ions, and organic ions such as quaternary ammonium ions. Specifically, Li + , Na + , K. + , Ca 2+ , Ba 2+ Examples of anions include anions of various fluorine compounds, halide ions, etc. Specifically, ClO4 - , SCN - , BF4 - , AsF6 - , CF3SO3 - , CF3SO2NSO2CF3 - , PF6 - , I - , Br - , Cl - In addition, by using a salt compound as the EC compound, the EC compound may also function as a supporting electrolyte. Examples of EC compounds that are also salt compounds include viologen derivatives.

[0030] The method for forming the EC layer 23 is not particularly limited, and examples thereof include a method of injecting a liquid containing a solvent and an EC compound into the gap provided between the first electrode 21 and the second electrode 22 by a vacuum injection method, an atmospheric injection method, a meniscus method, or the like. Specifically, for example, a liquid containing a solvent and an EC compound is injected into a cell formed by the electrodes 21, 22 and the sealant 25 through an opening (not shown) formed in one of the electrodes 21, 22 or the sealant 25, and the opening is sealed with a sealing member.

[0031] (Redox substances and EC compounds) In the present invention, the EC layer 23 contains a solvent, an anodic redox material, and a cathodic redox material, and suppresses the influence of charge imbalance on the image due to poor decolorization caused by a so-called complementary EC element, at least one of which is an EC compound, in any of the following combinations (i) to (iii): (i) Anodic EC compounds and cathodic redox materials (ii) Cathodic EC compounds and anodic redox materials (iii) Anodic EC compounds and cathodic EC compounds Among these, the configuration (iii) is most preferably used because it can increase the coloring and bleaching contrast.

[0032] As used herein, the term "oxidation-reduction substance" refers to a compound that can be repeatedly oxidized and reduced within a predetermined potential range, and can be inorganic or organic, with no particular limitation. Among these, organic substances are preferred due to their compatibility with the usage environment. In this specification, the oxidation-reduction substance may be referred to as an anodic or cathodic oxidation-reduction substance. An anodic oxidation-reduction substance is typically a substance that is in a reduced state when no driving voltage is applied to the element, and becomes oxidized when a driving voltage is applied to the element. A cathodic oxidation-reduction substance is typically a substance that is in an oxidized state when no driving voltage is applied to the element, and becomes reduced when a driving voltage is applied to the element.

[0033] As used herein, the term "EC compound" refers to a type of redox substance, a compound whose optical properties change in the target light wavelength range of the EC element due to a redox reaction. Examples of optical properties include light absorption properties and light reflection properties, and are typically light absorption properties. EC compounds can also be said to be compounds whose light transmittance changes in the target light wavelength range of the EC element due to a redox reaction. The phrase "changes in optical properties" here typically refers to switching between a light absorbing state and a light transmitting state. In this case, the EC compound can also be said to be a compound whose light absorbing state and a light transmitting state change due to a redox reaction.

[0034] As used herein, the term "anodic EC compound" refers to an EC compound whose optical properties change due to an oxidation reaction in the target wavelength region of the EC device when the EC device is operated. An oxidation reaction typically involves the removal of electrons from the EC compound. Furthermore, as used herein, the term "cathodic EC compound" refers to an EC compound whose optical properties change due to a reduction reaction in the target wavelength region of the EC device when the EC device is operated. A reduction reaction typically involves the addition of electrons to the EC compound. Typical examples of anodic EC compounds include compounds that change from a light-transmitting state to a light-absorbing state due to an oxidation reaction when the EC device is operated. Typical examples of cathodic EC compounds include compounds that change from a light-transmitting state to a light-absorbing state due to a reduction reaction when the EC device is operated. However, the term is not limited to these examples and may also refer to compounds that change from a light-absorbing state to a light-transmitting state due to an oxidation reaction or a reduction reaction when the EC device is operated. In the following description, in order to easily visualize the change in the light absorption properties of an EC compound, a typical example will be taken, in which an EC element changes from a light-transmitting state (bleached state) to a light-absorbing state (colored state) when driven.

[0035] Both the anodic and cathodic EC compounds undergo oxidation or reduction reactions, taking at least two distinct states, by controlling the voltage applied between the first electrode 21 and the second electrode 22 or by switching the EC device on and off. In this specification, the EC compound in its oxidized state through one or more oxidation reactions is referred to as its "oxidized form," and the EC compound in its reduced state through one or more reduction reactions is referred to as its "reduced form." That is, the anodic EC compound is in its reduced form when the EC device is not in operation, but partially becomes its oxidized form when the EC device is in operation. Similarly, the cathodic EC compound is in its oxidized form when the EC device is not in operation, but partially becomes its reduced form when the EC device is in operation.

[0036] Some literature describes the state of an EC compound as changing from an oxidant to a neutral state and then to a reduced state (or vice versa). However, in the following explanation, we will use the terms oxidant and reduced state, recognizing that a reduced state is essentially the state produced when an oxidant is reduced, and an oxidant is essentially the state produced when a reduced state is oxidized. For example, ferrocene (a neutral molecule as a whole) containing divalent iron is the reduced state of ferrocene (the anodic redox material) when ferrocene functions as an anodic redox material. When this reduced state is oxidized to a trivalent iron state (ferrocenium ion), it is the oxidized state of ferrocene (the anodic redox material), specifically the first oxidized state. Furthermore, when a dicationic salt of a viologen functions as a cathodic EC compound, the dicationic salt is the oxidized state of the cathodic EC compound. Furthermore, a monocationic salt obtained by one-electron reduction of the dicationic salt is the reduced state of the cathodic EC compound, specifically the first reduced state.

[0037] The EC compound according to the present invention is preferably an organic compound, and may be either a low-molecular-weight organic compound or a high-molecular-weight organic compound, but is preferably a low-molecular-weight organic compound having a molecular weight of 2000 or less. Furthermore, both the anodic EC compound and the cathodic EC compound are preferably compounds that change from a decolorized form to a colored form upon activation of the EC device. The EC compound may contain multiple types of anodic EC compounds and multiple types of cathodic EC compounds.

[0038] Examples of the anodic EC compound include thiophene derivatives, amines having an aromatic ring (e.g., phenazine derivatives, triallylamine derivatives), pyrrole derivatives, thiazine derivatives, triallylmethane derivatives, bisphenylmethane derivatives, xanthene derivatives, fluoran derivatives, spiropyran derivatives, etc. Among these, as the anodic EC compound, low-molecular-weight amines having an aromatic ring are preferred, and dihydrophenazine derivatives are most preferred.

[0039] This is because using these compounds as EC compounds makes it easy to provide EC devices with the desired absorption wavelength profile and has high durability against repeated use. In their neutral state (reduced form), these compounds have an absorption peak in the ultraviolet region, no absorption in the visible light region, and a bleached state with high transmittance in the visible light region. When these molecules become radical cations (oxidized forms) through an oxidation reaction, the absorption peak shifts to the visible light region, resulting in a colored state. The absorption wavelength of these molecules can be freely designed by expanding or contracting their π-conjugation length or by changing the substituents to modify the π-conjugated system. The term "small molecule" here refers to a molecular weight of 2000 or less, excluding counterions.

[0040] The cathodic EC compound is not particularly limited, but examples thereof include pyridine derivatives such as viologen derivatives, quinone compounds, etc. Among these, pyridine derivatives such as viologen derivatives are most preferably used.

[0041] Therefore, the cathodic EC compound is preferably a compound having a pyridine skeleton or a quinone skeleton, and more preferably a compound represented by the following general formula (1).

[0042] [ka]

[0043] In the general formula (1), X1 and X2 are each independently selected from an alkyl group, an aralkyl group, and an aryl group. The alkyl group, the aralkyl group, and the aryl group may have a substituent. R 11 ~R 18 are each independently a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group, an aryl group, a heterocyclic group, a substituted amino group, a halogen atom, or an acyl group. The alkyl group, the alkoxy group, the aralkyl group, the aryl group, and the heterocyclic group may have a substituent. - and A2 -each independently represents a monovalent anion.

[0044] [Charge balance / imbalance] The concept of charge balance / imbalance will be explained below with reference to the drawings. FIG. 3 is a diagram for explaining the concept of charge balance / imbalance. Note that FIG. 3 is a complementary EC element, and is directed to a system in which an anodic EC compound and a cathodic EC compound are used in combination. FIG. 3 shows a first electrode E1, which is an anode, and a second electrode E2, which is a cathode. In FIG. 3, A is the reduced form (discolored state) of the anodic EC compound, and A + is the oxidized form (colored state) of the anodic EC compound. Furthermore, in FIG. 3, C is the oxidized form (decolored state) of the cathodic EC compound, and C - is the reduced form (colored state) of the cathodic EC compound.

[0045] 3(a) shows the coloring process of an EC device. When a coloring voltage is applied between the first electrode E1 and the second electrode E2, an oxidation reaction of the anodic EC compound A shown in the following (α) proceeds at the first electrode E1, and a reduction reaction of the cathodic EC compound C shown in the following (β) proceeds at the second electrode E2. A → A + +e - (α) C+e - →C - (β)

[0046] As these reactions proceed, the EC layer becomes colored.

[0047] Figure 3(b) shows the decoloring process, which is the opposite process to the coloring process. To decolorize the EC layer, a decoloring voltage (e.g., short circuit (0 V)) is applied between the first electrode E1 and the second electrode E2, causing the reverse reaction of the reaction shown in Figure 3(a) to proceed, as indicated by the arc-shaped arrow in Figure 3(b). This allows the colored EC compound to return to its decolored state.

[0048] When the reactions shown in Figures 3(a) and (b) are repeated, the charge balance of the EC element is normal, and the element normally repeats coloring and fading. On the other hand, when an EC element is operated, a process other than this normal coloring / decoloring may occur in some part of the device, causing the charge balance to be lost. There are several reasons for this, but here we will take the degradation of the reduced form of the cathodic EC compound as an example and explain it using Figure 3(c). The reduced form C of the cathodic EC compound that has been colored through the normal coloring process - When the anodic EC compound is degraded and can no longer react at the second electrode E2, the anodic EC compound oxidized A is also produced at the first electrode E1. + However, the anodic EC compound loses its electron supply source and is no longer able to react. In the following explanation, this phenomenon is referred to as a charge imbalance. As a result of the charge imbalance, the EC element exhibits a color loss problem in which a colored body of the anodic EC compound remains, even though the anodic EC compound is normal.

[0049] Charge imbalance can occur due to irreversible electron transfer reactions (particularly electrode reactions) of the substrates involved in the redox reaction. Specifically, this can be caused by impurities (derived from the EC compound, environmental impurities (oxygen, water, etc.), or sealants) or chemical reactions between radicals. The following two are typical examples. The first is the irreversible reduction of oxygen that has entered the EC element, which results in poor bleaching, with the colored body of the anodic EC compound remaining. The second is reducing impurities contained in the EC compound or sealant, which results in poor bleaching, with the colored body of the cathodic EC compound remaining.

[0050] Current-Based Charge Imbalance Detection Method In order to suppress the effects of defective decoloration due to charge imbalance, it is necessary to detect the defective decoloration. A detection method involves detecting the colored body of the EC compound remaining during decolorization of the EC element. Therefore, an optical method can be cited as a first method. However, since optical methods require a reference light source and a subject, they can be easily performed at service centers, etc., but when processing is performed inside an imaging device, the size and facilities that can be applied are limited. In contrast, an electrical detection method would be desirable because it can be easily used inside the imaging device. Therefore, an electrical detection method is selected as the method for detecting charge imbalance in the present invention.

[0051] The mechanism of the electrical charge imbalance detection method of the present invention is described below. Under normal (ideal) conditions, when no voltage is applied to an EC element (often in a bleached state), the reduced form of the anodic redox substance (including the EC compound) and the oxidized form of the cathodic redox substance (including the EC compound) are present, while the oxidized form of the anodic redox substance and the reduced form of the cathodic redox substance are almost absent. However, in an EC layer in a charge imbalance state, the oxidized form of the anodic redox substance or the reduced form of the cathodic redox substance remain due to the charge imbalance. If these are EC compounds, they remain in a colored state, resulting in poor bleaching. In this state, the oxidized and reduced forms of the same EC compound coexist in the EC solution in the same EC layer. In a solution-type EC element in which the EC compound is not immobilized on an electrode, the EC compound can move freely within the EC layer. As a result, the reaction between the oxidized and reduced forms of the same (or homopolar) EC compound (redox substance) can proceed at the paired electrode. In EC devices, the EC compounds and redox substances used in the EC layer are selected to have high reversibility in the redox reaction in order to ensure the durability of the EC device. Therefore, the reaction between the oxidized and reduced forms of the same (or the same polarity) EC compound (redox substance) proceeds with only a slight overvoltage.

[0052] The relationship between this reaction and voltage will be explained using Figure 4. Figure 4 is a potential diagram, with the vertical axis representing potential (negative at the top). Figure 4(a) shows the potential diagram when the EC element is colored. The oxidation reaction of the anodic EC compound progresses at the first electrode E1, and the decolorized substance becomes the colored substance A. + At the second electrode E2, the cathodic EC compound undergoes a reduction reaction, and the cathodic EC compound changes from a decolorized form to a colored form C - For this reaction to proceed, the redox potential (E 0’ A ) and the more negative redox potential (E 0’ C ) and the difference V AC In addition, an overvoltage must be applied to allow the reaction to proceed. (V AC If the potential is not large enough, the coloring reaction will proceed even without external voltage application, resulting in an EC element with low transmittance, which is undesirable.) In contrast, Figure 4(b) shows an example of a potential diagram of an EC element in which the anodic EC compound remains as a defective bleached product. In this case, the EC layer contains a reduced form (bleached form) A and an oxidized form (colored form) A of the anodic EC compound. + (Furthermore, there exists an oxidized form (decolorized form) C of the cathodic redox material (including the EC compound), but it is omitted from the diagram here.) At this time, the reduced form A of the anodic EC compound is converted to the oxidized form A at the first electrode E1. + At the second electrode E2, the oxidation reaction is reversed to the oxidized form A of the anodic EC compound. + A reduction reaction can occur from to reduced form A. This reaction has the following two characteristics. (1) Because it is a highly reversible oxidation-reduction reaction of compounds with the same oxidation-reduction potential, V AC It does not require the application of a large voltage, and only a small overvoltage is required. (2) The oxidation reaction (coloring reaction in the example of Figure 4(b)) and reduction reaction (decoloring reaction in the example of Figure 4(b)) of the same compound proceed simultaneously, and the coloring and decoloring reactions cancel each other out, so the light absorption of the EC layer does not change as the reaction proceeds.

[0053] As a result, in an EC element with a charge imbalance, even when a small voltage, equal to or smaller than the voltage at which a substantial change in transmittance of the EC layer occurs, is applied between the first electrode E1 and the second electrode E2, causing an electrode reaction between the colored and decolored forms of the EC compound resulting from the charge imbalance, resulting in a current flow. This current is referred to as a charge imbalance current in this specification.

[0054] Also, from Fick's first law, the diffusion-limited current i in a thin-layer cell with the electrode distance d is lim is expressed by the following formula (1): i lim =2nAFDc / d (1) Here, n is the number of reaction electrons, A is the electrode area, F is the Faraday constant, D is the diffusion coefficient, and c is the concentration of the reactant. In cases where the decolorization failure is small enough to be addressed by image processing in the imaging device, the concentration of the colored EC compounds remaining in the decolorized state is significantly lower than the concentration of the EC compounds present in the decolorized state. (Severe charge imbalance color retention, where the concentration of the colored EC compounds is equal to or greater than the concentration of the EC compounds present in the decolorized state, is difficult to address by image processing alone in the imaging device.) Therefore, the charge imbalance current is limited by the diffusion of the colored EC compounds remaining in the decolorized state of the EC element, which has a relatively low concentration. As a result, according to the above equation (1), the charge imbalance current is proportional to the concentration of the colored EC compounds remaining in the decolorized state of the EC element, which has a low concentration. Furthermore, according to the above equation (1), the charge imbalance current is proportional to the diffusion coefficient. When the temperature increases, the viscosity of the solution changes (usually decreases) and the diffusion coefficient changes (usually increases). Therefore, the value of the charge imbalance current is affected by temperature. Therefore, in order to detect the degree of charge imbalance, it is preferable to measure the relationship between the charge imbalance current and temperature in advance, and then use that relationship to correct the charge imbalance current and calculate the degree of charge imbalance using the corrected value.

[0055] It is known that the diffusion coefficient changes with temperature. Therefore, it is preferable that the imaging device of the present invention has a temperature sensor that detects the temperature of the EC element and performs image processing based on the temperature and current. The relationship between the diffusion coefficient and temperature is known to be expressed by the Arrhenius equation (2) below. Here, D0 is a constant, Q is the activation energy of diffusion, R is the gas constant, and T is the absolute temperature. D=D0exp(-Q / RT) (2)

[0056] As expressed by the above formula (2), the diffusion coefficient generally increases with increasing temperature. Because the degree of temperature change in current often differs depending on the EC layer, it is preferable to measure the temperature dependence of the current in the EC layer in advance and correct the temperature change based on the results. A specific example is to calculate and store a temperature correction coefficient based on the temperature dependence of the current flowing through the EC layer, perform temperature correction of the current value with reference to the coefficient, and then perform image processing with reference to the corrected value.

[0057] [Image sensor] The image sensor 12 in FIG. 1 photoelectrically converts an image formed on its surface, and can be, for example, a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor Field-Effect Transistor) element. A CMOS element allows the MOS transistors of the area sensor section and peripheral circuits such as the driver circuit and A / D conversion circuit to be formed in the same process, significantly reducing the number of masks and process steps compared to a CCD. Furthermore, random access to any pixel is possible, facilitating thinned-out readout for display, and enabling real-time display at a high display rate. The image sensor used in the imaging device of the present invention is preferably an image sensor that acquires signals for at least three colors of light (RGB).

[0058] [Control Unit] The control unit 14 in FIG. 1 controls each component of the imaging device 10 by executing a preset program. The control unit 14 performs a series of signal processing operations on the image data, such as converting the analog image signal output from the imaging element 12 into a digital image signal (image data) via an A / D converter, gain adjustment, demosaic processing, gamma correction, color conversion, and color correction, as well as exposure control, distance measurement control, and white balance control. This control unit also controls the transmittance of the EC element 11. It is also preferable to change the transmittance control conditions of the EC element 11 based on information from a temperature sensor 16 that measures the temperature of the EC element 11. The functions of the control unit 14 may be performed by a single control unit or may be distributed across several components (with different names).

[0059] The imaging device of the present invention is characterized in that when a voltage equal to or lower than the voltage at which a substantial change in transmittance of the EC layer occurs is applied between the first and second electrodes of the EC element 11, the current flowing between the first and second electrodes is measured, and image processing is performed based on the measured current. The control unit 14 performs a series of operations, including applying a voltage to the EC element 11, measuring the current, and processing the image.

[0060] [Charge imbalance and image processing to compensate for it] <Charge imbalance causing defective erasure> The causes of charge imbalance bleaching failure are as described above in [Charge Balance / Imbalance], but the color and degree (the light absorption spectrum remaining when bleaching is insufficient) vary depending on the EC element and its operating conditions. Specifically, it varies depending on the EC element configuration (electrodes, sealant), EC compound (type, concentration), impurities, operating conditions (temperature, humidity, applied voltage, voltage application time, pattern), etc. Here, we will describe an anodic bleaching failure, in which the anodic EC compound remains as a colored substance after a high-temperature, high-humidity operating test, as an example. When anodic bleaching failure occurs, the colored spectrum of the anodic EC compound remains.

[0061] <Detecting charge imbalance> As described above in [Method for detecting charge imbalance based on current], a charge imbalance current flows through an EC element in a charge imbalance state. Figure 5 shows an example of the characteristics of the steady-state current when a voltage is applied to an EC element in a charge balanced state and a charge imbalance state. The horizontal axis of Figure 5 represents the voltage applied between the first and second electrodes, and the vertical axis represents the steady-state current when that voltage is applied. Figure 5(a) shows that the current for the color reaction of this EC element rises just before 0.4 V and exhibits a sigmoidal profile that increases up to 0.8 V. Figure 5(b) shows an enlarged view of the low-voltage region just before this point. An EC element in a charge balanced state shows almost no current flow up to around 0.2 V, whereas an EC element in a charge imbalance state shows a constant current between 0.1 V and 0.2 V. This is the charge imbalance current (i CIB ) To measure the charge imbalance current, it is preferable to measure it in a voltage range where the influence of the coloring reaction current is small, i.e., at a voltage below the voltage at which a substantial change in transmittance of the EC layer occurs. Three examples of this voltage range are described below: a method for determining the voltage range from the maximum absorbance change of the EC element, a method for determining the voltage range from the absorbance change-current profile, and a method for determining the voltage range from the half-wave potential difference of the redox reaction related to the coloring and fading of the EC compound.

[0062] As a method for setting based on the maximum absorbance change of the EC element, a voltage range that gives an absorbance change of 1 / 100 or less, preferably 1 / 1000 or less, of the maximum absorbance change of the EC element can be mentioned.

[0063] The method for setting the absorbance change-steady current profile from the absorbance change-current profile is described below. Figure 6 shows an example of an absorbance change-steady current profile of an EC element in a charge imbalance state. Figure 6(b) is a partial enlarged view of Figure 6(a). In Figure 6, the horizontal axis represents the absorbance change (Abs) and the vertical axis represents the steady current. EC elements often show a linear absorbance change-steady current profile. The steady current (i ic) is set to a voltage range below which a substantial change in the transmittance of the EC layer occurs. Also, when measuring the steady-state current at a constant voltage step as shown in Figure 6, the current (i d ) is also preferably used as the value of the charge imbalance current.

[0064] The method for setting the potential difference based on the half-wave potential difference of the oxidation-reduction reaction for coloring and fading of an EC compound is described below. The half-wave potential of the oxidation-reduction reaction for coloring and fading of an EC compound can be calculated by subtracting a predetermined value (e.g., 0.3 V) from the absolute value of the difference between the potential of the anodic EC compound and the potential of the cathodic EC compound. In an example where a dihydrophenazine derivative is used as the anodic EC compound and a viologen derivative is used as the cathodic EC compound, the potential difference is preferably 0.5 V or less, and more preferably 0.3 V or less.

[0065] The lower limit of the voltage to be applied when detecting charge imbalance is also described. When measuring steady-state charge imbalance current, if the absolute value of the voltage is greater than zero, a charge imbalance current proportional to the concentration is observed. Therefore, it is preferable that the absolute value of the voltage applied when detecting charge imbalance be greater than zero. Furthermore, to more clearly observe the charge imbalance current, it is preferable to apply an overvoltage sufficient to promote the reaction of the EC compound remaining during bleaching. A specific example of this voltage (absolute value) that sufficiently promotes the oxidation-reduction of reversible redox substances is 57 mV or more, which is the ideal value for the peak-to-peak voltage in a cyclic voltammogram. This ensures that a sufficient overvoltage is applied to promote the reaction of the EC compound remaining during bleaching. When detecting charge imbalance by applying an AC voltage and measuring the charge transfer resistance or the like from the current response, it is not necessary to apply a sufficient overvoltage as with steady-state current. In a charge imbalance state, a significant exchange current flows through the electrode, allowing charge imbalance to be detected with a lower applied voltage than when measuring steady-state current. The applied voltage at this time should be greater than zero in absolute value, and a specific example is a few mV to several tens of mV.

[0066] Charge imbalance can also be detected by measuring the transient current response rather than the steady-state current. For example, the transient current generated when the potential is stepped is proportional to the concentration of the substrate (here, the colored form of the EC compound remaining after bleaching). Therefore, charge imbalance can also be detected by measuring the transient current. Furthermore, if the colored form of the EC compound remains after bleaching, both the colored and bleached forms of the EC compound are present in the EC layer, resulting in a small charge transfer resistance when a voltage is applied. This is because, as shown in Figure 4, the redox reaction of the same material proceeds at opposing electrodes, allowing current to flow even with a small voltage. Therefore, charge imbalance can also be detected by applying an AC voltage and measuring the charge transfer resistance from the current response. In these cases, it is preferable to apply a voltage below the voltage at which a substantial change in the transmittance of the EC layer occurs during detection.

[0067] In an EC layer without charge imbalance, as shown in Figure 4(a), reactive substrates are present when a large voltage is applied, but almost no reactive substrates are present when a small voltage below the voltage at which a substantial change in the transmittance of the EC layer occurs is applied. Therefore, charge transfer (electrode reaction) hardly occurs when a small voltage below the voltage at which a substantial change in the transmittance of the EC layer occurs is applied. Therefore, when a small AC voltage is applied, a large charge transfer resistance is observed. In contrast, in an EC layer with charge imbalance, as shown in Figure 4(b), reactive substrates are present at both the anode and cathode with a small potential difference (voltage). Therefore, charge transfer (electrode reaction) occurs even when a small voltage below the voltage at which a substantial change in the transmittance of the EC layer occurs is applied. Therefore, even when a small AC voltage is applied, a relatively small charge transfer resistance is observed. In this way, charge imbalance can be detected by applying an AC voltage and measuring the charge transfer resistance from the current response. The charge transfer resistance can be estimated from the diameter of the arc that appears when a Nyquist plot of the impedance measured at different frequencies is performed. In practice, it is preferable to measure in advance the frequencies that give plots corresponding to the radius of the arc, and estimate the charge transfer resistance from the difference in impedance at those frequencies.

[0068] <Relationship between charge imbalance and image processing> By detecting charge imbalance and compensating for the defective bleaching of the EC element, the effect of the defective bleaching on the image captured by the imaging device can be reduced. In the present invention, image processing is used as a compensation method. This image processing compensates for the defective bleaching of the EC element due to charge imbalance, thereby compensating for the light absorption of the anodic EC compound or the cathodic EC compound. Furthermore, the absorbance of this light absorption is proportional to the charge imbalance, i.e., the remaining colorant concentration of the EC compound, and therefore proportional to the charge imbalance current. Therefore, it is preferable that this image processing compensate for the remaining light absorption of the EC compound in an amount proportional to the charge imbalance current.

[0069] The EC device of the present invention preferably uses organic low-molecular-weight EC compounds. Aromatic amine derivatives, particularly dihydrophenazine derivatives, are preferred as anodic EC compounds. Pyridine derivatives, particularly viologen derivatives, or compounds containing multiple similar pyridinium ions in the molecule are preferred as cathodic EC compounds. The typical absorption peak wavelength ranges of the colored forms of these compounds are 450 nm to 550 nm for dihydrophenazine derivatives and 400 nm to 450 nm and 600 nm to 740 nm for viologen derivatives. Therefore, in the case of anodic charge imbalance caused by residual anodic EC compounds, images often show reduced signals for B and G among R (red), G (green), and B (blue). In the case of cathodic charge imbalance caused by residual cathodic EC compounds, images often show reduced signals for R and B.

[0070] In the imaging device of the present invention, image processing is performed to compensate for the absorption of the colorants of the EC compound used in such EC elements. This image processing can be related to color or brightness. Specifically, compensation parameters are selected based on the degree of charge imbalance and the polarity (anodic or cathodic). Specifically, for color, the compensation can be performed by relatively increasing the signal of the RGB components corresponding to the absorption region of the colorants of the EC compound, while for brightness, the compensation can be performed by compensating for the decrease in brightness due to the absorption of the colorants of the EC compound. For color, for example, white balance and color balance adjustments are performed. Below, we will explain an example of image processing using white balance correction when an anodic charge imbalance occurs. In the case of charge imbalance bleaching failure due to residual colorants of the dihydrophenazine derivative, an image with reduced B and G signals is obtained, as described above. In the imaging device, a voltage below the voltage at which a substantial change in the transmittance of the EC layer occurs is applied, and the charge imbalance current is measured to detect the degree of charge imbalance. The B gain is then increased to compensate for the decreased B signal, and the R gain is decreased to compensate for the relatively increased R signal. The amount of change in gain at this time is preferably a value calculated in advance from the spectrum of the EC compound used in the EC element.

[0071] The polarity of the charge imbalance that occurs in the EC element used in the imaging device of the present invention is often determined by the combination of EC compounds used in the EC layer. For example, in durability tests of EC elements using a dihydrophenazine derivative as the anodic EC compound and a viologen derivative as the cathodic EC compound, charge imbalance due to residual coloration of the anodic EC compound often occurs. However, depending on the combination of EC compounds and driving conditions, charge imbalance with a polarity opposite to the normal trend can also occur. While the technique of measuring the current value when applying a voltage below the voltage at which a substantial change in transmittance occurs in the EC layer used in the imaging device of the present invention can easily obtain information about the degree of charge imbalance, it is not good at determining the polarity of the charge imbalance. A preferred method for determining the polarity of this charge imbalance is to use color information from the signal acquired by the imaging device. Specifically, when a subject is photographed, if the signal corresponding to the absorption region of the EC compound with one polarity of RGB is relatively reduced, it is considered to be a charge imbalance due to residual coloration of the EC compound with the polarity corresponding to the absorption corresponding to the signal attenuation. A reference subject is preferably used as the subject in this case. The following describes an example of an EC element using a dihydrophenazine derivative as the anodic EC compound and a viologen derivative as the cathodic EC compound. When an image is obtained in which the B and G signals are relatively reduced, a charge imbalance occurs due to the colorant remaining in the anodic EC compound. When an image is obtained in which the R signal is relatively reduced, a charge imbalance occurs due to the colorant remaining in the cathodic EC compound. In addition to detecting the degree of charge imbalance through current measurement, the imaging device of the present invention can also use discrimination of the polarity of this charge imbalance to more accurately detect the charge imbalance state of the EC element. Then, by performing image processing to compensate for the absorption of the colorant in the EC compound based on this accurate detection of the charge imbalance state, it is possible to compensate for the color loss of the EC element (light absorption by the EC compound) and improve the quality of the captured image.

[0072] 〔effect〕 In the imaging device of the present invention, when a voltage equal to or lower than the voltage at which a substantial change in transmittance of the EC layer occurs is applied between the first and second electrodes of the EC element, charge imbalance is detected based on the current flowing between the first and second electrodes. The effect of the charge imbalance on the resulting image can be reduced by performing image processing related to color or brightness that compensates for the bleaching defect caused by the charge imbalance, specifically, the light absorption of the EC compound.

[0073] The method of the present invention has the following features. The charge imbalance state of the EC element can be detected electrically without requiring a special configuration such as a reference light source or a reference object. The effect of charge imbalance on the captured image can be reduced without changing the characteristics of the EC element. This method of detecting charge imbalance takes advantage of the characteristics of solution-type EC devices, in which the EC compound is dissolved in a solvent. Therefore, it is difficult to apply this method to fixed-type EC devices, in which the EC compound is fixed to the electrode, or deposition-type EC devices, in which the EC compound is deposited on the electrode. It is also difficult to apply this method to electrodeposition-type EC devices, in which metal is deposited on the electrode. [Example]

[0074] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Specific examples of the anodic EC compounds and cathodic EC compounds used in this example are shown below. (2) to (4) are anodic EC compounds, and (5) to (7) are cathodic EC compounds. However, the EC compounds used in the present invention are not limited to these. These anodic EC compounds, which are aromatic amine derivatives and dihydrophenazine derivatives, and these cathodic EC compounds, which are pyridine derivatives and viologen derivatives, were synthesized by the method described in WO 2020 / 121845.

[0075] [ka]

[0076] [ka]

[0077] (Fabrication of EC element) An EC device having the configuration shown in FIG. 2 was fabricated by the following steps. (1) Fabrication of EC element body: Two sheets of transparent conductive glass (first substrate 26, second substrate 27) coated with an indium-doped tin oxide (ITO) film were prepared. Next, a thermosetting epoxy adhesive mixed with 30 μm spacer beads was applied to the periphery of the transparent conductive glass as a sealant. After that, the two sheets of transparent conductive glass were overlapped so that the ITO films (which would become first electrode 21 and second electrode 22) faced each other, and the adhesive was heated to harden. This bonded substrate 26 and substrate 27 together. The sealant was applied by opening a portion of the periphery as an injection port.

[0078] (2) Injection of electrolyte solution: The anodic EC compound and the cathodic EC compound were dissolved in propylene carbonate containing 10 wt% PMMA (polymethyl methacrylate) as a thickener so that the dimming concentration was the concentration shown in Table 1.

[0079] [Table 1]

[0080] Next, the electrolyte solution was injected into the EC element body through the injection port, and then sealed with the photothermosetting epoxy adhesive to obtain six EC elements. The maximum absorbance of these EC elements was 2.4 on average from 425 nm to 680 nm.

[0081] (3) Durability of EC elements A voltage of 0.7 V was applied between the first and second electrodes of the EC element in a constant temperature and humidity chamber at 60°C and 90% RH to induce a colored state. After 500 hours, the first and second electrodes were short-circuited to decolorize the element. The EC element was placed in front of the image sensor of an imaging device equipped with a lens, and achromatic reference subjects were photographed under artificial sunlight. The changes in white balance gain due to endurance driving were evaluated through simulation. The imaging device used employed an image sensor that captures signals for three colors of light (RGB). From this, it was found that R gain decreased and B gain increased during endurance driving. The decrease in R gain and increase in B gain (relatively low light absorption in the R region and relatively high light absorption in the B region) were determined to be due to a charge imbalance caused by residual colored bodies in the anodic EC compound, and this was used for image processing correction. The difference absorbance at the time of decolorization (absorbance of remaining color, ΔAbs) is calculated by subtracting the absorbance at the time of decolorization before endurance driving from the absorbance at the time of decolorization (short circuit) of the EC element after endurance driving. off The spectra are shown in Figure 7. From this, it was found that, although there were differences in the degree, a residual color, mainly due to the absorption of the anodic EC compound, with a peak around 500 nm was observed in several EC devices.

[0082] (4) Measurement of charge imbalance current and calculation of correction coefficient A voltage of 0.15 V was applied between the first and second electrodes of the EC element and held for 10 seconds, and the steady-state current flowing between the first and second electrodes was measured. The absorbance change, calculated by subtracting the absorbance at short circuit (bleaching) from the absorbance at 0.15 V, was below the lower limit of measurement of the spectrometer and was less than 1 / 1000 of the maximum absorbance of the EC element. The steady-state current (i ic The voltage applied was 0.315 V. The temperature of the EC element at this time was 25°C.

[0083] An EC element was placed in front of the image sensor of an imaging device equipped with a lens, and achromatic reference subjects were photographed under artificial sunlight. The changes in white balance gain due to endurance driving were evaluated through simulation. Figure 8 shows the relationship between white balance gain change (no change is set to 1: vertical axis) and charge imbalance current (steady-state current: horizontal axis). From this, it was found that R gain decreased linearly as the charge imbalance progressed, and B gain increased linearly as the charge imbalance progressed. A correction coefficient was calculated from this line and used in image processing.

[0084] (5) Image processing using correction coefficients The effect of charge imbalance decolorization defects on images (changes in white balance gain) is described below, comparing the changes before and after image processing. Image processing used the relationship between charge imbalance current and white balance gain change calculated in the previous section to perform white balance gain correction in the control unit for decolorization defects caused by charge imbalance remaining in the colored body of the anodic EC compound. Table 2 shows the effect of charge imbalance decolorization defects on changes in the white balance gain of captured images after endurance driving compared to the EC element before endurance driving in the decolorized state, before and after image processing, and the amount of suppression achieved by image processing.

[0085] [Table 2]

[0086] Before image processing, the white balance change was a maximum of 4.3% (Sample 2), but after image processing it was reduced to a maximum of 0.7% (Sample 2).It was also confirmed that the white balance change was suppressed in all samples, improving the quality of the captured images.

[0087] The following effects were confirmed from this example. (A) In a complementary EC element in which both the oxidized and reduced forms of an EC compound are dissolved in a solvent, charge imbalance bleaching failure occurs. When a voltage lower than the voltage at which a substantial change in transmittance of the EC layer occurs is applied between the first and second electrodes, a charge imbalance current resulting from the reaction between the oxidized and reduced forms of the EC compound of the same polarity flows between the first and second electrodes. (B) By performing image processing based on the charge imbalance current proportional to the amount of colorant remaining in the EC compound during decolorization, the decolorization failure of the EC element (light absorption by the EC compound) can be compensated for, improving the quality of the captured image. (C) The quality of the captured image is improved by determining the polarity of the charge imbalance based on the ratio of the signals to the three types of RGB light and the charge imbalance current, and then performing image processing.

[0088] Example 2 An example of impedance-based imaging is described. (1) Impedance measurement An EC device was fabricated and subjected to endurance driving in the same manner as in Example 1. An AC voltage of ±10 mV was applied between the first and second electrodes of this EC device, with a short circuit at 0 V, at a frequency of 100 kHz to 1 Hz, and the impedance was calculated from the current flowing during this application. The maximum absorbance change of the EC device was less than 1 / 1000. The obtained impedance was fitted to the equivalent circuit shown in Figure 9, and a correction coefficient was calculated using the obtained charge transfer resistance R2. In Figure 9, C1 and C2 are capacitors, R1, R2, and R3 are resistors, and Ws1 is a Warburg element.

[0089] (2) Measurement of charge imbalance current and calculation of correction coefficient As in Example 1, the change in white balance gain due to endurance driving was evaluated by simulation. Figure 10 shows the relationship between the change in white balance gain (no change is 1: vertical axis) and the charge transfer resistance R2 (horizontal axis). From this, it was found that the R gain and B gain change exponentially as the charge imbalance progresses. This curve was used as a correction coefficient for image processing.

[0090] (3) Image processing using correction coefficients The effect of charge imbalance decolorization defects on images (changes in white balance gain) is described below, comparing the changes before and after image processing. Image processing used the relationship between charge imbalance current and white balance gain change calculated in the previous section to perform white balance gain correction in the control unit for decolorization defects caused by charge imbalance remaining in the colored body of the anodic EC compound. Table 3 shows the effect of charge imbalance decolorization defects on changes in the white balance gain of captured images after endurance driving compared to the EC element before endurance driving in the decolorized state, before and after image processing, and the amount of suppression achieved by image processing.

[0091] [Table 3]

[0092] Before image processing, the white balance change was a maximum of 4.3% (Sample 2), but after image processing it was reduced to a maximum of 0.5% (Sample 1).It was also confirmed that the white balance change was suppressed in all samples, improving the quality of the captured images. From this example, the following effects were confirmed. (A) The quality of the captured image is improved by performing image processing based on the impedance calculated from the current that flows when an AC voltage equal to or lower than the voltage at which a substantial change in transmittance occurs in the electrochromic layer is applied between the first electrode and the second electrode.

[0093] Example 3 An example of correction for temperature changes will be described below. (1) Calculation of temperature correction coefficient The temperature dependence of steady-state current was measured when a voltage of 0.15 V was applied between the first and second electrodes of an EC element similar to that of Example 1. As a result, the current value when the temperature of the electrochromic element was 40°C was 1.50 times that at 25°C.

[0094] (2) Current measurement A temperature sensor was attached to the surface of the EC element that had been subjected to the same durability driving as in Example 1, and the element was incorporated into an imaging device. When the element temperature was 40° C., current was measured in the same manner as in Example 1.

[0095] (3) Image processing using temperature correction coefficients Using the calculated temperature correction coefficient, the current value at 25°C was estimated from the current value measured at 40°C, and white balance gain correction was performed using this value in the same manner as in Example 1. Table 4 shows the effect of charge imbalance and color loss defects on changes in the white balance gain of the captured image, compared to the EC element before endurance driving in the color loss state, before and after image processing, and the amount of suppression by the image processing.

[0096] [Table 4]

[0097] Before image processing, the white balance change was a maximum of 4.3% (Sample 2), but after image processing it was reduced to a maximum of 0.7% (Sample 2).It was also confirmed that the white balance change was suppressed in all samples, improving the quality of the captured images. From this example, the following effects were confirmed. (A) The quality of the captured image is improved by installing a temperature sensor in the imaging device to detect the temperature of the electrochromic element and performing image processing based on the detected temperature and current. [Explanation of symbols]

[0098] 10: imaging device, 11: EC element, 21: first electrode, 22: second electrode, 23: EC layer

Claims

1. a first electrode, a second electrode, and an electrochromic layer disposed between the first electrode and the second electrode; the electrochromic layer has a solvent, and an anodic redox material and a cathodic redox material dissolved in the solvent, and at least one of the anodic redox material and the cathodic redox material is an electrochromic compound; an imaging device characterized in that, when a voltage equal to or lower than a voltage at which a substantial change in transmittance of the electrochromic layer occurs is applied between the first electrode and the second electrode, image processing is performed to compensate for defective decoloring of the electrochromic element based on a current flowing between the first electrode and the second electrode.

2. 2. The imaging device according to claim 1, wherein the image processing is related to color or brightness.

3. 3. The imaging device according to claim 1, wherein the image processing compensates for light absorption of the electrochromic compound.

4. 4. The imaging device according to claim 1, wherein the imaging device compensates for residual light absorption of the electrochromic compound in an amount proportional to the current.

5. 5. The imaging device according to claim 1, further comprising a temperature sensor for detecting a temperature of the electrochromic element, and performing image processing based on the temperature and the current.

6. 6. The imaging device according to claim 1, wherein the imaging device performs image processing based on impedance calculated from a current flowing between the first electrode and the second electrode when an AC voltage equal to or lower than a voltage at which a substantial change in transmittance occurs in the electrochromic layer is applied between the first electrode and the second electrode.

7. 7. The imaging device according to claim 1, wherein the imaging device has an imaging element that acquires signals for at least three colors of light, RGB, and performs image processing based on a ratio of the signals and the current.

8. 8. The imaging device according to claim 1, wherein the electrochromic compound is a low-molecular organic compound.

9. 9. The imaging device according to claim 1, wherein the anodic redox substance is an anodic electrochromic compound, and is an aromatic amine derivative.

10. 10. The imaging device according to claim 9, wherein the aromatic amine derivative is a dihydrophenazine derivative.

11. 11. The imaging device according to claim 1, wherein the cathodic oxidation-reduction substance is the cathodic electrochromic compound and is a pyridine derivative.

12. 12. The imaging device according to claim 1, wherein both an oxidized form and a reduced form of the electrochromic compound are dissolved in the solvent.

13. 13. The imaging device according to claim 1, wherein the current is a current resulting from a reaction between an oxidized form and a reduced form of an electrochromic compound of the same polarity occurring between the first electrode and the second electrode.

14. A device comprising: a first electrode; a second electrode; and an electrochromic layer disposed between the first electrode and the second electrode; the electrochromic layer has a solvent, and an anodic redox material and a cathodic redox material dissolved in the solvent, and at least one of the anodic redox material and the cathodic redox material is an electrochromic compound; An imaging device characterized by performing image processing to compensate for remaining light absorption of the electrochromic compound in an amount proportional to the current flowing between the first electrode and the second electrode when a voltage equal to or lower than the voltage at which a substantial change in transmittance occurs in the electrochromic layer is applied between the first electrode and the second electrode.

15. A device comprising: a first electrode; a second electrode; and an electrochromic layer disposed between the first electrode and the second electrode; the electrochromic layer has a solvent, and an anodic redox material and a cathodic redox material dissolved in the solvent, and at least one of the anodic redox material and the cathodic redox material is an electrochromic compound; An imaging device characterized in that, when an AC voltage equal to or lower than a voltage at which a substantial change in transmittance occurs in the electrochromic layer is applied between the first electrode and the second electrode, image processing is performed based on impedance calculated from a current flowing between the first electrode and the second electrode.

16. A device comprising: a first electrode; a second electrode; and an electrochromic layer disposed between the first electrode and the second electrode; the electrochromic layer has a solvent, and an anodic redox material and a cathodic redox material dissolved in the solvent, and at least one of the anodic redox material and the cathodic redox material is an electrochromic compound; An imaging device characterized in that, when a voltage equal to or lower than a voltage at which a substantial change in transmittance occurs in the electrochromic layer is applied between the first electrode and the second electrode, image processing is performed based on a current generated from a reaction between an oxidized form and a reduced form of an electrochromic compound of the same polarity that occurs between the first electrode and the second electrode.

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