JP2020016836A - Light control device and light detection device - Google Patents

Abstract

To provide a light control device capable of controlling incident light intensity in multiple wavelength ranges.SOLUTION: A light control device provided herein comprises an electrochromic element and is configured to change transmittance in a plurality of wavelength regions. The light control device controls the change in transmittance in each of the plurality of wavelength ranges in which the transmittance varies.SELECTED DRAWING: None

Description

  The present invention relates to a light control device and a light detection device.

2. Description of the Related Art Currently, imaging devices for automobiles and driving assistance systems using the same are being actively developed. In image pickup apparatuses, especially in moving image pickup apparatuses, a light transmittance reduction element such as an ND filter is often arranged on the incident light path of the light receiving device, and advanced information collection is performed by adjusting the amount of light incident on the light receiving device. Is possible. The light transmittance variable element, which enables the transmittance of the light transmittance reduction element to be electrically controlled, expands the degree of freedom of exposure adjustment, making it possible to acquire data that was not possible with a fixed transmittance element. Make it possible.
As the light transmittance variable element, elements such as a liquid crystal element and an electrochromic (hereinafter sometimes referred to as “EC”) element are being developed. Above all, the EC element has a useful feature as a variable light transmittance element that can achieve both a low light transmittance during coloring and a high light transmittance during erasing.
Patent Literature 1 discloses an optical device that calculates focus detection information using an EC element as a light transmittance variable element.

JP 2006-292981 A

The method of Patent Literature 1 is that, by using EC as a variable light transmittance element, it is possible to control light transmittance in a necessary wavelength region (red region) while increasing light transmittance in a light transmitting state. It is effective. On the other hand, if the wavelength range in which the light transmittance variable element can be controlled and the independence of control can be further improved, the information that can be obtained by the photodetector can be further enhanced.
SUMMARY An advantage of some aspects of the invention is to provide a light control device capable of controlling the amount of incident light in a plurality of wavelength bands.

  The light control device of the present invention is a light control device including an electrochromic element and having a plurality of wavelength regions in which the transmittance changes, wherein the change in the transmittance is controlled for each wavelength region in which the transmittance changes. It is characterized by that.

  INDUSTRIAL APPLICABILITY The light control device of the present invention can control the amount of incident light in a plurality of wavelength bands, and can be suitably used for a light detection device such as an imaging device.

It is a schematic diagram which shows an example of a structure of the EC element used in embodiment of this invention. It is a schematic diagram which shows an example of a structure of the photodetector which concerns on embodiment of this invention. FIG. 1 is a schematic diagram illustrating an example of a configuration of an imaging device according to an embodiment of the present invention. It is a schematic diagram which shows the outline of the photodetector of an Example. 3 is an absorption spectrum of a colored state of an EC compound used in Examples.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

光 Light control device≫
A light control device according to an embodiment of the present invention is a light control device including an electrochromic element and having a plurality of wavelength regions in which transmittance changes. Then, in the light control device of the present embodiment, the change in transmittance is controlled for each wavelength region in which the transmittance changes, and preferably, the change in transmittance is independently controlled. The wavelength region in which the transmittance changes is preferably any one of the infrared region, red region, green region, and blue region.

  Specifically, the light control device of the present embodiment is preferably configured by an optical filter using a plurality of electrochromic compounds (EC compounds) that can change light absorption characteristics in different light wavelength regions. . An EC compound is a material that can change the optical characteristics electrically. The light control device of the present embodiment includes an EC element that can electrically change the transmittance using an EC compound. The EC element has a higher maximum transmittance of, for example, 90% or more in a visible light region than a liquid crystal element or the like well known as a dimming element. For this reason, even if a plurality of elements are arranged on the optical path, the degree of decrease in the maximum value of the amount of light incident on the photodetector arranged downstream of the dimming element is small, and the practically usable transmittance (For example, a transmittance of about 60 to 80%).

  Although the control range of the transmittance of the EC element is not particularly limited, both the maximum transmittance (when the EC element is not colored) and the minimum transmittance (when the coloring density of the EC element is maximum) are used for the light control device. It is desired to satisfy the performance as described above. As a specific numerical value, a value of 100% to 0.01% is ideally exemplified, and a value of 95% to 0.1% is practically exemplified. As for the control of the transmittance between these, there may be ON / OFF control, but it is preferable that the control can be performed with a plurality of gradations or a stepless gradation.

  An EC element is an element having a pair of electrodes and an electrochromic layer (EC layer) containing an EC compound, which is disposed between the electrodes. EC devices include those using inorganic materials and those using organic materials, and those using organic materials include those using high-molecular-weight organic materials and those using low-molecular-weight organic materials. There is. Although any device can be used as the EC device of the present embodiment, an EC device using a low-molecular organic material is particularly preferably used from the viewpoint of contrast and maximum transmittance.

Examples of the light control device of the present embodiment include the following two types.
Type 1: A plurality of EC elements are provided, and each of the plurality of EC elements has a different wavelength region in which the transmittance changes.
Type 2: One EC element is provided, and the one electrochromic element has a plurality of electrochromic compounds having different wavelength regions in which transmittance changes.

  Type 1 includes a plurality of EC elements using a plurality of EC compounds whose light absorption characteristics change in different light wavelength regions. That is, this is a type of dimming device in which a plurality of EC elements having different wavelength regions in which light absorption characteristics change are stacked on an optical path. The EC compound used for each of the plurality of EC elements may be singular or plural.

  Type 2 includes one EC element using a plurality of EC compounds whose light absorption characteristics change in different light wavelength regions. That is, a plurality of EC compounds whose light absorption characteristics can be changed in different light wavelength regions are used in one EC element, and the light absorption characteristics of the plurality of EC compounds are separately controlled. As a specific example, a plurality of materials having different applied voltages for changing the light absorption characteristics are arranged in one EC element, and the wavelength dependence of the transmittance of the EC element is changed by the applied voltage. More specifically, there are an EC compound a that absorbs light of wavelength λa when oxidized at potential Ea and an EC compound b that absorbs light of wavelength λb when oxidized at potential Eb. <Eb is assumed. At this time, when the electrode potential E satisfies E <Ea, the EC compound a does not absorb light having the wavelength λa, and the EC compound b does not absorb light having the wavelength λb. When the electrode potential E is set to Ea <E <Eb, the EC compound a absorbs light having the wavelength λa, but the EC compound b does not absorb light having the wavelength λb. Further, when the electrode potential E> Eb is set, the EC compound a absorbs light of the wavelength λa, and the EC compound b absorbs light of the wavelength λb. In this way, a plurality of EC compounds capable of changing the light absorption characteristics in different light wavelength regions can be used in one EC element, and the light absorption characteristics of the plurality of EC compounds can be controlled separately.

  The advantage of Type 1 is that by using a plurality of EC elements, the selection range of the EC compound in each element can be expanded. As a specific example, a material can be selected without worrying about the relationship of the oxidation-reduction potential between EC compounds having different elements. It is also possible to easily perform coloring and decoloring by selecting one of the EC compounds and to precisely control the concentration of each element.

  Type 2 is characterized in that the number of transparent electrodes and the like can be reduced by using a single EC element, so that the transmittance at the time of decoloring is high, the structure can be easily reduced, and the cost is superior.

  Although any type can be used as the light control device of the present embodiment, type 1 is preferable from the viewpoint of independently controlling the light wavelength region.

<EC element>
FIG. 1 is a schematic diagram illustrating an example of the configuration of an EC element used in the present embodiment. The EC device of the present embodiment has a pair of electrodes 1 and an EC layer 2 disposed between the pair of electrodes. Further, the EC element may include the substrate 3 and the sealing material 4. The EC layer has an EC compound. Note that the EC element in FIG. 1 is an example of the EC element configuration of the present embodiment, and is not limited to this. For example, a layer of an antireflection film may be provided between the substrate 3 and the electrode 1 or between the electrode 1 and the EC layer 2.

[Electrode 1]
As the electrode 1 of the EC element, a transparent conductive electrode is preferably used. As the material of the transparent conductive electrode, a material having transparency and conductivity and having stability during the reaction of the EC compound can be preferably used. For example, a transparent conductive oxide electrode such as indium tin oxide (ITO) or fluorine-doped tin oxide is preferably used. Alternatively, a thin metal wire or thin film may be disposed to reduce the resistance value, or another conductive material such as CNT may be used.

[EC layer 2]
The EC layer 2 has an EC compound that is a compound exhibiting EC properties. Specific examples include inorganic oxides such as tungsten oxide and iridium oxide, and organic high molecular weight compounds include polythiophene and polyaniline. Examples of the organic low molecular weight EC compound include a derivative of a pyridine salt, an aromatic amine compound, and a derivative of a heterocyclic compound, and these may be used after being dissolved in a solvent. These materials may be used alone or in combination of two or more. Among them, it is preferable to combine a pyridine salt derivative with a heterocyclic compound, and it is particularly preferable to combine a viologen-based compound with an aromatic amine compound.

  The EC layer 2 may have a layer made of an EC compound and a layer made of an electrolyte. Further, the EC layer 2 may be provided as a solution having an EC compound and an electrolyte. Such a form can be said that the EC layer 2 is a solution layer. In the EC device according to the present embodiment, the EC layer 2 is preferably a solution layer. When the EC layer 2 is a solution layer, an organic compound having EC properties, a solution, and other dissolved substances may be collectively referred to as an EC medium or an EC solution.

  The solvent for dissolving the EC compound is selected according to the application in consideration of the solubility of the solute including the EC compound, the vapor pressure, the viscosity, the potential window, and the like, but may be a solvent having polarity. preferable. Specifically, methanol, ethanol, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, γ-butyrolactone, γ-valerolactone, sulfolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, acetonitrile, propionnitrile, benzonitrile, dimethylacetamide And organic polar solvents such as methylpyrrolidinone and dioxolane, and water, and two or more kinds may be used in combination. The EC layer 2 may contain an electrolyte, a viscosity modifier, a UV stabilizer, and the like, as necessary.

  The electrolyte is not limited as long as it is an ion-dissociable salt, has good solubility in a solvent, and shows high compatibility in a solid electrolyte. Among them, an electrolyte having an electron donating property is preferable. These electrolytes can also be called supporting electrolytes.

Examples of the electrolyte include inorganic ion salts such as various alkali metal salts and alkaline earth metal salts, and quaternary ammonium salts and cyclic quaternary ammonium salts. Specifically, _{LiClO 4, LiSCN, LiBF 4,} LiAsF 6, LiCF 3 SO 3, LiPF 6, LiI, NaI, NaSCN, NaClO 4, NaBF 4, NaAsF 6, KSCN, the KCl like Li, Na, K alkaline (CH ₃ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (n-C ₄ H ₉ ) ₄ NBF ₄ , (n-C ₄ H ₉ ) ₄ NPF ₆ , (C _{2 H 5) 4 NBr, (C} 2 H 5) 4 NClO 4, include _{(n-C 4 H 9)} 4 NClO 4 4 quaternary ammonium salts and cyclic quaternary ammonium salts such as.

  Further, a highly viscous or gelled EC medium containing a polymer or a gelling agent may be used. These polymers and gelling agents can also be called thickeners. By having a thickener and increasing the viscosity of the EC solution, it becomes difficult for the organic compound to form an association, and the temperature dependence of the absorption spectrum can be reduced. Therefore, the EC solution preferably has a thickener.

  The viscosity of the EC solution may be between 10 and 5000 cP, and between 50 and 1000 cP. The viscosity of the EC solution may be 150 cP or less, preferably 100 cP or less, more preferably 65 cP or less. The viscosity of the EC solution may be 20 cP or more, preferably 50 cP or more.

  The thickener may have a weight ratio of 20% by weight or less when the weight of the electrochromic layer is 100% by weight. Preferably it is 1 wt% or more and 15 wt% or less, more preferably 5 wt% or more and 10 wt% or less.

  The polymer is not particularly limited, and examples thereof include polyacrylonitrile, carboxymethylcellulose, polyvinyl chloride, polyalkylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, and Nafion (registered trademark). Polymethyl methacrylate, polyethylene oxide and polypropylene oxide are preferred.

  When the viscosity of the EC solution is high, the movement of molecules in the EC solution can be suppressed, so that the association may be suppressed in some cases. On the other hand, since the movement of electrons in the EC solution is suppressed, the response speed of the EC element is reduced, and it is not preferable that the viscosity is too large.

[Substrate 3]
As the substrate 3, a light-transmissive base material is used. Here, “light transmissivity” means that the corresponding substrate, electrode, or the like transmits light, and that the transmittance is 50% or more and 100% or less. Specifically, glass, a polymer compound, or the like is used, and coating such as antireflection is performed as necessary.

[Seal material 4]
The sealing material 4 is preferably used to hold the EC layer 2 between a pair of electrodes and to keep the distance between the two electrodes. The sealing material 4 is preferably a material that is chemically stable, hardly permeates gas and liquid, and does not inhibit the oxidation-reduction reaction of the EC compound. For example, an inorganic material such as a glass frit, an organic material such as an epoxy resin or an acrylic resin, a metal, or the like can be used. Note that the sealing material 4 may have a function of maintaining the distance between the electrodes by, for example, containing a spacer material.

  When the sealing material 4 does not have a function of defining the distance between the electrodes, a spacer may be separately provided to maintain the distance between the two electrodes. As a material for the spacer, an inorganic material such as silica beads or glass fiber, or an organic material such as polyimide, polytetrafluoroethylene, polydivinylbenzene, fluoro rubber, or epoxy resin can be used.

<Controller>
The light control device of the present embodiment may include a controller that controls the transmittance of the EC element. As a method of controlling the transmittance of the EC element by the controller, a method suitable for the element to be used is adopted. Specifically, for a desired transmittance setting value, a method of inputting a predetermined condition into the EC element, or by comparing the transmittance setting value with the transmittance of the EC element, There is a method of selecting and inputting conditions so as to match. The parameters to be changed include a voltage, a current, and a duty ratio.

≪Light detection device≫
A light detection device according to an embodiment of the present invention includes the light control device of the present invention and a light detector (first light detector) that detects light transmitted through the light control device. FIG. 2 is a schematic diagram illustrating an example of the configuration of the photodetector according to the embodiment of the present invention. 2, the light detection device 10 includes a light control device 11, a first light detector 12, and a second light detector 13. The dimmer 11 is arranged on an optical path incident on the first photodetector 12. The incident light 14 that has entered the photodetector 10 enters the first photodetector 12 through the dimmer 11. As will be described later, when part or all of the first photodetector 12 is used as the second photodetector 13, the second photodetector 13 is not necessarily required.

  The light detection device 10 may include an imaging optical system including a lens, an aperture, and the like, and other filters such as a UV and an IR filter, as necessary. In this case, it is preferable that the incident light is incident on the first photodetector 12 through a photographing optical system, a filter, and the like. Further, the light detection device 10 may include a controller 15 that controls light absorption characteristics of a plurality of electrochromic materials constituting the light control device 11. The light absorption characteristics of the electrochromic material can be controlled by referring to the light intensity detected by the second light detector 13 through the controller 15.

  The light detection device 10 is a device that measures the amount of incident light 14 incident on the light detection device 10 using the first light detector 12. The light detection device 10 may be an imaging device. In that case, an imaging element is used as the first light detector 12.

<Dimming device 11>
The light detection device 10 has the light control device 11 of the present invention described above. The light detection device 10 of FIG. 2 has a type 1 light control device 11. Specifically, the light control device 11 of FIG. 2 includes three EC elements, and each of the EC elements contains a plurality of EC materials capable of changing the transmittance in different light wavelength regions. .

<First photodetector 12>
The first light detector 12 is a light detector for acquiring the light intensity characteristics that the light detection device 10 aims at. Specifically, if the light detection device 10 is an imaging device, it is an image sensor, and if the light detection device 10 is, for example, a spectrophotometer, it is an optical semiconductor or a photomultiplier tube.

<Second photodetector 13>
The second photodetector 13 is a photodetector having sensitivity in a part of the wavelength range to which the first photodetector 12 has sensitivity, preferably in a plurality of different light wavelength ranges. The plurality of different light wavelength regions in which the second photodetector 13 has sensitivity are preferably a plurality of different wavelength regions in which the transmittance of the light control device 11 changes, and in this embodiment, a plurality of EC compound light beams. It corresponds to a plurality of different light wavelength regions where the absorption characteristics change. The wavelength region in which the second photodetector 13 has sensitivity is preferably any one of the infrared region, the red region, the green region, and the blue region. The second photodetector 13 has a function of detecting the intensity of the incident light 14 incident on the photodetector 10 for each wavelength region and controlling the dimmer 11 based on the information. A specific example will be described below. The second photodetector 13 has sensitivity corresponding to light centered on the wavelengths λA and λB, and can detect the intensity of light corresponding to each wavelength region. Here, it is assumed that the incident light 14 incident on the photodetector 10 is incident, and the incident light 14 has a sufficiently high light intensity in the wavelength region of λB compared to λA. When the incident light 14 is directly incident on the first photodetector 12 and data is acquired under exposure conditions corresponding to the light intensity of λB, data in the wavelength region of λA may not be acquired with sufficient gradation. . The second photodetector 13 includes a plurality of different light wavelength regions (here, wavelength regions centered on the wavelengths λA and λB) in which the light absorption characteristics of the plurality of EC compounds used in the light control device 11 change. Has a sensitivity in a light wavelength region corresponding to. Therefore, if the light absorption characteristics of these plural EC compounds can be controlled, the transmittance in the wavelength region centering on the wavelengths λA and λB can be controlled. Therefore, by appropriately reducing the light transmittance of the EC element using the EC compound in the wavelength region around the wavelength λB, data is obtained with sufficient gradation in both the wavelength regions around λA and λB. It is possible to do.

  At least one of the plurality of different light wavelength regions in which the second photodetector 13 has sensitivity, and at least one of the plurality of different light wavelength regions in which the light absorption characteristics of the plurality of EC compounds change, Both preferably include a wavelength region of mainly infrared light. Thus, as described in, for example, Example 1 (recognition of a rear-view camera) described later, information in a visible light region where light detection technology is most advanced is obtained, and infrared light including information that cannot be obtained with visible light is obtained. Region information can be acquired by one photodetector. Therefore, it is possible to collect information at a higher level than when only information in the visible light region or information in the infrared light region is used. The infrared light here refers to light having a wavelength of 700 nm to 1 mm, and particularly to near-infrared light having a wavelength of 700 nm to 2.5 μm.

  The arrangement of the second photodetector 13 may be on the optical path, upstream or downstream of the light control device 11. Further, the second photodetector 13 may be arranged by branching the optical path, and the position at which the optical path is branched may be upstream or downstream of the light control device 11.

  When the second photodetector 13 is arranged upstream of the light control device 11, it is advantageous in that the incident light is not reduced by the light control device 11 and the incident light intensity can be obtained more directly. In that case, it is preferable that the second photodetector 13 is arranged so as not to be a shadow on the first photodetector 12.

When the second photodetector 13 is arranged downstream of the light control device 11, the incident light transmitted through the light control device 11 can be detected, so that information including the transmittance of the light control device 11 can be obtained. Can be This is advantageous from the viewpoint of controlling (for example, feedback) the light control device 11 in response to the incident light. In the case where the second photodetector 13 is disposed downstream, part or all of the first photodetector 12 may be used as the second photodetector 13. When part or all of the first photodetector 12 is used as the second photodetector 13, it is most preferably used because it has the following advantages.
1. The light control device 11 can be controlled by directly using the information on the light intensity reaching the first photodetector 12 from which the light detection device 10 acquires the target light intensity characteristics. As a result, conditions suitable for obtaining the desired light intensity characteristics can be directly given.
2. Since it is not necessary to separately install the second photodetector 13, it is advantageous for space saving and cost reduction.

  Also, when the second photodetector 13 is arranged with the optical path branched, it is advantageous in that the degree of freedom in arrangement increases.

<Controller 15>
In the photodetector 10 of the present embodiment, the amount of light incident on the first photodetector 12 can be controlled by changing the transmittance. The light absorption characteristics of the EC compound can be controlled with reference to the light intensity detected by the second light detector 13.

  A specific example of the operation method of the controller 15 will be described below. As an example, a case will be described in which a dimming device 11 including three types of EC elements each using an EC compound having an absorption peak at λa, λb, and λc is used. The second photodetector 13 has sensitivity to wavelengths corresponding to the absorption peaks λa, λb, λc of the EC compound. When each EC element is in the light transmitting state, the first light detector 12 is irradiated with incident light. At this time, it is assumed that the light intensity detected by the second photodetector 13 is such that the light intensity corresponding to the wavelength λa is saturated and the light intensity corresponding to the wavelengths λb and λc is appropriate. In this case, by setting the condition for the EC element using an EC compound having an absorption peak at the wavelength λa to a colored state, the light intensity corresponding to the wavelength λa is reduced, and the detection state of the light corresponding to the wavelength λa is set to an appropriate state. It can be. The controller 15 increases the voltage for the voltage control method, the current for the current control method, and the duty ratio for the Hals width modulation method for the EC element corresponding to the wavelength λa, The coloring density of the corresponding EC element can be increased and the incident light can be reduced. In addition, it is also preferable to set the initial coloring state of each EC element to an intermediate density and increase or decrease the coloring density according to the intensity of incident light. For example, when the incident light intensity is high, the coloring density of the EC element is increased. For example, when the incident light intensity is low, the coloring density of the EC element is reduced. At this time, the above-described method (increase in voltage or the like) can be used to increase the coloring density of the EC element, and conversely, reduction of the voltage or the like is used to decrease the coloring density.

<Application example>
The photodetector 10 of the present embodiment can control, preferably independently control the amount of light incident on the first photodetector 12 for each wavelength region. This is useful in the following cases.

[Example 1: Recognition of rear view camera]
2. Description of the Related Art It has been widely practiced to enhance the safety by presenting an image behind a vehicle acquired by a camera installed at the rear of the vehicle to a driver. The rear-view camera is often provided with an IR filter in order to select and acquire information on visible light, excluding the influence of infrared light among sunlight. On the other hand, when an image is acquired by this camera at night, light is radiated from a light source installed at the rear of the vehicle to compensate for the insufficient light quantity compared to daytime. A method is widely used in which invisible IR light is selected as the light so that the driver of the following vehicle is not dazzled. In this case, in order to acquire an image with the same camera as in the daytime, it is necessary to remove the IR filter. In addition, when strong visible light from a following vehicle or the like is incident and the amount of incident IR light is too small as compared with the visible light, it is desirable to have a mechanism for reducing the visible light. In such a case, if there is a light control device 11 that can control the amount of light incident on the first photodetector 12 for each wavelength region, this problem can be solved. For example, if there is a light control device 11 that can independently control the visible light and the IR light, it is possible to select the visible light information while eliminating the influence of the infrared light by absorbing and reducing the IR light in the daytime and transmitting the visible light. You can get it. Also, at night, by transmitting the IR light and reducing the visible light, the IR light emitted from the light source transmits the reflected light reflected on the subject while controlling the transmittance of the visible light, thereby controlling the transmittance of the following vehicle. Even if strong visible light enters, an image by IR reflected light can be clearly obtained.

[Example 2: Front camera recognition]
It has been widely studied to improve the safety by presenting and recording to a driver an object detected from an image acquired by a camera installed at the front of a car (for example, behind a rearview mirror). Have been. If the transmittance of visible light incident on the camera can be controlled for each wavelength band, the ability of the camera to recognize a captured image can be increased. For example, when the intensity of red light such as a brake light of a vehicle in front is high, and when the transmittance cannot be controlled independently for each wavelength band, in order to prevent the saturation, the transmittance is controlled over the entire wavelength range. The amount of incident light is reduced. Examples include introduction of an ND filter and shortening of the exposure time. In such a case, light in other surrounding wavelength regions, for example, blue light, the amount of incident light such as green light is also reduced, and objects recognized by light of that wavelength, such as signs, other vehicles, The detection sensitivity for pedestrians and the like will be reduced. On the other hand, when the transmittance can be controlled for each wavelength band, by selecting and reducing the transmittance of red light having high intensity, blue light and green light can be prevented while preventing saturation of red light. It is possible to maintain the amount of incident light such as light. As a result, it is possible to prevent the detection sensitivity of the object recognized by the light of the wavelength from being lowered.

≪Imaging device≫
The light detection device of the present invention may be an imaging device. In that case, an imaging element is used as the first light detector 12. FIG. 3 is a schematic diagram illustrating an example of a configuration of the imaging device according to the present embodiment.

  The imaging device 100 is an imaging device including a lens unit 102 and an imaging unit 103. The imaging device 100 according to the present embodiment is, for example, a digital camera or a digital video camera. The optical filter 101 as a light control device included in the imaging device 100 according to the present embodiment may be provided immediately before the imaging device 110. Immediately before the image sensor 110 means that there is no member disposed between the image sensor 110 and the optical filter 101. When the imaging device 100 has a lens, it may be provided outside the lens. Providing the optical filter 101 outside the lens refers to disposing the optical filter 101 such that the lens is disposed between the optical filter 101 and the image sensor 110. When the imaging device 100 has a plurality of lenses, the imaging device 100 may be provided between the lenses.

  The lens unit 102 is a rear focus type zoom lens that performs focusing after the stop. In FIG. 3A, the lens unit 102 includes the optical filter 101 and an imaging optical system having a plurality of lenses or lens groups. The optical filter 101 is the light control device of the present invention. The optical filter 101 may be arranged such that light passing through the optical filter 101 passes through the imaging optical system, or may be arranged such that light passing through the imaging optical system passes through the optical filter 101. Good. The optical filter 101 may be arranged closer to the image sensor 110 than the lens, or may be arranged closer to the object than the lens. The lens unit 102 is detachably connected to the imaging unit 103 via a mount member (not shown).

  The lens unit 102 includes, in order from the subject (object) side, a first lens group 104 having a positive refractive power, a second lens group 105 having a negative refractive power, a third lens group 106 having a positive refractive power, and a positive lens group. The optical filter 101 includes four lens groups of a fourth lens group 107 having a refractive power of. Zooming is performed by changing the distance between the second lens group 105 and the third lens group 106, and focusing is performed by moving a part of the fourth lens group 107. The lens unit 102 has, for example, an aperture stop 108 between the second lens group 105 and the third lens group 106, and has an aperture stop 108 between the third lens group 106 and the fourth lens group 107. It has an optical filter 101. The light passing through the lens unit 102 is arranged so as to pass through each of the lens groups 104 to 107, the aperture stop 108, and the optical filter 101, and the light amount can be adjusted using the aperture stop 108 and the optical filter 101. .

  The imaging unit 103 includes a glass block 109 and an imaging device 110. The glass block 109 is a glass block such as a low-pass filter, a face plate, and a color filter. The image sensor 110 is a sensor unit that receives light that has passed through the lens unit 102, and may be a CCD, a CMOS, or the like. Further, the imaging element 110 may be another light receiving element, for example, an optical sensor such as a photodiode, and an element that acquires and outputs information on light intensity or wavelength can be used as appropriate.

  In the present embodiment, the optical filter 101 is disposed between the third lens group 106 and the fourth lens group 107 in the lens unit 102, but the imaging device 100 is not limited to this configuration. For example, the optical filter 101 may be located either before (subject side) or after (the imaging unit 103 side) the aperture stop 108, or before any of the first to fourth lens groups 104 to 107. Later, it may be between the lens groups. If the optical filter 101 is arranged at a position where light converges, there is an advantage that the area of the optical filter 101 can be reduced.

  Further, the configuration of the lens unit 102 is not limited to the above-described configuration. For example, in addition to the rear focus type, an inner focus type in which focusing is performed before the stop may be used, or another type may be used. In addition to the zoom lens, a special lens such as a fisheye lens or a macro lens can be appropriately selected.

  Further, in the present embodiment, the EC element and the driving device of the optical filter 101 are arranged inside the lens unit 102. However, the imaging device 100 of the present embodiment is not limited to this, and the EC element of the optical filter 101 exists in the lens unit, and the driving device for the EC element is disposed outside the lens unit 102, that is, in the imaging unit 103. It may be. When the driving device is disposed outside the lens unit 102, the driving unit is connected to an EC element inside and outside the lens unit 102 through wiring to control the driving.

  In the configuration of the above-described imaging apparatus 100, the optical filter 101 is disposed inside the lens unit 102, but is not limited to this, and the imaging unit 103 has the optical filter 101 as shown in FIG. It may be. In FIG. 3B, the optical filter 101 is arranged immediately before the image sensor 110. The optical filter 101 is disposed at an appropriate position inside the image pickup unit 103, and if the image pickup element 110 is disposed to receive light passing through the optical filter 101, the optical filter 101 is connected to the image pickup element 110 and the glass block 109. It may be arranged at a position other than between the positions. When the optical filter 101 is built in the imaging unit 103, the lens unit 102 to be connected does not have to have the optical filter 101, so that a dimmable imaging device using an existing lens unit is configured. Becomes possible.

  The imaging device 100 according to the present embodiment is applicable to a product having a combination of light amount adjustment and an imaging element. For example, it can be used for a camera, a digital camera, a video camera, a digital video camera, and can also be applied to a product having a built-in imaging device such as a mobile phone, a smartphone, a PC, and a tablet.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

≫Outline of photodetector 装置
FIG. 4 is a schematic diagram showing an outline of the photodetector of this embodiment. In the photodetector 10, the incident light 14 enters the image pickup device, which is the first photodetector 12 also serving as the second photodetector, through the dimming device 11 including four EC elements through the incident optical system 16. . The incident optical system 16 includes an optical system such as a lens and a stop. A UV cut filter 17 for preventing UV light from entering the light control device 11 is provided upstream of the light control device 11 on the optical path, and an IR light having a long wavelength exceeding 760 nm to the first photodetector 12 is provided downstream. The IR cut filter 18 for preventing the above is arranged. The photodetector 10 detects the intensity of incident light for each detection wavelength region of the first photodetector 12 and controls the transmittance of the dimmer 11 through the controller 15 to make the intensity of incident light appropriate. I do. Then, the information is recorded in the image processing / recording device 19 under suitable conditions. As shown in Table 1, the four EC devices are four types of EC devices using EC compounds having absorption peaks at 460 nm, 520 nm, 610 nm, and 730 nm, respectively. Further, the image pickup device serving as the first photodetector 12 has sensitivity in a wavelength region corresponding to each of the four EC devices. Specifically, it has sensitivity in the IR region of 730 nm in addition to the three visible regions of RGB having peaks at 600 nm, 520 nm, and 460 nm, respectively.

<< Production of EC device >>
Four EC devices having the structure shown in FIG. 1 were manufactured by the following method. Two transparent conductive glasses (substrate 3) on which an indium-doped tin oxide (ITO) film (electrode 1) was formed were prepared and arranged so that the ITO films faced each other. Then, the outer peripheries of the two transparent conductive glasses were bonded using a sealing material 4 in which spacer beads having a particle size of 50 μm were mixed. A solution was prepared by dissolving an anodic compound (a compound that is oxidized when a voltage was applied) and a cathodic compound (a compound that was reduced when a voltage was applied) in propylene carbonate at a concentration of 20 mmol / L. The solution was filled into a space formed by the two substrates 3 and the sealing material 4 by injecting the solution into a transparent conductive glass from an injection port (not shown) formed in advance. Thereafter, the injection port (not shown) was sealed with a sealant to obtain an EC element. The structural lists and combinations of the anodic compound and the cathodic compound used in each EC device are shown below.

  Among the above compounds, compounds 1, 2, 3, and 5 are EC compounds whose light absorptivity changes in a corresponding wavelength region due to an oxidation-reduction reaction. FIG. 5 shows the absorption spectra of these colored states. In FIG. 5, the horizontal axis is the wavelength, and the vertical axis is the normalized absorbance. On the other hand, compounds 4 and 6 are oxidation-reduction substances whose light absorptivity hardly changes in the corresponding wavelength region (not EC compounds), and are the recipients of electrons when coloring EC compounds 1, 2, 3, and 5 Function as

<< Production of dimming device >>
The dimmer 11 was formed by stacking four EC elements. Each EC element was controlled by pulse width modulation driving using the applied voltage shown in Table 2. Specifically, the following control was performed. A table summarizing the relationship between the transmittance and the duty ratio of each EC element is created in advance. The transmittance of the EC device was controlled by changing the duty ratio with reference to a table so that the incident light intensity in each wavelength region was measured by the imaging device and the value was used to obtain an appropriate incident light intensity.

動作 Operation and evaluation of light detection device≫
In the case of “Example 1: recognition of rear view camera” described above, the photodetector was operated and evaluated. Assuming a daytime use environment, the subject was photographed under simulated sunlight irradiation, and the obtained image was evaluated. Table 3 shows the results.

  In an image in which the control state of the EC element is colored only by the EC-IR, an image having a color balance close to the appearance may be greatly disturbed by setting all the control states of the EC element to the transmission state. confirmed. This is because the transmission of IR light could be suppressed by coloring the EC-IR, but it also enters the RGB part of the image sensor, and the response of the R part having a high transmittance in the IR region becomes particularly large. It is considered that it is.

  Next, assuming a use environment at night, the subject was irradiated with an LED array having a peak wavelength of 730 nm mounted on the photodetector to photograph the subject. This reproduces the situation in which the invisible IR light is irradiated and photographed so as not to dazzle the driver of the following vehicle at night. As a result, an image in which the subject could be clearly recognized was obtained.

In this embodiment, by controlling the plurality of EC elements as a light control device, with reference to the light intensity detected by the image sensor having sensitivity in the light wavelength region where the light absorption characteristics of the plurality of EC compounds change. By controlling the incident light intensity of visible light / infrared light, the following has become possible.
By controlling visible light and IR light independently, in daytime conditions, IR light is absorbed and reduced, visible light is transmitted and the influence of infrared light is removed, and visible light information is selected and acquired. To do.
In a nighttime situation, the IR light emitted from the light source transmits the reflected light reflected on the subject.

1: electrode, 2: electrochromic layer, 3: substrate, 4: sealing material, 10: photodetector, 11: dimmer, 12: first photodetector, 13: second photodetector, 14 : Incident light, 15: controller, 16: incident optical system, 17: UV cut filter, 18: IR cut filter, 19: image processing / recording device

Claims (17)

  A light control device including an electrochromic element and having a plurality of wavelength regions in which transmittance changes, wherein the change in the transmittance is controlled for each wavelength region in which the transmittance changes. apparatus.   The light control device according to claim 1, wherein the change in the transmittance is independently controlled for each wavelength region in which the transmittance changes.   3. The light control device according to claim 1, further comprising one electrochromic element, wherein the one electrochromic element includes a plurality of electrochromic compounds having different wavelength regions in which transmittance changes. 4.   The light control device according to claim 1, further comprising a plurality of electrochromic elements, wherein each of the plurality of electrochromic elements has a different wavelength region in which the transmittance changes.   5. The light control device according to claim 4, wherein at least one of the plurality of electrochromic elements includes a plurality of electrochromic compounds having different wavelength regions in which the transmittance changes. 6.   The light control device according to any one of claims 1 to 5, wherein the wavelength region in which the transmittance changes is one of an infrared region, a red region, a green region, and a blue region. apparatus.   7. The light control device according to claim 1, further comprising a controller, wherein the controller controls the change in the transmittance for each wavelength region in which the transmittance changes. 8. apparatus.   The electrochromic element includes a pair of electrodes and an electrochromic layer including an electrochromic compound, which is disposed between the pair of electrodes, wherein the electrochromic compound is a low-molecular organic material. The light control device according to any one of claims 1 to 7, wherein   A light detection device, comprising: the light control device according to claim 1; and a photodetector that detects light transmitted through the light control device. The photodetector has sensitivity in a plurality of different wavelength regions corresponding to the wavelength region in which the transmittance of the light control device changes,
The light control device according to claim 9, wherein the change in the transmittance is controlled for each wavelength region in which the transmittance changes with reference to the light intensity detected by the photodetector. The photodetector according to any one of the preceding claims.   The photodetector according to claim 10, wherein the wavelength range in which the photodetector has sensitivity is any one of an infrared region, a red region, a green region, and a blue region. A light detection device comprising the light control device according to any one of claims 1 to 8, a first light detector, and a second light detector,
The first photodetector detects light transmitted through the light control device,
The photodetector, wherein the second photodetector has sensitivity in a part of a wavelength range to which the first photodetector has sensitivity.   13. The photodetector according to claim 12, wherein the second photodetector has sensitivities in a plurality of different wavelength ranges corresponding to a wavelength range in which the transmittance of the light control device changes.   The light control device, wherein a change in the transmittance is controlled for each wavelength region in which the transmittance changes with reference to the light intensity detected by the second photodetector. Item 14. The photodetector according to item 12 or 13.   The wavelength region in which the second photodetector has sensitivity is any one of an infrared region, a red region, a green region, and a blue region. 3. The photodetector according to claim 1.   The apparatus according to any one of claims 9 to 15, further comprising a controller, wherein the controller controls a change in transmittance of the light control device for each wavelength region in which the transmittance changes. The photodetector according to any of the preceding claims.   The photodetector according to any one of claims 9 to 16, wherein the photodetector is an imaging device, and the photodetector is an imaging device.

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