JPWO2018221598A1 - Infrared and visible light control devices - Google Patents

Abstract

The present application provides a light control device capable of emitting light in the infrared region and light in the visible region at the time of incidence as different polarizations on the side to be detected, and controlling the light amount by the polarizations. To do. Specifically, at least one polarizing plate having polarization performance for light in the infrared range, at least one polarizing plate having polarization performance for light in the visible range, and a medium having a phase or phase controllable Provided is a light control device including a medium, which controls incident light in the infrared region and light in the visible region into polarized lights different from each other to control transmitted light in the infrared region and transmitted light in the visible region.

Description

  The present invention relates to a light control device that controls light in an infrared region and a visible region.

  BACKGROUND ART A polarizing plate having a light transmitting / shielding function is used for a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. The field of application of this LCD includes small devices such as calculators and watches in the early days, notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, indoor and outdoor information display devices, measuring devices, and the like. Further, the present invention can be applied to a lens having a polarizing function, and is applied to sunglasses with improved visibility, and in recent years, polarized glasses compatible with 3D televisions and the like.

  A general polarizing plate is a polarizing film such as a stretch-oriented film of polyvinyl alcohol or a derivative thereof, or a polyene-based film oriented by generating polyene by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol-based film. The substrate is produced by dyeing or containing iodine or a dichroic dye as a polarizing element. Of these, the iodine-based polarizing film using iodine as a polarizing element has excellent polarization performance, but is weak to water and heat, and has poor durability when used for a long time at high temperature and high humidity. There's a problem. On the other hand, a dye-based polarizing film using a dichroic dye as a polarizing element has better moisture resistance and heat resistance than an iodine-based polarizing film, but generally has insufficient polarizing performance. In other words, the polarizing plate has a polarizing function for a wavelength in the visible wavelength range, and is not a polarizing plate for the infrared wavelength range.

  In recent years, in applications such as recognition light sources for touch panels, security cameras, sensors, forgery prevention, and communication devices, not only polarizing plates for visible wavelengths but also polarizing plates for infrared regions have been required. In response to such demands, an infrared polarizing plate obtained by polyene-forming an iodine-based polarizing plate as in Patent Document 1, an infrared polarizing plate to which wire grit is applied as in Patent Document 2 or 3, and a Patent Document 4 An infrared polarizer obtained by stretching glass containing fine particles and a type using a cholesteric liquid crystal as disclosed in Patent Document 5 or 6 are reported. In Patent Literature 1, the durability is weak, and the heat resistance, the wet heat durability, and the light resistance are weak, so that it is not practical. The wire grid type as disclosed in Patent Literature 2 or 3 can be processed into a film type, and at the same time, is spreading as it is stable as a product. However, if the surface does not have nano-level irregularities, the optical properties are not maintained, so the surface must not be touched. Therefore, its use is limited, and furthermore, anti-reflection or anti-glare processing is required. Is difficult. The glass-stretched type containing fine particles as in Patent Document 4 has high durability and high dichroism, and thus has reached practical use. However, since it is glass that is stretched while containing fine particles, the element itself is easily broken, fragile, and it is difficult to perform surface processing and bonding to other substrates because it lacks flexibility like a conventional polarizing plate. There was a problem. The techniques of Patent Literature 5 and Patent Literature 6 are techniques using circularly polarized light that have been published for a long time. However, the color changes depending on the viewing angle, and basically, a polarizing plate using reflection is used. Therefore, it was difficult to form stray light or absolutely polarized light. That is, there is no polarizing plate that is an absorption type polarizing element like a general iodine-based polarizing plate, is a film type, has flexibility, and has a high durability corresponding to an infrared wavelength region. Furthermore, it only has the function of a polarizing plate in the infrared region, and cannot control the polarization in the visible region.

  Therefore, even though each of the polarized light in the infrared region and the polarized light in the visible region can be controlled, a polarizing plate that can simultaneously control the polarized light in each region has not been obtained.

  In addition, there has been no device that can switch between visible and infrared light and switch independently.

US 2,494,686 JP-A-2006-148871 JP 2006-507517 A JP-A-2004-86100 WO 2015/087709 JP 2013-064798 A

Polarization and its applications, Kyoritsu Shuppansha, Chapter 2 (p14-30)

  It is an object of the present application to provide a light control device capable of controlling incident light having a wavelength in the infrared region and light having a wavelength in the visible region so as to be simultaneously different polarized lights.

  It is another object of the present invention to provide an optical control capable of simultaneously controlling the incident polarized light in the infrared region and the polarized light in the visible region in the respective regions. In addition, the optical system that can control the amount of light by switching the infrared light and the visible light from the same light source in the infrared and visible regions on the side to be detected, that is, the visible light It is an object of the present invention to provide an element capable of dynamically switching between infrared light and switching.

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, using a medium having a phase or a medium capable of controlling the phase, the light in the infrared region and the light in the visible region are respectively controlled to different polarized lights. By doing so, it has been found that the polarization of light in the infrared region at the time of incidence and the polarization of light in the visible region at the time of incidence can emit different polarizations in the infrared region and the visible region on the side where detection is performed. Was.

  In addition, the present inventors provide a light control device that simultaneously uses visible light and infrared light, wherein at least one polarizing plate having polarization performance with respect to infrared light is provided. In a light control device equipped with at least one polarizing plate having polarization performance with respect to the above, the amount of transmitted light in the infrared region and the amount of transmitted light in the visible region can be controlled by a medium capable of dynamically controlling the phase. Further, the present inventors have found a light control device that can function as a switching element for switching between infrared light and visible light. An optical system that can control the light quantity by switching between the infrared light quantity and the visible light quantity at the incident side, in the infrared light range and the visible light range, while using the same light source. Was found.

That is, the gist configuration of the present invention is as follows.
1)
At least one polarizing plate (IR polarizing plate) having polarization performance for infrared light, at least one polarizing plate (VIS polarizing plate) having polarization performance for visible light, and a medium having a phase or An optical control device that includes a medium whose phase can be controlled and controls transmitted light in an infrared region and transmitted light in a visible region by converting incident infrared light and visible light into different polarized lights.
2)
The angle θi between the angle when the phase difference value Rλ of the medium having the phase or the phase controllable medium is indicated and the angle when linearly polarized light is developed in the infrared region is 0 ≦ θi <180 ° The light control device according to 1), wherein
3)
The angle θv between the angle indicating the phase difference value Rλ of the medium having a phase or the medium capable of controlling the phase and the angle at which linearly polarized light is developed in the visible region is −90 ° <θv <180 °. The light control device according to 1) or 2), wherein
4)
When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, The light control device according to any one of (1) to (3), which satisfies the relationship of (1) or Expression (2):
Vλ−RD ≦ Rλ ≦ Vλ + RD Equation (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Equation (2)
(However, RD shows 0 to 40 nm).
5)
When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, The light control device according to any one of (1) to (3), which satisfies the relationship of (3) or Expression (4):
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Equation (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Equation (4)
(However, RD shows 0 to 40 nm).
6)
When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, (5) The light control device according to any one of (1) to (3), which satisfies the relationship of Expression (6).
Vλ × 3 / 2−RD ≦ Rλ ≦ Vλ × 3/2 + RD Equation (5)
(However, RD shows 0 to 40 nm.)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Equation (6)
(However, RD shows 0 to 40 nm.)
7)
The light control device according to any one of 1) to 6) for simultaneously controlling visible light and infrared light, wherein the phase controllable medium is capable of dynamically controlling the phase. Light control device that is the medium.
8)
The light control device according to 7), wherein the medium whose phase can be dynamically controlled is a liquid crystal panel (liquid crystal cell).
9)
The light control device according to 8), wherein the liquid crystal used in the liquid crystal panel (liquid crystal cell) is a TN liquid crystal (Twisted Nematic liquid crystal) or an STN liquid crystal (Super Twisted Nematic liquid crystal).
10)
The light control device according to any one of 7) to 9), wherein a contrast ratio between transmitted light and non-transmitted light of visible light and infrared light is 10 or more.
11)
The light control device according to any one of 1) to 10), including one polarizing plate (VIS-IR polarizing plate) having polarization performance with respect to visible light and infrared light.
12)
The light control device according to 11), wherein a difference between orthogonal transmittance of infrared light and orthogonal transmittance of visible light in the VIS-IR polarizing plate is 1% or less.
13)
The light control device according to any one of 1) to 12), wherein a difference between an orthogonal transmittance of light in an infrared region and an orthogonal transmittance of light in a visible region in the IR polarizing plate is 10% or more.
14)
A polarizing plate having an IR polarizing plate having an orthogonal transmittance of infrared light of 1% or less and a difference from a visible light transmittance of 10% or more, and the VIS polarizing plate having a high transmittance in an infrared region; Any of 1) to 13), including at least one polarizing plate which indicates that the transmission of light in the infrared region is hardly affected and that the orthogonal transmittance of light in the visible region is 1% or less. The light control device according to claim 1.
15)
The light control device according to any one of 1) to 14), wherein the IR polarizing plate or the VIS-IR polarizing plate is an absorption polarizing plate.
16)
The light control device according to any one of 1) to 15), wherein the IR polarizing plate or the VIS-IR polarizing plate is a film.
17)
The light control device according to any one of 1) to 16), wherein a medium having a phase difference or a medium whose phase can be controlled and at least one polarizing plate are laminated.
18)
A liquid crystal display device, a forgery prevention device, or a sensor including the light control device according to any one of 1) to 17).

  According to the present invention, light in the infrared region and light in the visible region at the time of incidence can be emitted as different polarized lights on the side to be detected, and the amount of light can be controlled by the polarized lights.

  In one embodiment, according to the present invention, the amount of light in the infrared region and the amount of light in the visible region when incident from the same light source are detected. By performing switching so that the light is transmitted or non-transmitted, the amount of each light can be controlled.

  The light control device of the present invention includes at least one polarizing plate (IR polarizing plate) having polarization performance for infrared light and at least one polarizing plate (VIS polarization) having polarization performance for visible light. Plate) and a medium having a phase or a phase-controllable medium, and the incident infrared light and visible light are converted into different polarized lights, so that infrared transmitted light and visible light are transmitted. Is controlled.

  In one embodiment, the light control device of the present invention includes a medium capable of dynamically controlling the phase when light in the visible region and light in the infrared region are simultaneously incident, and converts the light in the infrared region and the light in the visible region respectively. It is characterized in that the transmitted light in the infrared region and the transmitted light in the visible region are controlled by controlling the polarized light to be different.

  The IR polarizing plate is not particularly limited as long as it is a polarizing plate capable of controlling polarization at a wavelength in the infrared region. Examples of the polarizing plate include a polyene type to which an iodine-based polarizing plate is applied as in Patent Literature 1, a wire grid type polarizing plate as in Patent Literatures 2 and 3, and metal particles in glass as in Patent Literature 4. And a polarizing plate containing a dye, and a dye-based polarizing plate containing a dye. The dye-based polarizing plate is preferably used in the present application. This dye-based polarizing plate can be made into a film type, is easily laminated with another polarizing plate, a retardation plate, etc., is flexible, and has a feature that optical control is easy. I have.

  The IR polarizing plate has a polarization performance with respect to light in a part or the whole wavelength range of 700 to 1400 nm.

  The VIS polarizing plate is not particularly limited as long as it is a polarizing plate capable of controlling polarization at a wavelength in the visible region. As the polarizing plate, for example, an iodine-based polarizing plate, a dye-based polarizing plate, a dye-based polarizing plate capable of controlling polarization only at a specific wavelength, a polarizing plate of a type using a polyene, and the like may be used. It is preferable to combine a plurality of types of dye-based polarizing plates that can control only the polarization of the dye, or a plurality of types of dye-based polarizing plates that can polarize only the specific wavelength, to obtain a polarizing element that can control the polarization of only the light of the specific wavelength. It is preferable to provide polarization performance only for light of a specific wavelength, since it becomes possible to detect or control polarization at a specific wavelength.

The VIS polarizing plate has polarization performance for light in a part or all of the wavelength range of 400 to 700 nm. It is preferable that the transmittance in the infrared region is high and has no absorption, and there is no particular limitation as long as the light in the infrared region is higher than the visible transmittance. "No absorption" indicates that the film has a high transmittance in the infrared region and has little effect on the transmission of light in the infrared region. However, the single transmittance of a general polarizing plate is usually 30 to 45. %, It can be used as the visible (VIS) polarizing plate of the present invention as a polarizing plate having a function of transmitting infrared light when a single transmittance equal to or higher than that at each wavelength in the infrared region. Specifically, the transmittance in the infrared region is at least 40%, preferably at least 50%, more preferably at least 60%, further preferably at least 70%, particularly preferably at least 80%. In particular, when the two VIS polarizing plates are orthogonal to each other, the transmittance in the infrared region is 30% or more, preferably 40% or more, more preferably 50% or more, still more preferably 60%, and particularly preferably 70% or more. It can be used as a particularly preferred VIS polarizing plate.

  Examples of the medium having the above-mentioned phase include those called retardation films, wave plates, and retardation films.

  Examples of the medium whose phase can be controlled include a liquid crystal panel (liquid crystal cell) in which liquid crystal generally used in a liquid crystal monitor or the like is sealed and whose phase can be controlled by electricity or the like.

  Here, “phase controllable” means that the phase of light as a wave can be controlled. When focusing on the polarization performance, for example, a wavelength plate or a phase controllable medium (wave plate or the like) is an optical functional element that gives a predetermined phase difference to linearly polarized light, and polarized light is applied to light of a specific axis. On the other hand, it is possible to provide different phases on other axes (eg 90 °). That is, by providing a wavelength plate or the like on the optical path for one polarized light, it becomes possible to make the polarized light of the opposite axis, or to newly impart circularly polarized light, elliptically polarized light, or the like. Therefore, a wave plate or the like can change the polarization state of incident light by giving a phase difference between two orthogonal polarization components using an oriented birefringent material (eg, a stretched film) or the like. It can be said. For example, when the wavelength of a specific light is λ, the retardation plate of the λ / 2 retardation plate is set at 45 ° with respect to the axis of the polarized light, so that the wavelength plate or the like can be used as a wavelength plate or the like. By rotating the incident linearly polarized light by 90 °, polarized light having a polarization axis in a direction (90 °) orthogonal to the incident polarization axis can be emitted. Also, by setting the slow axis of the λ / 2 retardation plate at 22.5 ° with respect to the axis of the polarized light, the linearly polarized light incident on the wave plate (retardation plate) is rotated by 45 ° to be incident. Can be emitted with polarized light that is inclined at 45 ° to the polarized axis. Further, when the slow axis of the λ / 4 retardation plate is set at 45 ° with respect to the polarization axis, linearly polarized light incident on the wave plate (retardation plate) can be emitted as circularly polarized light. I can do it.

  The retardation plate, wavelength plate, and retardation film can be used as long as the slow axis or fast axis of the light of the film can be rotated with respect to the absorption axis of the polarizing plate.

  A phase controllable liquid crystal panel (liquid crystal cell) is a medium for electrically controlling the phase. As a method of controlling the liquid crystal driving, there are various methods such as TN (Twisted Nematic), STN (Super Twisted Nematic), IPS (In-Plane-Switching), and VA (Virtual Allocation). There is no particular limitation as long as the liquid crystal and the control method can control the phase of light in the infrared region. Preferably, TN (Twisted Nematic), STN (Super Twisted Nematic) or the like is used. These are preferred because the driving voltage is low, the price is low, and the polarization rotation of 0-90 ° is easily controlled.

  The light control device controls the light in the infrared region and the light in the visible region to be polarized lights different from each other by a medium having a phase or a medium capable of controlling the phase. Thereby, the polarization of the light in the infrared region at the time of incidence and the polarization of the light in the visible region at the time of incidence can be sensed as different polarizations on the respective sides to be detected. Specifically, by controlling the polarization of the visible light that is visible to the human eye and the infrared light that is hardly visible at the same time, the light amount of the visible light and the infrared light is simultaneously adjusted. It is possible to continuously transmit the light in the infrared region while controlling the transmission or non-transmission of the light in the visible region. The reverse control is also possible, that is, it is possible to continue transmitting the visible light while controlling the transmission or non-transmission of the infrared light. It is possible to provide a light control device capable of simultaneously controlling the polarization and light amount of each of the lights.

  Conventionally, the infrared sensor and the visible camera need to use different types of detectors for detection of infrared light and detection of visible light, respectively. One sensor and one visible camera can be controlled by the light control device. For example, in a camera such as a mobile phone, a separate light control device is generally required for an authentication camera for the infrared region and a camera for the visible region. Since the transmission and non-transmission of light and infrared light can be switched, it is possible to perform infrared region authentication, visible region photographing, and the like using one light control device. Further, by applying this light control device, it is possible to apply it to advanced security and the like. In addition, since it is possible to control light transmission type devices, circular polarization control in the infrared to visible range and linear polarization control, etc., by applying these, for example, to devices using the light reflection polarization function, security applications, etc. Can also be applied.

  In one embodiment, an angle (phase of incident light) when a phase difference value Rλ of a medium having a phase or a phase controllable medium (a phase difference plate) is developed, and linearly polarized light is produced (emitted) in an infrared region. It is preferable that the angle (phase difference) θi between the angle and the angle (the phase of the emitted light) in this case be in the range of 0 ≦ θi <180 °. When the angle θi is 0 °, that is, when installed coaxially, the polarized light in the infrared region becomes light which is not affected or hardly affected by the retardation plate, and the phase difference which is the phase difference value of λ / 2. When a plate is provided, by setting the angle θi at 45 °, it is possible to emit polarized light having an axis which is inverted by 90 ° from the incident linearly polarized light and has an opposite axis.

  Further, the angle (position) between the angle at which the phase difference value Rλ of the retardation plate is developed (the phase of the incident light) and the angle when the linearly polarized light is developed in the visible region (the phase of the emitted light). With the light control device in which (phase difference) θv is in the range of −90 ° <θv <180 °, the phase difference in the visible region can also be controlled. θv and θi may be the same, but may be different, as long as the polarization state of light of a specific wavelength can be controlled by the phase difference plate. In other words, the number of retardation plates to be used is not limited to one, and the light control device of the present invention has a plurality of positions like a general liquid crystal display using a combination of a ４λ plate and a や λ plate. A phase difference plate may be used.

When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference plate is RD (Retarder Dispersion), and the phase difference value of the phase difference plate is Rλ, the following equation (1) or equation: The light control device satisfying the relationship (2) functions as a phase plate capable of providing Vλ in the visible region, and functions as a phase plate capable of providing Iλ / 2 in the infrared region.
Vλ−RD ≦ Rλ ≦ Vλ + RD Equation (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Equation (2)
(However, RD indicates 0 to 40 nm)
In the above light control device, when the slow axis of the retardation plate having Rλ is provided at 45 ° with respect to the incident linearly polarized light, the polarized light at the time of incidence can be maintained in the visible region. Although it continues to function as a retardation plate, in the infrared region, by functioning as a λ / 2 polarizing plate, it becomes possible to emit a reverse polarization axis to the incident polarization axis. In the case where the slow axis of the retardation plate having this Rλ is provided at 45 ° with respect to the incident linearly polarized light, and a polarizing plate having an absorption axis orthogonal to the incident axis is provided on the emission side. In this case, it is possible to provide a light control device capable of transmitting light in the visible region but absorbing light in the infrared region. When it is desired that both the light in the visible region and the light in the infrared region are not transmitted (absorbed), the slow axis of the retardation plate having Rλ may be set at 0 ° instead of 45 °. As described above, by controlling the slow axis of the retardation plate having Rλ satisfying the relationship of the above equation (1) or equation (2), the axis of linearly polarized light, elliptically polarized light, and the like can be controlled. . The RD is preferably in the range of 0 to 40 nm, more preferably 0 to 25 nm, further preferably 0 to 15 nm, and particularly preferably 0 to 5 nm. The control of the polarization axis using the phase can be performed with reference to Non-Patent Document 1 and the like.

Further, the light control device that satisfies the relationship of the following Expression (3) or Expression (4) functions as a phase difference plate that can provide λ / 2 in the visible region, and can provide λ / 4 in the infrared region. Functions as a phase difference plate. Note that Iλ, Vλ, RD, and Rλ are as defined above.
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Equation (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Equation (4)
(However, RD indicates 0 to 40 nm)
In the above light control device, by providing the slow axis of the retardation plate having Rλ at 45 ° where linearly polarized light is incident, it functions as a λ / 2 polarizing plate in the visible region, In the infrared region, it functions as a retardation plate that can function as a λ / 4 polarizing plate, and can output incident polarized light as circularly polarized light. Thereby, when a polarizing plate having an absorption axis orthogonal to the incident axis is provided on the emission side, the visible region can be controlled in polarization while keeping linearly polarized light, whereas the infrared region can be controlled as circularly polarized light. . When it is desired that both the light in the visible region and the light in the infrared region are not transmitted (absorbed), the slow axis of the retardation plate having Rλ may be set at 0 ° instead of 45 °. As described above, by controlling the slow axis of the retardation plate having Rλ that satisfies Expressions (3) and (4), the axis of linearly polarized light, the elliptically polarized light, and the like can also be controlled. In the case of the above configuration, reflection control in the visible region is possible, and transmission control in the infrared region is also possible. As a preferable configuration, for example, a visible region, and a polarizing plate capable of controlling the infrared region, a medium having a phase or a phase controllable medium, a visible region, and a configuration of a polarizing plate capable of controlling the infrared region may be used. , Visible region, and a polarizing plate capable of controlling the infrared region, a medium having a phase or a medium capable of controlling the phase, a polarizing plate capable of controlling the visible region, a polarizing plate capable of controlling the infrared region, and the like are exemplified. However, the configuration is not limited. Furthermore, the use of this method also enables polarization control utilizing the fact that reflected light has polarization in the infrared region. For example, when performing reflection control with a single polarizing plate, in the infrared region, a polarizing plate, a λ / 4 retardation plate, and a reflecting plate are laminated in this order, and the retardation of the retardation plate is delayed with respect to the absorption axis of the polarizing plate. When the phase axis is set at 45 ° where linearly polarized light is incident, the linearly polarized light that has entered the light from the polarizing plate is converted into circularly polarized light by the phase difference plate, and the light reflected by the reflecting plate is inverted. The light is converted into circularly polarized light, and as a result, a function capable of preventing reflection can be realized. However, in this case, since the light in the visible region continues to maintain the state of linearly polarized light, the light is reflected, and the reflected light can be detected. Further, even in the case of using this reflection, by setting the slow axis of the retardation plate at 0 ° with respect to the absorption axis of the infrared polarizing plate, the polarized light in the infrared region is maintained in a linearly polarized state. Function as a light control device that can reflect both visible light and infrared light. In the case of the present light control device, the RD is preferably in the range of 0 to 40 nm, preferably 0 to 25 nm, more preferably 0 to 15 nm, and particularly preferably 0 to 5 nm.

Further, the light control device satisfying the relationship of the following Expression (5) or Expression (6) functions as a phase difference plate that can provide 3 / 2λ in the visible region, and can provide 1 / 2λ in the infrared region. Functions as a phase difference plate. Note that Iλ, Vλ, RD, and Rλ are as defined above.
Vλ × 3 / 2−RD ≦ Rλ ≦ Vλ × 3/2 + RD Equation (5)
(However, RD indicates 0 to 40 nm)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Equation (6)
(However, RD indicates 0 to 40 nm)
In the above light control device, by providing the slow axis of the retardation plate having Rλ at 45 ° where linearly polarized light is incident, the retardation plate functions as a 3 / 2λ polarizing plate in the visible region or is incident. It becomes possible to emit circularly polarized light of the polarized light, and in the infrared region, it functions as a λ / 2 polarizer as a phase difference plate capable of emitting incident polarized light in the opposite axis. Thus, when a polarizing plate having an absorption axis perpendicular to the incident axis is provided on the emission side, the polarized light in the visible region can be controlled as circularly polarized light, whereas the infrared region can be controlled as linearly polarized light. Become. When it is desired that both the light in the visible region and the light in the infrared region are not transmitted (absorbed), the slow axis of the retardation plate having Rλ may be set at 0 ° instead of 45 °. As described above, by controlling the slow axis of the retardation plate having Rλ satisfying Expressions (5) and (6), the axis of linearly polarized light, elliptically polarized light, and the like can be controlled. As a preferable configuration, for example, a visible region, and a polarizing plate capable of controlling the infrared region, a medium having a phase or a phase controllable medium, a visible region, and a configuration of a polarizing plate capable of controlling the infrared region may be used. , Visible region, and a polarizing plate capable of controlling the infrared region, a medium having a phase or a medium capable of controlling the phase, a polarizing plate capable of controlling the visible region, a polarizing plate capable of controlling the infrared region, and the like are exemplified. However, the configuration is not limited. Furthermore, the use of this method also enables polarization control utilizing the fact that reflected light has polarization in the infrared region. In the case of the above configuration, reflection control in the visible region is possible, and transmission control in the infrared region is also possible. For example, when performing reflection control with a single polarizing plate, in the visible region, a polarizing plate, a ／ λ polarizing plate, and a reflecting plate are laminated in this order, and a phase difference is formed on the reflecting plate with respect to the absorption axis of the polarizing plate. By setting the slow axis of the plate at 45 °, light is incident from the polarizing plate. Linearly polarized light is converted to circularly polarized light by the phase difference plate, and light reflected by the reflecting plate is converted to inverted circularly polarized light. As a result, a function capable of preventing reflection can be realized. However, in this case, since the light in the infrared region keeps maintaining the state of linearly polarized light, the light is reflected and the reflected light can be detected. Further, even in the case of using this reflection, by setting the slow axis of the retardation plate at 0 °, it functions as a light control device capable of reflecting either visible light or infrared light. In the case of the present light control device, the RD is preferably in the range of 0 to 40 nm, preferably 0 to 25 nm, more preferably 0 to 15 nm, and particularly preferably 0 to 5 nm.

  In the IR polarizing plate of the light control device of the present invention, the transmittance of light in the infrared region (wavelength of 700 to 1400 nm) (in the infrared region) when the two polarizing plates are overlapped so that the absorption axes are orthogonal to each other. Orthogonal transmittance of light) and transmittance of light in the visible region (wavelength of 400 to 700 nm) when two polarizing plates are overlapped so that the absorption axes are orthogonal (orthogonal transmittance of light in the visible region). ) Is preferably 10% or more, because the polarization control of light in the visible region and light in the infrared region is further facilitated. For example, when the polarizing plate has polarization performance for light in the infrared range and also has polarization performance for light in the visible range, the phase difference plate allows Although the polarization can be controlled, if one polarizing plate has a degree of polarization of 100% of the light of 400 to 1400 nm, it imparts polarization performance only to light in the infrared region, or to light in the visible region. It becomes difficult to provide the polarization performance only when it is used. On the other hand, by using a polarizing plate having polarization performance for light in each wavelength region, by selecting an appropriate polarizing plate according to the wavelength, polarization control can be performed at various wavelengths. In other words, in the infrared region, a polarizing plate that can be controlled only by the wavelength of infrared light is used, and in the visible region, a polarizing plate that can be controlled only by the wavelength of visible light is used. Or, it is preferable because transmittance can be controlled. However, a polarizing plate having polarization performance in the infrared region may have polarization performance also in the visible region, and thus does not necessarily have only polarization performance in the infrared region. However, as the function of the light control device of the present invention, it is important to emit light having different phases (polarized light) between infrared light and visible light, and thus the detected light amounts (energy) It is sufficient that the magnitude (S / N ratio) of the becomes clear. Therefore, in the IR polarizing plate, the transmittance of light of 700 to 1400 nm when the two polarizing plates are superimposed so that the absorption axes are orthogonal to each other, instead of providing the polarizing performance of 100% at all wavelengths, is obtained. When the difference between the transmittance of light of 400 to 700 nm and the transmittance of light of 400 to 700 nm is 10% or more when the two polarizing plates are overlapped so that the absorption axes are orthogonal to each other, the light of visible light and the light of infrared light are Preferably, the polarization control is further facilitated, and the difference in transmittance is more preferably 20%, further preferably 30%, and particularly preferably 40% or more.

  An IR polarizer having an orthogonal transmittance of 1% or less in a wavelength range of light in the infrared region, and an orthogonal polarizer having no light absorption in the wavelength range of light in the infrared region and having an orthogonal transmittance of 1%. % Is preferable because it can control the polarization performance for infrared light and the polarization performance for visible light, respectively. Further, the above-mentioned light control device is preferable for improving the contrast between infrared light and visible light. In addition, it is possible to use each polarizing plate on a different axis, and it is possible to separately control the visible light and the infrared light by the wavelength and wavelength axis for controlling the axis of each polarized light. Becomes As the orthogonal transmittance of each of the infrared light and the visible light, if it is independently 1% or less, the light can be sufficiently controlled, but preferably 0.3% or less, more preferably 0.3% or less. The content is preferably 0.1% or less, more preferably 0.01% or less, and particularly preferably 0.005% or less. For example, if the parallel transmittance is 40% and the orthogonal transmittance is 0.1%, a contrast ratio of 40: 0.1, that is, 400: 1, which is the ratio, can be provided. That is, since the contrast of the polarizing plate greatly affects the optical control device of the present invention, it is preferable to control the optical control device within the above range.

  Regarding the control of light in the infrared region and light in the visible region in the light control device of the present invention, the contrast of the amount of light required when switching between transmission and non-transmission (shielding) is required to be the ratio of the contrast of a general paper medium. It is said that. In other words, the contrast ratio between transmission and light shielding should be 10: 1 or more, preferably 100: 1 or more, and more preferably 1000: 1 or more.

  In constructing the light control device, it is preferable that at least one of the IR polarizing plates is an absorption polarizing plate. The absorption type polarizing plate has a feature that does not generate stray light. As the IR polarizing plate, a wire grit type is generally used, but in the case of a polarizing plate that expresses a polarizing function by controlling refraction or reflection of light, a scattered light, a condensed light, an object with intense brightness and darkness, Light having a wavelength other than the original wavelength or light having an intensity is generated due to reflection, refraction, resonance (resonance), phase modulation, or the like of light due to an unspecified shape, overlap of light, movement of light position, or the like. In this case, light having a wavelength other than the original wavelength or light having an intensity becomes stray light. It is important not to generate such stray light in order to prevent erroneous detection. That is, it is preferable to use a polarizing plate that does not generate stray light. For example, when the IR polarizing plate is an absorption polarizing plate, it can be preferably used because optical control is easy because stray light and the like are hardly generated.

  Each of the above polarizing plates can be easily laminated and can be made flexible. In order to make the polarizing plates flexible, it is preferable that at least one of the IR polarizing plates is a film. In particular, since lamination is possible, it is preferable to laminate with a medium having a phase or a medium whose phase can be controlled. By laminating, it is difficult to reduce the transmittance due to the influence of interface reflection and the like, which is preferable for light control.

  In addition, each of the above-described polarizing plates, a medium having a phase, or a medium whose phase can be controlled can be rotated by a signal such as light or electricity, and each can be set to a desired angle, and the setting can be changed. It is.

  The light control device can simultaneously control the polarization of light in the infrared region and light in the visible region at the same time, so that light in the visible region that can be recognized by human eyes and infrared light that is difficult to recognize The polarization of the light can be controlled simultaneously. Therefore, it is possible to provide a liquid crystal display device capable of switching detection between infrared light and visible light, a photographing device such as a camera capable of controlling the polarization of infrared light and visible light, and high security. It is possible to apply the light control device to various applications such as a forgery prevention device or a sensor that functions with infrared light and visible light, and a system that combines the light control device with various applications. It is also possible to use as.

<Example>
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

<Preparation of polarizing plate (IR polarizing plate) having polarization performance for infrared light>
A 45 ° C. aqueous solution containing the azo compound of the following chemical formula (1) at a concentration of 0.3% and the sodium sulfate at a concentration of 0.1% was prepared as a staining solution. A 75 μm-thick polyvinyl alcohol film was immersed in the staining solution for 5 minutes. Next, the film was stretched 5 times in a solution of a 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining the tension state, to obtain a polarizing element. A triacetylcellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd .; trade name: TD-80U) obtained by alkali treatment was laminated on both sides of this polarizing element via an adhesive of a polyvinyl alcohol aqueous solution, and 835 nm was applied. A polarizing plate having a high polarizing function at the center was obtained. The polarizing plate was used as an IR polarizing plate.

<Preparation of polarizing plate (VIS polarizing plate) having polarization performance for visible light>
Kayarus Supra Orange 2GL (manufactured by Nippon Kayaku Co., Ltd.) was added to C.I. I. Prepare a 45 ° C. aqueous solution in which Direct Red 81 has a concentration of 0.01%, Blue KW (manufactured by Nippon Kayaku) has a concentration of 0.04%, and sodium sulfate has a concentration of 0.1%. A staining solution was used. A 75 μm-thick polyvinyl alcohol film was immersed in the staining solution for 3 minutes and 30 seconds. Next, the film was stretched 5 times in a solution of a 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining the tension state, to obtain a polarizing element. A triacetyl cellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd .; trade name: TD-80U) obtained by alkali treatment was laminated on both sides of the polarizing element via an adhesive of an aqueous polyvinyl alcohol solution. A polarizing plate having a polarizing function in the visible region of 650 nm was obtained. The polarizing plate was used as a VIS polarizing plate.

<Preparation of polarizing plate (VIS-IR polarizing plate) capable of controlling infrared light and visible light>
The azo compound of the above chemical formula (1) was brought to a concentration of 0.6%, Kayarus Supra Orange 2GL (manufactured by Nippon Kayaku Co., Ltd.) to a concentration of 0.02% and C.I. I. Prepare a 45 ° C. aqueous solution in which Direct Red 81 has a concentration of 0.01%, Blue KW (manufactured by Nippon Kayaku) has a concentration of 0.04%, and sodium sulfate has a concentration of 0.1%. A staining solution was used. A 75 μm-thick polyvinyl alcohol film was immersed in the staining solution for 5 minutes. Next, the film was stretched 5 times in a solution of a 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining the tension state, to obtain a polarizing element. A triacetyl cellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd .; trade name: TD-80U) obtained by alkali treatment was laminated on both sides of the polarizing element via an adhesive of an aqueous polyvinyl alcohol solution. A polarizing plate having a polarizing function at 900 nm was obtained. The polarizing plate was used as a VIS-IR polarizing plate.

<Measurement of transmittance of polarizing element>
(Measurement of transmittance of polarizing plate)
Using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.), each of the obtained polarizing plates was used at 380 to 1100 nm at a single transmittance (Ts), a parallel transmittance (Tp), and a cross transmittance (Tc) at each wavelength. ) And the degree of polarization (ρ) were measured. The single transmittance (Ts) is the transmittance obtained by measuring one polarizing plate, and the parallel transmittance (Tp) is obtained by measuring the two light absorbing axes of the two polarizing plates in parallel. The orthogonal transmittance (Tc) is a transmittance obtained by measuring the respective light absorption axes of two polarizing plates at right angles, and the degree of polarization is calculated by the equation (7). The value obtained.

Degree of polarization (%) = 100 × [(Tp−Tc) / (Tp + Tc)] ^1/2 Equation (7)

  The individual transmittances (Ts), parallel transmittances (Tp), and orthogonal transmittances (Tc) of the obtained polarizing plates at wavelengths of 420 nm, 555 nm, 830 nm, and 840 nm are shown below. Table 1 shows values when an IR polarizing plate is used, Table 2 shows values when a VIS polarizing plate is used, and Table 3 shows values when a VIS-IR polarizing plate is used.

<Examples A1 to A4>
Production and evaluation of light control device The light emitted from the light source unit of the above U-4100 was configured as a VIS-IR polarizing plate, a retardation plate, a VIS polarizing plate, and an IR polarizing plate in this order when viewed from the light source side. The light was applied to the apparatus, and the transmitted light was allowed to enter the detection unit of U-4100. As the retardation plate, a polycarbonate-based retardation plate exhibiting a retardation value of 420 nm at each wavelength of 420 nm and 840 nm was used. The transmittance was measured when the slow axis of this retardation plate was inclined at 0 ° and 45 ° with respect to the VIS-IR polarizing plate. At that time, the measurement was carried out while changing the respective polarization axes of the VIS polarizing plate and the IR polarizing plate. The results are shown in Table 4. 0 ° in Table 4 means that the retardation plate has a slow axis of 0 ° with respect to the absorption axis of the VIS-IR polarizing plate, and the VIS polarizing plate or the IR polarizing plate has a absorption axis of 0 ° (coaxial). ). The same applies to 45 ° and 90 °. St indicates that the transmittance detected by U-4100 is strong (30 to 50%), and Mi indicates that the transmittance detected by U-4100 is medium (10 to 25%). "We" indicates that the transmittance detected by U-4100 is weak (0 to 2%).

<Examples A5 to A8>
The light control device was evaluated in the same manner as in Examples 1 to 4, except that a polycarbonate-based retardation plate showing a retardation value of 210 nm at each wavelength of 420 nm and 840 nm was used. The results are shown in Table 5.

<Examples A9 to A12>
The light control device was evaluated in the same manner as in Examples 1 to 4, except that a polycarbonate-based retardation plate showing a retardation value of 415 nm at each wavelength of 555 nm and 830 nm was used. The results are shown in Table 6.

<Examples A13 to A14>
The light emitted from the light source unit of the U-4100 is irradiated to a light control device having a VIS polarizing plate, an IR polarizing plate, a retardation plate, and a reflecting plate in this order as viewed from the light source side. -4100. As the retardation plate, a polycarbonate-based retardation plate exhibiting a retardation value of 210 nm at each wavelength of 420 nm and 840 nm was used. The transmittance was measured when the slow axis of this retardation plate was inclined at 0 ° and 45 ° with respect to the VIS polarizing plate. At that time, the measurement was performed while variously changing the respective polarization axes of the IR polarizing plate. The results are shown in Table 7. 0 ° in Table 7 means that the retardation plate has a slow axis of 0 ° and the IR polarizing plate has an absorption axis of 0 ° (coaxial) with respect to the absorption axis of the VIS polarizing plate. Indicates that The same applies to 45 ° and 90 °. St, (Mi), and We mean the same as in Table 4.

<Examples A15 to A16>
The light emitted from the light source unit of the U-4100 is irradiated to a light control device having a VIS polarizing plate, an IR polarizing plate, a retardation plate, and a reflecting plate in this order as viewed from the light source side. -4100. As the retardation plate, a polycarbonate-based retardation plate exhibiting a retardation value of 415 nm at each wavelength of 555 nm and 830 nm was used. The transmittance was measured when the slow axis of this retardation plate was inclined at 0 ° and 45 ° with respect to the VIS polarizing plate. At that time, the measurement was performed while variously changing the respective polarization axes of the IR polarizing plate. The results are shown in Table 8. In Table 8, 0 °, 45 °, 90 °, St, (Mi), and We mean the same as in Table 7.

<Comparative Examples A1 to A4>
Table 9 shows the results of measuring the transmittance using the light control devices (Comparative Examples 1 to 4) in which the retardation plates were removed from Examples A1 to A4. As in the case of the conventional polarizing plate, the transmittance decreased when the absorption axes of the polarizing plates were orthogonal to each other at each wavelength, and the transmittance increased when the absorption axes were parallel. The optical device can only control the transmittance at the parallel position and the orthogonal position, which are the functions of the conventional polarizing plate, and cannot provide an optical device that can individually control the transmittance at each wavelength.

<Comparative Examples A5 to A6>
Table 10 shows the results of measuring the transmittances using the light control devices (Comparative Examples 5 to 6) in which the phase difference plates were removed from Examples A13 to A14. As in the case where one conventional polarizing plate was placed on a mirror, no change was observed in the transmittance, and no change was observed in the incident light between visible light and infrared light.

  From the results of Examples A1 to A12, it can be seen that the respective light control devices can control the amounts of infrared light and visible light with respect to the same light source. In each of Examples A5 to A8 and Examples A13 to A14, and Examples A9 to A12 and Examples A15 to A16, the result is obtained by light control at the time of transmission of light and the result of light control at the time of reflection. It turns out that the result is different. According to the above results, the light control device obtained by the present invention is capable of emitting visible light and infrared light with different light amounts even when the same light source having visible light and infrared light is used. And it was shown to be effective as a device capable of converting into polarized light.

<Example B1>
The light emitted from the light source unit of the U-4100 is applied to a light control device configured in the order of a VIS-IR polarizing plate, an STN-type liquid crystal cell, a VIS polarizing plate, and an IR polarizing plate as viewed from the light source side, and transmitted. This light was made to enter the detection unit of U-4100. At this time, the VIS-IR polarizer is laminated so that the absorption axis of the VIS polarizer is parallel to the absorption axis of the VIS-IR polarizer, and the absorption axis of the IR polarizer is set to 90 ° with respect to the absorption axis of the VIS-IR polarizer. They were used in a laminated manner. As to the bonding to the liquid crystal cell, the one to which each polarizing plate was bonded so as to have the lowest transmittance in the visible region when a voltage was applied to the STN cell was used as a measurement sample of the present invention. The STN type liquid crystal cell is arranged so as to have a slow axis in a 45 ° direction when an initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/100 at 420 nm and 840 nm. One having a phase of 2λ was used. Table 4 shows the measurement results of the light at the wavelength of 420 nm and the wavelength of 840 nm when the voltage is turned ON and OFF. Based on the amount of light transmitted through only the VIS-IR polarizing plate, the amount of light (%) when entering the detection unit of U-4100 after passing through the light control device is shown.

<Example B2>
The light emitted from the light source unit of the U-4100 is applied to a light control device configured in the order of a VIS-IR polarizing plate, an STN-type liquid crystal cell, a VIS polarizing plate, and an IR polarizing plate as viewed from the light source side, and transmitted. This light was made to enter the detection unit of U-4100. At that time, the VIS polarizing plate is laminated so that the absorption axis of the VIS polarizing plate is perpendicular to the absorption axis of the VIS-IR polarizing plate, and the absorption axis of the IR polarizing plate is set to 0 ° with respect to the absorption axis of the VIS-IR polarizing plate. They were used in a laminated manner. Regarding the bonding to the liquid crystal cell, the one in which each polarizing plate was bonded so that the transmittance was lowest in the visible region when no voltage was applied to the STN cell was used as the measurement sample of the present application. The STN type liquid crystal cell is arranged so as to have a slow axis in a 45 ° direction when an initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/100 at 420 nm and 840 nm. One having a phase of 2λ was used. Table 4 shows the results of the light at the wavelength of 420 nm and the wavelength of 840 nm when the voltage is turned ON and OFF. Based on the amount of light transmitted through only the VIS-IR polarizing plate, the amount of light (%) incident on the detection unit of U-4100 after passing through the light control device is shown.

<Example B3>
The light emitted from the light source unit of the U-4100 is incident on the VIS polarizing plate, the configuration of the IR polarizing plate, the STN type liquid crystal cell, and the reflecting plate in this order as viewed from the light source side, and the reflected light is detected by the detecting unit of the U-4100. Was made to enter. The IR polarizing plate is bonded at 45 ° to the absorption axis of the VIS polarizing plate. For bonding to the liquid crystal cell, when no voltage is applied to the STN cell, the reflectance is the lowest in the infrared region. What adhered each polarizing plate so that it might be used as a measurement sample of this application. The STN type liquid crystal cell is arranged so as to have a slow axis in a 45 ° direction when an initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/100 at 420 nm and 840 nm. One having a phase of 4λ was used. Table 4 shows the measurement results of the light at the wavelength of 420 nm and the wavelength of 840 nm when the voltage is turned ON and OFF. Based on the amount of light reflected from only the VIS-IR polarizing plate and the reflecting plate, the amount of light (%) incident on the detection unit of U-4100 after reflection from the light control device is shown.

<Example B4>
As the evaluation of the light control device, the light emitted from the light source unit of the above U-4100 was viewed from the light source side, and was constituted by a VIS-IR polarizing plate, a TN type liquid crystal cell, a VIS polarizing plate, and an IR polarizing plate. In the detection section. At this time, the VIS-IR polarizer is laminated so that the absorption axis of the VIS polarizer is parallel to the absorption axis of the VIS-IR polarizer, and the absorption axis of the IR polarizer is set to 90 ° with respect to the absorption axis of the VIS-IR polarizer. They were used in a laminated manner. As for the bonding to the liquid crystal cell, when a voltage is applied to the TN cell, the polarizing plate for infrared region is bonded to the polarizing plate so that the transmittance in the infrared region is minimized. Was. Table 11 shows the results of the light at the wavelength of 420 nm and the wavelength of 840 nm when the voltage is turned ON and OFF. The results show the amount of light (%) incident on the detection unit of U-4100 after passing through the light control device and based on the amount of light transmitted through only the VIS-IR polarizing plate.

  From the results of Examples B1 to B4, it can be seen that in each light control device, the amount of infrared light and visible light can be dynamically controlled independently using the same light source. In particular, in Examples B1 and B2, light control for visible light and infrared light at the time of transmission, that is, switching of the transmittance of visible light and infrared light by a medium that dynamically develops a phase. Turned out to be possible. In addition, in Example B3, it was found that the light control of the light control device was effective even when the reflection plate was used. From the above results, the light control device obtained in the present invention can control by simply switching the respective transmittances between visible light and infrared light even if the same light source is used. It has been shown to be effective as a possible device.

It is possible to control the polarization of incident infrared light and visible light at the same time so that they are different from each other, and switch between detection of infrared light and visible light. Liquid crystal display devices, imaging devices such as cameras that can control the polarization of infrared light and visible light, anti-counterfeiting devices that can provide advanced security, or infrared light and visible light It can be applied to various uses such as a functioning sensor.

Claims (18)

  At least one polarizing plate (IR polarizing plate) having polarization performance for infrared light, at least one polarizing plate (VIS polarizing plate) having polarization performance for visible light, and a medium having a phase or An optical control device that includes a medium whose phase can be controlled and controls transmitted light in an infrared region and transmitted light in a visible region by converting incident infrared light and visible light into different polarized lights.   The angle θi between the angle when the phase difference value Rλ of the medium having the phase or the phase controllable medium is indicated and the angle when linearly polarized light is developed in the infrared region is 0 ≦ θi <180 ° The light control device according to claim 1, wherein:   The angle θv between the angle indicating the phase difference value Rλ of the medium having a phase or the medium capable of controlling the phase and the angle at which linearly polarized light is developed in the visible region is −90 ° <θv <180 °. The light control device according to claim 1 or 2, wherein When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, The light control device according to any one of claims 1 to 3, which satisfies the relationship of (1) or (2).
Vλ−RD ≦ Rλ ≦ Vλ + RD Equation (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Equation (2)
(However, RD shows 0 to 40 nm). When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, The light control device according to any one of claims 1 to 3, which satisfies the relationship of (3) or (4):
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Equation (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Equation (4)
(However, RD shows 0 to 40 nm). When the wavelength of light in the infrared region is Iλ, the wavelength of light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of a medium having a phase or a phase controllable medium is Rλ, The light control device according to any one of claims 1 to 3, wherein the light control device satisfies the relationship of (5) or Expression (6).
Vλ × 3 / 2−RD ≦ Rλ ≦ Vλ × 3/2 + RD Equation (5)
(However, RD shows 0 to 40 nm.)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Equation (6)
(However, RD shows 0 to 40 nm.)   The light control device according to any one of claims 1 to 6, for simultaneously controlling visible light and infrared light, wherein the phase controllable medium is capable of dynamically controlling the phase. Light control device that is the medium.   The light control device according to claim 7, wherein the medium whose phase can be dynamically controlled is a liquid crystal panel (liquid crystal cell).   The light control device according to claim 8, wherein the liquid crystal used in the liquid crystal panel (liquid crystal cell) is a TN liquid crystal (Twisted Nematic liquid crystal) or an STN liquid crystal (Super Twisted Nematic liquid crystal).   The light control device according to any one of claims 7 to 9, wherein a contrast ratio of transmission to non-transmission of each of visible light and infrared light is 10 or more.   The light control device according to any one of claims 1 to 10, further comprising one polarizing plate (VIS-IR polarizing plate) having polarization performance with respect to visible light and infrared light.   The light control device according to claim 11, wherein a difference between an orthogonal transmittance of infrared light and an orthogonal transmittance of visible light in the VIS-IR polarizing plate is 1% or less.   The light control device according to claim 1, wherein a difference between an orthogonal transmittance of light in an infrared region and an orthogonal transmittance of light in a visible region in the IR polarizing plate is 10% or more.   A polarizing plate having an IR polarizing plate having an orthogonal transmittance of infrared light of 1% or less and a difference from a visible light transmittance of 10% or more, and the VIS polarizing plate having a high transmittance in an infrared region; And at least one polarizing plate that indicates that it has little effect on the transmission of light in the infrared region and that has an orthogonal transmittance of 1% or less for light in the visible region. The light control device according to claim 1.   The light control device according to any one of claims 1 to 14, wherein the IR polarizing plate or the VIS-IR polarizing plate is an absorption polarizing plate.   The light control device according to any one of claims 1 to 15, wherein the IR polarizing plate or the VIS-IR polarizing plate is a film.   The light control device according to any one of claims 1 to 16, wherein a medium having a phase difference or a phase controllable medium and at least one polarizing plate are laminated. A liquid crystal display device, a forgery prevention device, or a sensor comprising the light control device according to claim 1.