WO2018221598A1

WO2018221598A1 - Light control device for infrared region and visible region

Info

Publication number: WO2018221598A1
Application number: PCT/JP2018/020781
Authority: WO
Inventors: 典明望月
Original assignee: 日本化薬株式会社; 株式会社ポラテクノ
Priority date: 2017-06-02
Filing date: 2018-05-30
Publication date: 2018-12-06
Also published as: CN110622061B; CN110622061A; TWI763860B; JPWO2018221598A1; JP7111703B2; TW201908780A

Abstract

The present invention provides a light control device whereby light in the infrared region and light in the visible region at the time of incidence thereof can be emitted each with different polarization on a detection side thereof, and light quantity of the light can be controlled by the polarization thereof. Specifically, the present invention provides a light control device including at least one polarizing plate having polarization performance for light in the infrared region, at least one polarizing plate having polarization performance for light in the visible region, and a medium having a phase or a medium capable of phase control, the light control device converting incident light in the infrared region and incident light in the visible region each into different polarized light and thereby controlling transmitted light in the infrared region and transmitted light in the visible region.

Description

Infrared and visible light control devices

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

A polarizing plate having a light transmission / shielding function is used in a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. Applications of this LCD include small computers 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, it can be applied to a lens having a polarization function, and has been applied to sunglasses with improved visibility, and in recent years to polarized glasses compatible with 3D televisions.

A general polarizing plate is a polarizing film such as a stretched and oriented film of polyvinyl alcohol or a derivative thereof, or a polyene film obtained by orienting a polyene by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol film. The substrate is produced by dyeing or containing iodine or a dichroic dye as a polarizing element. Among these, an iodine-based polarizing film using iodine as a polarizing element is excellent in polarization performance, but is weak against water and heat, and is durable when used for a long time at high temperature and high humidity. There's a problem. On the other hand, although a dye-type polarizing film using a dichroic dye as a polarizing element is superior in moisture resistance and heat resistance to an iodine-type polarizing film, the polarizing performance is generally not sufficient. That is, the polarizing plate has a polarizing function with respect to the wavelength for the visible wavelength range, and is not the polarizing plate for the infrared wavelength range.

In recent years, in applications such as recognition light sources for touch panels, security cameras, sensors, anti-counterfeiting, and communication devices, polarizing plates used in the infrared region as well as polarizing plates for visible wavelengths are required. In response to such a request, an infrared polarizing plate obtained by polyeneizing an iodine-based polarizing plate as in Patent Document 1, an infrared polarizing plate using wire grit as in Patent Document 2 or 3, and Patent Document 4 A type using an infrared polarizer obtained by stretching glass containing fine particles or a cholesteric liquid crystal as disclosed in Patent Document 5 or 6 has been reported. In patent document 1, durability is weak, heat resistance, wet heat durability, and light resistance are weak, and it has not reached practicality. The wire grid type as disclosed in Patent Document 2 or 3 can be processed into a film type, and at the same time, is becoming popular because it is stable as a product. However, since the optical properties cannot be maintained if there are no nano level irregularities on the surface, the surface must not be touched, and therefore the applications used are limited, and antireflection and anti-glare processing is also required. Is difficult. The glass drawing type containing fine particles as in Patent Document 4 has high durability and high dichroism, and thus has practicality. However, because it is a stretched glass containing fine particles, the element itself is easily broken, fragile, and lacks flexibility like a conventional polarizing plate, so it is difficult to perform surface processing and bonding with other substrates. There was a problem. Although the techniques of Patent Document 5 and Patent Document 6 are techniques using circularly polarized light that have been published for a long time, the color changes depending on the viewing angle, and basically a polarizing plate using reflection. For this reason, it is difficult to form stray light or absolute polarized light. That is, there is no polarizing plate corresponding to an infrared wavelength region which is an absorptive polarizing element like a general iodine-based polarizing plate, is flexible in film type and has high durability. Furthermore, it only has the function of a polarizing plate in the infrared region, and cannot control the polarization in the visible region.

Thus, even though it has been possible to control each of the polarized light in the infrared region and the polarized light in the visible region, it has not been possible to obtain a polarizing plate capable of controlling the polarized light in each region at the same time.

In addition, there was no element that could switch between visible and infrared light and switched independently.

US 2,494,686 specification Japanese Patent Laid-Open No. 2016-148871 Special table 2006-507517 JP 2004-86100 A International Publication No. 2015/087709 JP 2013-064798 A

An object of the present application is to provide a light control apparatus that can control incident infrared wavelength light and visible wavelength light so that they simultaneously become different polarized lights.

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

As a result of diligent research to solve the above problems, the inventors of the present invention controlled infrared light and visible light to different polarized light using a medium having a phase or a medium capable of phase control. As a result, it is found that the polarized light of the infrared light at the time of incidence and the polarized light of the visible light at the time of incidence can emit different polarized light in the infrared region and the visible region on the detection side. It was.

In addition, the inventors of the present invention are light control devices that use light in the visible region and light in the infrared region at the same time, comprising at least one polarizing plate having polarization performance with respect to light in the infrared region, and light in the visible region. Controlling the amount of transmitted light in the infrared region and the amount of transmitted light in the visible region with a medium that can dynamically control the phase in a light control device equipped with at least one polarizing plate having polarization performance And a light control device that can function as a switching element between infrared light and visible light. Furthermore, while using the same light source, an optical system capable of controlling the light amount by switching between the infrared region and the visible region in the infrared region and the visible region on the side where the light amount in the infrared region and the light amount in the visible region are detected. I 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 with respect to light in the infrared region, at least one polarizing plate (VIS polarizing plate) having polarization performance with respect to light in the visible region, and a medium having a phase or A light control device that includes a phase-controllable medium and controls incident light in the infrared region and transmitted light in the visible region by changing incident infrared light and visible light to different polarized lights.
2)
An angle θi between an angle when the phase difference value Rλ of a medium having phase or a phase controllable medium is shown and an angle when linearly polarized light is expressed in the infrared region is 0 ≦ θi <180 ° The light control device according to 1), which falls within a range of
3)
An angle θv between an angle indicating a phase difference value Rλ of a medium having a phase or a phase controllable medium and an angle when linearly polarized light is expressed in the visible range is −90 ° <θv <180 ° The light control device according to 1) or 2), which falls within the range of
4)
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, (1) or the light control apparatus according to any one of 1) to 3) that satisfies the relationship of the mathematical formula (2):
Vλ−RD ≦ Rλ ≦ Vλ + RD Formula (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Formula (2)
(However, RD indicates 0 to 40 nm).
5)
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, (3) or the light control device according to any one of 1) to 3) satisfying the relationship of the mathematical formula (4):
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Formula (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Formula (4)
(However, RD indicates 0 to 40 nm).
6)
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, The light control device according to any one of 1) to 3) satisfying a relationship of (5) or Formula (6).
Vλ × 3 / 2−RD ≦ Rλ ≦ Vλ × 3/2 + RD Formula (5)
(However, RD indicates 0 to 40 nm.)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Formula (6)
(However, RD indicates 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 can dynamically control the phase. Light control device that is a medium.
8)
7. The light control device according to 7), wherein the medium capable of dynamically controlling the phase is a liquid crystal panel (liquid crystal cell).
9)
The light control device according to 8), wherein a liquid crystal used in the liquid crystal panel (liquid crystal cell) is a TN liquid crystal (Twisted Nematic liquid crystal) or a 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 of transmission to non-transmission of each 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 the difference between the orthogonal transmittance of light in the infrared region and the orthogonal transmittance of light in the visible region is 1% or less in the VIS-IR polarizing plate.
13)
The light control device according to any one of 1) to 12), wherein a difference between the orthogonal transmittance of light in the infrared region and the orthogonal transmittance of light in the visible region is 10% or more in the IR polarizing plate.
14)
In the IR polarizing plate, a polarizing plate in which the orthogonal transmittance of light in the infrared region is 1% or less and a difference from the transmittance of light in the visible region is 10% or more, and the VIS polarizing plate has a high transmittance in the infrared region. Any one of 1) to 13), including at least one polarizing plate that is less susceptible to the transmission of light in the infrared region and that has an orthogonal transmittance of light in the visible region of 1% or less The light control device according to one item.
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-type 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 capable of phase control and at least one polarizing plate are laminated.
18)
A liquid crystal display device, an anti-counterfeiting device, or a sensor comprising the light control device according to any one of 1) to 17).

According to the present invention, it is possible to emit light in the infrared region and light in the visible region at the time of incidence as different polarized lights on the detected side, and to control the light amount by the polarized light.

In one aspect, according to the present invention, the amount of light in the infrared region and the amount of light in the visible region upon incidence from the same light source are detected on the side where the light in the infrared region and the light in the visible region are in the respective regions. By switching so as to be transmissive or non-transmissive, 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, respectively, so that the infrared transmitted light and the visible transmitted light are different from each other. It is characterized by controlling.

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

The IR polarizing plate is not particularly limited as long as it is a polarizing plate capable of controlling polarization at wavelengths in the infrared region. Examples of the polarizing plate include a polyene type using an iodine-based polarizing plate as in Patent Document 1, a wire grid type polarizing plate as in Patent Document 2 and Patent Document 3, and metal particles on glass as in Patent Document 4. Examples thereof include a glass polarizing plate that is mixed and stretched, and a dye-based polarizing plate containing a dye. In the present application, a dye-based polarizing plate is preferably used. This dye-based polarizing plate can be made into a film type, and can be easily laminated with other polarizing plates, retardation plates, etc., and has a feature that it is flexible and easy to optically control. Yes.

The IR polarizing plate has polarization performance with respect to light in part or all of the 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 visible wavelength. The polarizing plate may be, 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 polyene, etc. It is preferable to combine a plurality of types of dye-type polarizing plates capable of controlling only the polarization or dye-type polarizing plates capable of polarizing only a specific wavelength to obtain a polarizing element capable of controlling the polarization of only light having a specific wavelength. By providing a polarization performance for only light of a specific wavelength, it is preferable because polarization at a specific wavelength can be detected or controlled.

The VIS polarizing plate has polarization performance with respect to light in a part or all of the wavelength region of 400 to 700 nm. It is preferable that the transmittance in the infrared region is high and has no absorption, and is not particularly limited as long as the light in the infrared region is higher than the visible transmittance. “Non-absorbing” means high transmittance in the infrared region, and hardly affects the transmission of light in the infrared region. Therefore, if each wavelength in the infrared region has a single transmittance equal to or higher than that, it can be used as a visible (VIS) polarizing plate of the present application as a polarizing plate having a function of transmitting infrared light. Specifically, the transmittance in the infrared region is 40% or more, preferably 50% or more, more preferably 60% or more, still more preferably 70%, and particularly preferably 80% or more. In particular, the transmittance in the infrared region when two VIS polarizing plates are orthogonal to each other is 30% or more, preferably 40% or more, more preferably 50% or more, further preferably 60%, particularly preferably 70% or more. It can be used as a particularly preferred VIS polarizing plate.

Examples of the medium having the above phase include those referred to as a retardation plate, a wave plate, and a retardation film.

Also, examples of the medium capable of phase control include a liquid crystal panel (liquid crystal cell) in which a liquid crystal generally used in a liquid crystal monitor or the like is sealed and the 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 polarization performance, for example, a wave plate, a phase controllable medium, etc. (wave plate, etc.) are optical functional elements that give a predetermined phase difference to linearly polarized light. On the other hand, different phases can be provided in other axes (for example 90 °). In other words, by providing a wavelength plate or the like on the optical path for one polarized light, it becomes possible to obtain polarized light of the opposite axis, or newly add circularly polarized light, elliptically polarized light, or the like. Therefore, a wave plate or the like is an element that can change the polarization state of incident light by providing a phase difference between two orthogonal polarization components using an oriented birefringent material (for example, a stretched film). It can be said. For example, when the wavelength of the specific light is λ, the wave plate is set to 45 ° with respect to the axis of polarization by setting the slow axis of the phase difference plate of λ / 2 to 45 °. The incident linearly polarized light can be rotated by 90 °, and polarized light having a polarization axis in a direction orthogonal (90 °) to the incident polarization axis can be emitted. Also, by setting the slow axis of the λ / 2 retardation plate to 22.5 ° with respect to the polarization axis, the linearly polarized light incident on the wave plate (retardation plate) is rotated by 45 ° and incident. It is possible to emit light having a polarization inclined by 45 ° with respect to the polarization 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, wave plate, and retardation film that can be used are not particularly limited as long as the slow axis or the fast axis of the film light can be rotated with respect to the absorption axis of the polarizing plate.

A liquid crystal panel (liquid crystal cell) capable of phase control is a medium for electrically controlling the phase. There are various liquid crystal driving methods to be controlled, such as TN (Twisted Nematic), STN (Super Twisted Nematic), IPS (In-Plane-Switching), and VA (Virtual Allocation). As long as the liquid crystal and control method can control the phase of light in the infrared region. Preferably, TN (Twisted Nematic), STN (Super Twisted Nematic), etc. are mentioned. These are preferable because the driving voltage is low, the price is low, and the polarization rotation of 0-90 ° is easy to control.

The light control device controls the light in the infrared region and the light in the visible region to be different polarized lights by a medium having a phase or a medium capable of phase control. Thereby, the polarization of infrared light at the time of incidence and the polarization of light at the time of incidence can be perceived as different polarizations on the detected side. Specifically, the amount of light in the visible region and the amount of light in the infrared region are adjusted simultaneously by simultaneously controlling the polarization of light in the visible region visible to the human eye and light in the infrared region that is difficult to visually recognize. This makes it possible to continue to transmit light in the infrared region while controlling to transmit or not transmit light in the visible region. In addition, the reverse control is also possible, that is, it is possible to continue to transmit light in the visible region while controlling to transmit or not transmit light in the infrared region. It is possible to provide a light control device capable of simultaneously controlling the polarization and light quantity of each of the light.

Conventionally, an infrared sensor and a visible camera had to use different types of detectors for detecting light in the infrared region and for detecting light in the visible region. It is possible to control the sensor and the visible camera with one light control device. For example, a camera such as a mobile phone generally requires separate light control devices for an infrared authentication camera and a visible camera, but by using the light control device, a visible light control device can be used. Since it is possible to switch between transmission and non-transmission of light and infrared light, it is possible to perform infrared region authentication and visible region photography using a single light control device. Furthermore, by applying this light control device, it can be applied to advanced security. In addition, since it is possible to control light transmission type devices, circularly polarized light control and linearly polarized light control in the infrared to visible region, application of these to, for example, devices that apply the light reflection polarization function, security applications, etc. Can also be applied.

In one aspect, an angle (phase of incident light) when a phase difference value Rλ of a medium having a phase or a phase controllable medium (phase difference plate) is expressed, and linearly polarized light is emitted (emitted) It is preferable that the light control device has an angle (phase difference) θi in the range of 0 ≦ θi <180 ° with respect to the angle (phase of the emitted light). When the angle θi is 0 °, that is, when it is installed coaxially, the polarized light in the infrared region becomes light that is not influenced or hardly received by the phase difference plate, and a phase difference that is a phase difference value of λ / 2. When a plate is provided, by setting the angle θi to 45 °, it is possible to emit polarized light having an axis opposite to that of the incident linearly polarized light by 90 °.

Furthermore, the angle (position) between the angle (phase of incident light) where the phase difference value Rλ of the phase difference plate is expressed and the angle (phase of outgoing light) when linearly polarized light is expressed in the visible range. The phase difference in the visible range can be controlled by the light control device in which the phase difference θv is in the range of −90 ° <θv <180 °. θv and θi may be the same or different from each other, as long as the polarization state of light having a specific wavelength can be controlled by the phase difference plate. That is, the number of retardation plates to be used is not limited to one, and the light control device of the present invention also has a plurality of positions so that a general liquid crystal display uses a combination of a 1 / 4λ plate, a 1 / 2λ plate, or the like. 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 retardation plate error is RD (Retarder Dispersion), and the retardation value of the retardation plate is Rλ, the following formula (1) or formula The light control device satisfying the relationship (2) functions as a phase difference plate capable of providing Vλ in the visible range, and functions as a phase difference plate capable of providing Iλ / 2 in the infrared range.
Vλ−RD ≦ Rλ ≦ Vλ + RD Formula (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Formula (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 set at 45 ° with respect to the incident linearly polarized light, the polarized light at the time of incidence can be maintained in the visible range. Although it continues to function as a retardation plate, in the infrared region, it can function as a λ / 2 polarizing plate to emit a reverse polarization axis of the incident polarization axis. When the slow axis of the retardation plate having Rλ is provided at 45 ° with respect to incident linearly polarized light, a polarizing plate having an absorption axis perpendicular to the incident axis is provided on the output side. In this case, it is possible to provide a light control device that can transmit light in the visible range but can absorb light in the infrared range. When it is desired that both visible light and infrared light are not transmitted (absorbed), the slow axis of the retardation plate having Rλ may be set at 0 ° instead of 45 °. Thus, by controlling the slow axis of the retardation plate having Rλ that satisfies the relationship of the above formula (1) or formula (2), the axis of linearly polarized light and elliptically polarized light can be controlled. . The RD is preferably in the range of 0 to 40 nm, more preferably 0 to 25 nm, still more preferably 0 to 15 nm, and particularly preferably 0 to 5 nm. Control of the polarization axis using the phase can be performed with reference to Non-Patent Document 1 and the like.

In addition, the light control device that satisfies the relationship of the following formula (3) or formula (4) functions as a retardation plate that can provide λ / 2 in the visible range, and can provide λ / 4 in the infrared range. Functions as a phase difference plate. Note that Iλ, Vλ, RD, and Rλ are as defined above.
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Formula (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Formula (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, and the incident polarized light. In the infrared region, it functions as a retardation plate that can function as a λ / 4 polarizing plate, and the incident polarized light can be emitted as circularly polarized light. As a result, when a polarizing plate having an absorption axis orthogonal to the incident axis is provided on the exit side, the polarization can be controlled while the linear region is linearly polarized, whereas the infrared region can be controlled as circularly polarized light. . When it is desired that both visible light and infrared light 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 mathematical expressions (3) and (4), the axis of linearly polarized light and elliptically polarized light can be controlled. With the above configuration, reflection control in the visible range is possible, and transmission control in the infrared range is also possible. As a preferable configuration, for example, a polarizing plate capable of controlling the visible region and the infrared region, a medium having a phase or a medium capable of phase control, a polarizing plate capable of controlling the visible region and the infrared region may be used. Illustrative examples include: a polarizing plate capable of controlling the visible region and the infrared region; a medium having a phase or a phase-controllable medium; a polarizing plate capable of controlling the visible region; and a polarizing plate capable of controlling the infrared region. However, the configuration is not limited. Furthermore, when this method is used, polarization control can be performed by applying 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, the polarizing plate, the λ / 4 retardation plate, and the reflection plate are laminated in this order, and 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 incident from the polarizing plate is converted into circularly polarized light by the phase difference plate, and the light reflected by the reflecting plate is reversed. It is converted into circularly polarized light, and as a result, a function capable of preventing reflection can be exhibited. However, in this case, since the light in the visible range continues to maintain the state of linear polarization, the light is reflected and the reflected light can be detected. Furthermore, even in the case of use in this reflection, by setting the slow axis of the retardation plate to 0 ° with respect to the absorption axis of the infrared polarizing plate, the infrared polarized light is maintained in a linearly polarized state. It functions as a light control device capable of reflecting both visible light and infrared light. In the case of this light control apparatus, RD may be 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 addition, the light control device that satisfies the relationship of the following formula (5) or formula (6) functions as a phase difference plate that can provide 3 / 2λ in the visible range, and can provide 1 / 2λ in the infrared range. 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 Formula (5)
(However, RD indicates 0 to 40 nm)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Formula (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, it functions as a 3 / 2λ polarizing plate in the visible region or is incident. It becomes possible to emit circularly polarized light of polarized light, and in the infrared region, it functions as a retardation plate capable of emitting incident polarized light on the opposite axis as a λ / 2 polarizing plate. As a result, when a polarizing plate having an absorption axis orthogonal to the incident axis is provided on the output side, the polarized light in the visible range 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 visible light and infrared light 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 mathematical expressions (5) and (6), the linearly polarized light axis, the elliptically polarized light, and the like can be controlled. As a preferable configuration, for example, a polarizing plate capable of controlling the visible region and the infrared region, a medium having a phase or a medium capable of phase control, a polarizing plate capable of controlling the visible region and the infrared region may be used. Illustrative examples include: a polarizing plate capable of controlling the visible region and the infrared region; a medium having a phase or a phase-controllable medium; a polarizing plate capable of controlling the visible region; and a polarizing plate capable of controlling the infrared region. However, the configuration is not limited. Furthermore, when this method is used, polarization control can be performed by applying the fact that reflected light has polarization in the infrared region. With the above configuration, reflection control in the visible range is possible, and transmission control in the infrared range is also possible. For example, when performing reflection control with a single polarizing plate, in the visible range, a polarizing plate, a 3 / 4λ polarizing plate, and a reflecting plate are laminated in this order, and the phase difference with respect to the absorption axis of the polarizing plate is formed on the reflecting plate. By setting the slow axis of the plate at 45 °, the incident linearly polarized light from the polarizing plate is converted to circularly polarized light by the phase difference plate, and the light reflected by the reflecting plate is converted to reverse circularly polarized light. As a result, a function capable of preventing reflection can be exhibited. However, in this case, since the light in the infrared region continues to maintain the state of linear polarization, the light is reflected and the reflected light can be detected. Furthermore, even when used in this reflection, by setting the slow axis of the phase difference plate to 0 °, it functions as a light control device that can reflect either visible light or infrared light. In the case of this light control apparatus, RD may be 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) when the two polarizing plates are stacked so that the absorption axes are orthogonal to each other (in the infrared region). (The orthogonal transmittance of light) and the transmittance of light in the visible region (wavelength of 400 to 700 nm) (orthogonal transmittance of light in the visible region) when the two polarizing plates are stacked so that the absorption axes are orthogonal to each other ) Is preferably 10% or more because polarization control of visible light and infrared light becomes easier. For example, when the polarizing plate has polarization performance for infrared light and also has polarization performance for visible light, the retardation plate Polarization can be controlled, but if one polarizing plate has a degree of polarization of 100% of light of 400 to 1400 nm, it imparts polarization performance only to infrared light, or to visible light It becomes difficult to impart polarization performance only. On the other hand, by using a polarizing plate having polarization performance for light in each wavelength region, polarization control can be performed at various wavelengths by selecting an appropriate polarizing plate according to the wavelength. In other words, using a polarizing plate that can be controlled only by the wavelength of light in the infrared region in the infrared region, and using a polarizing plate that can be controlled only by the wavelength of light in the visible region in the infrared region, polarization control at various wavelengths. Or, it is preferable because the transmittance can be controlled. However, since a polarizing plate having polarization performance in the infrared region may also have polarization performance in the visible region, it does not necessarily have only polarization performance in the infrared region. However, as a 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. It is sufficient that the size (S / N ratio) becomes clear. Therefore, the IR polarizing plate does not give 100% polarization performance at all wavelengths, but has a light transmittance of 700 to 1400 nm when the two polarizing plates are stacked so that the absorption axes are orthogonal to each other. The difference between the light transmittance of 400 to 700 nm when the two polarizing plates are stacked so that the absorption axes are orthogonal to each other is 10% or more, so that the light in the visible region and the light in the infrared region are This is preferable because polarization control is further facilitated, and the difference in transmittance is more preferably 20%, still more preferably 30%, and particularly preferably 40% or more.

An IR polarizing plate having an orthogonal transmittance of 1% or less in the wavelength range of light in the infrared region, and no absorption of light in the wavelength range of light in the infrared region, and the orthogonal transmittance of the polarizing plate is 1 The light control device including at least one VIS polarizing plate exhibiting% or less is preferable because the polarization performance with respect to light in the infrared region and the polarization performance with respect to light in the visible region can be controlled. Furthermore, the light control device is preferable because it improves the contrast between light in the infrared region and light in the visible region. In addition, it is possible to use each polarizing plate on a different axis, and it is possible to control light separately for visible light and infrared light at the wavelength and wavelength axis for which each polarization axis is to be controlled. It becomes. The orthogonal transmittance of each of the light in the infrared region and the light in the visible region can be sufficiently controlled by being independently 1% or less, preferably 0.3% or less, more preferably It may be 0.1% or less, more preferably 0.01% or less, and particularly preferably 0.005% or less. For example, when the parallel transmittance is 40%, when the orthogonal transmittance is 0.1%, the contrast ratio of 40: 0.1, that is, 400: 1 can be provided. That is, since the influence of the contrast of the polarizing plate on the optical control device of the present invention is large, it is preferable to control within the above range.

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

When constructing the light control device, it is preferable that at least one of the IR polarizing plates is an absorptive polarizing plate. The absorptive polarizing plate is characterized by not generating stray light. As the IR polarizing plate, a wire grid type is generally used. Light of a wavelength other than the original wavelength or intensity of light appears due to light reflection, refraction, resonance (resonance), phase modulation, etc. due to conditions such as unspecified shape, overlapping of light, or movement of the light position. 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 absorptive polarizing plate, stray light or the like is hardly generated, and thus optical control is easy, so that it can be preferably used.

Each of the above polarizing plates can be easily laminated and can be made flexible, and at least one of the IR polarizing plates is preferably a film in order to make it flexible. In particular, since lamination is possible, lamination with a medium having a phase or a medium capable of phase control is preferable. By laminating, a decrease in transmittance due to the influence of interface reflection or the like is unlikely to occur, which is preferable in controlling light.

In addition, each polarizing plate, medium having phase or medium capable of phase control is 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 control the polarization of infrared light and visible light at the same time, so that visible light that can be recognized by human eyes and infrared light that is difficult to recognize. The polarization of light can be controlled simultaneously. Therefore, it is possible to provide a liquid crystal display device capable of switching between detection of infrared light and visible light, a photographing device such as a camera capable of controlling polarization of infrared light and visible light, and high security. The above-mentioned light control device can be applied to various applications such as anti-counterfeiting devices or sensors that function in infrared light and visible light respectively, and a system that combines various applications and light control devices. Can also be used.

<Example>
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these.

<Preparation of polarizing plate (IR polarizing plate) having polarization performance for infrared light>
An aqueous solution at 45 ° C. having an azo compound of the following chemical formula (1) at a concentration of 0.3% and mirabilite at a concentration of 0.1% was prepared as a staining solution. A polyvinyl alcohol film having a thickness of 75 μm was immersed in the staining solution for 5 minutes. Next, the film was stretched 5 times in a solution of 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining a tensioned 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 is laminated on both sides of this polarizing element via an adhesive of polyvinyl alcohol aqueous solution, and 835 nm is laminated. A polarizing plate having a high polarization 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.) at a concentration of 0.02%, C.I. I. Prepare a 45 ° C. aqueous solution with Direct Red 81 at a concentration of 0.01%, Blue KW (manufactured by Nippon Kayaku Co., Ltd.) at a concentration of 0.04%, and sodium nitrate at a concentration of 0.1%. A staining solution was obtained. 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 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining a tensioned 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 is laminated on both sides of this polarizing element via an adhesive of polyvinyl alcohol aqueous solution, and 400- 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.

<Production of polarizing plate (VIS-IR polarizing plate) capable of controlling light in the infrared region and light in the visible region>
The azo compound of the above chemical formula (1) is at a concentration of 0.6%, Kayarusu Supra Orange 2GL (manufactured by Nippon Kayaku Co., Ltd.) at a concentration of 0.02%, C.I. I. Prepare a 45 ° C. aqueous solution with Direct Red 81 at a concentration of 0.01%, Blue KW (manufactured by Nippon Kayaku Co., Ltd.) at a concentration of 0.04%, and sodium nitrate at a concentration of 0.1%. A staining solution was obtained. A polyvinyl alcohol film having a thickness of 75 μm was immersed in the staining solution for 5 minutes. Next, the film was stretched 5 times in a solution of 3% boric acid aqueous solution at 50 ° C., washed with water and dried while maintaining a tensioned 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 is laminated on both sides of this polarizing element via an adhesive of polyvinyl alcohol aqueous solution, and 400- 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)
For each of the obtained polarizing plates, using a spectrophotometer (U-4100, manufactured by Hitachi, Ltd.), the single transmittance (Ts), the parallel transmittance (Tp), and the orthogonal transmittance (Tc) at each wavelength at 380 to 1100 nm. ), And the degree of polarization (ρ) was measured. The single transmittance (Ts) is the transmittance obtained by measuring one polarizing plate, and the parallel transmittance (Tp) is obtained by measuring the respective light absorption axes of the two polarizing plates in parallel. The orthogonal transmittance (Tc) is a transmittance obtained by measuring the light absorption axes of the two polarizing plates orthogonal to each other, and the degree of polarization is calculated by Equation (7). This is the value obtained.

Polarization degree (%) = 100 × [(Tp−Tc) / (Tp + Tc)] ^1/2 Formula (7)

The single transmittance (Ts), parallel transmittance (Tp), and orthogonal transmittance (Tc) at wavelengths of 420 nm, 555 nm, 830 nm, and 840 nm of the obtained polarizing plates 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 Light control in which light emitted from the light source unit of U-4100 is configured in the order of VIS-IR polarizing plate, retardation plate, VIS polarizing plate, and IR polarizing plate when viewed from the light source side. The device was irradiated with light so that the transmitted light was incident on the detection unit of U-4100. A polycarbonate retardation plate showing a retardation value of 420 nm at each wavelength of 420 nm and 840 nm was used as the retardation plate. The transmittance was measured when the slow axis of this retardation plate was tilted at 0 ° and 45 ° with respect to the VIS-IR polarizing plate. At that time, the measurement was performed by changing various polarization axes of the VIS polarizing plate and the IR polarizing plate. The results are shown in Table 4. The 0 ° in Table 4 means that the retardation axis is 0 ° with respect to the absorption axis of the VIS-IR polarizing plate, and the slow axis is 0 ° with the VIS polarizing plate or IR polarizing plate (coaxial). ) Is installed. The same applies to 45 ° and 90 °. St indicates that the transmittance detected by U-4100 is strong (30-50%), and Mi indicates that the transmittance detected by U-4100 is medium (10-25%). “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 phase difference 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 phase difference 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 configured in the order of a VIS polarizing plate, an IR polarizing plate, a retardation plate, and a reflecting plate when viewed from the light source side, and the reflected light is reflected by U -4100 was made incident on the detection unit. A polycarbonate retardation plate showing a retardation value of 210 nm at each wavelength of 420 nm and 840 nm was used as the retardation plate. The transmittance was measured when the slow axis of this retardation plate was tilted at 0 ° and 45 ° with respect to the VIS polarizing plate. At that time, the measurement was performed by changing various polarization axes of the IR polarizing plate. The results are shown in Table 7. “0 °” in Table 7 indicates that the retardation axis is 0 ° with respect to the absorption axis of the VIS polarizing plate, and the absorption axis is 0 ° (coaxial) with the IR polarizing plate. It shows 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 configured in the order of a VIS polarizing plate, an IR polarizing plate, a retardation plate, and a reflecting plate when viewed from the light source side, and the reflected light is reflected by U -4100 was made incident on the detection unit. A polycarbonate retardation plate showing a retardation value of 415 nm at each wavelength of 555 nm and 830 nm was used as the retardation plate. The transmittance was measured when the slow axis of this retardation plate was tilted at 0 ° and 45 ° with respect to the VIS polarizing plate. At that time, the measurement was performed by changing various 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 device (Comparative Examples 1 to 4) obtained by removing the retardation plate from Examples A1 to A4. As in the case of the conventional polarizing plate, if the absorption axis of the polarizing plate is orthogonal to each wavelength, the transmittance is lowered, and if the absorption axis is parallel, the transmittance is increased. It has only been possible to control the transmissivity at the parallel position and the orthogonal position, which is a function of a conventional polarizing plate, but it has not become an optical apparatus capable of individually controlling the transmissivity at each wavelength.

<Comparative Examples A5 to A6>
Table 10 shows the results of measuring the transmittance using the light control device (Comparative Examples 5 to 6) obtained by removing the retardation plate from Examples A13 to A14. As in the case of placing a conventional polarizing plate on a mirror, no change in transmittance was observed, and no change was observed in incident light between visible light and infrared light.

From the results of Examples A1 to A12, it can be seen that each light control device can control the amount of light in the infrared region and the light in the visible region with respect to the same light source. Further, in each of Examples A5 to A8 and Examples A13 to A14, and Examples A9 to A12 and Examples A15 to A16, the results obtained by the light control during light transmission and the light control during reflection are obtained. It can be seen that the results are different. Based on the above results, the light control device obtained by the present invention uses different amounts of light in the visible region and in the infrared region, even when the same light source having visible light and infrared light is used. It has been 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 irradiated 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 when viewed from the light source side, and transmitted. The incident light is made incident on the detection unit of U-4100. At that time, the absorption axis of the VIS-IR polarizing plate is laminated so that the absorption axis of the VIS-IR polarizing plate is parallel to the absorption axis of the VIS-IR polarizing plate, and the absorption axis of the IR polarizing plate is 90 ° with respect to the absorption axis of the VIS-IR polarizing plate. It was used by laminating. As for the bonding to the liquid crystal cell, when the voltage was applied to the STN cell, each polarizing plate was bonded so as to have the lowest transmittance in the visible region, and 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 the 45 ° direction when the initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/1 at each wavelength of 420 nm and 840 nm. The one having a phase of 2λ was used. At that time, Table 4 shows the measurement results of light of 420 nm wavelength and 840 nm wavelength when the voltage is turned on and off. Based on the amount of light transmitted through the VIS-IR polarizing plate alone, the amount of light (%) when the light enters the detection unit of the 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 irradiated 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 when viewed from the light source side, and transmitted. The incident light is made incident on the detection unit of U-4100. At that time, the absorption axis of the VIS-IR polarizing plate is stacked 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. It was used by laminating. Regarding the bonding to the liquid crystal cell, when the voltage was not applied to the STN cell, each polarizing plate was bonded so as to have the lowest transmittance in the visible region, and used as a measurement sample of the present application. The STN type liquid crystal cell is arranged so as to have a slow axis in the 45 ° direction when the initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/1 at each wavelength of 420 nm and 840 nm. The one having a phase of 2λ was used. Table 4 shows the results of light having a wavelength of 420 nm and a wavelength of 840 nm when the voltage is turned on and off. Based on the amount of light transmitted through the VIS-IR polarizing plate alone, 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 light source side in the order of the VIS polarizing plate, the configuration of the IR polarizing plate, the STN type liquid crystal cell, and the reflecting plate, and the reflected light is detected by the detecting unit of the U-4100 It was made to enter. The IR polarizing plate is bonded at 45 ° with respect to the absorption axis of the VIS polarizing plate, and the bonding to the liquid crystal cell has the lowest reflectance in the infrared region when no voltage is applied to the STN cell. What stuck each polarizing plate was used as a measurement sample of this application. The STN type liquid crystal cell is arranged so as to have a slow axis in the 45 ° direction when the initial axis is set to 0 ° when a voltage is applied, and the phase difference is 1/1 at each wavelength of 420 nm and 840 nm. The one having a phase of 4λ was used. At that time, Table 4 shows the measurement results of light of 420 nm wavelength and 840 nm wavelength when the voltage is turned on and off. Based on the amount of light reflected from the VIS-IR polarizing plate and the reflector, only the amount of light (%) incident on the detection unit of U-4100 after reflection from the light control device is shown.

<Example B4>
As an evaluation of the light control device, the light emitted from the light source unit of the above U-4100 is configured as a VIS-IR polarizing plate, a TN type liquid crystal cell, a VIS polarizing plate, and an IR polarizing plate as viewed from the light source side. It was made to enter into the detection part. At that time, the absorption axis of the VIS-IR polarizing plate is laminated so that the absorption axis of the VIS-IR polarizing plate is parallel to the absorption axis of the VIS-IR polarizing plate, and the absorption axis of the IR polarizing plate is 90 ° with respect to the absorption axis of the VIS-IR polarizing plate. It was used by laminating. Regarding the bonding to the liquid crystal cell, when a voltage is applied to the TN cell, the polarizing plate is bonded so that the transmittance in the infrared region is minimized by the polarizing plate for infrared region, and used as the measurement sample of the present application. It was. Table 11 shows the results of light having a wavelength of 420 nm and a wavelength of 840 nm when the voltage is turned on and off. The result shows the amount of light (%) incident on the detection unit of U-4100 after passing through the light control device, based on the amount of light transmitted through the VIS-IR polarizing plate alone.

From the results of Examples B1 to B4, it can be seen that each light control device can independently and independently control the amount of light in the infrared region and the light in the visible region while using the same light source. In particular, in Examples B1 and B2, optical control for visible light and infrared light during transmission, that is, switching of transmittance of visible light and infrared light by a medium that dynamically develops a phase. Was found to be possible. Moreover, in Example B3, it was found that the light control of the light control device is effective even when a reflector is used. From the above results, the light control device obtained by the present invention can easily switch the transmittance between visible light and infrared light even when 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 wavelength light and visible wavelength light so that they are simultaneously different polarizations, and it is possible to switch between detection of infrared light and visible light. Liquid crystal display devices, photographing 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 applications such as a functioning sensor.

Claims

At least one polarizing plate (IR polarizing plate) having polarization performance with respect to light in the infrared region, at least one polarizing plate (VIS polarizing plate) having polarization performance with respect to light in the visible region, and a medium having a phase or A light control device that includes a phase-controllable medium and controls incident light in the infrared region and transmitted light in the visible region by changing incident infrared light and visible light to different polarized lights.
An angle θi between an angle when the phase difference value Rλ of a medium having phase or a phase controllable medium is shown and an angle when linearly polarized light is expressed in the infrared region is 0 ≦ θi <180 ° The light control device according to claim 1, which falls within the range.
An angle θv between an angle indicating a phase difference value Rλ of a medium having a phase or a phase controllable medium and an angle when linearly polarized light is expressed in the visible range is −90 ° <θv <180 ° The light control device according to claim 1, wherein the light control device falls within the range.
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, The light control device according to any one of claims 1 to 3, wherein the light control device satisfies the relationship of (1) or formula (2):
Vλ−RD ≦ Rλ ≦ Vλ + RD Formula (1)
(However, RD indicates 0 to 40 nm)
Iλ / 2−RD ≦ Rλ ≦ Iλ / 2 + RD Formula (2)
(However, RD indicates 0 to 40 nm).
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, The light control apparatus according to any one of claims 1 to 3, wherein the light control apparatus satisfies the relationship of (3) or (4):
Vλ / 2−RD ≦ Rλ ≦ Vλ / 2 + RD Formula (3)
(However, RD indicates 0 to 40 nm)
Iλ / 4−RD ≦ Rλ ≦ Iλ / 4 + RD Formula (4)
(However, RD indicates 0 to 40 nm).
When the wavelength of the light in the infrared region is Iλ, the wavelength of the light in the visible region is Vλ, the error of the phase difference value is RD, and the phase difference value of the medium having the phase or the phase controllable medium is Rλ, respectively, The light control apparatus according to any one of claims 1 to 3, wherein the light control apparatus satisfies the relationship of (5) or (6).
Vλ × 3 / 2−RD ≦ Rλ ≦ Vλ × 3/2 + RD Formula (5)
(However, RD indicates 0 to 40 nm.)
Iλ × 1 / 2−RD ≦ Rλ ≦ Iλ × 1/2 + RD Formula (6)
(However, RD indicates 0 to 40 nm.)
The light control apparatus according to any one of claims 1 to 6, wherein the light in the visible region and the light in the infrared region are controlled simultaneously, wherein the phase-controllable medium is dynamically phase-controllable. Light control device that is a medium.
The light control device according to claim 7, wherein the medium capable of phase control 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 a 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, 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 the difference between the orthogonal transmittance of infrared light and the orthogonal transmittance of visible light in the VIS-IR polarizing plate is 1% or less.
The light control device according to any one of claims 1 to 12, wherein a difference between the orthogonal transmittance of light in the infrared region and the orthogonal transmittance of light in the visible region is 10% or more in the IR polarizing plate.
In the IR polarizing plate, a polarizing plate in which the orthogonal transmittance of light in the infrared region is 1% or less and a difference from the transmittance of light in the visible region is 10% or more, and the VIS polarizing plate has a high transmittance in the infrared region. And at least one polarizing plate showing that it is difficult to affect the transmission of light in the infrared region and has an orthogonal transmittance of light in the visible region of 1% or less. The light control device according to one item.
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-type 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 medium capable of phase control 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 any one of claims 1 to 17.