JP2018036314A - Polarization image sensor and polarization image sensor fabrication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarization image sensor, and a polarization image sensor fabrication method that enable a near-infrared ray to detect polarization information on light carrying information on a measurement object without reducing an amount of light of visible light.SOLUTION: A polarization image sensor has: a sensor array that has solid state image pick-up elements two-dimensionally arrayed; a reflection type polarization plate that reflects polarized light of the near-infrared ray and transmits light other than the polarized light thereof; and a pattern phase difference plate that is divided into a plurality of areas corresponding to one or more solid state image pick-up elements in the same in-plane, and has two or more kinds of areas mutually different in a direction of a slow axis. The polarization image sensor has a reflection type circular polarization plate between the sensor array and the pattern phase difference plate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarization image sensor for detecting polarized light and a method for manufacturing the polarization image sensor.

A polarization image sensor that detects the state of polarization of light from a subject is known.
According to this polarization image sensor, information that cannot be obtained with a normal black-and-white image or color image is obtained, such as the inclination of the surface of an object, the clarification of shapes and boundaries that are difficult to discriminate, and the detection of the state of stress applied to the object. be able to.
Therefore, the polarization image sensor can be used in various fields such as inspection, medical care, driving assistance, operation, and security.

As such a polarization image sensor, for example, a polarization imaging apparatus described in Patent Document 1 is known.
As an example, this polarization imaging apparatus is divided into three or more wavelength plate regions having different optical axis directions, and of the incident light, the optical axis of each region depends on each region, and the polarization component orthogonal to this optical axis. A wave plate array including one or more polarizing plate units that generate different phase differences, a polarizer on which light transmitted through the wave plate array is incident, and a CCD (Charge Coupled Device) that measures light transmitted through the polarizer ) A light receiving element array such as a sensor, and a polarization component and a non-polarized light component received by the light receiving element array, and an image processing unit.

International Publication No. 2008/10156

  According to the polarization imaging apparatus described in Patent Literature 1, it is possible to detect the polarization state of light carrying an image to be observed, for example, to detect the shape of the observation object.

Here, in the polarization imaging apparatus described in Patent Document 1, visible light is processed and analyzed using a wave plate or a polarizer using a photonic crystal.
Therefore, the light received by the light receiving element array has a reduced amount of light in the visible light region. For example, it is difficult to reproduce a visible image together with the detection result of the polarization state.

  An object of the present invention is to solve such a problem of the prior art, and without reducing the amount of light in the visible light region, the light carrying information of the object to be imaged, such as the light reflected by the object to be imaged. It is an object of the present invention to provide a polarization image sensor capable of detecting a polarization state and a method for manufacturing the polarization image sensor.

In order to solve this problem, the polarization image sensor of the present invention includes a sensor array having solid-state imaging elements arranged in a two-dimensional matrix,
A reflective polarizer that reflects near-infrared polarized light in a specific wavelength region and transmits other light; and
A pattern position that is divided into a plurality of regions corresponding to one or a plurality of solid-state image sensors of the sensor array in the same plane, and has two or more regions having the same phase difference and different slow axis directions. A phase difference plate, and
Provided is a polarization image sensor in which a reflective polarizing plate is disposed between a sensor array and a pattern phase difference plate.

In such a polarization image sensor of the present invention, the reflective polarizing plate is a reflective circular polarizing plate that selectively reflects near-infrared right circularly polarized light or left circularly polarized light in a specific wavelength region, and has a pattern phase difference. The plate is preferably a pattern λ / 4 plate.
Moreover, it is preferable that a sensor array has a solid-state image sensor which detects visible light, and a solid-state image sensor which detects near infrared rays.
Moreover, it is preferable to have a band pass filter that selectively transmits near-infrared light and visible light on the side opposite to the reflective polarizing plate of the pattern retardation plate.
In the pattern retardation plate, it is preferable that one of the divided regions does not have an in-plane retardation.
Moreover, it is preferable to have a photo-alignment film between the reflective polarizing plate and the pattern retardation plate.
Moreover, it is preferable to have a photo-alignment film between the sensor array and the reflective polarizing plate.
Moreover, it is preferable that the reflective polarizing plate is formed by fixing at least one polymerizable liquid crystal compound in a cholesteric liquid crystal phase state.
Furthermore, it is preferable that the pattern retardation plate is formed by fixing at least one polymerizable liquid crystal compound.

In addition, the method for manufacturing a polarization image sensor according to the present invention reflects near-infrared polarized light in a specific wavelength region on the light-receiving surface side of a sensor array having solid-state imaging elements arranged in a two-dimensional matrix, and otherwise. A polarizing plate forming step of forming a reflective polarizing plate that transmits the light, and
Divided into a plurality of regions corresponding to one pixel or a plurality of pixels of the solid-state image sensor of the sensor array within the same plane, which is performed after the polarizing plate formation step, the phase differences are equal, and the directions of the slow axes are mutually There is provided a method for producing a polarization image sensor, comprising a phase difference plate forming step of forming a pattern phase difference plate having two or more different regions.

In such a method for producing a polarizing image sensor of the present invention, the polarizing plate formation step includes at least one polymerizable liquid crystal compound, at least one chiral agent, and at least one type on the surface where the reflective polarizing plate is formed. It is preferable to fix the cholesteric liquid crystal phase after applying the coating liquid containing the polymerization initiator in order to form the cholesteric liquid crystal phase.
In addition, before the polarizing plate forming step, a step of forming a photo-alignment film on the formation surface of the reflective polarizing plate, and a step of irradiating linearly polarized light to the photo-alignment film to impart alignment regulation force Is preferred.
In the retardation plate forming step, a coating liquid containing at least one polymerizable liquid crystal compound and at least one polymerization initiator is applied to the formation surface of the pattern retardation plate, and the polymerizable liquid crystal compound is applied. It is preferable to include polymerizing and fixing the polymerizable liquid crystal compound after the alignment.
In addition, before the retardation plate forming step, the alignment film forming step for forming the photo-alignment film on the formation surface of the pattern retardation plate, and linearly polarized light is irradiated to the photo-alignment film through the pattern photomask. In addition, it is preferable to include a regulating force applying step for applying an alignment regulating force for forming slow axes in different directions in the same plane of the pattern retardation plate.
In the retardation plate forming step, it is preferable to partially form a region having no in-plane retardation in the same plane.
Also, in the regulating force applying step, by providing a portion that does not irradiate the linearly polarized light to the photo-alignment film, a region having no in-plane retardation is formed in the same plane in the pattern retardation plate. Is preferred.
Further, in the regulation force applying step, by providing a region that irradiates the non-polarized light to the photo-alignment film and imparts the vertical alignment regulation force, the pattern retardation plate has an in-plane position within the same plane. It is preferable to partially form a region having no phase difference.
In addition, as a retardation plate forming step after the regulating force imparting step, a coating containing at least one polymerizable liquid crystal compound and at least one polymerization initiator on the photo-alignment film given the orientation regulating force. After applying the liquid and orienting the polymerizable liquid crystal compound, a step of partially irradiating light through which the polymerization initiator reacts through the photomask to polymerize and fix the polymerizable liquid crystal compound, and a photomask By heating the uncured part that has been shielded from light to an isotropic phase, and then irradiating light with which the polymerization initiator reacts to polymerize and fix the polymerizable liquid crystal compound in the uncured part, In the pattern retardation plate, it is preferable to partially form a region having no in-plane retardation in the same plane.
Further, after the regulating force imparting step, as a retardation plate forming step, coating comprising at least one polymerizable liquid crystal compound and at least one polymerization initiator on the photo-alignment film given the orientation regulating force. Applying the liquid and orienting the polymerizable liquid crystal compound, and then partially irradiating light through which the polymerization initiator reacts through a photomask to align and polymerize the polymerizable liquid crystal compound, and In the pattern retardation plate, an in-plane retardation is produced in the same plane by performing a development process using a solvent in which the polymerizable liquid crystal compound is dissolved and performing a process of removing an uncured portion blocked by a photomask. It is preferable to partially form a region that does not have.

  According to the present invention, it is possible to detect the polarization state of light that carries information about a subject such as light reflected by the subject without reducing the amount of visible light.

It is a figure which shows notionally an example of the polarization image sensor of this invention. It is a figure which shows notionally the structure of the sensor array of the polarization image sensor shown in FIG. It is a figure which shows the spectral characteristic of each site | part which comprises the polarization image sensor shown in FIG. 1, and is an example at the time of setting a specific wavelength range to 850 nm +/- 50nm. It is a conceptual diagram for demonstrating the structure of the polarization image sensor shown in FIG. It is a conceptual diagram for demonstrating the effect | action of the polarization image sensor shown in FIG. It is a conceptual diagram for demonstrating the effect | action of the polarization image sensor shown in FIG. It is a figure which shows notionally another example of the pattern phase difference plate utilized for the polarization image sensor of this invention.

  Hereinafter, a polarization image sensor and a method for manufacturing the polarization image sensor of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

In the present invention, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Unless otherwise specified, the angle or the like includes a generally allowable error range.
In the present invention, “(meth) acrylate” is used in the meaning of “one or both of acrylate and methacrylate”.

In the present invention, visible light is light having a wavelength visible to the human eye among electromagnetic waves, and indicates light in a wavelength region of 380 to 780 nm. Invisible light is light in a wavelength region of less than 380 nm or a wavelength region of more than 780 nm.
Although not limited to this, among visible light, light in the wavelength region of 420 to 490 nm is blue (B) light, and light in the wavelength region of 495 to 570 nm is green (G) light. The light in the wavelength region of 620 to 750 nm is red (R) light.
Furthermore, in the present invention, infrared (infrared light) is light in a wavelength region exceeding 780 nm and 1 mm or less, and among these, near infrared (near infrared region) is a wavelength region exceeding 780 nm and 2000 nm or less. Light.

The present invention aims to detect the polarization state in the near-infrared region, but in order to increase the detection accuracy of the polarization state, it is preferable to have a configuration that detects only near-infrared light in a specific wavelength region. .
The specific wavelength region can be arbitrarily set, but a region of 1200 nm or less which is a detection wavelength of a silicon photodiode generally used for a sensor array is preferable, and a near-infrared light source which is a general near-infrared light source. Most preferably, the typical wavelengths of infrared LEDs are 850 nm and / or 940 nm. By using the near-infrared light source matched to the detection wavelength region of the present invention, it is possible to accurately detect the polarization state of transmitted light and reflected light when the detection target is irradiated with the near-infrared light source.

FIG. 1 conceptually shows an example of the polarization image sensor of the present invention.
The polarization image sensor 10 shown in FIG. 1 includes a sensor array 12, a first alignment film 14, a reflective circularly polarizing plate 16, a second alignment film 18, a pattern λ / 4 plate 20, a bandpass filter 24, It is comprised.
The bandpass filter 24 includes a cholesteric reflection layer 30 and a near infrared filter 34. The cholesteric reflective layer 30 includes a right circularly polarized cholesteric layer 30r and a left circularly polarized cholesteric layer 30l.

In FIG. 1, in order to simplify the drawing and clearly show the configuration of the polarization image sensor 10 of the present invention, one pixel in the polarization image sensor 10 of the present invention, that is, a solid in the sensor body 40 described later. Only 4 × 4 = 16 imaging elements 40a are shown.
However, in practice, the polarization image sensor 10 of the present invention is configured by two-dimensionally arranging one pixel in the arrangement direction (x direction and y direction) of a solid-state imaging device 40a described later.

FIG. 2 conceptually shows the sensor array 12.
The sensor array 12 includes a sensor body 40, a color filter 42, an infrared blocking layer 46, a microlens 48, and a planarization layer 50.
The sensor body 40 has a solid-state image sensor 40a. The color filter 42 includes a red filter 42R, a green filter 42G, a blue filter 42B, and an infrared filter 42IR.

In FIG. 2, the sensor body 40 shows only four solid-state image sensors 40a. However, in reality, a large number of solid-state image sensors 40a are arranged two-dimensionally (x direction and y direction). It is the same as in FIG.
In FIG. 2, in order to clearly show the configuration of the sensor array 12, the color filter 42 includes a red filter 42 </ b> R, a green filter 42 </ b> G, a blue filter 42 </ b> B, and an infrared filter 42 </ b> IR arranged side by side. However, actually, as conceptually shown in FIG. 1 and FIG. 4 to be described later, each filter has one 2 × 2 four solid-state imaging device 40a as one unit. Correspondingly, any one of four types of filters is provided, and a 2 × 2 array of these four types of filters is repeatedly provided two-dimensionally in the array direction of the solid-state imaging device 40a. It is the same.

As described above, the sensor body 40 includes the solid-state image sensor 40a.
The sensor main body 40 is generally known as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) including a solid-state imaging device 40a such as a photodiode.
The solid-state imaging element 40a detects light and functions as a light receiving element. For light detection, for example, photoelectric conversion is used. In the sensor body 40, a plurality of solid-state imaging elements 40a are two-dimensionally arranged in the x direction and the y direction (see FIGS. 1 and 4). In the illustrated example, 4 × 4 = 16 solid-state imaging elements. The element 40a (16 pixels) constitutes one pixel. The solid-state image sensor 40a is made of, for example, silicon or germanium.
The solid-state imaging device 40a is not particularly limited as long as it can detect light. Any one of a PN junction type, a PIN (p-intrinsic-n) junction type, a Schottky type, and an avalanche type is used. be able to.

  In addition, the sensor main body 40 includes a substrate such as a silicon substrate, a wiring layer for outputting signal charges obtained by the solid-state imaging device 40a to the outside, and solid-state imaging in which light that has passed through filters of each color is adjacent. A known optical sensor called a CCD sensor or a CMOS sensor, such as a blocking layer made of a metal film or the like for preventing incident on the element 40a, and an insulating layer made of BPSG (Boron Phosphorus Silicon Glass). You may have various members of.

A color filter 42 is provided on the light receiving surface of the sensor body 40.
The color filter 42 includes a red filter 42R, a green filter 42G, a blue filter 42B, and an infrared filter 42IR. The color filter 42 corresponds to one solid-state imaging device 40a of the sensor body 40, and the red filter 42R, green Any of the filter 42G, the blue filter 42B, and the infrared filter 42IR is provided.

FIG. 3 shows the spectral characteristics of each part constituting the polarization image sensor 10. The horizontal axis of the spectrum conceptual diagram shown in FIG. 3 indicates the wavelength (nm), and the vertical axis indicates the transmittance. FIG. 3 shows an example when the specific wavelength region is set to 850 nm ± 50 nm (800 to 900 nm), but in the present invention, the wavelength region can be arbitrarily set, Needless to say, the spectral characteristics can be arbitrarily changed.
The color filter 42 is a known three primary color and infrared absorption type color filter used for a CCD sensor or the like.
As conceptually shown in the third-stage CF (Color Filter) 42 from the top of FIG. 3, the red filter 42R transmits red light and infrared light and absorbs visible light other than red light ( The green filter 42G transmits green light and infrared light and absorbs visible light other than green light ([green] column in FIG. 3), and the blue filter 42B It transmits blue light and infrared light and absorbs visible light other than blue light ([Blue] column in FIG. 3). The infrared filter 42IR transmits infrared light (IR (Infra Red)), It absorbs visible light (infrared column in FIG. 3).

  The color filter 42 may be other than red, green, and blue for visible light. For example, the color filter 42 may be a complementary color filter having a transmitted light spectrum in the cyan, magenta, and yellow regions with respect to visible light.

Here, an infrared blocking layer 46 is provided between the sensor body 40 and the red filter 42R, the green filter 42G, and the blue filter 42B corresponding to visible light.
The infrared blocking layer 46 is an absorption-type infrared filter that blocks by absorbing or reflecting infrared rays in a predetermined wavelength region.

All of the solid-state imaging devices 40a of the sensor body 40 are sensitive to near infrared rays. Each of the filters for each color of visible light transmits infrared rays.
In the solid-state imaging device 40a corresponding to the filters of the three primary colors, not only the light components of the corresponding colors but also infrared rays are incident on the solid-state imaging device and measured as the light components of the respective colors.
Such an infrared component becomes noise with respect to appropriate red light, green light, and blue light, and contributes to deterioration of the image quality of an image taken by the image sensor.

  The infrared blocking layer 46 is provided to eliminate such inconveniences. As an example, as shown conceptually in the fourth row from the top of FIG. 3, a specific wavelength in the near infrared (in the illustrated example, Is absorbed or reflected and cut (cut) by absorbing or reflecting (850 nm ± 50 nm), thereby removing noise caused by infrared rays from the measurement of visible light of each color.

The infrared blocking layer 46 includes, as an example, an infrared absorbing material having infrared absorbing ability, and as an example, an infrared absorbing dye mixed with a binder resin is exemplified.
Various known infrared absorbing dyes can be used depending on the wavelength region to be absorbed.
Specifically, examples of the infrared absorbing dye include those having a dithiol complex, an aminothiol complex, a phthalocyanine, a naphthalocyanine, a phosphate ester copper complex, a nitroso compound, and a metal complex thereof as a main skeleton. Examples of the metal portion of the complex include iron, magnesium, nickel, cobalt, copper, steel, vanadium zinc, palladium, platinum, titanium, indium, and tin. In addition, examples of the element of the coordination moiety include organic ligands having sites such as various halogens, amine groups, nitro groups, and thiol groups. Furthermore, substituents such as an alkyl group, a hydroxy group, a strong ruxoxyl group, an amino group, a nitro group, a cyano group, a fluorinated alkyl group, and an ether group may be introduced.
Examples of infrared absorbing dyes include methine dyes such as cyanine and merocyanine, triarylmethane, squarylium, anthraquinone, naphthoquinone, quatarylene, perylene, stiltyl, imonium, diimonium, cucumber, oxanol, diketo Organic compounds such as pyrrolopyrrole and aminium salts are also preferably exemplified. In addition, examples of the infrared absorbing dye include metal oxides such as IT0 (Indium Tin Oxide), AZ0 (Aluminium doped zinc oxide), tungsten oxide, antimony oxide, and cesium tungsten.

  A micro lens 48 is provided on the color filter 42, that is, on the side of the color filter 42 opposite to the sensor body 40.

The microlens 48 is provided corresponding to each of the red filter 42R, the green filter 42G, the blue filter 42B, and the infrared filter 42IR of the color filter 42, that is, corresponding to each of the solid-state imaging device 40a.
The micro lens 48 is a convex lens whose center is formed thicker than the edge, and condenses light on the solid-state imaging device 40a. All the microlenses 48 have the same shape.

  Such a microlens 48 can be formed of various known materials as long as they satisfy the optical characteristics necessary for the lens. The microlens 48 is formed of a resin material as an example, but is not limited thereto. Examples of the resin material used for the microlens 48 include styrene resin, (meth) acrylic resin, styrene-acrylic copolymer resin, and siloxane resin.

The planarization layer 50 planarizes the surface on the reflective circularly polarizing plate 16 (first alignment film 14) side on the microlens 48 that is a convex lens. The planarization layer 50 may also serve as a bonding layer for bonding the upper layer (first alignment film 14 in the illustrated example) and the planarization layer 50 together.
The flattening layer 50 only needs to have sufficient light transmittance, and is formed of, for example, various resin materials. Examples of the resin material forming the planarizing layer 50 include fluorine-containing silane compounds such as fluorine-containing siloxane resins, (meth) acrylic resins, styrene resins, and epoxy resins.

  Note that the microlens 48 and the planarization layer 50 preferably have a refractive index of the microlens 48 larger than that of the planarization layer.

A reflective circularly polarizing plate 16 is provided on the planarizing layer 50, that is, the sensor array 12 via the first alignment film 14. In the following description, “reflection-type circularly polarizing plate 16” is also simply referred to as “circularly polarizing plate 16”.
The circularly polarizing plate 16 is formed by fixing a cholesteric liquid crystal phase. Therefore, the circularly polarizing plate has wavelength selective reflectivity. In the polarization image sensor 10 of the illustrated example, the circularly polarizing plate 16 has a specific wavelength (850 nm in the illustrated example) in the near infrared, as conceptually shown in the second stage (circularly polarizing plate 16) from the top of FIG. Reflects right-hand circularly polarized light in the wavelength region of ± 50 nm and transmits other light.

As described above, the circularly polarizing plate 16 is a layer formed by fixing a cholesteric liquid crystal phase. The cholesteric liquid crystal phase has wavelength selective reflectivity that exhibits selective reflectivity at a specific wavelength.
The central wavelength λ of selective reflection of the cholesteric liquid crystal phase depends on the pitch P (= helical period) of the helical structure in the cholesteric liquid crystal phase, and follows the relationship between the average refractive index n of the cholesteric liquid crystal phase and λ = n × P. Therefore, the selective reflection wavelength can be adjusted by adjusting the pitch of the spiral structure. Since the pitch of the cholesteric liquid crystal phase depends on the kind of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these.
Further, the half width Δλ (nm) of the selective reflection band (circular polarization reflection band) indicating selective reflection depends on Δn of the cholesteric liquid crystal phase and the pitch P of the helix, and follows the relationship of Δλ = Δn × P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by the type of liquid crystal compound forming the circularly polarizing plate 16 and its mixing ratio, and the temperature at which the orientation is fixed.
For the measurement of spiral sense and pitch, it is possible to use the method described in “Introduction to Liquid Crystal Chemistry Experiments”, edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editorial Committee Maruzen 196 pages. it can.

The reflected light of the cholesteric liquid crystal phase is circularly polarized. Whether the reflected light is right-handed circularly polarized light or left-handed circularly polarized light depends on the twist direction of the spiral in the cholesteric liquid crystal phase. The selective reflection of circularly polarized light by the cholesteric liquid crystal phase reflects right circularly polarized light when the twist direction of the spiral of the cholesteric liquid crystal phase is right, and reflects left circularly polarized light when the twist direction of the spiral is left.
Accordingly, in the illustrated example, the circularly polarizing plate 16 is a layer formed by fixing a right-twisted cholesteric liquid crystal phase. The direction of rotation of the cholesteric liquid crystal phase, that is, the circularly polarized light reflected by the circularly polarizing plate 16 can be adjusted by the type of liquid crystal compound forming the cholesteric liquid crystal phase or the type of chiral agent added.
Further, the circularly polarizing plate 16 may reflect left circularly polarized light instead of reflecting right circularly polarized light.

The circularly polarizing plate 16 may be composed of a single layer or a multilayer structure.
Widening the wavelength range of reflected light, that is, the wavelength range of light to be blocked, can be realized by sequentially laminating layers with shifted center wavelengths λ of selective reflection. Also known is a technique for expanding the wavelength range by a method of stepwise changing the helical pitch in the layer called the pitch gradient method, specifically, Nature 378, 467-469 (1995), Examples include the methods described in Japanese Patent No. 281814 and Japanese Patent No. 4990426.

The circularly polarizing plate 16 formed by fixing the cholesteric liquid crystal phase may be formed by the following method as an example.
The same applies to the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l of the cholesteric reflective layer 30 constituting the bandpass filter 24 described later in terms of a layer formed by fixing the cholesteric liquid crystal phase. Therefore, by replacing the circularly polarizing plate 16 in the following description with the right circularly polarized cholesteric layer 30r or the left circularly polarized cholesteric layer 301, the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l can be formed in the same manner.

The structure in which the cholesteric liquid crystal phase is fixed may be a structure in which the alignment of the liquid crystal compound that is the cholesteric liquid crystal phase is maintained. Typically, the polymerizable liquid crystal compound is in an alignment state of the cholesteric liquid crystal phase. Thus, any structure may be used as long as it is polymerized and cured by ultraviolet irradiation, heating, or the like to form a layer having no fluidity, and at the same time, the orientation state is not changed by an external field or an external force.
In the structure in which the cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained, and the liquid crystal compound may not exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may have a high molecular weight by a curing reaction and lose liquid crystallinity.

As an example of a material used for forming a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, a liquid crystal composition containing a liquid crystal compound can be given. The liquid crystal compound is preferably a polymerizable liquid crystal compound.
The liquid crystal composition containing the liquid crystal compound used for forming the cholesteric liquid crystal layer preferably further contains a surfactant. The liquid crystal composition used for forming the cholesteric liquid crystal layer may further contain a chiral agent and a polymerization initiator.

  In particular, the liquid crystal composition forming the circularly polarizing plate 16 that reflects right-handed circularly polarized light is preferably a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a chiral agent that induces right-handed twist, or a polymerization initiator.

--Polymerizable liquid crystal compound--
The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a disk-like liquid crystal compound, but is preferably a rod-like liquid crystal compound.
Examples of the rod-like polymerizable liquid crystal compound that forms the cholesteric liquid crystal phase include a rod-like nematic liquid crystal compound. Examples of rod-like nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used.

  The polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into the liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and more preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081 and JP-A 2001-328773, and the like. Two or more kinds of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used in combination, the alignment temperature can be lowered.

  Specific examples of the polymerizable liquid crystal compound include compounds represented by the following formulas (1) to (14).

[In the compound (11), X ¹ is 2 to 5 (integer)]

  Further, as the polymerizable liquid crystal compound other than the above, a cyclic organopolysiloxane compound having a cholesteric liquid crystal phase as disclosed in JP-A-57-165480 can be used. Further, the above-mentioned polymer liquid crystal compound includes a polymer in which a mesogenic group exhibiting liquid crystal is introduced into the main chain, a side chain, or both positions of the main chain and the side chain, and a polymer cholesteric in which a cholesteryl group is introduced into the side chain. A liquid crystal, a liquid crystalline polymer as disclosed in JP-A-9-133810, a liquid crystalline polymer as disclosed in JP-A-11-293252, or the like can be used.

  Moreover, it is preferable that the addition amount of the polymeric liquid crystal compound in a liquid-crystal composition is 75-99.9 mass% with respect to solid content mass (mass except a solvent) of a liquid-crystal composition, and 80-99. It is more preferable that it is mass%, and it is still more preferable that it is 85-90 mass%.

--Chiral agent (optically active compound)-
The chiral agent has a function of inducing a helical structure of a cholesteric liquid crystal phase. The chiral agent may be selected according to the purpose because the twist direction or the spiral pitch of the spiral induced by the compound is different.
That is, when forming the circularly polarizing plate 16, a chiral agent that induces right twist is used.

The chiral agent is not particularly limited, and is a known compound (for example, liquid crystal device handbook, Chapter 3-4, chiral agent for TN (twisted nematic), STN (Super Twisted Nematic), 199 pages, Japan Science Foundation) 142), 1989), isosorbide and isomannide derivatives can be used.
A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, they are derived from the repeating unit derived from the polymerizable liquid crystal compound and the chiral agent by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. A polymer having repeating units can be formed. In this embodiment, the polymerizable group possessed by the polymerizable chiral agent is preferably the same group as the polymerizable group possessed by the polymerizable liquid crystal compound. Accordingly, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Further preferred.
The chiral agent may be a liquid crystal compound.

  It is preferable that the chiral agent has a photoisomerizable group because a pattern having a desired reflection wavelength corresponding to the emission wavelength can be formed by irradiation with a photomask such as actinic rays after coating and orientation. As the photoisomerization group, an isomerization site of a compound exhibiting photochromic properties, an azo group, an azoxy group, or a cinnamoyl group is preferable. Specific examples of the compound include JP 2002-80478, JP 2002-80851, JP 2002-179668, JP 2002-179669, JP 2002-179670, and JP 2002-2002. Use the compounds described in JP-A No. 179681, JP-A No. 2002-179682, JP-A No. 2002-338575, JP-A No. 2002-338668, JP-A No. 2003-313189, and JP-A No. 2003-313292. Can do.

  The content of the chiral agent in the liquid crystal composition is preferably from 0.01 to 200 mol%, more preferably from 1 to 30 mol%, based on the amount of the polymerizable liquid crystal compound.

--Polymerization initiator--
When the liquid crystal composition contains a polymerizable compound, the liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator that can start the polymerization reaction by ultraviolet irradiation. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850), oxadiazole compounds (US Pat. No. 4,221,970), and the like. .
The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 12% by mass with respect to the content of the polymerizable liquid crystal compound. .

-Crosslinking agent-
The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and improve the durability. As the cross-linking agent, one that can be cured by ultraviolet rays, heat, moisture, or the like can be suitably used.
There is no restriction | limiting in particular as a crosslinking agent, According to the objective, it can select suitably, For example, polyfunctional acrylate compounds, such as a trimethylol propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; Glycidyl (meth) acrylate , Epoxy compounds such as ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; hexa Isocyanate compounds such as methylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylto Alkoxysilane compounds such as methoxy silane. Moreover, a well-known catalyst can be used according to the reactivity of a crosslinking agent, and productivity can be improved in addition to membrane strength and durability improvement. These may be used individually by 1 type and may use 2 or more types together.
3-20 mass% is preferable with respect to solid content mass of a liquid crystal composition, and, as for content of a crosslinking agent, 5-15 mass% is more preferable. If content of a crosslinking agent is in the said range, the effect of a crosslinking density improvement will be easy to be acquired, and stability of a cholesteric liquid crystal phase will improve more.

The liquid crystal composition is preferably used as a liquid when forming a cholesteric liquid crystal layer.
The liquid crystal composition may contain a solvent. There is no restriction | limiting in particular as a solvent, Although it can select suitably according to the objective, An organic solvent is used preferably.
The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone, alkyl halides, amides, sulfoxides, hetero Examples thereof include ring compounds, hydrocarbons, esters, ethers and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, ketones are preferable in consideration of environmental load. The above-described components such as the above-mentioned monofunctional polymerizable monomer may function as a solvent.

As an example, the circularly polarizing plate 16 is applied to the first alignment film 14 with a liquid crystal composition for forming the circularly polarizing plate 16 including a polymerizable liquid crystal compound, a chiral agent that induces right twist, and a polymerization initiator. Then, the cholesteric liquid crystal phase having the right circular polarization reflection characteristic by heating may be formed by fixing the cholesteric liquid crystal phase by ultraviolet irradiation (ultraviolet exposure).
Note that the application, drying, and ultraviolet irradiation of the liquid crystal composition may all be performed by known methods.

As described above, the first alignment film 14 is provided between the sensor array 12 (flattening layer 50) and the circularly polarizing plate 16.
The first alignment film 14 is a layer for maintaining the orientation of the cholesteric liquid crystal phase in the circularly polarizing plate 16 formed by fixing the cholesteric liquid crystal phase.

As the first alignment film 14, various known materials used as alignment films for cholesteric liquid crystal layers can be used.
Preferably, the first alignment film 14 is a photo-alignment film. As an example, the photo-alignment film generates anisotropy on the surface of the photo-alignment film by irradiating linearly polarized light or oblique non-polarized light with a wavelength causing a photochemical reaction to photoactive molecules such as azobenzene polymer and polyvinyl cinnamate. Thus, the alignment of the molecular long axis on the outermost surface of the film is generated by incident light, and the alignment regulating force for aligning the liquid crystal in contact with the outermost surface molecule is formed.
In addition to the above-mentioned materials, the photo-alignment film is made of photoisomerization, photodimerization, photocyclization, photocrosslinking, photolysis, and photolysis by irradiation with linearly polarized light having a wavelength that causes photochemical reaction of photoactive molecules. -Any bond may be used as long as it generates anisotropy on the film surface by any reaction. For example, "Hasegawa Masaki, Journal of Japanese Liquid Crystal Society, Vol.3 No.1, p3 (1999)", " Various photo-alignment film materials described in Yasumasa Takeuchi, Journal of the Japanese Liquid Crystal Society, Vol. 3 No. 4, p262 (1999), etc. can be used.

  As an example, such a first alignment film 14 forms a photo-alignment film on the surface of the sensor array 12 (planarization layer 50), and irradiates the photo-alignment film with linearly polarized light to impart alignment regulating force. Therefore, it may be formed.

On the (reflection type) circularly polarizing plate 16, a pattern λ / 4 plate 20 is provided via a second alignment film 18. That is, in the polarization image sensor 10 of the present invention, the circularly polarizing plate 16 is disposed between the sensor array 12 and the pattern λ / 4 plate 20.
The pattern λ / 4 plate 20 is a λ / 4 plate (λ / 4 phase difference plate) and corresponds to one pixel or a plurality of pixels of the solid-state imaging device 40a of the sensor array 12 (sensor body 40) in the same plane. Thus, two or more types of regions that are divided into a plurality of regions and have the same phase difference and different slow axis directions are included.

In the illustrated example, since the circularly polarizing plate 16 is used as the reflective polarizing plate, the pattern λ / 4 plate 20 (pattern (2n + 1) / 4λ plate) is used as the pattern retardation plate. However, the present invention is not limited to this, and various configurations can be used.
As an example, a configuration in which a reflective linear polarizing plate is used as the reflective polarizing plate and a pattern λ / 2 plate (pattern (2n + 1) / 2λ plate) is used as the pattern retardation plate is exemplified. Various known reflective linear polarizing plates can be used. As the pattern λ / 2 plate, a known pattern λ / 2 plate or a pattern λ / 4 plate that conforms to the pattern λ / 4 plate 20 can be used.

As described above, any one of the red filter 42R, the green filter 42G, the blue filter 42B, and the infrared filter 42IR of the color filter 42 is provided corresponding to one solid-state imaging device 40a.
In the illustrated polarization image sensor 10, as conceptually shown in FIGS. 1 and 4, a red filter 42R, a green filter 42G, and a blue filter are associated with each of the 2 × 2 four solid-state imaging devices 40a. One of the four types of filters, 42B and infrared filter 42IR, is provided one by one.
As conceptually shown in FIGS. 1 and 4, the pattern λ / 4 plate 20 is divided in accordance with the areas corresponding to the four 2 × 2 solid-state imaging devices 40a provided with the four types of filters. Has been.

As described above, the polarization image sensor 10 includes 4 × 4 = 16 solid-state imaging devices 40a, and constitutes one pixel in the polarization image sensor 10. Accordingly, in the polarization image sensor 10, one pixel in the polarization image sensor 10 is formed by four 2 × 2 regions 20 a to 20 d in the pattern λ / 4 plate 20 conceptually shown in FIG. 4.
The regions 20a to 20d have the same phase difference and different directions of the slow axis. 1 and 4 and FIGS. 5 to 7 described later, the arrows of the regions 20a to 20d of the pattern λ / 4 plate 20 (20A) indicate the direction of the slow axis in each region.
Specifically, assuming that the two-dimensional arrangement direction of the solid-state imaging devices 40a in the sensor array 12 (sensor body 40) is the x direction and the y direction orthogonal to the x direction, the slow axis of the region 20a is the x direction. The slow axis in the region 20b has an angle of 45 ° with respect to the x direction, the slow axis in the region 20c has an angle of 90 ° with respect to the x direction, and in the region 20d The slow axis has an angle of 135 ° (−45 °) with respect to the x direction.
The present invention has such a pattern λ / 4 plate 20 and the circularly polarizing plate 16 described above, so that the amount of visible light is reduced, that is, the sensitivity of visible light is reduced, and near infrared light in a predetermined wavelength region is used. The polarization of the light carrying the information to be photographed can be detected. This will be described in detail later.

As described above, the pattern λ / 4 plate 20 is a λ / 4 plate. A λ / 4 plate (a plate having a λ / 4 function) is a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). More specifically, the plate has an in-plane retardation value of Re (λ) = λ / 4 (or an odd multiple thereof) at a predetermined wavelength λnm. This expression only needs to be achieved at any wavelength in the near infrared (for example, 850 nm).
In each region of the pattern λ / 4 plate 20, the in-plane retardation Re (850) having a wavelength of 850 nm is not particularly limited, but is preferably 200 to 225 nm, more preferably 205 to 220 nm, and still more preferably 210 to 215 nm.
When the pattern λ / 4 plate 20 is formed of a plurality of layers including a support or the like, the entire pattern λ / 4 plate 20 including all layers shows the range of this in-plane retardation. Is preferred.

Examples of a method for forming the pattern λ / 4 plate 20 (patterned optically anisotropic layer) containing a liquid crystal compound include a method of fixing the liquid crystal compound in an aligned state. In this case, as a method for immobilizing the liquid crystal compound, a method of polymerizing and immobilizing a polymerizable liquid crystal compound having an unsaturated double bond (polymerizable group) as the liquid crystal compound is preferably exemplified. . For example, a composition for forming the pattern λ / 4 plate 20 containing a liquid crystal compound having an unsaturated double bond (polymerizable group) is applied to the forming surface directly or through an alignment film, and cured by irradiation with ionizing radiation. (Polymerization) to fix the liquid crystal compound. The pattern λ / 4 plate 20 may have a single layer structure or a laminated structure.
The kind of the unsaturated double bond contained in the liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, etc. are mentioned preferably, and a (meth) acryloyl group is more preferable.

In general, liquid crystal compounds can be classified into a rod-shaped type and a disk-shaped type based on their shapes. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used. Two or more kinds of rod-like liquid crystal compounds, two or more kinds of disk-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disk-like liquid crystal compound may be used. In order to fix the liquid crystal compound described above, the pattern λ / 4 plate 20 is preferably formed using a rod-like liquid crystal compound or a discotic liquid crystal compound having a polymerizable group. The liquid crystal compound preferably has two or more polymerizable groups in one molecule. When the liquid crystal compound is a mixture of two or more, it is preferable that at least one liquid crystal compound has two or more polymerizable groups in one molecule.
As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-T-11-53019 and paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. As the liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 can be preferably used. However, it is not limited to these.

In order to make the in-plane retardation in the pattern λ / 4 plate 20 within the above range, the alignment state of the liquid crystal compound may be controlled. At this time, when using a rod-like liquid crystal compound, it is preferable to fix the rod-like liquid crystal compound in a horizontally aligned state. When using a discotic liquid crystal compound, the discotic liquid crystal compound is fixed in a vertically aligned state. It is preferable to do this. In the present invention, “the rod-like liquid crystal compound is horizontally aligned” means that the director of the rod-like liquid crystal compound and the layer surface are parallel, and “the discotic liquid crystal compound is vertically aligned” means that the discotic liquid crystal compound is circular. The board surface and the layer surface are perpendicular. It is not strictly required to be horizontal or vertical, but each means a range of ± 20 ° from an accurate angle. It is preferably within ± 5 °, more preferably within ± 3 °, even more preferably within ± 2 °, and most preferably within ± 1 °.
Moreover, in order to make a liquid crystal compound into a horizontal alignment and a vertical alignment state, you may use the additive (alignment control agent) which accelerates a horizontal alignment and a vertical alignment. Various known additives can be used as the additive.

Examples of the method of forming the pattern λ / 4 plate 20 include the following preferred embodiments, but the present invention is not limited to these, and various known methods can be used.
The first preferred embodiment uses a plurality of actions for controlling the alignment of the liquid crystal compound, and then eliminates any action by an external stimulus (such as heat treatment) to make the predetermined alignment control action dominant. It is. As the above method, for example, the liquid crystal compound is brought into a predetermined alignment state by a combined action of the alignment control ability by the alignment film and the alignment control ability of the alignment controller added to the liquid crystal compound, and then fixed. After one phase difference region is formed, one of the actions (for example, the action by the alignment control agent) disappears by external stimulus (heat treatment, etc.), and the other orientation control action (the action by the alignment film) becomes dominant. , Thereby realizing another alignment state and fixing it to form the other retardation region. Details of this method are described in paragraphs [0017] to [0029] of JP 2012-008170 A, the contents of which are incorporated herein by reference.

  A 2nd suitable aspect is an aspect using a pattern orientation film. In this embodiment, pattern alignment films having different alignment control capabilities are formed, a liquid crystal compound is disposed thereon, and the liquid crystal compound is aligned. The liquid crystal compounds achieve different alignment states depending on the alignment control ability of the pattern alignment film. By fixing the respective alignment states, the slow axis of each region of the pattern λ / 4 plate 20 is formed according to the pattern of the alignment film. The pattern alignment film can be formed by using a printing method, mask rubbing with respect to the rubbing alignment film, a method of performing linearly polarized mask exposure on the photo alignment film, or the like. From the viewpoint that large-scale equipment is unnecessary and easy manufacture, a method of performing mask exposure on the photo-alignment film and a method of using a printing method are preferable. Details of this method are described in paragraphs [0166] to [0181] of JP2012-032661, and the contents thereof are incorporated herein by reference.

  As a third preferred embodiment, for example, a photoacid generator is added to the alignment film. In this example, a photoacid generator is added to the alignment film, and pattern exposure exposes a region where the photoacid generator is decomposed to generate an acidic compound and a region where no acid compound is generated. In the light unirradiated part, the photoacid generator remains almost undecomposed, and the interaction between the alignment film material, the liquid crystal compound, and the alignment control agent added as necessary dominates the alignment state, The slow axis is oriented in a direction perpendicular to the rubbing direction. When the alignment film is irradiated with light and an acidic compound is generated, the interaction is no longer dominant, the rubbing direction of the rubbing alignment film controls the alignment state, and the liquid crystal compound has its slow axis parallel to the rubbing direction. To parallel orientation. As the photoacid generator used in the alignment film, a water-soluble compound is preferably used. Examples of photoacid generators that can be used include Prog. Polym. Sci. 23, page 1485 (1998). As the photoacid generator, pyridinium salts, iodonium salts and sulfonium salts are particularly preferably used. Details of this method are described in Japanese Patent Application No. 2010-289360, the contents of which are incorporated herein by reference.

As described above, the second alignment film 18 is disposed between the pattern λ / 4 plate 20 and the circularly polarizing plate 16.
The second alignment film 18 corresponds to the pattern alignment film exemplified in the second preferred embodiment of the method for forming the pattern λ / 4 plate 20 (patterned optically anisotropic layer) described above.

The alignment film generally contains a polymer as a main component. The polymer material for alignment film is described in many documents, and many commercially available products can be obtained. The polymer material used is preferably polyvinyl alcohol or polyimide, and derivatives thereof. In particular, modified or unmodified polyvinyl alcohol is preferred. For the alignment film that can be used in the present invention, refer to the modified polyvinyl alcohol described in WO01 / 88574A1, page 43, line 24 to page 49, line 8, and patent No. 3907735, paragraphs [0071] to [0095]. be able to. The alignment film is usually subjected to a known rubbing treatment. That is, the alignment film is usually preferably a rubbing alignment film that has been rubbed.
As described above, the pattern alignment film, that is, the second alignment film 18 is preferably a photo-alignment film. Although it does not specifically limit as a photo-alignment film | membrane, The thing as described in Paragraphs [0024]-[0043] of WO2005 / 096041 and the brand name LPP-JP265CP by Rolitechnologies can be used.

As described above, the second alignment film 18 (pattern alignment film) using the photo-alignment film is formed by, for example, a method in which linearly polarized light is mask-exposed on the photo-alignment film.
First, a composition for forming the second alignment film 18 is applied to the formation surface of the second alignment film 18 (the surface of the circularly polarizing plate 16) by a known method such as spin coating, dried, and photo-aligned. A film is formed.

Then, all the regions corresponding to the regions 20b to 20d other than the region 20a of the pattern λ / 4 plate 20 are masked with a pattern photomask or the like, and a linear polarizing plate such as a wire grid polarizing plate is set to a transmission axis x. Arrange them in the same direction. Thereafter, light for aligning the photo-alignment film, for example, ultraviolet light is irradiated to the photo-alignment film through the linear polarizing plate. By this ultraviolet light irradiation, the region corresponding to the region 20a of the photo-alignment film is aligned in the x direction.
Next, the regions corresponding to the regions 20a, 20c, and 20d other than the region 20b are all masked, and the linearly polarizing plate is disposed with the transmission axis at 45 ° with respect to the x direction. Thereafter, similarly, the photo-alignment film is irradiated with ultraviolet light through a linear polarizing plate. Thereby, the region 20b of the photo-alignment film is aligned at an angle of 45 ° with respect to the x direction.
Next, all regions corresponding to the regions 20a, 20b and 20d other than the region 20c are masked, and the linearly polarizing plate is disposed with the transmission axis at 90 ° with respect to the x direction. Thereafter, similarly, the photo-alignment film is irradiated with ultraviolet light through a linear polarizing plate. Thereby, the region 20c of the photo-alignment film is aligned at an angle of 90 ° with respect to the x direction.
Further, all the regions corresponding to the regions 20a to 20c other than the region 20d are masked, and the linearly polarizing plate is disposed with the transmission axis being 135 ° (−45 °) with respect to the x direction. Thereafter, similarly, the photo-alignment film is irradiated with ultraviolet light through a linear polarizing plate. Thereby, the region 20d of the photo-alignment film is aligned at an angle of 135 ° with respect to the x direction.

  After forming the second alignment film 18 obtained by aligning the photo-alignment film in this manner, the pattern λ / 4 plate 20 is formed on the second alignment film 18 as described above, thereby forming the same in-plane. , The pattern λ / 4 plate 20 having the same phase difference in each of the regions 20a to 20d and different slow axis directions can be formed.

  Note that, when the pattern λ / 4 plate 20 is formed on the second alignment film 18 or the like, patterning with a size of several μm is required, but an exposure light source for that purpose is represented by an i-line stepper or the like. The use of an optically controlled exposure apparatus is preferred, and a polarized light irradiation stepper capable of irradiating linearly polarized light controlled in a specific direction is most preferred.

In the present invention, the pattern λ / 4 plate 20 is not limited to being formed of four regions having different slow axis directions. That is, one pixel of the polarization image sensor 10 is not limited to being formed of four regions having different slow axis directions.
For example, the pattern λ / 4 plate may be formed of two regions or three regions having different slow axis directions, and the pattern λ / 4 plate may be formed of five regions having different slow axis directions. You may form in the above area | region.
Furthermore, in the illustrated example, one region of the pattern λ / 4 plate 20 corresponds to the four solid-state imaging devices 40a of the sensor array 12 (sensor body 40), but the present invention is not limited to this. That is, one area of the pattern λ / 4 plate 20 may correspond to 1 to 3 solid-state image sensors 40 a of the sensor array 12, or five or more solid-state image sensors of the sensor array 12. It may correspond to 40a.

A band pass filter 24 is disposed on the pattern λ / 4 plate 20.
The bandpass filter 24 includes a cholesteric reflection layer 30 and a near infrared filter 34. Further, the cholesteric reflective layer 30 includes a right circularly polarized cholesteric layer 30r and a left circularly polarized cholesteric layer 30l.

Both the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l constituting the cholesteric reflective layer 30 are formed by fixing the cholesteric liquid crystal phase and having wavelength selective reflectivity, like the circularly polarizing plate 16. . In the illustrated example, the right circularly polarized cholesteric layer 30r reflects right circularly polarized light in a wavelength region of 900 to 1200 nm in the near infrared and transmits other light. The left circularly polarized cholesteric layer 301 reflects the left circularly polarized light in the wavelength region of 900 to 1200 nm in the near infrared and transmits other light. Therefore, all the circularly polarized light in the wavelength region of 900 to 1200 nm is reflected by the cholesteric reflective layer 30.
On the other hand, the near-infrared filter 34 absorbs or reflects and blocks light in the near-infrared wavelength region of more than 700 nm and not more than 800 nm.
Therefore, as shown in the upper part of FIG. 3 (BPF 24), the bandpass filter 24 transmits visible light of 700 nm or less and light in a wavelength region of more than 800 nm and less than 900 nm in the near infrared.

As described above, both the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l are layers formed by fixing a cholesteric liquid crystal phase.
As described above, the cholesteric liquid crystal phase has wavelength selective reflectivity that exhibits selective reflectivity at a specific wavelength. The central wavelength λ of selective reflection of the cholesteric liquid crystal phase depends on the pitch P of the helical structure in the cholesteric liquid crystal phase, and the half width Δλ (nm) of the selective reflection band (circular polarization reflection band) showing selective reflection is the cholesteric liquid crystal phase. As described above, it depends on Δn and helix pitch P.
The right circularly polarized cholesteric layer 30r is a layer formed by fixing a right twisted cholesteric liquid crystal phase, and the left circularly polarized cholesteric layer 30l is a layer formed by fixing a left twisted cholesteric liquid crystal phase.

As described above, the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l can be formed in the same manner as the circularly polarizing plate 16.
Therefore, the right circularly polarized cholesteric layer 30r is prepared by preparing a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a chiral agent that induces right twist, and a polymerization initiator. If the liquid crystal composition is applied to the formation surface of the layer 30r and heated to form a cholesteric liquid crystal phase having a right circularly polarized light reflection property, and further, the cholesteric liquid crystal phase is fixed by irradiation with ultraviolet rays. Good.
The left circularly polarized cholesteric layer 30l is prepared by preparing a polymerizable liquid crystal composition including a polymerizable liquid crystal compound, a chiral agent that induces left twist, and a polymerization initiator. If the liquid crystal composition is applied to the formation surface of the layer 30l and heated to make the liquid crystal composition a cholesteric liquid crystal phase having left-circular polarization reflection characteristics, and further, the cholesteric liquid crystal phase is fixed by irradiation with ultraviolet rays. Good.

As with the circularly polarizing plate 16, the right circularly polarized cholesteric layer 30r and / or the left circularly polarized cholesteric layer 30l may be composed of a single layer or a multilayer structure.
The order of forming the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l may be reversed. That is, the cholesteric reflective layer 30 may have a configuration in which the left circularly polarized cholesteric layer 30l is provided on the lower sensor array 12 side and the right circularly polarized cholesteric layer 30r is disposed on the left circularly polarized cholesteric layer 30l.

As described above, the near-infrared filter 34 absorbs or reflects light in the near-infrared wavelength region of more than 700 nm and not more than 800 nm to block it.
Such a near-infrared filter 34 is the same as the above-described infrared blocking layer 46 except that the wavelength region to be blocked is different.

As described above, in the polarization image sensor 10, the transmission region of the bandpass filter 24 is designed so as to transmit light in the wavelength region reflected by the circularly polarizing plate 16 and in the visible light region. It is necessary to design the wavelength band reflected by the circularly polarizing plate 16 that is transmitted through the bandpass filter 24 to be blocked by the infrared blocking layer 46.
The band pass filter 24 is designed so as to block infrared rays longer than the reflection wavelength region by the circularly polarizing plate 16. In the illustrated example, this region is reflected and blocked by the cholesteric reflective layer 30.
In addition, the absorption region by the color filter 42 in the light in the visible region is designed to be a transmission region of the bandpass filter 24.
Further, the wavelength region between the reflection wavelength region by the circularly polarizing plate 16 and the absorption wavelength region by the color filter 42 is designed to be blocked by the band pass filter 24. In the illustrated example, this region is blocked by the near infrared filter 34.
Thereby, as shown in the lower part of FIG. 3, the final spectrum of blue light, green light, red light, and infrared light can be obtained.

In the illustrated example, the bandpass filter 24 includes a cholesteric reflective layer using cholesteric liquid crystal and a near-infrared filter 34 using an infrared absorbing dye, but the present invention is not limited to this. The band pass filter 24 may be configured using a laminated film in which films made of an inorganic compound are laminated.
That is, the band-pass filter 24 can use various known configurations as long as it can transmit light in a plurality of target wavelength regions.
As an example, a configuration in which a wavelength region of more than 700 nm and not more than 800 nm is absorbed by a dye layer, and a wavelength region of 900 to 1200 nm is reflected by a dielectric multilayer film,
A structure in which a wavelength region of 700 nm to 800 nm is absorbed and reflected by a dye layer and a cholesteric liquid crystal layer, and a wavelength region of 900 to 1200 nm is reflected by a cholesteric liquid crystal layer;
A configuration in which a wavelength region of more than 700 nm and not more than 800 nm is reflected by a cholesteric liquid crystal layer, and a wavelength region of 900 to 1200 nm is also reflected by a cholesteric liquid crystal layer, and
Examples include a configuration in which a wavelength region of more than 700 nm and not more than 800 nm is reflected by the dielectric multilayer film, and a wavelength region of 900 to 1200 nm is also reflected by the dielectric multilayer film.

  Hereinafter, the polarization image sensor of the present invention will be described in more detail by describing the operation of the polarization image sensor 10.

When light carrying information to be measured, such as light reflected by a measurement target (observation target), enters the polarization image sensor 10, first, the near-infrared filter 34 of the bandpass filter 24 firstly exceeds 700 nm to 800 nm in the near infrared. Is absorbed or reflected and blocked by the left circularly polarized cholesteric layer 30l, and the left circularly polarized light in the 900 to 1200 nm wavelength region is reflected, and the right circularly polarized cholesteric layer 30r reflects the 900 to 1200 nm wavelength region. The right circularly polarized light is reflected.
As a result, the light transmitted through the bandpass filter 24 is visible light of 700 nm or less and near infrared light in a wavelength region of more than 800 nm and less than 900 nm, as shown in the uppermost part (BPF 24) of FIG.

The light transmitted through the bandpass filter 24 then enters the pattern λ / 4 plate 20.
Here, the light transmitted through the band-pass filter 24 has only linearly polarized light components inclined by ± 45 ° with respect to the slow axis in the incident regions 20a to 20d in the regions 20a to 20d of the pattern λ / 4 plate 20. It is converted into a corresponding circularly polarized component.

The light transmitted through the pattern λ / 4 plate 20 then passes through the second alignment film 18 and enters the circularly polarizing plate 16.
As described above, the circularly polarizing plate 16 reflects the right circularly polarized light in the wavelength region of 800 to 900 nm in the near infrared, as shown in the second stage (circularly polarizing plate 16) from the top of FIG. Transmits light.
Therefore, visible light, that is, red light, blue light, and green light are transmitted through the circularly polarizing plate 16 as they are.
On the other hand, the near-infrared ray in the wavelength region of more than 800 nm and less than 900 nm that has passed through the bandpass filter 24 is converted into a circularly polarized light component because the corresponding linearly polarized light component is converted into a circularly polarized light component by the pattern λ / 4 plate 20. Accordingly, the right circularly polarized light is reflected and only the left circularly polarized light is transmitted. That is, the amount of light transmitted through the circularly polarizing plate 16 changes according to the proportion of the linearly polarized light component incident on the pattern λ / 4 plate 20.

The light transmitted through the pattern λ / 4 plate 20 then passes through the first alignment film 14 and enters the sensor array 12. The light incident on the sensor array 12 is dimmed by the microlens 48 so as to be condensed on the corresponding solid-state imaging device 40a, and then incident on the color filter 42.
As shown in the third row (CF42) from the top in FIG. 3, among the color filters 42, the light incident on the red filter 42R is only red light and near infrared light, and the light incident on the green filter 42G is green light and near infrared light. Only blue light and near-infrared light pass through only the infrared light, and only near-infrared light passes through the infrared filter 42IR.

The light of each color and the near infrared rays that have passed through the red filter 42R, the green filter 42G, and the blue filter 42B are then incident on the infrared blocking layer 46, and the fourth stage (infrared blocking layer 46) from the top of FIG. As shown in the figure, infrared rays are absorbed or reflected to be blocked, and as shown in the lower part of FIG. 3 (final spectrum), they are incident on the corresponding solid-state imaging device 40a as red light, green light, and blue light, respectively. The light is measured and output as a visible light image signal (image information).
As described above, in the polarization image sensor 10, 4 × 4 = 16 pixels (16 solid-state imaging devices 40 a) corresponding to the four regions 20 a to 20 d of the pattern λ / 4 plate 20, and 1 of the polarization image sensor 10. Configure the pixel.
Therefore, the image signal of red light, green light and blue light is obtained by adding the signals of the four pixels of each color in one pixel to the image signal of each color in one pixel, or four signals of each color in one pixel. The average value of the pixel signals is used as an image signal of each color in this one pixel.

On the other hand, the light that has passed through the infrared filter 42IR is directly incident on the corresponding solid-state imaging device 40a and photometrically measured.
Here, as described above, the amount of light transmitted through the circularly polarizing plate 16 of the near infrared ray in the wavelength region of 800 to 900 nm changes according to the ratio of the linearly polarized component before entering the pattern λ / 4 plate 20. ing. Therefore, the intensity of near infrared light that passes through the infrared filter 42IR and enters the solid-state imaging device 40a varies in the regions 20a to 20d according to the ratio of the incident linearly polarized light component.

For example, as conceptually shown in FIG. 5, it is assumed that the linearly polarized light incident on the polarization image sensor 10 is the linearly polarized light L1 in the x direction. In this case, in the region 20a of the pattern λ / 4 plate 20, the direction of the linearly polarized light and the slow axis of the λ / 4 plate coincide with each other, so that the linearly polarized light is not converted. Accordingly, 50% of the light transmitted through the region 20a is reflected by the circularly polarizing plate 16, so that the intensity of near infrared light measured by the solid-state imaging device 40a after passing through the infrared filter 42IR is about half. At this time, the output of the solid-state imaging device 40a is set to 50 for convenience.
On the other hand, in the regions 20b and 20d of the pattern λ / 4 plate 20, the angle formed by the direction of linearly polarized light and the slow axis of the λ / 4 plate is 45 °, and the light passing through the region 20b becomes left circularly polarized light. The light passing through the region 20d becomes right circularly polarized light. Therefore, the output of the solid-state imaging device 40a by the light transmitted through the infrared filter 42IR is 100 in the region 20b and 0 in the region 20d.
Further, in the region 20c of the pattern λ / 4 plate 20, the direction of linearly polarized light and the slow axis of the λ / 4 plate are orthogonal, so that the linearly polarized light incident on the region 20c is not converted. For this reason, the output of the solid-state imaging device by the light transmitted through the infrared filter 42IR is 50 as in the region 20a.

Alternatively, as conceptually shown in FIG. 6, it is assumed that the linearly polarized light incident on the polarization image sensor 10 is a linearly polarized light L2 of 45 ° with respect to the x direction. In this case, the direction of linearly polarized light coincides with the slow axis of the λ / 4 plate in the region 20b of the pattern λ / 4 plate 20, so that the linearly polarized light transmitted through the region 20b is not converted. Accordingly, the output of the solid-state imaging device 40a by the light transmitted through the infrared filter 42IR is 50.
On the other hand, in the regions 20a and 20c of the pattern λ / 4 plate 20, the angle formed by the direction of linearly polarized light and the slow axis of the λ / 4 plate is 45 °, and the light passing through the region 20a becomes right circularly polarized light. The light passing through the region 20c becomes left circularly polarized light. Therefore, the output of the solid-state imaging device 40a by the light transmitted through the circularly polarizing plate 16 and transmitted through the infrared filter 42IR is 0 in the region 20a and 100 in the region 20c.
In the region 20d of the pattern λ / 4 plate 20, the direction of linearly polarized light and the slow axis of the λ / 4 plate are orthogonal to each other, so that linearly polarized light incident on the region 20c is not converted. Accordingly, the output of the solid-state imaging device 40a by the light transmitted through the infrared filter 42IR is 50.

As described above, in the polarization image sensor 10 in which one pixel is composed of 4 × 4 = 16 solid-state imaging devices 40a and regions 20a to 20d, solid-state imaging by light transmitted through the infrared filter 42IR in one pixel of the polarization image sensor 10 is performed. The output of the element 40a has a pattern corresponding to the state of polarized light incident on the polarization image sensor 10.
Therefore, by measuring in response to linearly polarized light in various states and analyzing and storing the output pattern, the light incident on one pixel of the polarization image sensor 10 has a linearly polarized light component in which direction. It can be judged whether it has. For example, by creating and storing a reference table indicating the relationship between the state of linearly polarized light and the output pattern of the solid-state imaging device 40a corresponding to the infrared filter 42IR in one pixel of the polarization image sensor 10, From the pattern of the output signal of the solid-state imaging device 40a corresponding to the infrared filter 42IR in the pixel, a reference table is used to detect in which direction the light incident on each pixel of the polarization image sensor 10 has a linearly polarized component. it can.
That is, according to the present invention, by using the pattern λ / 4 plate 20 having regions with different slow axis directions and the circularly polarizing plate 16 formed by fixing the cholesteric liquid crystal phase, red light, green light, and Without reducing the visible light of blue light, the polarization of light carrying the information to be measured can be detected by providing the near infrared with polarization information.

In addition, when the light which carries the information of measurement object, such as reflected light of a measurement object, does not contain polarization | polarized-light, the solid-state imaging which received the light which permeate | transmitted the infrared filter 42IR corresponding to each area | region 20a-20d The output of the element 40a becomes uniform.
In other words, if there is a significant difference in the output of the solid-state imaging device 40a that has received the light transmitted through the infrared filter 42IR, it can be determined that the light carrying the information to be measured contains polarized light.

  The detection result of polarized light is, for example, a color image of a measurement object read by measurement of red light, green light and blue light carrying information of the measurement object such as reflected light of the measurement object, depending on the state of polarization. Appropriately, the image may be expressed as an image by a method for imparting a set color tone, a method for imparting a hatching or a halftone dot that is appropriately set according to the state of polarization.

  As an example, such a polarization image sensor 10 forms a (polarization-type) circularly polarizing plate 16 that reflects the right circularly polarized light of near-infrared light and transmits other light on the light receiving surface side of the sensor array 12. Pattern λ / 4 having regions 20a to 20d having the same phase difference and different slow axis directions in the same plane, which is performed after the polarizing plate forming step and the circular polarizing plate 16 are formed. The plate 20 can be manufactured by a method including a λ / 4 plate forming step.

First, the infrared blocking layer 46 is formed corresponding to the solid-state imaging device 40a that measures the visible light of each pixel on the light incident surface of the sensor body 40. Next, as shown in FIGS. 1 and 4, a color filter 42 having a red filter 42R, a green filter 42G, a blue filter 42B, and an infrared filter 42IR is formed corresponding to each solid-state imaging device 40a of the sensor body 40. To do.
Next, a microlens 48 is formed on the color filter 42 corresponding to each color and infrared filter.
Further, the sensor array 12 is manufactured by forming the planarization layer 50 so as to planarize the surface by filling the irregularities formed by the microlenses 48.
The infrared blocking layer 46, each color or infrared filter, the microlens 48, and the planarizing layer 50 may be formed by a known method corresponding to the forming material.

Next, the first alignment film 14 is formed on the surface of the planarizing layer 50, that is, the formation surface of the circularly polarizing plate 16, and the circularly polarizing plate 16 is formed on the first alignment film 14.
The first alignment film 14 may be formed by a known method according to the forming material. The first alignment film 14 is preferably a photo-alignment film as described above. That is, the first alignment film 14 is formed by applying a composition to be the first alignment film 14 (photo-alignment film) to the planarization layer 50, that is, the formation surface of the circularly polarizing plate 16 by a known method such as spin coating. After drying, a process of forming a photo-alignment film (optical isomerization composition layer) is performed, and then linearly polarized light is irradiated to the photo-alignment film via a linear polarizing plate such as a wire grid polarizing plate, thereby controlling the alignment. It is preferable to form by performing a step of applying force.
Further, as described above, the circularly polarizing plate 16 is prepared by preparing a polymerizable liquid crystal composition containing the polymerizable liquid crystal compound to be the circularly polarizing plate 16, a chiral agent that induces right twist, and a polymerization initiator. The liquid crystal composition is applied to the first alignment film 14 by a known method such as spin coating, and then the liquid crystal composition is converted into a cholesteric liquid crystal phase having right circular polarization reflection characteristics by heating. Further, the circularly polarizing plate 16 is formed by fixing the cholesteric liquid crystal phase by irradiation with ultraviolet rays (polarizing plate forming step).

Next, the second alignment film 18 is formed on the surface of the circularly polarizing plate 16, that is, the formation surface of the pattern λ / 4 plate 20, and the pattern λ / 4 plate 20 is formed on the surface of the second alignment film 18.
The second alignment film 18 is formed by performing an alignment film forming process for forming a photo-alignment film and a regulating force applying process. In the alignment film forming step, as described above, a composition for forming the second alignment film 18 (photo-alignment film) is applied to the formation surface of the second alignment film 18 by a known method such as spin coating, It is a step of drying to form a photo-alignment film. Further, as described above, the regulating force imparting step is a step of masking the formed photo-alignment film with a pattern photomask or the like and irradiating the photo-alignment film with linearly polarized light through the linearly polarizing plate. In the illustrated example, the masking region of the photo-alignment film is changed according to the regions 20a to 20d of the pattern λ / 4 plate 20, and the direction of the transmission axis of the linearly polarizing plate is 0 ° with respect to the x direction. By changing to 45 °, 90 °, and 135 ° sequentially, and aligning the regions corresponding to the regions 20a to 20d of the photo-alignment film, the pattern λ / 4 plate 20 is delayed in different directions within the same plane. The orientation regulating force for forming the phase axis is applied.
As described above, the pattern λ / 4 plate 20 is prepared by preparing a coating liquid containing one or more polymerizable liquid crystals to be the pattern λ / 4 plate 20 and one or more polymerization initiators. By applying onto 18, the polymerizable liquid crystal compound is brought into an aligned state, and then the polymerizable liquid crystal compound is polymerized and fixed by irradiation of ultraviolet rays or the like (λ / 4 plate forming step).

Next, the right circularly polarized cholesteric layer 30r and the left circularly polarized cholesteric layer 30l are formed on the pattern λ / 4 plate 20 to form the cholesteric reflective layer 30, and the near infrared ray is further formed on the cholesteric reflective layer 30. The filter 34 is formed to produce the polarization image sensor 10.
As described above, the right circularly polarized cholesteric layer 30r is prepared by preparing a polymerizable liquid crystal composition including a polymerizable liquid crystal compound, a chiral agent that induces right twist, and a polymerization initiator. By applying to the formation surface of the circularly polarized cholesteric layer 30r and heating, the liquid crystal composition becomes a cholesteric liquid crystal phase having a right circularly polarized reflection property, and further, by fixing the cholesteric liquid crystal phase by irradiation with ultraviolet rays, Form.
The left circularly polarized cholesteric layer 30l is prepared by preparing a polymerizable liquid crystal composition including a polymerizable liquid crystal compound, a chiral agent that induces left twist, and a polymerization initiator. The liquid crystal composition is applied to the formation surface of the layer 30l and heated to change the liquid crystal composition into a cholesteric liquid crystal phase having left-circular polarization reflection characteristics, and further, the cholesteric liquid crystal phase is fixed by irradiation with ultraviolet rays.
Furthermore, the near-infrared filter 34 may be formed by a known method corresponding to the forming material, similarly to the infrared blocking layer 46.

In the polarization image sensor 10 shown in FIGS. 1 to 6, the pattern λ / 4 plate 20 is a λ / 4 plate in which all the regions 20a to 20d have in-plane retardation, but the present invention is not limited to this. Not done.
For example, like the pattern λ / 4 plate 20A conceptually shown in FIG. 7, the regions 20a to 20c have the same phase difference in the same plane and the slow axis similar to that of the pattern λ / 4 plate 20 described above. It is also possible to use a pattern λ / 4 plate having a configuration in which only the region 20d has no in-plane retardation, that is, isotropic.
Note that the term “having no in-plane retardation” means that the in-plane retardation is λ / 40 nm or less at a predetermined wavelength λ nm, and for example, the in-plane retardation Re (850) at a wavelength of 850 nm is 21.3 nm or less. It is preferable that

Such a region 20d of the pattern λ / 4 plate 20A is in a state similar to a blank blank. Therefore, the light incident on the region 20d passes through the pattern λ / 4 plate 20A as it is and enters the circularly polarizing plate 16.
Here, when the light carrying the information to be measured, such as the reflected light of the measurement object, has a circularly polarized component that is shifted to the left or right, the light is transmitted through the region 20d of the pattern λ / 4 plate 20A to be circularly polarized. Of the light incident on the plate 16, right-circularly polarized near-infrared light in the wavelength region of 800 to 900 nm is reflected and left-circularly polarized near-infrared light in the same wavelength region is transmitted. Thus, the amount of light transmitted through the circularly polarizing plate 16 changes.
That is, by measuring the light transmitted through the region 20d of the pattern λ / 4 plate 20A, it is possible to detect the circularly polarized information of the light carrying the information to be measured.

  Therefore, by using a pattern λ / 4 plate in which at least one region is open as in the pattern λ / 4 plate 20A, light carrying information on the measurement target such as reflected light of the measurement target. It is possible to detect not only linearly polarized information but also circularly polarized information.

  When the pattern λ / 4 plate has a region having no in-plane phase difference, for example, one pixel of the polarization image sensor is set at 45 ° in the direction of the slow axis similar to the pattern λ / 4 plate 20. You may form by five area | regions which consist of four different area | regions and one area | region which does not have an in-plane phase difference.

Such a pattern λ / 4 plate 20A in which one or more regions do not have an in-plane retardation can be formed by various methods. Examples of preferable methods include the following methods.
First, in the formation of the second alignment film 18 described above, a composition for forming the second alignment film 18 (photo-alignment film) is applied and dried to form the photo-alignment film (alignment film forming step). In the step of masking the formed photo-alignment film with a pattern photomask or the like and irradiating the photo-alignment film with linearly polarized light through the linearly polarizing plate (regulatory force applying step), the region corresponding to the region 20d is linearly polarized. A method of forming a region 20d having no in-plane retardation on the pattern λ / 4 plate 20A by not applying an alignment regulating force to this region of the photo-alignment film by not irradiating the film is exemplified.

  As another method, similarly, in the formation of the second alignment film 18, after forming the photo-alignment film, in the step of irradiating the photo-alignment film with linearly polarized light (regulatory force applying step), the region corresponding to the region 20d is formed. Is applied to the pattern λ / 4 plate 20A by irradiating non-polarized light to the region corresponding to the region 20d of the photo-alignment film to be the second alignment film 18 by applying an alignment regulating force to be vertically aligned. A method of partially forming the region 20d which is a region having no in-plane retardation is exemplified.

  As another method, in the formation of the pattern λ / 4 plate 20A (pattern λ / 4 plate forming step) after the formation of the second alignment film 18 as described above, the second is given an alignment regulating force. On the alignment film 18 (photo-alignment film), as described above, a coating liquid containing one or more polymerizable liquid crystal compounds and one or more polymerization initiators to be a pattern λ / 4 plate is applied and polymerized. After aligning the polymerizable liquid crystal compound, the polymerizable liquid crystal compound in the regions 20a to 20c is partially polymerized by irradiating light with which the polymerization initiator reacts through a photomask that shields the portion corresponding to the region 20d. Then, the uncured region 20d shielded from light by the photomask is heated to an isotropic phase, and then the region 20d is irradiated with light that reacts with the polymerization initiator. Polymerizing and fixing polymerizable liquid crystal compounds Step by performing a method of forming a region 20d having no in-plane phase difference pattern lambda / 4 plate 20A is illustrated.

  Furthermore, as another method, the second alignment film is given the alignment regulating force in the formation of the pattern λ / 4 plate 20A (pattern λ / 4 plate forming step) after the second alignment film 18 is formed as described above. On the alignment film 18 (photo-alignment film), as described above, a coating liquid containing one or more polymerizable liquid crystal compounds and one or more polymerization initiators to be a pattern λ / 4 plate is applied and polymerized. After aligning the polymerizable liquid crystal compound, the polymerizable liquid crystal compound in the regions 20a to 20c is partially polymerized by irradiating light with which the polymerization initiator reacts through a photomask that shields the portion corresponding to the region 20d. By performing a fixing step, then performing a development process with a solvent in which the polymerizable liquid crystal compound of the coating solution dissolves, and performing a step of removing the coating solution in the uncured region 20d that is blocked by a photomask ,pattern A method of forming a region 20d having no in-plane retardation is illustrated in / 4 plate 20A.

  The polarization image sensor and the method for manufacturing the polarization image sensor of the present invention have been described in detail above. However, the present invention is not limited to the above-described examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course, you can go.

  It can be suitably used for an imaging apparatus such as a digital camera or a smartphone.

DESCRIPTION OF SYMBOLS 10 Polarization image sensor 12 Sensor array 14 1st alignment film 16 (reflection type) Circularly polarizing plate 18 2nd alignment film 20, 20A Pattern (lambda) / 4 board 20a-20d area | region 24 Band pass filter 30 Cholesteric reflection layer 30r Right circular polarization cholesteric Layer 30l Left circularly polarized cholesteric layer 34 Near infrared filter 40 Sensor body 40a Solid-state imaging device 42 Color filter 42R Red filter 42G Green filter 42B Blue filter 42IR Infrared filter 46 Infrared blocking layer 48 Microlens 50 Flattening layer

Claims (19)

A sensor array having a solid-state imaging device arranged in a two-dimensional matrix;
A reflective polarizer that reflects near-infrared polarized light in a specific wavelength region and transmits other light; and
It is divided into a plurality of regions corresponding to one or a plurality of the solid-state imaging devices of the sensor array within the same plane, and has two or more types of the regions having the same phase difference and different slow axis directions. A pattern retardation plate, and
The polarization image sensor, wherein the reflective polarizing plate is disposed between the sensor array and the pattern retardation plate.   The reflective polarizing plate is a reflective circular polarizing plate that selectively reflects near-infrared right circularly polarized light or left circularly polarized light in the specific wavelength region, and the pattern retardation plate is a pattern λ / 4 plate. The polarization image sensor according to claim 1.   The polarization image sensor according to claim 1, wherein the sensor array includes a solid-state imaging device that detects visible light and a solid-state imaging device that detects near infrared rays.   The polarization image sensor according to any one of claims 1 to 3, further comprising a band-pass filter that selectively transmits near-infrared light and visible light on a side opposite to the reflective polarizing plate of the pattern retardation plate.   5. The polarization image sensor according to claim 1, wherein one of the divided regions has no in-plane retardation in the pattern phase difference plate.   The polarization image sensor according to claim 1, further comprising a photo-alignment film between the reflective polarizing plate and the pattern retardation plate.   The polarization image sensor according to claim 1, further comprising a photo-alignment film between the sensor array and the reflective polarizing plate.   The polarizing image sensor according to claim 1, wherein the reflective polarizing plate is formed by fixing at least one polymerizable liquid crystal compound in a cholesteric liquid crystal phase state.   The polarization image sensor according to any one of claims 1 to 8, wherein the pattern retardation plate is formed by fixing at least one polymerizable liquid crystal compound. Polarized light that forms a reflective polarizing plate that reflects near-infrared polarized light in a specific wavelength region and transmits other light on the light receiving surface side of a sensor array having a solid-state imaging device arranged in a two-dimensional matrix. Plate forming process, and
Divided into a plurality of regions corresponding to one pixel or a plurality of pixels of the solid-state image sensor of the sensor array within the same plane, which are performed after the polarizing plate formation step, and have the same phase difference and slow axes to each other And a phase difference plate forming step of forming a pattern phase difference plate having two or more of the regions having different directions. A method for producing a polarization image sensor.   In the polarizing plate forming step, a coating liquid containing at least one polymerizable liquid crystal compound, at least one chiral agent, and at least one polymerization initiator is applied to the formation surface of the reflective polarizing plate. The method for producing a polarization image sensor according to claim 10, comprising fixing the cholesteric liquid crystal phase after forming the cholesteric liquid crystal phase.   Before the polarizing plate forming step, a step of forming a photo-alignment film on the formation surface of the reflective polarizing plate, and a step of irradiating linearly polarized light to the photo-alignment film to impart an alignment regulating force. The manufacturing method of the polarization image sensor of Claim 10 or 11 containing.   In the retardation plate forming step, a coating liquid containing at least one polymerizable liquid crystal compound and at least one polymerization initiator is applied to the formation surface of the pattern retardation plate, and the polymerizable liquid crystal compound is applied. The method for producing a polarization image sensor according to any one of claims 10 to 12, further comprising polymerizing and fixing the polymerizable liquid crystal compound after aligning the liquid crystal.   Prior to the retardation plate forming step, an alignment film forming step for forming a photo-alignment film on the formation surface of the pattern retardation plate, and linearly polarized light is irradiated to the photo-alignment film through a pattern photomask. And the regulation force provision process of providing the orientation regulation force for forming the slow axis of a different direction in the same surface of the said pattern phase difference plate is described in any one of Claims 10-13. A method for manufacturing a polarization image sensor.   The method for manufacturing a polarization image sensor according to claim 10, wherein in the phase difference plate forming step, a region having no in-plane retardation is partially formed in the same plane.   In the regulating force imparting step, by providing a portion that does not irradiate the linearly polarized light to the photo-alignment film, a region having no in-plane retardation is formed in the same plane in the pattern retardation plate. The manufacturing method of the polarization image sensor of Claim 14.   In the regulating force applying step, in the pattern retardation plate, in-plane in the same plane, by partially providing a region that irradiates the non-polarized light to the photo-alignment film and gives a vertical alignment regulating force. The method for manufacturing a polarization image sensor according to claim 14, wherein a region having no phase difference is partially formed. After the regulating force imparting step, the retardation plate forming step includes at least one polymerizable liquid crystal compound and at least one polymerization initiator on the photo-alignment film given the orientation regulating force. Applying a coating liquid, orienting the polymerizable liquid crystal compound, partially irradiating light through which a polymerization initiator reacts through a photomask, and polymerizing and fixing the polymerizable liquid crystal compound; and
After heating the uncured portion, which is blocked by the photomask to be isotropic, to irradiate light with which the polymerization initiator reacts, the polymerizable liquid crystal compound in the uncured portion is polymerized and fixed. The manufacturing method of the polarization image sensor of Claim 14 which forms the area | region which does not have an in-plane phase difference in the same surface in the said pattern phase difference plate by performing a process. After the regulating force imparting step, the retardation plate forming step includes at least one polymerizable liquid crystal compound and at least one polymerization initiator on the photo-alignment film given the orientation regulating force. A process of applying a coating liquid and orienting the polymerizable liquid crystal compound, and then partially irradiating light through which a polymerization initiator reacts through a photomask to fix the polymerizable liquid crystal compound to be polymerized and fixed. ,and,
In the pattern retardation plate, in-plane in-plane by performing a development process with a solvent in which the polymerizable liquid crystal compound is dissolved and performing a step of removing an uncured portion blocked by the photomask. The method for manufacturing a polarization image sensor according to claim 14, wherein a region having no phase difference is partially formed.