JP6413369B2 - Diffraction grating, imaging device, display device, and method of manufacturing diffraction grating - Google Patents

Description

  The present invention relates to a diffraction grating that emits incident light as a plurality of diffracted lights.

In recent years, diffraction grating techniques have been proposed in various forms (for example, Patent Document 1). The diffraction grating described in Patent Document 1 includes a retardation layer formed in a checkered pattern in which two rectangular regions having different optical axis directions are alternately repeated in an in-plane direction, A function as a low-pass filter of the optical system is realized by emitting as diffracted light.
Such a diffraction grating is manufactured by applying an ultraviolet curable liquid crystal material on a substrate and irradiating ultraviolet rays through a checkered pattern mask. For example, after the base material is cut into a single sheet, application of a liquid crystal material or irradiation with ultraviolet rays is performed. For this reason, in the case of mass-producing such a diffraction grating, it may not be possible to manufacture it efficiently.

WO2008 / 004570 Publication

  The present invention has been made in view of such circumstances, and provides a diffraction grating, an imaging device, and a display device that emit incident light as a plurality of diffracted lights and can be efficiently manufactured.

  The present inventor has intensively studied to solve the above problems, and has arrived at the idea of laminating a plurality of retardation layers in which band-like regions having different optical axis directions are formed, thereby completing the present invention. It was.

(1) A plurality of retardation layers in which a first belt-like region and a second belt-like region having different optical axis directions are alternately and repeatedly formed in a plane perpendicular to incident light are stacked, A diffraction grating having a periodic structure in which the refractive index changes periodically,
The band-shaped region is disposed non-parallel to the band-shaped region of the other retardation layer;
A diffraction grating characterized by

  According to (1), a belt-like region of each retardation layer can be formed continuously while being sequentially conveyed by a roll, and a diffraction grating that can be efficiently manufactured can be provided. In addition, since the band-like region related to the phase difference layer is arranged non-parallel to the band-like regions related to the other phase difference layers, incident incident light is converted into, for example, a corresponding two-dimensional array of pixels of the image sensor. The light can be emitted by diffracted light.

  (2) In (1), the direction of the optical axis of the band-like region is a direction parallel to a plane perpendicular to the incident light.

  According to (2), the orientation of the optical axis of the belt-like region can be facilitated.

  (3) In (1) or (2), two retardation layers are provided, and the belt-like region of one retardation layer is perpendicular to the belt-like region of the other retardation layer. Has been placed.

  According to (3), diffracted light having a cross-shaped pattern can be emitted from the incident spot light.

  (4) An imaging apparatus in which any one of the diffraction gratings (1) to (3) is arranged on the front side of the imaging surface of the imaging element.

  According to (4), the diffraction grating can be used as a low-pass filter for subject light incident on the image sensor.

  (5) A display device in which any one of the diffraction gratings (1) to (3) is arranged on the front side of the display surface of a display unit that displays an image.

  According to (5), it is possible to suppress deterioration in image quality due to shadows of pixel electrodes of a display unit such as an LCD or OLED.

  In the present invention, since a plurality of retardation layers formed by alternately repeating the first belt-like region and the second belt-like region having different optical axis directions are stacked, each of the retardation layers is sequentially conveyed by a roll. Each band-like region can be formed continuously, and a diffraction grating that can be efficiently manufactured can be provided. In addition, since the belt-like region of the retardation layer is arranged non-parallel to the belt-like regions of the other retardation layers, incident incident light is converted into two-dimensional diffracted light corresponding to, for example, an array of pixels of the image sensor. Can be emitted.

It is a figure which shows the diffraction grating which concerns on 1st Embodiment of this invention. It is a flowchart which shows the manufacturing process of a diffraction grating. It is a figure which shows the detail of the exposure process of a diffraction grating. It is a figure which shows the diffraction grating which concerns on 2nd Embodiment of this invention. It is a figure which shows the phase difference film which comprises the diffraction grating which concerns on 2nd Embodiment of this invention. It is a figure which shows the diffraction grating which concerns on 3rd Embodiment of this invention. It is the photograph which image | photographed the spot light irradiated to an Example and a comparative example. It is the photograph which image | photographed the diffracted light radiate | emitted from the diffraction grating which concerns on the Example of this invention. It is the photograph which image | photographed the diffracted light radiate | emitted from the diffraction grating of the comparative example. It is the figure which plotted the diffracted light radiate | emitted from the diffraction grating which concerns on the Example of this invention. It is the figure which plotted the diffracted light radiate | emitted from the diffraction grating of the comparative example. It is a photograph which shows a diffracted light when the angle which the strip | belt-shaped area | region which concerns on each phase difference layer makes is 120 degree | times. It is a photograph which shows the diffracted light at the time of providing three phase difference layers.

[First Embodiment]
FIG. 1 is a diagram showing a diffraction grating according to the first embodiment of the present invention. FIG. 1A is a diagram showing a cross section of the diffraction grating of the present embodiment, and FIG. 1B is an exploded perspective view of the diffraction grating of the present embodiment.
The diffraction grating according to the first embodiment emits incident light as diffracted light. For example, the diffraction grating is provided together with an infrared filter on the imaging surface side of an imaging element of an imaging device such as a camera and is included in incident light. It is used as a low-pass filter that suppresses the generation of moire fringes caused by high-frequency components.

  Here, in the diffraction grating 1, as shown in FIG. 1, the retardation film 7 and the retardation film 17 are bonded via the adhesive layer 5. The retardation film 7 is provided with an alignment layer 3 and a retardation layer 4 in this order on one surface of a substrate 2 made of a transparent film such as TAC (triacetyl cellulose), acrylic, and cycloolefin polymer. The phase difference film 17 is the same film as the phase difference film 7, and on one surface of the substrate 12 made of a transparent film such as TAC (triacetyl cellulose), acrylic, cycloolefin polymer, the alignment layer 13, The phase difference layer 14 is sequentially provided. In addition, although the base material 2 and the base material 12 can apply various transparent film materials widely, it is preferable to apply the TAC film material excellent in the optical characteristic.

  In the diffraction grating 1, a retardation layer 4 and a retardation layer 14 are formed of a liquid crystal material that is solidified (cured) while maintaining refractive index anisotropy. The alignment direction of the liquid crystal material is the alignment layer 3 and It is determined by the alignment regulating force of the alignment layer 13 and is patterned. Note that the alignment state of the liquid crystal molecules is exaggerated by an elongated ellipse in FIG. By this patterning, the diffraction grating 1 is formed by alternately repeating the first band-shaped areas A and the second band-shaped areas B sequentially with a constant width, and the band-shaped areas having different refractive indexes for transmitted light. A periodic structure is formed.

  In the diffraction grating 1, after the photo-alignment material layer is made of the photo-alignment material, the photo-alignment material layer is irradiated with ultraviolet rays by linearly polarized light, and thereby the photo-alignment technique is applied to apply the alignment layer 3 and the alignment layer 13. Is formed. Here, the ultraviolet rays applied to the photo-alignment material layer are set so that the direction of polarization is different by 90 degrees between the first strip region A and the second strip region B. With respect to the liquid crystal material provided in the layer 14, liquid crystal molecules are aligned in the corresponding directions in the first strip region A and the second strip region B, and a phase difference corresponding to transmitted light is given. Note that the liquid crystal molecules in each band-like region are aligned in parallel or substantially in parallel with the plane orthogonal to the transmitted light.

Although various materials to which a photo-alignment technique can be applied can be applied as the photo-alignment material, in this embodiment, after the alignment, the alignment does not change by irradiation with ultraviolet rays. For example, a photo-dimerization type Use materials. The light dimerization type material is described in “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H. Seiberle and A. Schuster: Nature, 381, 212 (1996).
For example, in this embodiment, as shown in FIG. 1B, the strip regions A and B of the alignment layer 13 are arranged at right angles so as to be non-parallel to the strip regions A and B of the alignment layer 3. In this way, it is formed. Thereby, the diffraction grating 1 can emit, for example, a diffracted light having a cross-shaped pattern (see FIG. 8) with respect to the incident spot light.
Here, non-parallel means that the direction (longitudinal direction) in which the band-shaped region of the alignment layer 13 extends is the alignment layer when viewed from the direction in which incident light is incident (direction in which the alignment layer, retardation layer, etc. are laminated). 3 is a state that is not parallel to the direction in which the strip-shaped region 3 extends, that is, is inclined with respect to the longitudinal direction of the strip-shaped region of the alignment layer 3.

(Retardation layer)
The retardation layer 4 and the retardation layer 14 contain a polymerizable liquid crystal composition. This polymerizable liquid crystal composition can contain an antiblocking agent and the like in addition to a liquid crystal compound exhibiting liquid crystallinity and having a polymerizable functional group in the molecule (hereinafter also referred to as “rod-like compound”).

  The rod-shaped compound has a refractive index anisotropy, and has a function of imparting a desired phase difference by regularly arranging with the alignment regulating force of the alignment layer 3 and the alignment layer 13. Examples of the rod-like compound include materials exhibiting a liquid crystal phase such as a nematic phase and a smectic phase, but the nematic phase is easier to arrange regularly than liquid crystal compounds exhibiting other liquid crystal phases. It is more preferable to use the rod-shaped compound shown.

  Specific examples of the rod-shaped compound used in the present embodiment include compounds represented by the following formulas (1) to (16).

)

  The adhesive layer 5 is a layer for adhering the retardation film 7 and the retardation film 17, and for example, an adhesive made of an ultraviolet curable resin can be used.

〔Manufacturing process〕
FIG. 2 is a flowchart showing the manufacturing process of the diffraction grating 1. In the manufacturing process of the diffraction grating 1, the long transparent film material is sequentially processed by the processing process shown in FIG. 2 to produce a diffraction grating. Here, in this production process, the base material is provided by a long transparent film material wound around a roll, and in the alignment layer creating process SP2, the coating liquid relating to the photo-alignment film is applied by a die or the like, and then dried. Cured, thereby producing a photo-alignment material layer. Subsequently, in this alignment layer creating step SP2, the photo-alignment layer is formed on the substrate by irradiating ultraviolet rays in the exposure step. Here, in the exposure step, the first belt-shaped region or the region corresponding to the second belt-shaped region is selectively exposed by irradiation with ultraviolet light using linearly polarized light using a mask, and then linearly polarized light whose polarization directions are orthogonal to each other. This is performed by irradiating the entire surface with ultraviolet rays. Details of the exposure step will be described later.
Subsequently, in the manufacturing step SP3 of the retardation layer, the liquid crystal material coating liquid is applied and dried with a die or the like, and then the liquid crystal material is oriented by irradiation with ultraviolet rays while the liquid crystal molecules are aligned. Curing is performed to produce a retardation layer, and a long retardation film is completed.

Next, this manufacturing process cuts out a long phase difference film to a desired magnitude | size in cutting process SP4, and obtains a phase difference film. That is, the retardation film 7 and the retardation film 17 are cut out from one long retardation film.
And in bonding process SP5, the phase difference film 7 and phase difference film 17 which were cut out are bonded together with the adhesive agent of the ultraviolet curable resin which comprises the contact bonding layer 5. FIG. At this time, each strip region related to the retardation layer 14 is affixed so as to be arranged non-parallel to each strip region of the retardation layer 4, for example, at right angles in the present embodiment. Thus, the diffraction grating 1 is manufactured.
Next, in the manufacturing process, in the inspection process SP6, the manufactured diffraction grating is inspected for defects, appearance, and the like.

FIG. 3 is a diagram showing details of the exposure process. In addition, in FIG. 3 and the following description, although the exposure process of the alignment layer 3 is demonstrated, it is the same also about the alignment layer 13. FIG.
This manufacturing process is performed by irradiating ultraviolet rays (polarized ultraviolet rays) by linearly polarized light through a mask 16 that shields the portion corresponding to the first belt-like region A or the second belt-like region B. For the second strip region B or the first strip region A, the photo-alignment material film is oriented in a desired direction (FIG. 3A). Thereby, this manufacturing process executes the first exposure process. Subsequently, in this manufacturing process, the entire surface is irradiated with linearly polarized light whose polarization direction is 90 degrees different from that of the first exposure process, whereby the first strip region A or the second unexposed area is exposed in the first exposure process. The strip-shaped region B is exposed, and the photo-alignment material film is oriented in a desired direction in the first strip-shaped region A or the second strip-shaped region B (FIG. 3B). Thereby, in this manufacturing process, the first strip region A and the second strip region B are sequentially exposed by two exposure processes to produce the alignment layer 3.

In the manufacturing process described above, a long retardation film is formed by sequentially processing a substrate made of a transparent film material provided by a roll while being conveyed. Here, each phase difference film 7 and 17 is cut out from one elongate phase difference film, and is bonded so that each strip | belt-shaped area | region may become mutually non-parallel. Therefore, the diffraction grating 1 of this embodiment should just produce one type of phase difference film in a manufacturing process, and can improve the manufacturing efficiency in mass production significantly.
In addition, since the retardation film is produced by sequentially processing the substrate made of the transparent film material provided by the roll, the direction of the substrate extending in the direction of the belt-like region of the retardation layer is conveyed. Since it is efficiently manufactured by making it the same as the direction, the diffraction grating 1 of this embodiment can also improve the manufacturing efficiency in mass production.
Furthermore, as in the diffraction grating described in FIG. 2 of Patent Document 1 described above, the orientation direction of the liquid crystal molecules is not only parallel to the plane perpendicular to the incident light (the plane parallel to the sheet surface of the diffraction grating). In the case where the film is also vertically aligned, it is difficult to efficiently produce a large amount because the above-described manufacturing method cannot mix horizontal alignment and vertical alignment on one type of alignment film. . However, in the diffraction grating 1 of the present embodiment, the liquid crystal molecules in the band-like region are aligned in parallel or substantially parallel to a plane orthogonal to the incident light (a plane parallel to the sheet surface of the diffraction grating). The alignment of the liquid crystal molecules can be performed while sequentially transporting the base material, and this can also improve the production efficiency in mass production.
In addition, since the diffraction grating of the present embodiment has two retardation films bonded together, the angle formed by the band-shaped region of each retardation film 7 and the band-shaped region of the retardation film 17 can be easily set to an angle other than a right angle. Can be adjusted. Thereby, the pattern of the diffracted light emitted from the diffraction grating can be appropriately changed.
In the diffraction grating according to the present embodiment, each band-shaped region of the retardation layer is arranged non-parallel (for example, at right angles in the present embodiment) to each band-shaped region of the other retardation layer. Can be emitted as a plurality of diffracted lights.

[Second Embodiment]
FIG. 4 is a diagram showing a diffraction grating according to the second embodiment of the present invention. FIG. 5 is a view showing a retardation film constituting a diffraction grating according to the second embodiment of the present invention.
The diffraction grating 101 of the second embodiment differs from the diffraction grating of the first embodiment in the layer configuration on the retardation layer 4. Note that, in the following description and drawings, the same reference numerals or the same reference numerals (last two digits) are given to the portions that perform the same functions as those of the first embodiment described above, and redundant descriptions are omitted as appropriate. To do.

As shown in FIG. 4, the diffraction grating 101 is provided with an alignment layer 3, a retardation layer 4, an adhesive layer 5, a retardation layer 14, and an alignment layer 13 in this order on one surface of the substrate 2.
The diffraction grating 101 of this embodiment includes a retardation film 7 composed of the substrate 2, the alignment layer 3, and the retardation layer 4 shown in FIG. 5A, and a retardation film 17 shown in FIG. The phase difference film 7, the phase difference layer 14 and the alignment layer 13 are integrated with each other through the adhesive layer 5. The transfer method is used for this integration process. Applied.

  Here, in the transfer method, for example, when a desired layer is formed on a base material, the layer is not directly formed on the base material but can be peeled once on a releasable support. After forming the layer by laminating the layers, according to the process, demand, etc., the layer formed on the support is finally deposited on the substrate (the substrate to be transferred) on which the layer is to be laminated. In this method, a desired layer is formed on the substrate by peeling and removing the support.

  In this embodiment, the retardation film 17 is laminated on the retardation film 7 by a transfer method. Therefore, the substrate to be transferred is the retardation film 7, and the layer (transfer layer) used for transfer is a laminate of the alignment layer 13 and the retardation layer 14 of the retardation film 17.

  FIG. 5B is a diagram illustrating a configuration of the retardation film 17. The retardation film 17 is provided with an alignment layer 13 and a retardation layer 14 on the separator film 12.

  Here, the separator film 12 is a substrate that is detachably supported on a layer to be transferred (transfer layer), and is appropriately peeled and removed when the transfer layer is bonded and laminated on the transfer target substrate. is there. In this embodiment, a PET (Polyethylene terephthalate) film, which is a transparent film material, is applied, whereby the transfer body of the retardation film is configured to be able to inspect optical characteristics. The PET film is corona-treated, thereby appropriately setting the adhesion between the PET film and a release layer described later. When the peelability from the transfer layer is insufficient, the separator film 12 may be provided with a release layer that promotes peeling on the transfer layer side.

  The adhesive layer 5 is a layer for adhering the transfer layer and the substrate to be transferred. For example, an adhesive made of an ultraviolet curable resin can be used.

Here, the phase difference films 7 and 17 of the diffraction grating 101 are prepared by individually individually processing in advance while conveying a substrate made of a transparent film material provided by a roll. Specifically, the alignment layers 3 and 13 of the respective retardation films are dried and cured after the coating liquid relating to the photo-alignment film is applied to the base material 2 and the separator film 12 by a die or the like, respectively. Produced. Here, the exposure process of the band-shaped region of each retardation layer is the same as the exposure process of the band-shaped region of the retardation layer of the first embodiment described above. That is, in this exposure step, the first polarization region or the region corresponding to the second stripe region is selectively exposed by irradiation of ultraviolet rays with linear polarization using a mask, and then the linearly polarized light whose polarization direction is orthogonal. This is performed by irradiating the entire surface with ultraviolet rays (see FIG. 4). In addition, as above-mentioned, in order to ensure peelability with a transfer layer, you may provide the release layer etc. on the separator film 12 previously.
The diffraction grating 101 of the present embodiment is produced by cutting each retardation film produced by the above-mentioned roll into a predetermined dimension, rotating the film to a predetermined angle (for example, 90 degrees), and bonding them together. It will be.

  The diffraction grating 101 of the present embodiment is formed by bonding the retardation layer 4 of the retardation film 7 to the retardation layer 14 of the retardation film 17 with the adhesive layer 5 and then peeling the separator film 12. . At this time, each strip region related to the retardation layer 14 is affixed so as to be arranged non-parallel to each strip region of the retardation layer 4, for example, at right angles in the present embodiment.

As described above, the retardation film 7 and the retardation film 17 are produced while transporting the base material and the separator film made of the transparent film material provided by the rolls. B is manufactured continuously and efficiently by making the direction extending in a strip shape the same as the transport direction of the base material and performing the exposure process for each strip region. Therefore, the diffraction grating 101 of the present embodiment is efficiently manufactured even in mass production.
In addition, as in the diffraction grating described in FIG. 2 of Patent Document 1 described above, the orientation direction of the liquid crystal molecules is not only parallel to a plane perpendicular to the incident light (a plane parallel to the sheet surface of the diffraction grating). In the case where the film is also vertically aligned, it is difficult to efficiently produce a large amount because the above-described manufacturing method cannot mix horizontal alignment and vertical alignment on one type of alignment film. . However, in the diffraction grating 101 of the present embodiment, the liquid crystal molecules in the band-like region are aligned in parallel or substantially parallel to a plane orthogonal to the incident light (a plane parallel to the sheet surface of the diffraction grating). The alignment of the liquid crystal molecules can be performed while sequentially transporting the base material, and this can also improve the production efficiency in mass production.
Furthermore, since the diffraction grating of the present embodiment has two retardation films bonded together, the angle formed between the belt-like region of each retardation film and the belt-like region of another retardation film can be easily set to an angle other than a right angle. Can be adjusted. Thereby, the pattern of the diffracted light emitted from the diffraction grating can be appropriately changed.

[Third Embodiment]
FIG. 6 is a diagram showing a diffraction grating according to the third embodiment of the present invention.
The diffraction grating 201 of the third embodiment is different from the diffraction grating of the first embodiment in that an alignment layer and a retardation layer are formed on the front surface and the back surface of the substrate. Note that, in the following description and drawings, the same reference numerals or the same reference numerals (last two digits) are given to the portions that perform the same functions as those of the first embodiment described above, and redundant descriptions are omitted as appropriate. To do.
As shown in FIG. 6, the diffraction grating 201 has an orientation layer 3 and a retardation layer 4 sequentially provided on one surface (front surface) of the base material 2, and the other surface (back surface) of the base material 2. An alignment layer 13 and a retardation layer 14 are sequentially provided thereon.

The diffraction grating 201 of the present embodiment is manufactured as follows.
First, the base material 2 is provided by the long transparent film material wound up by the roll, and after the coating liquid which concerns on a photo-alignment film | membrane is apply | coated with the die | dye etc. on the surface of the base material, it is dried and hardened, Thus, a photo-alignment material layer is produced. Subsequently, the photo-alignment layer 3 is produced by irradiating ultraviolet rays in the exposure process.
Subsequently, after coating and drying a liquid crystal material coating solution with a die or the like, the liquid crystal material is cured by irradiation with ultraviolet rays, whereby the retardation layer 4 is produced.

Next, the substrate is cut, turned into a sheet, and then inverted. After the coating liquid related to the photo-alignment film is applied to the back surface of the substrate with a die or the like, it is dried and cured, thereby the photo-alignment material A layer is produced, and the alignment layer 13 is produced by irradiating ultraviolet rays in the exposure process.
Subsequently, after coating and drying a liquid crystal material coating solution with a die or the like, the liquid crystal material is cured by irradiation with ultraviolet rays, and the retardation layer 14 is produced. At this time, each strip region related to the retardation layer 14 is formed so as to be arranged non-parallel to each strip region related to the retardation layer 4, for example, at right angles in the present embodiment.

Like the diffraction grating shown in FIG. 2 of Patent Document 1 described above, the orientation direction of the liquid crystal molecules is not only parallel to the plane orthogonal to the incident light (the plane parallel to the sheet surface of the diffraction grating), but also perpendicular. In such a case, it is difficult to efficiently produce a large amount because a horizontal alignment and a vertical alignment cannot be mixed on one type of alignment film in the above-described manufacturing method. However, in the diffraction grating 201 of the present embodiment, the liquid crystal molecules in the band-like region are aligned in parallel or substantially parallel to a plane perpendicular to the incident light (a plane parallel to the sheet surface of the diffraction grating). The alignment of the liquid crystal molecules can be performed while sequentially transporting the base material, and the production efficiency in mass production can be improved.
Furthermore, since the alignment layer and the retardation layer are respectively formed on the front surface and the back surface of the base material 2 in the diffraction grating of the present embodiment, the adhesive layer 5 and the base material 12 are provided as compared with the above-described embodiment. It can be omitted and the thickness can be reduced.
In the diffraction grating according to the present embodiment, each band-shaped region of the retardation layer is arranged non-parallel (for example, at right angles in the present embodiment) to each band-shaped region of the other retardation layer. Can be emitted as a plurality of diffracted lights.

[Evaluation]
Next, evaluation of the diffracted light emitted from the diffraction grating by making the spot light incident on the diffraction grating will be described.
FIG. 7 is a photograph of spot light irradiated on the example and the comparative example. FIG. 8 is a photograph of the diffracted light emitted from the diffraction grating according to the embodiment of the present invention. FIG. 9 is a photograph of the diffracted light emitted from the diffraction grating of the comparative example. FIG. 10 is a diagram plotting the diffracted light emitted from the diffraction grating according to the embodiment of the present invention. FIG. 11 is a diagram in which the diffracted light emitted from the diffraction grating of the comparative example is plotted.

As described in the above embodiment, the diffraction grating of the example is formed by laminating two retardation layers formed by alternately repeating the first and second strip regions having different optical axis directions. The band-like regions related to each phase layer are arranged at right angles to each other (see FIG. 1).
The diffraction grating according to the comparative example is a diffraction grating according to Patent Document 1 in which two rectangular regions having different optical axis directions are formed in a checkered pattern.
The spot light incident on the diffraction gratings of the example and the comparative example is light emitted from a point light source as shown in FIG.

When spot light is incident on the diffraction grating of the comparative example, as shown in FIG. 9, diffracted light having a cross-shaped pattern is emitted from the diffraction grating of the comparative example.
When the distance from the irradiation position of the spot light to the irradiation surface of the diffraction grating is 1500 mm and a laser beam of 550 nm is incident on the diffraction grating of the comparative example with a pitch of 100 μm, the pitch of the diffraction light is about 8 as shown in FIG. 2 mm.
Further, when the spot light is incident on the diffraction grating of the embodiment, as shown in FIG. 8, diffracted light having a cross-shaped pattern is emitted from the diffraction grating of the embodiment.
The distance from the irradiation position of the spot light to the irradiation surface of the diffraction grating is 1500 mm, and a laser beam of 550 nm is incident on the diffraction grating of the example in which two layers of 120 μm and 120 μm stripe retardation layers are laminated. As shown in FIG. 10, the pitch of the diffracted light was about 3.5 mm.
Thereby, it was confirmed that the diffraction grating of the Example by this invention can radiate | emit incident light as several diffracted light similarly to the diffraction grating of a comparative example. The diffracted light pattern of the comparative example is a cross-shaped diffracted light pattern by two rows of diffracted light dots, whereas the diffracted light pattern of the embodiment is a cross-shaped diffracted light pattern by one row of diffracted light dots. confirmed.

Here, as described above, the diffraction grating of the comparative example is manufactured by performing the application of the liquid crystal material, the exposure process, and the like after cutting the substrate into a single wafer, so that it is efficient in mass production. It cannot be manufactured well.
However, as described above, the diffraction grating of the embodiment according to the present invention can continuously form a band-like region related to the retardation layer while being sequentially conveyed by a roll, and therefore, compared with the diffraction grating of the comparative example. And can be manufactured much more efficiently.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously combined or modified with the configuration of the above-described embodiment without departing from the spirit of the present invention. Can do.
FIG. 12 is a photograph showing the diffracted light when the angle formed between the band-like regions of the respective retardation layers is 120 degrees. FIG. 13 is a photograph showing diffracted light when three retardation layers are provided.

(1) Although the photo-alignment material for forming the alignment layer has been shown as an example of using a material whose alignment is not changed by ultraviolet irradiation after being once aligned, the present invention is not limited to this, and repeated exposure processing A material whose orientation direction changes each time may be used. For example, a photoisomerization type photo-alignment material can be used. The photoisomerization is reported in “WM Gibbons, PJ Shannon, ST Sun and BJ Swetlin: Nature, 351, 49 (1991)”.
In this case, in the exposure step, the first band-shaped region and the region corresponding to the second band-shaped region are exposed by irradiation with ultraviolet rays using linearly polarized light, and then irradiated with ultraviolet rays using linearly polarized light whose polarization directions are orthogonal to each other. Each band-like region is formed by selectively exposing a region corresponding to one band-like region or the second belt-like region using a mask.

(2) In each embodiment, the example in which the respective band-like regions related to the phase difference layer 4 are arranged at right angles to the respective band-like regions related to the phase difference layer 14 is shown, but the present invention is not limited to this. , They may intersect at an angle other than 90 degrees. By doing so, the pattern of the diffracted light emitted from the diffraction grating can be made into another form. For example, when the band-like region related to the retardation layer 4 intersects the band-like region related to the retardation layer 14 at 120 degrees, diffracted light having a pattern as shown in FIG. 12 can be obtained.

(3) In each embodiment, the diffraction grating has been described as an example in which two retardation layers are stacked. However, the present invention is not limited to this, and three or more layers may be stacked. By doing so, the diffracted light emitted from the diffraction grating can be emitted in a desired form. For example, when three retardation layers are provided and the angle between the strip-like regions of each retardation layer is 120 degrees, diffracted light having a pattern as shown in FIG. 13 can be obtained. In this way, in this embodiment, the direction in which the diffracted light is emitted can be easily adjusted to an arbitrary direction including the cross direction as compared with the case where the diffraction grating is manufactured in a checkered pattern (comparative example).

(4) In each of the above-described embodiments, the case where the alignment layer is produced by photo-alignment has been described. However, the present invention is not limited to this, and is widely applied to the case where the alignment layer is produced by forming a rubbing treatment mark. can do.
Further, the alignment layer may be produced by a fine concavo-convex shape molding process using a moldable resin such as an ultraviolet curable resin. Specifically, a fine uneven shape is formed on the surface of each alignment layer by a molding die having a fine uneven shape on the surface corresponding to each of the first belt region A and the second belt region B. The retardation layer 4 may be patterned by the alignment regulating force due to the uneven shape.
Furthermore, the alignment layers 3 and 13 may be omitted by configuring the retardation layers 4 and 14 by applying a photo-alignment technique using a photo-alignable liquid crystal polymer having a photo-alignment function.

(5) In each embodiment, the diffraction grating is applied as a low-pass filter. However, the present invention is not limited to this. For example, the diffraction grating may be applied to an optical pickup such as a CD or a DVD.

(6) In each embodiment, although the diffraction grating showed the example used for imaging devices, such as a camera, it is not limited to this. The diffraction grating may be used for a display device having a display unit such as an LCD or an OLED. Specifically, the diffraction grating is disposed on the front side (observer side) of the display surface of the display unit. Thereby, it is possible to reduce the display of shadows such as pixel electrodes of the display unit, and it is possible to suppress deterioration in image quality.

(7) In the first embodiment, the diffraction grating 1 has been described as an example in which the base material 12 of the retardation film 17 is bonded to the retardation layer 4 of the retardation film 7 via the adhesive layer 5. It is not limited to this. For example, the phase difference layer 14 of the phase difference film 17 is bonded to the phase difference layer 4 of the phase difference film 7 via the adhesive layer 5, and the structure of the diffraction grating is changed to the base material 2, the alignment layer 3, the phase difference. The layer 4, the retardation layer 14, the alignment layer 13, and the base material 12 may be sequentially laminated.
In this case, the substrate 12 may be peeled from the alignment layer 13 as a separator film by the transfer method described in the second embodiment. By doing so, the layer thickness of the diffraction grating can be made thinner.

(8) In 3rd Embodiment, although the diffraction grating 201 showed the example in which the orientation layer and retardation layer were formed in the surface and back surface of the base material 2, it is not limited to this, For example, base The orientation layer 3, the retardation layer 4, the orientation layer 13, and the retardation layer 14 may be sequentially formed on one surface of the material 2.

DESCRIPTION OF SYMBOLS 1, 101, 201 Diffraction grating 2 Base material 3 Orientation layer 4 Retardation layer 5 Adhesion layer 7 Retardation film 12 Base material, separator film 13 Orientation layer 14 Retardation layer 17 Retardation film 16 Mask

Claims (5)

The first strip-like region and a second strip-like region where the angle of the optical axis within a plane perpendicular to the incident light becomes a right angle, the retardation layer formed alternately and repeatedly in a plane perpendicular to the incident light a plurality of stacked diffraction grating,
The first belt-like region and the second belt-like region of each of the plurality of stacked retardation layers are arranged non-parallel to each other ;
A diffraction grating characterized by The retardation layer is provided in two layers,
The diffraction grating according to claim 1 . The imaging device which has arrange | positioned the diffraction grating of Claim 1 or Claim 2 in the front side of the imaging surface of an image pick-up element. A display device in which the diffraction grating according to claim 1 or 2 is arranged in front of a display surface of a display unit that displays an image. It is a manufacturing method of the diffraction grating according to claim 1,
An alignment material is applied onto a long base material wound around a roll so that the angles formed by the optical axes of the first belt-like region and the region corresponding to the second belt-like region are perpendicular to each other. An alignment layer is formed by irradiating ultraviolet rays, a liquid crystal material is formed on the formed alignment layer to form a liquid crystal layer, and a plurality of retardation layers are multifaceted. A phase difference layer forming step of forming
A cutting step for separating the retardation layer multi-faced body formed by the retardation layer forming step;
A plurality of the retardation layers separated by the cutting step are bonded together so that the first belt-like region and the second belt-like region of each of the retardation layers are arranged non-parallel to each other. A bonding step;
A method for manufacturing a diffraction grating.