WO2023074626A1

WO2023074626A1 - Optical laminate, infrared information acquisition system, and meeting support system

Info

Publication number: WO2023074626A1
Application number: PCT/JP2022/039537
Authority: WO
Inventors: 麻未川口; 雄大沼田; 祥一松田; 美由東山
Original assignee: 日東電工株式会社
Priority date: 2021-10-28
Filing date: 2022-10-24
Publication date: 2023-05-04
Also published as: TW202329037A

Abstract

A meeting support system (300) comprises: an infrared information acquisition system (200); a facial expression recognition device (513) that recognizes a facial expression of each user (P1, P2, P3), on the basis of infrared information acquired through an optical laminate (100) by the infrared information acquisition system; and a storage device (520) that stores information about the facial expression recognized by the facial expression recognition device, in association with a position of the optical laminate and the acquisition time. The optical laminate has an optical filter layer (110) that transmits infrared rays, and diffuses and transmits visible light. The infrared information acquisition system comprises the optical laminate, and a plurality of infrared detection devices (210a).

Description

Optical Stacks, Infrared Information Acquisition Systems, and Conference Support Systems

TECHNICAL FIELD The present invention relates to an optical laminate, an infrared information acquisition system, and a conference support system, and in particular, an optical laminate capable of transmitting infrared rays and limiting the transmission of visible light. The present invention relates to an infrared information acquisition system that acquires information using infrared rays and a conference support system that uses such an infrared information acquisition system. Optical stacks are used, for example, as projection screens and/or whiteboards. The optical layered body is typically sheet-like. Here, the term "sheet-like" is used to mean including plate-like or film-like, regardless of the rigidity (flexibility) and thickness of the sheet.

In recent years, face recognition technology that identifies people from images captured by cameras has been used in various technical fields. Recently, face recognition technology has been further developed, and research and development of facial expression recognition technology for recognizing various facial expressions from facial images is underway (for example, Patent Documents 1 and 2). Facial expression recognition technology is applied to techniques for estimating various emotions based on facial expressions (for example, Patent Document 3).

JP 2014-41587 A WO2019/102619 JP 2016-149063 A JP 2019-509510 A (International Publication No. 2017/1246649)

The present inventor has conceived of a system that, for example, uses facial expression recognition technology to estimate the user's emotions, and uses information about the estimated emotions to support meetings aimed at, for example, brainstorming. At this time, in order to recognize various facial expressions from the user's face image, a highly accurate face image is required, which increases the number of cameras to be arranged. Then, as a result of the user being conscious of the camera, the facial expression is also affected. Also, when using a whiteboard or an electronic blackboard, it is difficult to obtain an image of the face while facing the whiteboard or electronic blackboard. Furthermore, there is a problem that the user becomes a shadow when optically acquiring the information written on the whiteboard.

Although Patent Document 4 discloses that an optical camouflage filter that blocks visible light and transmits near-infrared rays is used in a face recognition system (see FIG. 2F), it does not disclose the use of multiple light receivers. Not even suggested. Further, Patent Document 4 discloses an optical camouflage filter with an ink-receptive coating, but does not disclose or suggest a whiteboard having a writing layer on which writing and erasing can be repeated.

According to the embodiments of the present invention, solutions described in the following items are provided.

[Item 1]
An optical laminate having a first main surface and a second main surface opposite to the first main surface,
It has an optical filter layer that transmits infrared rays and diffuses and transmits visible light,
When the first main surface side is brighter than the second main surface side, an object placed on the second main surface side and spaced apart from the second main surface side is viewed from the first main surface side. make it impossible,
An optical layered body having a linear transmittance of 40% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less.

According to one embodiment, the optical layered body can make the object invisible from the first main surface side when the distance from the second main surface to the object is 9 cm or more. Further, according to one embodiment, the optical layered body can make the object invisible from the first main surface side even if the distance from the second main surface to the object is 1 cm.

[Item 2]
When a checkered pattern with a black-and-white luminance difference of 235 cd/cm ² is projected onto the second principal surface, a projection image having a black-and-white luminance difference of 20 cd/cm ² or more can be formed on the first principal surface. Optical laminate.

[Item 3]
3. The optical laminate according to item 1 or 2, having a linear transmittance of visible light of 20.0% or less.

[Item 4]
4. The optical laminate according to any one of items 1 to 3, wherein the diffuse transmittance of visible light is 10.0% or more and 40.0% or less.

[Item 5]
5. The optical laminate according to any one of items 1 to 4, further comprising a semi-reflecting layer arranged on the second main surface side of the optical filter layer and partially reflecting visible light.

[Item 6]
6. The optical laminate according to item 5, wherein the semi-reflective layer has polarization selectivity.

[Item 7]
7. The optical laminate according to any one of items 1 to 6, further comprising a decorative layer arranged on the first main surface side of the optical filter layer.

[Item 8]
8. The optical laminate according to any one of items 1 to 7, further comprising a surface protective layer disposed on the first main surface side of the optical filter layer.

[Item 9]
a writing layer disposed on the first main surface side of the optical filter layer;
7. The optical layered body according to any one of items 1 to 6, further comprising a substrate layer arranged on the second main surface side of the optical filter layer.

[Item 10]
The optical filter layer has a matrix and fine particles that serve as light scatterers dispersed in the matrix, and has a linearity of 60% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less. The optical stack of any of items 1 through 9, having transmittance.

[Item 11]
11. An optical laminate according to item 10, wherein the fine particles constitute at least colloidal amorphous aggregates.

[Item 12]
The transmittance curve of the visible light wavelength region of the optical filter layer has a curve portion where the linear transmittance monotonically decreases from the long wavelength side to the short wavelength side, and the curve portion is on the long wavelength side as the incident angle increases. 12. The optical layered product according to item 10 or 11, wherein the optical laminate shifts to

[Item 13]
an optical laminate according to any one of items 1 to 12;
a plurality of infrared detection devices disposed on the second main surface side of the optical laminate and spaced apart from the second main surface and arranged to receive infrared rays through the optical laminate; Infrared information acquisition system.

[Item 14]
14. An infrared information acquisition system according to item 13, further comprising at least one infrared light source device arranged to emit infrared rays toward the second main surface of the optical laminate.

[Item 15]
The at least one infrared light source device includes a first infrared light source device and a second infrared light source device, and the first infrared light source device and the second infrared light source device are different from each other on the second main surface of the optical stack. 15. An infrared information acquisition system according to item 14, configured to emit infrared light toward an area.

[Item 16]
16. Infrared information according to any one of items 13 to 15, further comprising a position sensor and configured to selectively operate one of the plurality of infrared detection devices according to the output of the position sensor. acquisition system.

[Item 17]
17. The infrared information acquisition system according to any one of items 13 to 16, wherein each of said plurality of infrared detection devices is a three-dimensional sensor or camera.

[Item 18]
an infrared information acquisition system according to any one of items 13 to 17;
a facial expression recognition device that recognizes facial expressions of a user based on infrared information acquired through the optical layered body by the infrared information acquisition system;
A meeting support system, comprising: a first storage device that stores information on the facial expression recognized by the facial expression recognition device in association with the position and acquisition time of the optical layered body.

[Item 19]
The optical laminate further has a writing layer disposed on the first main surface side of the optical filter layer,
a pattern recognition device that recognizes a pattern formed using infrared absorbing ink on the writing layer of the optical layered body based on the infrared information acquired through the optical layered body by the infrared information acquisition system;
19. The meeting support system according to item 18, further comprising a second storage device that stores information of the pattern recognized by the pattern recognition device in association with the position and acquisition time of the optical layered body.

[Item 20]
20. The meeting support system according to item 19, further comprising a character conversion device that converts the recognized pattern information into character information.

[Item 21]
21. The conference support system according to any one of items 18 to 20, further comprising a motion recognition device that recognizes a user's motion based on the infrared information acquired through the optical laminate by the infrared information acquisition system.

[Item 22]
22. The meeting support system according to any one of items 18 to 21, further comprising an output device that outputs information on the facial expression recognized by the facial expression recognition device.

[Item 23]
further comprising a projection device disposed on the second main surface side of the optical layered body and configured to emit visible light toward the optical layered body;
The projection device is configured to form a predetermined pattern of visible light on the second main surface of the optical layered body based on the facial expression information recognized by the facial expression recognition device. 23. A meeting support system according to any one of items 18-22.

[Item 24]
24. A meeting support system according to any one of items 18 to 23, further comprising a communication device and configured to output the visible light pattern formed by the projection device via the communication device.

According to an embodiment of the present invention, for example, in a meeting for brainstorming, an expression (or emotion) of a user is estimated from a facial image of a user without being visually recognized by the user, and information about the estimated expression (emotion) is provided. A conference support system is provided for supporting a conference. Further, according to the embodiments of the present invention, there are provided a visible light shielding IR transmissive sheet, a projection screen, an optical laminate used as a whiteboard, and an infrared information acquisition system, which are preferably used in such a conference support system.

1 is a schematic diagram showing an example of a state in which an optical layered body 100 is used as a projection screen/whiteboard 100 in a meeting support system according to an embodiment of the present invention; FIG. 1 is a schematic diagram showing an example configuration of an infrared information acquisition system 200 and a conference support system 300 according to an embodiment of the present invention; FIG. 1 schematically illustrates the configuration and optical properties of a projection screen/whiteboard 100 according to an embodiment of the present invention; FIG. 1 is a block diagram showing a configuration example of an infrared information acquisition system 200 and a conference support system 300 according to an embodiment of the present invention; 4 is a flow chart showing an example of operation of the conference support system 300 according to the embodiment of the present invention; 4 is a flow chart showing another example of the operation of the conference support system 300 according to the embodiment of the present invention; 9 is a flow chart showing still another example of the operation of the conference support system 300 according to the embodiment of the present invention; 2 is a schematic cross-sectional view of an optical filter layer 110; FIG. FIG. 4 is a diagram showing an example of a cross-sectional TEM image of the optical filter layer 110; 4 is a graph normalized by the maximum transmittance, showing an example of the incident angle dependence of the linear transmittance spectrum of the optical filter layer 110. FIG.

An optical laminate, an infrared information acquisition system, and a conference support system according to embodiments of the present invention will be described below with reference to the drawings. Optical laminates according to embodiments of the present invention can be used as visible light blocking IR transmissive sheets, projection screens, and whiteboards. The optical layered body, the infrared information acquisition system, and the conference support system according to the embodiments of the present invention are not limited to those exemplified below.

FIG. 1 schematically shows an example of a state in which an optical laminate 100 is used as a projection screen/whiteboard 100 in a meeting support system according to an embodiment of the present invention. FIG. 2 schematically shows a configuration example of an infrared information acquisition system 200 and a conference support system 300 according to an embodiment of the present invention. The optical laminate 100 exemplified here can be used as a rear projection type projection screen and also as a whiteboard. The substrate layer 120 and/or the writing layer 130 (see FIG. 3) may be omitted if used only as an IR transmitting sheet or projection screen. The optical layered body 100 may be referred to as a whiteboard 100 hereinafter.

The whiteboard 100 has an optical filter layer 110, a base layer 120 supporting the optical filter layer 110, and a writing layer 130 disposed on the optical filter layer 110, as will be described later with reference to FIG. . The optical filter layer 110 transmits infrared rays and diffusely transmits visible light. The whiteboard 100 has a first major surface (front) 12s and a second major surface (back) 14s opposite the first major surface 12s, and the substrate layer 120 is the second major surface of the optical filter layer 110. The writing layer 130 is arranged on the main surface 14s, and the writing layer 130 is arranged on the first main surface 12s side of the optical filter layer 110 . The space FS on the side of the first main surface 12s of the whiteboard 100 is called the front side space FS, and the space RS on the side of the second main surface 14s is sometimes called the back side space RS.

The writing layer 130 may be a known layer having a writing surface on which writing and erasing can be repeated. Examples of known layers include a hard coat layer and a glass layer. As the optical filter layer 110, as will be described later with reference to FIGS. 8, 9 and 10, the optical filter described in International Application PCT/JP2021/010413 filed by the present applicant is preferably used as the optical filter layer 110. However, it is not limited to this, and an optical filter having a high linear transmittance of infrared rays and a high diffuse reflectance of visible light, for example, an optical camouflage filter described in Patent Document 4 can also be used. In this specification, "infrared radiation" includes at least light (electromagnetic waves) with a wavelength in the range of 780 nm or more and 2000 nm or less. Moreover, "visible light" refers to light within the range of 400 nm or more and less than 780 nm.

When the optical laminate is used as a visible light shielding IR transmitting sheet, it may further have a decorative layer arranged on the front side of the optical filter layer. The decorative layer can have a design that matches the surrounding design. The design of the decorative layer is not particularly limited and may be, for example, a wood grain pattern, a tile pattern, or a single color. The design of the decorative layer is preferably composed of a material that transmits infrared rays. (colorant such as ink) may be used. The decorative layer can be formed, for example, on the optical filter layer by a known method such as printing. The decorative layer can also be formed by laminating a film or the like having a design.

A visible light shielding IR transmissive sheet can, for example, prevent participants from seeing infrared detection devices or position sensors when placing them around or to the side of a projection screen or whiteboard. For example, if a decorative layer with a wood grain tone is used, it is possible to provide a space that is familiar to the interior and allows participants to be in a natural state.

You may further have a protective layer arranged on the front side of the optical filter layer. The protective layer may be formed on the optical filter layer 110, or may be formed on the decorative layer when the decorative layer is provided on the front side of the optical filter layer. The protective layer may be, for example, a known hardcoat layer, antiglare layer, antireflection layer, and/or antifouling layer.

An adhesive layer (including a pressure-sensitive adhesive layer) may be provided between the layers that make up the optical laminate, if necessary. Also, the plurality of layers may have a base layer for supporting the layer that expresses the function of each layer. The base material layer is appropriately selected so as not to impair the optical properties of the optical layered body.

As shown in FIG. 1, the whiteboard 100 is preferably used in a meeting for the purpose of brainstorming, for example, where the whiteboard is utilized by a plurality of users P1, P2 and P3. The user P1 or the like writes various patterns such as characters, symbols, and illustrations on the writing surface of the whiteboard 100 using, for example, a marker. Alternatively, the user P1 or the like writes various patterns on the sticky note 12 using a marker or the like, and sticks the sticky note 12 on the writing surface of the whiteboard 100 . The size of the whiteboard 100 is not particularly limited, and for example, it may be arranged over the entire inner wall surface of the room.

Like the optical filter layer 110, the sticky note 12 preferably has an optical filter layer with a high linear transmittance of infrared rays and a high diffuse reflectance of visible light, and has a known writing layer on the optical filter layer. preferably. Inks used for markers and the like may or may not transmit infrared rays. When ink that does not transmit infrared rays is used, various patterns written with a marker or the like can be obtained by an infrared detection device. On the other hand, if ink that transmits infrared rays is used, the image of the user P1 or the like can be obtained by the infrared detection device without being blocked by various patterns written using a marker or the like. The infrared transmittance of ink can be set arbitrarily. A plurality of types of ink with different infrared transmittances may be prepared and used according to the purpose.

The infrared information acquisition system 200 according to the embodiment of the present invention, as shown in FIG. of

infrared detectors

210a and 210b. In FIG. 2, hollow arrows represent visible light VL and simple arrows represent infrared IR. Since the infrared information acquisition system 200 has a plurality of

infrared detection devices

210a and 210b, it is possible to acquire an image of the user P1 or the like with high accuracy. For example, a high-definition image can be acquired by dividing the area of the whiteboard 100, providing

infrared detection devices

210a and 210b, etc. for each area, and emitting infrared rays toward different areas. can be done. Also, by acquiring images of a specific user P1 or the like from different angles, for example, the shape of the face can be precisely measured. Alternatively, for example, different types of infrared detection devices may be arranged according to purposes such as motion detection and face image acquisition. Also, an infrared detection device focused on the writing surface of the whiteboard 100 and an infrared detection device focused at a distance of, for example, 20 cm to 50 cm from the whiteboard 100 may be arranged. In this specification, "infrared information" includes various patterns written on the writing surface of the whiteboard 100, image information obtained from the user P1, etc., three-dimensional information (shape information, distance information), and the like. A known infrared detection device may be selected according to the required information. The

infrared detectors

210a, 210b are, for example, three-dimensional sensors or cameras. There is no limit to the number and arrangement of infrared detectors.

As illustrated here, the infrared information acquisition system 200 may further include infrared

light source devices

220a and 220b arranged on the back side of the whiteboard 100 so as to emit infrared rays toward the whiteboard 100. For example, a plurality of infrared

light source devices

220a and 220b may be arranged corresponding to a plurality of

infrared detection devices

210a and 210b. At this time, for example, the operations of the infrared

light source devices

220a and 220b may be synchronized with the operations of the

infrared detection devices

210a and 210b.

The infrared information acquisition system 200 may further have a position sensor 230 . At this time, according to the output of the position sensor 230, it can be configured to selectively operate one of the plurality of

infrared detection devices

210a and 210b. For example, the position sensor 230 identifies a user who is close to the whiteboard 100, operates only one of the infrared

light source devices

220a and 220b according to the position of the user, and detects the

infrared detection devices

210a and 210b. 210b may be activated (eg, see FIG. 7).

The conference support system has an infrared information acquisition system 200 and a computer 500. The computer 500 operates as a facial expression recognition device (for example, the facial expression recognition device 513 in FIG. 4) that recognizes the user's facial expression based on infrared information acquired via the whiteboard 100 by the infrared information acquisition system 200, for example. and a storage device 520 capable of storing the facial expression information recognized by the facial expression recognition device in association with the position of the whiteboard 100 and acquisition time. The facial expression recognition device may be configured to further estimate an emotion based on facial expression information. Alternatively, emotion information corresponding to facial expression information may be stored in storage device 520 in advance. Note that the computer 500 can also control the infrared information acquisition system 200 .

The processor 510 is a pattern recognition device (for example, a 4) as a pattern recognizer 514). Information on the pattern recognized by the pattern recognition device is stored in the storage device 52 in association with the position of the whiteboard 100 and the acquisition time. The processor 510 may also act as a character conversion device (eg, 515 in FIG. 4) that converts the recognized pattern information into character information. Infrared absorbing inks are widely available commercially, for example, inks containing carbon, oil-based inks, dyes or pigments.

The processor 510 can also operate as a motion recognition device (for example, the motion recognition device 516 in FIG. 4) that recognizes the user's motion based on the infrared information acquired via the whiteboard 100 by the infrared information acquisition system. .

The processor 510 also operates as an image processing device (for example, the image processing device 512 in FIG. 4) that performs various image processing based on the infrared information acquired via the whiteboard 100 by the infrared information acquisition system. can. Processor 510 can perform various operations according to a program (software). The operations performed by the processor 510 may vary depending on the signals (information) output from the

infrared detectors

210a, 210b. Programs for controlling processor 510 may be stored in storage device 520, for example.

The computer 500 may further have an output device (eg, the communication/input/output device 530 in FIG. 4) that outputs various information obtained by the processor 510. The information to be output may be information stored in storage device 520 . For example, information about facial expressions (emotions) can be displayed, for example, on the computer screens of people participating in a meeting via a network.

The whiteboard 100 is configured to forward scatter visible light incident from the back, and also functions as a rear projection type projection screen. The conference support system 300 may further include

projection devices

310 a and 310 b arranged behind the whiteboard 100 and configured to emit visible light toward the whiteboard 100 . Here, an example of having two

projection devices

310a and 310b corresponding to different regions of the whiteboard 100 is shown, but the number of projection devices may be one, or three or more projection devices may be provided. .

Projection devices

310a and 310b form a predetermined visible light pattern (pattern 100R in FIG. 1) on the back surface of whiteboard 100, for example, based on facial expression (or emotion) information recognized by the facial expression recognition device. is configured to The pattern may be, for example, a pattern of colors corresponding to a recognized facial expression (emotion). The area onto which the pattern is projected includes, for example, the area on whiteboard 100 where the facial expression (emotion) is obtained. Further, by projecting and sharing the information written on the whiteboard 100, it is possible to produce an effect as if the users exist in the same space even if they are remote.

Next, refer to Figure 3. FIG. 3 is a diagram schematically illustrating the construction and optical properties of a projection screen/whiteboard 100 according to an embodiment of the invention.

As shown in FIG. 3 , the whiteboard 100 has an optical filter layer 110 , a base layer 120 supporting the optical filter layer 110 , and a writing layer 130 arranged on the optical filter layer 110 . The optical filter layer 110 has a linear transmittance of 60% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less, and diffusely reflects visible light. Details of the optical filter layer 110 will be described later with reference to FIGS. The base material layer 120 has mechanical strength as a whiteboard and has a high infrared transmittance. The base layer 120 may be formed of transparent plastic such as acrylic resin, for example. The thickness of the base material layer 120 is, for example, about 2 μm or more and about 10 cm or less. The writing layer 130 is, for example, a hard coat layer or a glass layer. The thickness of the writing layer 130 is, for example, about 2 μm or more and about 1 cm or less. The substrate layer 120 and/or the writing layer 130 may be omitted when used only as a visible light blocking IR transmitting sheet or projection screen.

In FIG. 3, the white arrow represents visible light VL, and the simple arrow represents infrared light IR. Ambient light incident on the whiteboard 100 from the writing layer 130 side, that is, from the user P1 side includes visible light VLa and infrared light IRa. Visible light VLa is backscattered (diffuse reflected) at the optical filter layer 110 (VLabs). The backscattered (diffuse reflected) visible light VLabs allows the whiteboard 100 to appear isotropically white. The transmitted visible light VLat is less intense than the backscattered (diffuse reflected) visible light VLabs. On the other hand, since the infrared transmittance of the optical filter layer 110 is high, the intensity of the transmitted infrared rays IRat is greater than that of the reflected infrared rays IRar. Reflected infrared IRar includes backscattered (diffuse reflected) infrared.

The infrared rays IRo emitted from the infrared light source device 220a or the like pass through the optical filter layer 110 with high infrared transmittance (transmitted infrared rays IRot). Part of the transmitted infrared radiation IRot is reflected by the user P1 (reflected infrared radiation IRotr) and is transmitted through the optical filter layer 110 again (transmitted infrared radiation IRotrt). The transmitted infrared rays IRotrt are received by the infrared detection device 210a or the like. From the received infrared rays, the facial image of the user P1 or the like and infrared information on the actions can be obtained. Similarly, infrared information is obtained that includes the pattern written on the writing surface of whiteboard 100 .

When the ambient infrared rays IRa are sufficiently strong, the infrared light source device 220a and the like can be omitted and the reflected infrared rays IRar can be used. However, more accurate infrared information can be obtained by using the infrared rays IRo emitted from the infrared light source device 220a or the like. Further, by emitting infrared rays IRo having a predetermined pattern (for example, a pattern of many dots), infrared information with higher accuracy can be obtained. Also, by synchronizing the operation of the infrared light source device 220a and the like with the operation of the infrared detection device 210a and the like, infrared information with higher accuracy can be obtained. Of course, by combining these, infrared information with higher accuracy can be obtained. At this time, the infrared rays IRa contained in the ambient light may be reduced.

On the other hand, the visible light VLp emitted from the projection device 310a enters the optical filter layer 110, becomes forward scattered visible light VLpfs, and is visually recognized by the user P1 and the like. Preferably, no infrared rays are emitted from the projection device 310a.

The whiteboard 100 can hide the

infrared detection devices

210a and 210b, the infrared

light source devices

220a and 220b, and/or the

projection devices

310a and 310b, the computer 500, and the position sensor 230, for example, from the user. Note that the computer 500 does not necessarily need to be placed in the same space (room) as the user.

Since the user is in the front space FS of the whiteboard 100, the rear space RS can be made darker than the front space FS. At this time, the brightness (illuminance) of the space is measured, for example, at a height of 100 cm from the floor, with the receiver of an illuminometer (for example, Spectromaster C-800 manufactured by Sekonic Co., Ltd.) facing upward (ceiling towards). For example, the illuminance of the front side space FS is about 300 lux or more, and the illuminance of the back side space RS can be easily reduced to less than about 200 lux. When there is such an illuminance difference, if the transmitted visible light VLat that is incident on the whiteboard 100 from the first main surface 12s and transmitted is strong, for example, it hits the infrared detector 210a, is reflected, and is transmitted through the whiteboard 100 again. , the infrared detection device 210a may be visually recognized by the user when reaching the first main surface 12s side. The whiteboard 100 can prevent this.

When the distance from the second main surface 14s to the object (for example, the infrared detection device 210a) is 9 cm or more, the whiteboard 100 sees the object from the first main surface 12s side, as will be described later with an embodiment. You can make it impossible. Also, even if the distance from the second main surface 14s to the object is 1 cm, the object can be made invisible from the first main surface 12s side. The visible light linear transmittance of such a whiteboard 100 is, for example, 20.0% or less. Also, the visible light diffuse transmittance of the whiteboard 100 is higher than the linear transmittance by, for example, 2% or more. The diffuse transmittance of visible light of the whiteboard 100 is, for example, 10.0% or more and 40.0% or less.

By controlling the thickness of the optical filter layer 110, optical characteristics such as infrared linear transmittance, visible light linear transmittance, and visible light diffuse reflectance can be adjusted. In addition to the optical filter layer 110, a semi-reflective layer that partially reflects visible light (also referred to as a “visible light transmissive reflective layer”) is provided on the second main surface 14s side of the optical filter layer 110. Further provision can adjust the visible light in-line transmittance and/or the visible light diffuse reflectance. At this time, a semi-reflective layer having polarization selectivity may be used.

The whiteboard 100 can form a projected image having a sufficient luminance difference on the first principal surface 12s when the image is projected onto the second principal surface 14s. As will be described later with examples, for example, when projected onto a general projection screen (for example, PRS-KBHD80 manufactured by Sanwa Supply Co., Ltd.), a checkered pattern with a black-and-white luminance difference of 235 cd/cm ² is used as the second pattern. When projected onto the second main surface 14s, a projection image having a luminance difference of 20 cd/cm ² or more between black and white can be formed on the first main surface 12s. The contrast ratio (black and white luminance difference) can be improved by using a whiteboard 100 with a polarization-selective semi-reflective layer and using a projection device capable of projecting polarized light.

FIG. 4 shows a block diagram of a configuration example of the infrared information acquisition system 200 and the conference support system 300 according to the embodiment of the present invention.

The infrared information acquisition system 200 has a whiteboard 100,

infrared detection devices

210a and 210b, and infrared

light source devices

220a and 220b. The infrared detection device 210a operates in synchronization with the infrared light source device 220a, and the infrared detection device 210b operates in synchronization with the infrared light source device 220b. The infrared information acquisition system 200 further has a position sensor 230, and depending on the position of the user detected by the position sensor 230, infrared detection device 210a and infrared light source device 220a or infrared detection device 210b and infrared light source device 220b. operates selectively. Infrared information acquisition system 200 is controlled by computer 500 .

The conference support system 300 has a projection device 310 and a speaker 320 in addition to the infrared information acquisition system 200 . Conference support system 300 is also controlled by computer 500 . Computer 500 includes, for example, processor 510 , storage device 520 , communication/input/output device 530 , operating unit 540 and display device 550 . The processor 510 variously processes the infrared information obtained from the

infrared detectors

210 a and 210 b via the communication/input/output device 530 . By installing programs (software) stored in the storage device 520, for example, the processor 510 operates as an image processing device 512, a facial expression recognition device 513, a pattern recognition device 514, a character conversion device 515, and a motion recognition device 516. can operate as A known program can be used as a program for executing each process. The storage device 520 stores the processing results of the processor 510 (e.g., facial expression (emotion) information, motion information, patterns and character information formed on the whiteboard 100 using infrared absorbing ink) at the position of the whiteboard 100 and acquires them. It can be stored in association with time. Computer 500 can be managed and controlled by a user using operation unit 540 and display device 550 .

Meeting support system 300 forms a predetermined pattern of visible light (which may include an image) on the back of whiteboard 100 by projection device 310 based on facial expression (emotion) information obtained by processing of processor 510 . do. Also, the conference support system 300 can output a predetermined sound from the speaker 320 based on the facial expression (emotion) information obtained by the processing of the processor 510 . These visual and/or audible effects aid in meetings such as brainstorming. Also, facial expression (emotion) information obtained by the processing of the processor 510 can be shared, for example, with people participating in the conference via a network. Also, facial expression (emotion) information can be associated with patterns and character information formed on the whiteboard 100 using infrared absorbing ink.

An example of the operation of the conference support system 300 will be described with reference to FIGS. 5, 6 and 7. FIG. Emotional information and character information can be associated by performing each step of the flow chart shown in FIG. By performing each step of the flow chart shown in FIG. 6, a visual effect can be given by the projection device in association with the action. By performing each step of the flow chart shown in FIG. 7, the whiteboard 100 is divided into left and right regions, and the infrared light source device and the imaging device as the infrared detection device provided for each region are selectively selected according to the position of the user. can be operated.

FIG. 5 is a flow chart showing an example of the operation of the conference support system 300 according to the embodiment of the present invention. The following steps are performed.

(Step S11)
Infrared rays IR1 are emitted from the rear surface of the optical layered body 100 from the infrared light source device 220a.

(Step S12)
Infrared detection device 210a acquires the image of user P1 as image data IMG1. The image data IMG1 recognizes not only the user P1, but also a plurality of people such as the user P2 and the user P3, and acquires their respective images.

(Step S13)
The obtained object signal IMG1 is taken into the computer 500, and the image processing device 512 in the processor 510 performs face extraction processing via the communication/input/output device 530. FIG.

(Step S14)
The face information is stored in the storage device 520 .

(Step S15)
The obtained face information is compared with the emotion reference code stored in advance in the facial expression recognition device 513 to estimate the emotion.

(Step S21)
Infrared rays IR2 are emitted from the rear surface of the optical layered body 100 from the infrared light source device 220b.

(Step S22)
The infrared detection device 210b acquires the design or characters written directly on the sticky note 12 or the optical layered body 100 as image data IMG2. The image data IMG2 may be used to obtain user information as well as information on the optical layered body.

(Step S23)
The obtained signal IMG2 is taken into the computer 500, and the pattern recognition device 514 in the processor 510 through the communication/input/output device 530 extracts characters and patterns.

(Step S24)
Character and design information is stored in the storage device 520 .

(Step S25)
The obtained character and pattern information is collated with the character reference code stored in advance in the character conversion device 515 to estimate the character.

(Step S26)
A predetermined display code corresponding to the emotion obtained in step S15 is reflected in the character information obtained in step S25, and the display code is sent from the display control device 517 to the projection device 310 and the speaker 320 via the communication/input/output device 530. to reflect the emotion code in the character display method. The emotion code may be expressed by changing the color of the characters, or by combining the color, brightness, blinking, etc. of the lighting. Also, it may be reflected in the voice.

(Step S27)
The obtained information is shared with a remote system using the communication/input/output device 530, and the information is reflected on the projection device 310 and the speaker 320 at each location.

FIG. 6 is a flow chart showing another example of the operation of the conference support system 300 according to the embodiment of the present invention. The following steps are performed.

(Step S31)
The position sensor 230 emits an infrared ray L1.

(Step S32)
A position sensor 230 detects the motion/body position.

(Step S33)
A short history of detected motions is matched with stored motions by motion recognition device 516 in computer 500 and stored.

(Step S34)
Infer more complex motions from the tracked motions and match them with the stored motions.

(Step S35)
Whether or not the motion has meaning is determined by comparing it with the stored motion.

(Step S36)
Emotions are estimated by comparing actions and basic chords. Emotions may be feelings such as surprise, joy, or anger, or may be emphasis on meetings such as importance or attention. Emotions are read from actions, a predetermined display code is reflected, and the emotion code is reflected by the projection device 310 or the speaker 320 from the display control device 517 via the communication/input/output device 530 . As a method of expressing the emotion code, the color of the characters may be changed, or the color of the lighting, the illuminance, blinking, etc. may be combined. Also, it may be reflected in the voice.

Next, details of the optical filter layer 110 will be described with reference to FIGS. 8, 9 and 10. FIG.

The optical filter layer 110 preferably used in the optical laminate (visible light shielding IR transmitting sheet, projection screen or whiteboard) according to the embodiment of the present invention is an optical filter layer containing a matrix and fine particles dispersed in the matrix. 110, the fine particles form at least colloidal amorphous aggregates, and have a linear transmittance of 60% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less. For example, it is possible to obtain the optical filter layer 110 having a linear transmittance of 60% or more for light with wavelengths of 950 nm and 1550 nm. The wavelength range of light (near infrared rays) in which the in-line transmittance of the optical filter layer 110 is 60% or more is preferably, for example, 810 nm or more and 1700 nm or less, more preferably 840 nm or more and 1650 nm or less. Here, both the matrix and the fine particles are preferably transparent to visible light (hereinafter simply referred to as "transparent"). The optical filter layer 110 can appear white.

The optical filter layer 110 contains colloidal amorphous aggregates. A colloidal amorphous aggregate refers to an aggregate of colloidal particles (particle size of 1 nm to 1 μm) that does not have long-range order and does not cause Bragg reflection. When colloidal particles are distributed in a long-range order, they become so-called colloidal crystals (a type of photonic crystal), which is in contrast to Bragg reflection. That is, the fine particles (colloidal particles) included in the optical filter layer 110 do not form a diffraction grating.

The microparticles included in the optical filter layer 110 include monodisperse microparticles having an average particle diameter of 1/10 or more of the wavelength of infrared rays. That is, the average particle diameter of the fine particles is preferably at least 80 nm or more, preferably 150 nm or more, and more preferably 200 nm or more for infrared rays having a wavelength in the range of 780 nm or more and 2000 nm or less. Two or more monodisperse microparticles having different average particle diameters may be included. Individual microparticles are preferably approximately spherical. In the present specification, fine particles (plurality) are also used to mean aggregates of fine particles, and monodisperse fine particles mean that the coefficient of variation (value expressed as a percentage of standard deviation/average particle size) is 20% or less, Preferably 10% or less, more preferably 1 to 5%. The optical filter layer 110 uses particles having a particle diameter (particle diameter, equivalent volume sphere diameter) equal to or greater than 1/10 of the wavelength, thereby increasing the linear transmittance of infrared rays.

The average particle size was obtained here based on a three-dimensional SEM image. Specifically, as a focused ion beam scanning electron microscope (hereinafter referred to as "FIB-SEM"), a model number Helios G4 UX manufactured by FEI is used to acquire continuous cross-sectional SEM images and correct the continuous image position. After that, the three-dimensional image was reconstructed. Specifically, acquisition of a cross-sectional backscattered electron image by SEM and FIB (accelerating voltage: 30 kV) processing were repeated 100 times at intervals of 50 nm to reconstruct a three-dimensional image. The resulting three-dimensional image was binarized using the segmentation function of analysis software (AVIZO manufactured by Thermo Fisher Scientific) to extract the image of the fine particles. Next, in order to identify individual microparticles, the Separate object operation was performed, and then the volume of each microparticle was calculated. Assuming that each particle is a sphere, the diameter equivalent to volume sphere was calculated, and the value obtained by averaging the particle diameters of the fine particles was taken as the average particle diameter.

The optical filter layer 110 has a wavelength range of 780 nm or more and 2000 nm or less by adjusting any one of the refractive index of the particles and the matrix, the average particle size of the particles, the volume fraction, the distribution (degree of aperiodicity) and the thickness. 60% or more of the linear transmittance for light of at least part of the wavelengths.

The optical filter layer 110 can appear white. Here, white means that the x and y coordinates on the CIE1931 chromaticity diagram when the standard light is D65 light source are within the range of 0.25 ≤ x ≤ 0.40 and 0.25 ≤ y ≤ 0.40. refers to what is in Of course, the closer to x = 0.333 and y = 0.333, the higher the whiteness, preferably 0.28 ≤ x ≤ 0.37, 0.28 ≤ y ≤ 0.37, more preferably 0 .30≤x≤0.35 and 0.30≤y≤0.35. Also, L ^* measured by the SCE method on the CIE1976 color space is preferably 20 or more, more preferably 40 or more, even more preferably 50 or more, and particularly preferably 60 or more. If L ^* is 20 or more, it can be said to be substantially white. The upper limit of L ^* is 100, for example.

A schematic cross-sectional view of the optical filter layer 110 is shown in FIG. The optical filter layer 110 includes a matrix 112 transparent to visible light and transparent fine particles 114 dispersed in the transparent matrix 112 . Fine particles 114 behave as light scatterers. The optical filter layer 110 includes a layer in which fine particles 114 serving as light scatterers are dispersed in a matrix 112 . Microparticles 114 may, for example, constitute at least colloidal amorphous aggregates. At this time, other fine particles may be included that do not disturb the colloidal amorphous aggregates formed by the fine particles 114 .

The optical filter layer 110 has a substantially flat surface, as schematically shown in FIG. Here, the term "substantially flat surface" refers to a surface that does not have an uneven structure large enough to scatter (diffract) or diffusely reflect visible light or infrared light. Note that the optical filter layer 110 is, for example, film-like, but is not limited to this.

The transparent fine particles 114 are silica fine particles, for example. As the silica fine particles, for example, silica fine particles synthesized by the Stover method can be used. As the fine particles, inorganic fine particles other than silica fine particles may be used, and resin fine particles may be used. As the resin fine particles, for example, fine particles made of at least one of polystyrene and polymethyl methacrylate are preferable, and fine particles made of crosslinked polystyrene, crosslinked polymethyl methacrylate or crosslinked styrene-methyl methacrylate copolymer are preferable. More preferred. As such fine particles, for example, polystyrene fine particles or polymethyl methacrylate fine particles synthesized by emulsion polymerization can be appropriately used. Hollow silica fine particles and hollow resin fine particles containing air can also be used. Fine particles made of an inorganic material have the advantage of being excellent in heat resistance and light resistance. The volume fraction of the whole fine particles (including the matrix and fine particles) is preferably 6% or more and 60% or less, more preferably 20% or more and 50% or less, and even more preferably 20% or more and 40% or less. The transparent microparticles 114 may have optical isotropy.

Examples of matrix 112 include, but are not limited to, acrylics (eg, polymethyl methacrylate, polymethyl acrylate), polycarbonates, polyesters, poly(diethylene glycol bisallyl carbonate), polyurethanes, epoxies, and polyimides. . The matrix 112 is preferably formed using a curable resin (thermosetting or photocurable), and is preferably formed using a photocurable resin from the viewpoint of mass productivity. Various (meth)acrylates can be used as the photocurable resin. (Meth)acrylates preferably include bifunctional or trifunctional (meth)acrylates. Also, the matrix 112 preferably has optical isotropy. When a curable resin containing a polyfunctional monomer is used, the matrix 112 having a crosslinked structure can be obtained, so heat resistance and light resistance can be improved.

The optical filter layer 110 in which the matrix 112 is made of a resin material may be flexible and film-like. The thickness of the optical filter layer 110 is, for example, 10 μm or more and 10 mm or less. If the thickness of the optical filter layer 110 is, for example, 10 μm or more and 1 mm or less, or further 10 μm or more and 500 μm or less, the flexibility can be exhibited remarkably.

When silica fine particles with hydrophilic surfaces are used as the fine particles, it is preferable to form them, for example, by photocuring a hydrophilic monomer. Examples of hydrophilic monomers include polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, polyethylene glycol tri(meth)acrylate, polypropylene glycol (meth)acrylate, polypropylene glycol di(meth)acrylate, polypropylene glycol tri(meth)acrylate, ) acrylate, 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate, acrylamide, methylenebisacrylamide, ethoxylated bisphenol A di(meth)acrylate, but not limited to . These monomers may be used singly or in combination of two or more. Of course, the two or more types of monomers may include a monofunctional monomer and a multifunctional monomer, or may include two or more types of multifunctional monomers.

These monomers can be cured using a photopolymerization initiator as appropriate. Examples of photopolymerization initiators include carbonyl compounds such as benzoin ether, benzophenone, anthraquinone, thioxane, ketal, and acetophenone; sulfur compounds such as disulfide and dithiocarbamate; organic peroxides such as benzoyl peroxide; azo compounds; complexes, polysilane compounds, dye sensitizers, and the like. The amount to be added is preferably 0.05 to 3 parts by mass, more preferably 0.05 to 1 part by mass, based on 100 parts by mass of the mixture of the fine particles and the monomer.

Where n _M is the refractive index of the matrix with respect to visible light, and n _P is the refractive index of the fine particles, |n _M −n _P | (hereinafter sometimes simply referred to as refractive index difference) is 0.01 or more. is preferably 0.6 or less, more preferably 0.03 or more, and more preferably 0.11 or less. If the refractive index difference is less than 0.03, the scattering intensity becomes weak, making it difficult to obtain desired optical properties. In addition, if the refractive index difference exceeds 0.11, the in-line infrared transmittance may decrease. Further, for example, by using zirconia fine particles (refractive index: 2.13) and acrylic resin, if the difference in refractive index is set to 0.6, the linear transmittance of infrared rays can be adjusted by reducing the thickness. can be done. Thus, the infrared in-line transmittance can also be adjusted, for example, by controlling the thickness and refractive index difference of the optical filter layer. In addition, depending on the application, it can be used by overlapping with a filter that absorbs infrared rays. Note that the refractive index for visible light can be represented by the refractive index for light of 546 nm, for example. Here, unless otherwise specified, the refractive index refers to the refractive index for light of 546 nm.

FIG. 9 is a diagram showing a cross-sectional TEM image of the optical filter layer 110. FIG. The white circles in the TEM image in the figure are the silica fine particles, and the black circles are traces of the silica fine particles falling off. As shown in the cross-sectional TEM image of the optical filter layer 110, silica fine particles are dispersed almost uniformly.

FIG. 10 is a graph normalized by the maximum transmittance, showing the incident angle dependency of the linear transmittance spectrum of the optical filter layer 110. FIG. Looking at the transmittance curve of the optical filter layer 110 shown in FIG. 10, the curve portion where the linear transmittance monotonously increases from visible light to infrared rays shifts to the longer wavelength side (about 50 nm) as the incident angle increases. there is In other words, the curve portion where the linear transmittance monotonously decreases from infrared to visible light shifts to the long wavelength side as the incident angle increases. This characteristic incident angle dependence is considered to be due to the fact that the silica fine particles contained in the optical film form colloidal amorphous aggregates. Details of the structure, optical characteristics, and manufacturing method of the optical filter layer 110 are described in International Application PCT/JP2021/010413 filed by the present applicant. The entire disclosure of International Application PCT/JP2021/010413 is incorporated herein by reference. Figures 9 and 10 are the results of Example 1 described in the above international application.

Next, examples (Examples 1 to 5 and Comparative Examples 1 to 3) of the optical filter layer and the optical laminate having the optical filter layer described in the above international application will be described. Here, the optical filter of Example 6 (having an optical filter layer formed on a PET film) described in the above-mentioned international application with the thickness of the optical filter layer changed to 200 μm was used. In addition, the effect of the PET film on the optical properties is slight, and the optical properties are almost the same as those of an optical laminate in which an optical filter layer is formed directly on a semi-reflective layer formed of a material that partially reflects visible light. are the same.

A semi-reflective layer that partially reflects visible light (visible light transmissive reflective layer) has transmission and reflection properties that reflect part of incident visible light and transmit the remaining visible light. The visible light transmittance of the semi-reflective layer is preferably 10% to 70%, more preferably 15% to 65%, even more preferably 20% to 60%. The reflectance of the semi-reflective layer is preferably 30% or higher, more preferably 40% or higher, and even more preferably 45% or higher. With respect to infrared rays, it preferably has a transmittance characteristic of 10% or more, more preferably 15% or more, and still more preferably 20% or more. As the semi-reflective layer, for example, a half mirror, a reflective polarizer, a louver film, or the like can be used.

As the half mirror, for example, a multi-layer laminate in which two or more dielectric films having different refractive indices are laminated can be used. Such half mirrors preferably have a metallic luster. Materials for forming the dielectric film include metal oxides, metal nitrides, metal fluorides, thermoplastic resins (eg, polyethylene terephthalate (PET)), and the like. A multilayer laminate of dielectric films reflects a part of incident light at an interface due to the difference in refractive index between the laminated dielectric films. The reflectance can be adjusted by changing the phase of the incident light and the reflected light by adjusting the thickness of the dielectric film and adjusting the degree of interference between the two lights. The thickness of the half mirror made of a multilayer laminate of dielectric films can be, for example, 50 μm or more and 200 μm or less. As such a half mirror, for example, a commercially available product such as Toray's product name "Picasus" can be used.

A reflective polarizer has the function of transmitting polarized light in a specific polarization state (polarization direction) and reflecting light in other polarization states. The reflective polarizer may be linearly polarized or circularly polarized, but linearly polarized is preferred. The linear polarization separation type reflective polarizer is arranged so that the reflection axis direction is substantially parallel to the absorption axis direction of the absorption polarizer (specifically, the first polarizer and the second polarizer). placed.

As the linearly polarized light separation type reflective polarizer, for example, the one described in JP-A-9-507308 can be used. Examples of commercially available products include Nitto Denko's trade name "APCF", 3M trade name "DBEF", and 3M trade name "APF". Moreover, a commercially available product may be used as it is, or a commercially available product may be used after secondary processing (for example, stretching). Examples of the circularly polarized light separation type reflective polarizer include a laminate of a film in which cholesteric liquid crystal is fixed and a λ/4 plate. A wire grid type polarizing layer can also be used.

The optical properties of the optical layered bodies of Examples 1 to 5 are shown in Table 1, and the results of evaluating the optical properties of the optical layered bodies of Comparative Examples 1 to 3 are shown in Table 2.

Evaluation of performance as a projection screen was performed as follows. Using a short-focus projector (Ricoh Co., Ltd., PJWX4152N), when projected onto a general projection screen (Sanwa Supply Co., Ltd. PRS-KBHD80), the black and white luminance difference is 235 cd / cm ² optically. The black and white luminance difference (cd/cm ² ) of the projected image formed on the front surface (first main surface 12s) when projected onto the rear surface (second main surface 14s) of the laminate was determined. The length of one side of the squares forming the black and white checkered pattern was 5 mm. LUMINANCEMETER LS-150 manufactured by Konica Minolta Japan, Inc. was used to measure luminance. The illuminance of the back side space RS was about 160 lux, and the illuminance of the front side space FS was 542 lux. These illuminances were measured at a height of 100 cm from the floor surface with the light receiver of an illuminometer (Spectromaster C-800 manufactured by Sekonic Co., Ltd.) facing upward. Each sample of the optical laminate was also placed at a height of about 100 cm from the floor.

VIS non-visibility is defined as good (OK) when an object (for example, an infrared detector product) cannot be clearly seen through each optical filter, and bad (NG) when an object can be clearly seen. For IR visibility, for example, using an infrared camera, through each optical filter, the object can be clearly visually recognized as good (OK), and the object cannot be clearly visually recognized as bad (NG). . Here, the ISO 12233 resolution chart was used as the object, and the evaluation was performed by changing the distance from the second main surface of the optical layered body to the object to 0 cm, 1 cm, 3 cm, and 9 cm. The smaller the distance from the object to the second main surface, the easier it is to visually recognize the object, and the greater the distance, the harder it is to visually recognize the object.

VIS diffuse transmittance and VIS direct transmittance represent the average transmittance (%) of visible light in the wavelength range of 350 nm or more and 780 nm or less, and IR linear transmittance is infrared rays (near infrared rays) in the wavelength range of 780 nm or more and 1350 nm or less. represents the average transmittance (%) of The diffuse transmittance is the transmittance measured with the optical layered body placed in the opening of the integrating sphere, and the visibility when the optical layered body is in contact with an object (for example, an infrared detector) (distance is 0 cm). correlates with On the other hand, the linear transmittance is the transmittance measured in a state where the optical laminate is placed at a certain distance (for example, 20 cm) from the opening of the integrating sphere, and the optical laminate is placed away from the object. Correlates with visibility in condition. As a spectrometer, an ultraviolet-visible-near-infrared spectrophotometer UH4150 (manufactured by Hitachi High-Tech Science Co., Ltd.) was used, and measurements were performed at intervals of 1 nm.

First, with reference to Table 2, the optical properties of the optical layered body of the comparative example will be described.

Comparative Example 1 is a cloudy plastic plate (made of polystyrene, thickness 0.5 mm). The projected checkered pattern image has a black and white luminance difference as large as 134 cd/cm ² , and can be used as a projection screen. In addition, if the VIS in-line transmittance is low and the object is placed at a distance of at least 1 cm, the object can be made invisible. However, the IR straight-line transmittance was low, and the IR visibility was NG even at 0 cm. In other words, infrared information (for example, a user's facial image) cannot be acquired via the optical layered body of Comparative Example 1.

Comparative Example 2 corresponds to Comparative Example A described in the above international application and corresponds to the optical article described in JP-A-2013-65052. In Comparative Example 1, the black and white luminance difference of the projected checkerboard pattern image is as low as 7.4 cd/cm ² , and it is difficult to use it as a projection screen. The VIS linear transmittance is as low as 11%, and the VIS non-visibility is good, but the IR linear transmittance is as low as 33%, and the IR visibility is OK only at 0 cm. difficult to fully recognize.

Comparative Example 3 is an optical layered body having a metal thin film, and does not transmit visible light or infrared light. Therefore, it cannot be used as a projection screen. Also, the VIS non-visibility is OK, but the IR visibility is NG regardless of the distance.

Next, refer to Table 1. As can be seen from Table 1, all of Examples 1 to 5 have a black-and-white luminance difference of 20 cd/cm ² or more in the projected checkered pattern image, and all of them can be used as projection screens. In addition, the VIS in-line transmittance is 20% or less in either case, and the object can be made invisible by arranging it at a distance of at least 1 cm from the object. Moreover, all of them have an IR linear transmittance of 40% or more, and all of them have an OK IR visibility.

Example 1 is the optical filter described above (having a thickness of 200 μm in Example 6 of the above international application) and has a high in-line IR transmittance. The VIS in-line transmittance is 20% or less, and the object can be made invisible by placing it at a distance of at least 1 cm from the object. In addition, it can be seen that the VIS diffuse transmittance is as high as 39% and the color is white. The black and white luminance difference of the projected checkerboard pattern image is as high as 160 cd/cm ² , indicating that it can be used as a projection screen.

Example 2 is an optical laminate having the above optical filter and a linearly polarized light separation type reflective polarizer.

Example 3 is an optical laminate having the above optical filter and a wire grid type polarized light reflecting layer.

Examples 2 and 3 have a semi-reflective layer with polarization selectivity. Although non-polarized light is projected here, the black and white luminance difference of the projected checkerboard pattern image can be improved by projecting linearly polarized light.

Example 4 is an optical laminate having the above optical filter and a half mirror composed of a dielectric multilayer film so as to transmit infrared rays.

Example 5 is an optical laminate having the above optical filter and a half mirror composed of a dielectric multilayer film with visible light transmittance adjusted to 50%.

In order to acquire infrared information such as a user's face image through the optical layered body, it is preferable that an object at a position several tens of cm or more away from the optical layered body can be accurately recognized, and the IR linear transmittance is , is preferably 50% or more, more preferably 60% or more, further preferably 80% or more.

Optical laminates with large black and white luminance difference and high IR linear transmittance (e.g., Examples 1, 2 and 4) tend to be inferior in VIS non-visibility, but are at least 1 cm from the object. Spaced apart, objects can be made invisible. Since the infrared detector and the projection device are not placed close to the optical laminate at a distance of less than 1 cm, there is no practical problem. Therefore, considering the distance between the object and the optical stack, it is also possible to use an optical stack with a better black-and-white luminance difference and/or IR in-line transmittance of the projected checkerboard pattern image. By adjusting the optical properties of the optical filter layer and/or the semi-reflective layer, the projected checkerboard image black and white luminance difference and/or the IR linear transmittance can be improved.

According to an embodiment of the present invention, for example, a meeting support system for supporting a meeting for the purpose of brainstorming, a visible light shielding IR transmission sheet suitably used for such a meeting support system, a projection screen, an optical system used as a whiteboard A laminate and an infrared information acquisition system are provided.

Claims

An optical laminate having a first main surface and a second main surface opposite to the first main surface,
It has an optical filter layer that transmits infrared rays and diffuses and transmits visible light,
When the first main surface side is brighter than the second main surface side, an object placed on the second main surface side and spaced apart from the second main surface side is viewed from the first main surface side. make it impossible,
An optical layered body having a linear transmittance of 40% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less.
When a checkered pattern with a black-and-white luminance difference of 235 cd/cm 2 is projected onto the second principal surface, a projection image having a black-and-white luminance difference of 20 cd/cm 2 or more can be formed on the first principal surface. Optical laminate.
The optical laminate according to claim 1 or 2, which has a linear transmittance of visible light of 20.0% or less.
The optical laminate according to any one of claims 1 to 3, wherein the diffuse transmittance of visible light is 10.0% or more and 40.0% or less.
The optical laminate according to any one of claims 1 to 4, further comprising a semi-reflecting layer arranged on the second main surface side of the optical filter layer and partially reflecting visible light.
The optical laminate according to claim 5, wherein the semi-reflective layer has polarization selectivity.
The optical laminate according to any one of claims 1 to 6, further comprising a decorative layer arranged on the first main surface side of the optical filter layer.
The optical layered body according to any one of claims 1 to 7, further comprising a surface protective layer disposed on the first main surface side of the optical filter layer.
a writing layer disposed on the first main surface side of the optical filter layer;
The optical laminate according to any one of claims 1 to 6, further comprising a substrate layer arranged on the second main surface side of the optical filter layer.
The optical filter layer has a matrix and fine particles that serve as light scatterers dispersed in the matrix, and has a linearity of 60% or more for light of at least part of the wavelength range of 780 nm or more and 2000 nm or less. The optical laminate according to any one of claims 1 to 9, which has transmittance.
The optical laminate according to claim 10, wherein the fine particles constitute at least colloidal amorphous aggregates.
The transmittance curve of the visible light wavelength region of the optical filter layer has a curve portion where the linear transmittance monotonically decreases from the long wavelength side to the short wavelength side, and the curve portion is on the long wavelength side as the incident angle increases. 12. The optical stack according to claim 10 or 11, which shifts to .
an optical laminate according to any one of claims 1 to 12;
a plurality of infrared detection devices disposed on the second main surface side of the optical laminate and spaced apart from the second main surface and arranged to receive infrared rays through the optical laminate; Infrared information acquisition system.
The infrared information acquisition system according to claim 13, further comprising at least one infrared light source device arranged to emit infrared rays toward said second main surface of said optical layered body.
The at least one infrared light source device includes a first infrared light source device and a second infrared light source device, and the first infrared light source device and the second infrared light source device are different from each other on the second main surface of the optical stack. 15. The infrared information acquisition system of Claim 14, configured to emit infrared light toward an area.
16. Any one of claims 13 to 15, further comprising a position sensor, configured to selectively operate one of the plurality of infrared detection devices according to the output of the position sensor. infrared information acquisition system.
The infrared information acquisition system according to any one of claims 13 to 16, wherein each of said plurality of infrared detection devices is a three-dimensional sensor or camera.
An infrared information acquisition system according to any one of claims 13 to 17;
a facial expression recognition device that recognizes facial expressions of a user based on infrared information acquired through the optical layered body by the infrared information acquisition system;
A meeting support system, comprising: a first storage device that stores information on the facial expression recognized by the facial expression recognition device in association with the position and acquisition time of the optical layered body.
The optical laminate further has a writing layer disposed on the first main surface side of the optical filter layer,
a pattern recognition device that recognizes a pattern formed using infrared absorbing ink on the writing layer of the optical layered body based on the infrared information acquired through the optical layered body by the infrared information acquisition system;
19. The meeting support system according to claim 18, further comprising a second storage device that stores information on the pattern recognized by said pattern recognition device in association with the position of said optical layered body and acquisition time.
The meeting support system according to claim 19, further comprising a character conversion device that converts the information of the recognized pattern into character information.
21. The conference support according to any one of claims 18 to 20, further comprising a motion recognition device that recognizes a user's motion based on infrared information acquired through said optical layered body by said infrared information acquisition system. system.
The meeting support system according to any one of claims 18 to 21, further comprising an output device for outputting information on said facial expression recognized by said facial expression recognition device.
further comprising a projection device disposed on the second main surface side of the optical layered body and configured to emit visible light toward the optical layered body;
The projection device is configured to form a predetermined pattern of visible light on the second main surface of the optical layered body based on the facial expression information recognized by the facial expression recognition device. A meeting support system according to any one of claims 18 to 22.
24. A meeting support system according to any one of claims 18 to 23, further comprising a communication device, configured to output said visible light pattern formed by said projection device via said communication device. .