WO2012153685A1

WO2012153685A1 - Three-dimensional video recognition system and video display device for three-dimensional video recognition system

Info

Publication number: WO2012153685A1
Application number: PCT/JP2012/061584
Authority: WO
Inventors: 雅浩長谷川; 坂井　彰
Original assignee: シャープ株式会社
Priority date: 2011-05-12
Filing date: 2012-05-02
Publication date: 2012-11-15

Abstract

The present invention provides a three-dimensional video recognition system capable of reducing crosstalk at an oblique viewing angle, and a video display device for the three-dimensional video recognition system. The present invention is a three-dimensional video recognition system which comprises a video display device having a first linear polarization element (113), a λ/2 plate (118) (NZ coefficient = NZ, h) on the first linear polarization element (113), a first λ/4 plate (114) (NZ coefficient ≤ 1) on the a λ/2 plate (118), and active shutter glasses (120) having a second λ/4 plate (121), a liquid crystal panel (122) and a second linear polarization element (123) in this order, satisfies 40°≤φ1≤50° and 130°≤φ2≤140° or 130°≤φ1≤140° and 40°≤φ2≤50°, and satisfies 85°≤φ3≤95° and 0.7≤NZ, h≤0.8 or -5°≤φ3≤5° and 0.2≤NZ, h≤0.3 where φ1 and φ2 are the angles between the transmission axes (113t, 123t) of the first and second linear polarization elements and the in-plane slow axes (114s, 121s) of the first and second λ/4 plates, respectively, and φ3 is the angle between the transmission axis (113t) of the first linear polarization element and the in-plane slow axis (118s) of the λ/2 plate.

Description

Stereoscopic video recognition system and video display device for stereoscopic video recognition system

The present invention relates to a stereoscopic video recognition system and a video display device for a stereoscopic video recognition system. More specifically, the present invention relates to an active shutter glasses method (hereinafter also referred to simply as an active method) stereoscopic image recognition system and an active display device for a stereoscopic image recognition system.

As a stereoscopic image recognition system using glasses, an anaglyph method, a passive glasses method (hereinafter also simply referred to as a passive method), an active method, and the like are known. Both the passive method and the active method use polarized glasses.

The anaglyph method has very poor display quality, and a phenomenon in which the left-eye image and the right-eye image appear to be mixed, so-called crosstalk, occurs.

In the passive method, the polarized glasses themselves can be manufactured lightly and inexpensively, but separate pixels need to be used to generate the left-eye image and the right-eye image. For this reason, a spatial resolution twice as high as that when displaying a normal flat image is required when displaying a stereoscopic image, and the resolution of a stereoscopic image is generally low. Also, the display quality is lower than that of the active method. Furthermore, it is necessary to pattern each pixel with a birefringent layer such as a λ / 2 plate or a λ / 4 plate, which increases the cost of the video display device.

The active method is excellent in display performance. For example, when the spatial resolution of a video display device for a stereoscopic video recognition system (hereinafter also referred to as a 3D display device) is full high-definition (1920 × 1080), the full-high-definition resolution is maintained. Display can be made. The main performance required for an active 3D display device is a high frame rate and a high-performance image processing capability, which can be satisfied even with current high-end video display devices. That is, it can be developed as a 3D display device even before the spread of 3D content without creating a special member in the video display device itself.

Hereinafter, polarized glasses used in the active method are also referred to as active shutter glasses.

As an active 3D image recognition system, for example, a technique using active shutter glasses having a pair of polarizing plates and a liquid crystal interposed between the pair of polarizing plates is disclosed (for example, see Patent Document 1). . However, flicker may be felt when viewing the screen other than the display screen of the 3D display device with the glasses on.

As a countermeasure against this flicker, a first polarizing filter disposed on the display surface, a second polarizing filter disposed in front of both eyes of the observer, and a liquid crystal enclosure interposed between the both polarizing filters are used. The technique to do is disclosed (for example, refer patent document 2).

Further, as a method for producing a birefringent film for a liquid crystal display, a laminate is formed by adhering a shrinkable film on one or both sides of a resin film, and the laminate is subjected to a heat stretching treatment to stretch the resin film. Has been disclosed (see, for example, Patent Document 3).

JP-A 61-227498 JP 2002-82307 A Japanese Patent No. 2818983

Here, with reference to FIGS. 17 and 18, a stereoscopic video recognition system 1100 according to the comparative example 1 using the technique of Patent Document 2 will be described.

As shown in FIGS. 17 and 18, the system 1100 includes a liquid crystal display 1110 that functions as a 3D display device, and active shutter glasses 1120. The liquid crystal display 1110 includes a linearly polarizing plate 1111, a liquid crystal panel (liquid crystal cell) 1112, and a linearly polarizing plate 1113 in this order from the back side. The transmission axis of the polarizing plate 1111 is set to 0 ° azimuth, and the transmission axis of the polarizing plate 1113 is set to 90 ° azimuth. The glasses 1120 include a liquid crystal panel (liquid crystal cell) 1122 and a linearly polarizing plate 1123 in this order from the outside. The transmission axis of the polarizing plate 1123 is set to 0 ° azimuth.

The polarizing plate 1113 on the viewer side of the liquid crystal display 1110 and the polarizing plate 1123 of the glasses 1120 are arranged in crossed Nicols. In the system 1100, the polarizing plate 1113 and the liquid crystal panel 1122 and the polarizing plate 1123 of the glasses 1120 obtain a shutter function. That is, the shutter function is exhibited only when the display area (display screen) of the liquid crystal display 1110 is observed. Therefore, when an area other than the display area (for example, a surrounding wall) is observed, the glasses 1120 having one polarizing plate 1123 do not function as a shutter, and thus the observer does not feel flicker.

However, in the system 1100, the following two problems occur depending on the liquid crystal mode of the liquid crystal panel 1122 of the glasses 1120.
(1) When the observer himself / herself tilts his / her face (glasses 1120), the shutter function is lowered and crosstalk occurs.
(2) When the observer tilts his face (glasses 1120), the screen becomes dark.

Note that the case where the observer himself / herself tilts his / her face includes a case where the observer lies on the floor and observes the screen.

The cause of the problem (1) will be described. Here, a case will be described in which the liquid crystal mode of the liquid crystal panel 1122 is set to a mode in which the shutter light shielding state (close) can be obtained in a state where the phase difference of the liquid crystal layer of the liquid crystal panel 1122 is zero.
(I) When the face is not tilted, the polarizing plate 1113 and the polarizing plate 1123 are in a crossed Nicol state, and the phase difference of the liquid crystal layer of the liquid crystal panel 1122 is zero. Therefore, the shutter is in a light shielding state (see FIG. 19).
(Ii) When the face is tilted by 90 °, the polarizing plate 1123 is also tilted by 90 °, and the relationship between the polarizing plate 1113 and the polarizing plate 1123 becomes parallel Nicols. Therefore, the shutter is in a translucent state (open) (see FIG. 20).
As described above, when the shutter should be in a light shielding state, the light is in a translucent state, so that crosstalk occurs.

The cause of the above problem (2) will be described. Here, a case where the liquid crystal mode of the liquid crystal panel 1122 is set to a mode in which the light transmission state of the shutter can be obtained in a state where the liquid crystals of the liquid crystal panel 1122 are arranged in a 45 ° azimuth direction will be described.
(I) When the face is not tilted, a liquid crystal layer set to a λ / 2 condition exists between the polarizing plate 1113 and the polarizing plate 1123 in the crossed Nicols state. Therefore, the shutter is in a light transmitting state (see FIG. 21).
(Ii) When the face is tilted by 90 °, the relationship between the polarizing plate 1113 and the polarizing plate 1123 becomes parallel Nicol, and a liquid crystal layer set to a λ / 2 condition exists between them. Therefore, the shutter is in a light shielding state (see FIG. 22).
In this way, when the shutter should be in a light-transmitting state, the screen is darkened, and the screen becomes dark.

Patent Document 2 discloses a stereoscopic video recognition system for solving the problems (1) and (2). FIG. 23 shows a configuration of a stereoscopic video recognition system 1200 according to comparative form 2 using the technique of Patent Document 2.

As shown in FIG. 23, the system 1200 includes a video display device 1210 that functions as a 3D display device and active shutter glasses 1220. The display device 1210 includes a CRT 1211, a linear polarization filter 1212, and a λ / 4 plate 1213 in this order from the back side. The glasses 1220 include a λ / 4 plate 1221, a liquid crystal panel 1222, and a linear polarization filter 1223 in this order from the outside.

In the system 1200, the light emitted from the display device 1210 can be circularly polarized. Therefore, even when the observer himself / herself tilts his / her face (glasses 1220), the shutter function does not deteriorate as in the system 1100, and the screen does not become dark.

However, Patent Document 2 assumes a front view, that is, only when the display screen is observed in a state where the display screen of the 3D display device and the surface of the liquid crystal panel of the glasses are substantially parallel. Therefore, the case where the viewing angle direction is oblique (oblique viewing angle) is not described.

Further, at the time of filing of Patent Document 2, there was no biaxial film functioning as a λ / 4 plate, and the λ / 4 plate was a uniaxially stretched NZ coefficient of 1.0. Further, there is no technique for directly bonding the linearly polarizing element and the λ / 4 plate to each other, and it is necessary to dispose a TAC film as a protective film for the linearly polarizing element between the linearly polarizing element and the λ / 4 plate. It was.

As described above, in the system 1200, the shutter function does not deteriorate due to the effects of the λ / 4

plates

1213 and 1221 in the front view, but the shutter function decreases in the oblique viewing angle, and crosstalk occurs. This is because the phase difference of the λ / 4 plate 1213 deviates from the λ / 4 condition at an oblique viewing angle.

Therefore, the present inventors have studied various stereoscopic image recognition systems that can reduce the occurrence of crosstalk at an oblique viewing angle. Then, by setting the NZ coefficient of the first λ / 4 plate provided on the viewer side of the 3D display device to be less than 1, it was found that the transmittance at the time of light blocking the shutter can be reduced at an oblique viewing angle. A patent application has been filed (Japanese Patent Application No. 2010-265616. Hereinafter, this patent application is also referred to as a prior application).

Here, the stereoscopic image recognition system 1300 described in the prior application will be described with reference to FIG.

As shown in FIG. 24, the system 1300 includes a liquid crystal display 1310 that functions as a 3D display device, and active shutter glasses 1320. The liquid crystal display 1310 includes a linearly polarizing element 1311, a liquid crystal panel (liquid crystal cell) 1312, a linearly polarizing element 1313, and a λ / 4 plate 1314 in this order from the back side. The glasses 1320 include a λ / 4 plate 1321, a liquid crystal panel 1322, and a linearly polarizing element 1323 in this order from the outside.

In the system 1300, the shutter function at an oblique viewing angle is improved by optimizing the NZ coefficient of the λ / 4 plate 1314 within a range of less than 1.

However, in a specific orientation (for example, 45 ° orientation), the emitted light from the liquid crystal display 1310 may be elliptically polarized. As an example, FIGS. 25 and 26 illustrate a state in which the orbit of the polarization state in the system 1300 is projected onto the S1-S2 plane of the Poincare sphere. Here, a case where the NZ coefficient of the λ / 4 plate 1314 is set to 0.5 is illustrated. FIG. 25 shows a state at a polar angle of 60 ° and an azimuth angle of 0 °, and FIG. 26 shows a state at a polar angle of 60 ° and an azimuth angle of 45 °. 25 and 26, the polarization state immediately after exiting the polarizing element 1313 is indicated by a point P0, and the polarization state immediately after exiting the λ / 4 plate 1314 is indicated by a point P2. As shown in FIG. 25, when the polar angle is 60 ° and the azimuth angle is 0 °, the light transmitted through the λ / 4 plate 1314 is circularly polarized, but as shown in FIG. 26, the polar angle is 60 ° and the azimuth angle is 45 °. Then, the light transmitted through the λ / 4 plate 1314 does not become circularly polarized light.

Thus, the technique described in the prior application has room for improvement in terms of further improving the shutter function and further reducing the occurrence of crosstalk at an oblique viewing angle.

The present invention has been made in view of the above-described situation, and an object thereof is to provide a stereoscopic video recognition system and a video display device for a stereoscopic video recognition system that can reduce the occurrence of crosstalk at an oblique viewing angle. It is.

The inventors of the present invention have studied various stereoscopic image recognition systems that can reduce the occurrence of crosstalk at an oblique viewing angle, and have focused on using a λ / 2 plate together with a set of λ / 4 plates. A λ / 2 plate is provided on the viewer side of the linearly polarizing element of the 3D display device, and a first λ / 4 plate is provided on the viewer side of the λ / 2 plate. By providing the second λ / 4 plate to the optical disc and adjusting the characteristics and axial directions of these optical members, the light emitted from the first λ / 4 plate can be seen at an oblique viewing angle as compared with the conventional case. The present inventors have found that the polarization state can be made closer to circularly polarized light, and have conceived that the above-mentioned problems can be solved brilliantly, and have reached the present invention.

That is, one aspect of the present invention is an image display device having a first linearly polarizing element provided on the viewer side, a λ / 2 plate provided on the viewer side of the first linearly polarizing element, A first λ / 4 plate, a second λ / 4 plate, a liquid crystal panel (liquid crystal cell), and a second linearly polarizing element provided on the viewer side of the λ / 2 plate are arranged in this order from the outside. Active shutter glasses having an angle formed by the transmission axis of the first linearly polarizing element and the in-plane slow axis of the first λ / 4 plate is φ1, and the transmission of the second linearly polarizing element is When the angle formed between the axis and the in-plane slow axis of the second λ / 4 plate is defined as φ2, the following formulas (1) and (2) or (3) and (4) are satisfied, The NZ coefficient of the first λ / 4 plate is 1 or less, and the transmission axis of the first linearly polarizing element and the in-plane slow axis of the λ / 2 plate form. When the degree .phi.3, the NZ coefficient of the lambda / 2 plate NZ, defined is h, the following equation (5) and (6), or a stereoscopic image recognition system that satisfies (7) and (8).
40 ° ≦ φ1 ≦ 50 ° (1)
130 ° ≦ φ2 ≦ 140 ° (2)
130 ° ≦ φ1 ≦ 140 ° (3)
40 ° ≦ φ2 ≦ 50 ° (4)
85 ° ≦ φ3 ≦ 95 ° (5)
0.7 ≦ NZ, h ≦ 0.8 (6)
-5 ° ≦ φ3 ≦ 5 ° (7)
0.2 ≦ NZ, h ≦ 0.3 (8)
However, φ1 is measured as viewed from the first λ / 4 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the first linearly polarizing element. φ2 is measured from the side of the second λ / 4 plate, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the second linearly polarizing element. φ3 is measured as viewed from the λ / 2 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the first linearly polarizing element.

If the NZ coefficient of the first λ / 4 plate exceeds 1, the occurrence of crosstalk may not be sufficiently reduced at an oblique viewing angle.

The configuration of the stereoscopic image recognition system is not particularly limited by other components as long as such components are formed as essential. A preferred embodiment of the stereoscopic image recognition system will be described in detail below. The various forms shown below may be combined as appropriate.

In various embodiments, the NZ coefficient of the first λ / 4 plate is −0.6 or more and 0.6 or less from the viewpoint of effectively reducing the transmittance when the shutter is shielded at an oblique viewing angle. Is preferable, and is more preferably −0.2 or more and 0.4 or less.

Other preferable forms in the stereoscopic image recognition system include, for example, the following forms (A) to (D).

In the form (A), the λ / 2 plate is affixed on the viewer side surface of the first linearly polarizing element, and the first λ / 4 plate is the viewer side of the λ / 2 plate. The NZ coefficient of the first λ / 4 plate is 0 or more and 1 or less.

In the form (B), the λ / 2 plate is affixed on the viewer side surface of the first linearly polarizing element, and the first λ / 4 plate is the viewer side of the λ / 2 plate. The stereoscopic image recognition system further includes a retardation film affixed on the viewer side surface of the first λ / 4 plate, and the in-plane retardation of the retardation film is 10 nm or less, the thickness direction retardation of the retardation film is 20 nm or more and 80 nm or less, and the NZ coefficient of the first λ / 4 plate is −0.4 or more and 0.5 or less. .

In the form (C), the λ / 2 plate is affixed on the surface on the viewer side of the first linearly polarizing element, and the stereoscopic image recognition system is on the surface on the viewer side of the λ / 2 plate. And the first λ / 4 plate is affixed on the observer side surface of the retardation film, and the in-plane retardation of the retardation film is 10 nm or less. The retardation film has a thickness direction retardation of 20 nm or more and 80 nm or less, and the NZ coefficient of the first λ / 4 plate is −0.2 or more and 0.6 or less.

According to the above forms (A) to (C), the shutter function can be sufficiently exhibited in a polar angle (viewing angle) range wider than the polar angle range of −60 ° to + 60 °.

In the form (D), the liquid crystal panel is a first liquid crystal panel, and the video display device is a liquid crystal display, and includes a third linearly polarizing element, a second liquid crystal panel, and the first linearly polarizing element. In this order from the back side. A general liquid crystal display usually includes an observer-side linear polarizing plate (front polarizing plate). Therefore, according to the said form (D), the linearly polarized light element contained in a general surface polarizing plate can be utilized as a 1st linearly polarized light element, and it is not necessary to newly provide a 1st linearly polarized light element. . Therefore, cost reduction is possible.

The video display device used in the stereoscopic video recognition system is also one aspect of the present invention.

Thus, another aspect of the present invention provides a linearly polarizing element provided on the observer side, a λ / 2 plate provided on the observer side of the linearly polarizing element, and an observer of the λ / 2 plate When the angle formed by the transmission axis of the linearly polarizing element and the in-plane slow axis of the λ / 4 plate is defined as θ1, the following formula (I) or (II) is satisfied, the NZ coefficient of the λ / 4 plate is 1 or less, and the angle formed by the transmission axis of the linearly polarizing element and the in-plane slow axis of the λ / 2 plate is θ2, and the λ When the NZ coefficient of the / 2 plate is defined as NZ, h, the image display device for the stereoscopic image recognition system satisfies the following formulas (III) and (IV) or (V) and (VI).
40 ° ≦ θ1 ≦ 50 ° (I)
130 ° ≦ θ1 ≦ 140 ° (II)
85 ° ≦ θ2 ≦ 95 ° (III)
0.7 ≦ NZ, h ≦ 0.8 (IV)
-5 ° ≦ θ2 ≦ 5 ° (V)
0.2 ≦ NZ, h ≦ 0.3 (VI)
However, θ1 is measured as viewed from the λ / 4 plate side, and is measured as positive in the counterclockwise direction with respect to the direction of the transmission axis of the linearly polarizing element. θ2 is measured as viewed from the λ / 2 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the linearly polarizing element.

If the NZ coefficient of the λ / 4 plate exceeds 1, the occurrence of crosstalk may not be sufficiently reduced at an oblique viewing angle.

The configuration of the video display device for the stereoscopic image recognition system is not particularly limited by other components as long as such components are essential. A preferred embodiment of the video display device for the stereoscopic video recognition system will be described in detail below. The various forms shown below may be combined as appropriate.

Further, in the image display device for the stereoscopic image recognition system, the linearly polarizing element, the λ / 2 plate, the λ / 4 plate, the angle θ1, the angle θ2, the formula (I), the formula (II), The formula (III), the formula (IV), the formula (V), and the formula (VI) are respectively the first linearly polarizing element, the λ / 2 plate, and the first in the stereoscopic image recognition system. Λ / 4 plate, the angle φ1, the angle φ3, the equation (1), the equation (3), the equation (5), the equation (6), the equation (7), and the equation (8). Correspond.

In various forms, from the viewpoint of effectively reducing the transmittance at the time of shutter light shielding at an oblique viewing angle, the NZ coefficient of the λ / 4 plate is preferably −0.6 or more and 0.6 or less, It is more preferably −0.2 or more and 0.4 or less.

Other preferable forms of the stereoscopic image recognition system image display apparatus include, for example, the following forms (E) to (H).

In the embodiment (E), the λ / 2 plate is affixed on the viewer side surface of the linearly polarizing element, and the λ / 4 plate is affixed on the viewer side surface of the λ / 2 plate. The NZ coefficient of the λ / 4 plate is 0 or more and 1 or less.

In the form (F), the λ / 2 plate is affixed on the viewer side surface of the linearly polarizing element, and the λ / 4 plate is affixed on the viewer side surface of the λ / 2 plate. The image display device for a stereoscopic image recognition system further includes a retardation film affixed on the surface on the viewer side of the λ / 4 plate, and the in-plane retardation of the retardation film is 10 nm or less. The retardation in the thickness direction of the retardation film is 20 nm or more and 80 nm or less, and the NZ coefficient of the λ / 4 plate is −0.4 or more and 0.5 or less.

In the form (G), the λ / 2 plate is affixed on a viewer-side surface of the linearly polarizing element, and the video display device for a stereoscopic image recognition system is the viewer-side surface of the λ / 2 plate. Further comprising a retardation film affixed on, the λ / 4 plate is affixed on the observer side surface of the retardation film, the in-plane retardation of the retardation film is 10 nm or less, The retardation in the thickness direction of the retardation film is 20 nm or more and 80 nm or less, and the NZ coefficient of the λ / 4 plate is −0.2 or more and 0.6 or less.

According to the embodiments (E) to (G), the shutter function can be sufficiently exerted in a polar angle (viewing angle) range wider than the polar angle range of −60 ° to + 60 °.

In the form (H), the linearly polarizing element is a first linearly polarizing element, the stereoscopic image recognition system image display device is a liquid crystal display, the second linearly polarizing element, the liquid crystal panel, and the first Are provided in this order from the back side. A general liquid crystal display usually includes an observer-side linear polarizing plate (front polarizing plate). Therefore, according to the said form (H), the linearly polarizing element contained in a general surface polarizing plate can be utilized as a 1st linearly polarizing element, and it is not necessary to newly provide a 1st linearly polarizing element. . Therefore, cost reduction is possible.

In addition, the said 2nd linearly polarizing element and said liquid crystal panel in the said form (H) respond | correspond to the said 3rd linearly polarizing element and the said 2nd liquid crystal panel in the said form (D), respectively.

According to the present invention, it is possible to realize a stereoscopic video recognition system and a video display device for a stereoscopic video recognition system that can reduce the occurrence of crosstalk at an oblique viewing angle.

It is a perspective schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 1. FIG. 1 is a perspective exploded schematic diagram illustrating a configuration of a stereoscopic image recognition system of Embodiment 1. FIG. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 1. FIG. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional-image recognition system of Embodiment 1, and shows the state in which a shutter is light-shielding, and an observer does not tilt a face. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 1, and shows the state which the shutter inclined and the observer inclined the face 90 degrees. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional-image recognition system of Embodiment 1, and shows the state in which a shutter is translucent and an observer does not incline a face. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 1, and shows the state in which the shutter was translucent and the observer inclined the face 90 degrees. FIG. 6 is a schematic diagram showing a state in which the polarization state trajectory is projected onto the S1-S2 plane of the Poincare sphere in the stereoscopic image recognition system of Embodiment 1, and shows a state at a polar angle of 60 ° and an azimuth angle of 0 °. FIG. 5 is a schematic diagram showing a state in which the polarization state trajectory is projected onto the S1-S2 plane of the Poincare sphere in the stereoscopic image recognition system of Embodiment 1, and shows a state at a polar angle of 60 ° and an azimuth angle of 45 °. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional video recognition system of Embodiment 1, and shows the state which observed the screen of the video display apparatus from diagonally. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 2. FIG. The azimuth angle dependence of the transmittance | permeability in Embodiment 2 is shown. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 3. The azimuth angle dependence of the transmittance | permeability in Embodiment 3 is shown. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional image recognition system of Embodiment 4. The azimuth angle dependence of the transmittance | permeability in Embodiment 4 is shown. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional video recognition system which concerns on the comparison form 1. FIG. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional image recognition system which concerns on the comparison form 1. FIG. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional-image recognition system which concerns on the comparison form 1, and shows the state in which a shutter is light-shielding, and an observer does not tilt a face. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional image recognition system which concerns on the comparison form 1, and shows the case where a shutter will be in the translucent state as a result of inclining a face 90 degrees. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional image recognition system which concerns on the comparison form 1, and shows the state in which a shutter is a translucent state and an observer does not tilt a face. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional-image recognition system which concerns on the comparison form 1, and shows the case where a shutter will be in the light-shielding state as a result of inclining a face 90 degrees. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional video recognition system which concerns on the comparison form 2 using the technique of patent document 2. FIG. It is a perspective exploded schematic diagram which shows the structure of the three-dimensional video recognition system as described in a prior application. It is a schematic diagram which shows the state which projected the orbit of the polarization state in the S1-S2 plane of a Poincare sphere in the stereoscopic image recognition system described in the prior application, and shows a state at a polar angle of 60 ° and an azimuth angle of 0 °. It is a schematic diagram which shows the state which projected the track | orbit of the polarization state in the S1-S2 plane of a Poincare sphere in the three-dimensional-image recognition system described in a prior application, and shows the state in the polar angle of 60 degrees and the azimuth angle of 45 degrees.

In this specification, for the inside and outside of the active shutter glasses, the observer side when wearing glasses is defined as the inside, and the opposite side is defined as the outside.

In addition, for the front and rear of the video display device, the opposite side of the viewer (viewer) is defined as the back side. It can be said that the back side is the opposite side of the screen of the liquid crystal display device.

In this specification, the azimuth (azimuth angle) of the glasses is defined with the 3 o'clock direction as a reference (0 ° azimuth) viewed from the observer and the counterclockwise direction being positive when the observer is wearing the glasses. Is done. The azimuth (azimuth angle) of the video display device is based on the 3 o'clock direction as viewed from the observer (0 ° azimuth direction) when the viewer looks at the screen of the display device in front, and counterclockwise is positive. It is prescribed.

The linearly polarizing element has a function of extracting polarized light (linearly polarized light) that vibrates only in a specific direction from non-polarized light (natural light), partially polarized light, or polarized light. However, in this specification, the contrast of the linearly polarizing element does not necessarily need to be infinite, and may be 5000 or more (preferably 10,000 or more). Unless otherwise specified, the term “linearly polarizing element” or “polarizing element” in this specification refers to only an element having a polarizing function without including a protective film.

In this specification, the λ / 4 plate is a layer having a retardation of approximately ¼ wavelength with respect to light having a wavelength of at least 550 nm. The retardation (particularly the in-plane retardation Re) of the λ / 4 plate is ideally 137.5 nm for light having a wavelength of 550 nm, but may be 100 nm or more and 180 nm or less, and 120 nm or more and 160 nm or less. It is preferable that it is 130 nm or more and 145 nm or less.

The λ / 2 plate is a layer having a retardation of approximately ½ wavelength with respect to light having a wavelength of 550 nm. The retardation (particularly the in-plane retardation Re) of the λ / 2 plate is ideally 275 nm for light having a wavelength of 550 nm, but may be 250 nm or more and 300 nm or less, and 260 nm or more and 290 nm or less. Is preferable, and it is more preferable that it is 270 nm or more and 280 nm or less.

The in-plane retardation Re is the main refraction in the direction (that is, the direction of the slow axis) in which the refractive index is maximum in the in-plane direction of the birefringent layer (including the liquid crystal panel, λ / 2 plate, and λ / 4 plate). The main refractive index in the direction orthogonal to nx is defined as ny, the main refractive index in the out-of-plane direction, that is, the direction perpendicular to the surface of the birefringent layer is nz, and the thickness of the birefringent layer is d. When defined, Re = | nx−ny | × d is the in-plane direction phase difference (unit: nm). In contrast, the thickness direction retardation Rth is an out-of-plane direction (thickness direction) phase difference (unit: nm) defined by Rth = (nz− (nx + ny) / 2) × d.

The NZ coefficient is a parameter representing the degree of biaxiality of the birefringent layer, and is defined by NZ = (nx−nz) / (nx−ny).

In this specification, the measurement wavelength of optical parameters such as the main refractive index, phase difference, and NZ coefficient is 550 nm unless otherwise specified.

Even in the case of a birefringent layer having the same NZ coefficient, if the average refractive index of the birefringent layer = (nx + ny + nz) / 3 is different, the effective position of the birefringent layer with respect to incidence from an oblique direction is affected by the refraction angle. The phase difference is different and the design guideline becomes complicated. In order to avoid this problem, the NZ coefficient is calculated by unifying the average refractive index of each birefringent layer to 1.5 unless otherwise specified. Birefringent layers having an actual average refractive index different from 1.5 are also converted assuming an average refractive index of 1.5. The same treatment is applied to the thickness direction retardation Rth.

In this specification, a birefringent layer (birefringent film, retardation film) is a layer (film) having optical anisotropy. The birefringent layer means that at least one of the in-plane retardation Re and the absolute value of the thickness direction retardation Rth has a value of 10 nm or more, preferably from the viewpoint of sufficiently achieving the effects of the present invention. Means having a value of 20 nm or more.

The isotropic film means that both the in-plane retardation Re and the absolute value of the thickness direction retardation Rth have a value of 10 nm or less, preferably 5 nm or less. Means.

In this specification, the single transmittance (T) of a polarizing element is a transmittance when a single polarizing element is used, and is obtained from the formula: (k1 + k2) / 2.

The parallel transmittance (Tp) is a value of transmittance when two polarizing elements of the same type are stacked and used such that their absorption axes are parallel to each other.

The parallel transmittance (Tp) is obtained from the formula: (k1 ² + k2 ² ) / 2.

k1 and k2 are referred to as main transmittance, and the main transmittance k1 refers to the transmittance when linearly polarized light that vibrates in a direction parallel to the transmission axis is incident on the polarizing element. The main transmittance k2 refers to the transmittance when linearly polarized light that vibrates in a direction orthogonal to the transmission axis is incident on the polarizing element.

The orthogonal transmittance (Tc) is a value of transmittance when two polarizing elements of the same type are stacked and used so that their absorption axes are orthogonal to each other.

Further, the orthogonal transmittance (Tc) is obtained from the equation: k1 × k2.

Examples of the measuring device for the main transmittance k1 and the main transmittance k2 include an ultraviolet-visible spectrophotometer (trade name “V-7100” manufactured by JASCO Corporation). In order to make the measurement light (light incident on the polarizing element sample) linearly polarized light, an ideal polarizing element such as a Glan-Thompson prism or a Gran Taylor prism, which is prepared as an option of the measuring instrument, may be used. The spectral transmittance in the visible wavelength region (wavelength 380 nm to 780 nm) is measured, and the Y value that has been corrected for visibility with the two-degree field of view (C light source) defined in JIS Z8701-1982 is defined as the transmittance.

In this specification, the contrast (CR) of the polarizing element is obtained from the formula: CR = Tp / Tc by measuring the parallel transmittance (Tp) and the orthogonal transmittance (Tc) of the polarizing element.

In addition, even if these characteristics of a polarizing element are measured using what is called a polarizing plate containing members, such as a protective film and a birefringent layer, the same result as the case where it measures with a polarizing element single-piece | unit can be obtained.

Embodiments will be described below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited only to these embodiments.

(Embodiment 1)
As shown in FIG. 1, the stereoscopic video recognition system 100 according to the present embodiment includes a video display device (video display device for a stereoscopic video recognition system) 110 that functions as a 3D display device, and active shutter glasses 120. The

The display device 110 is alternately supplied with a right-eye video signal and a left-eye video signal, and the display device 110 has a parallax right-eye image and a left-eye image alternately. Are displayed in a time-sharing manner.

The glasses 120 can alternately switch between light transmission and light shielding (opening and closing of the shutter) of the left and right shutter parts (lens parts). The switching timing is synchronized with the right-eye image and the left-eye image. As a result, the right eye image is projected onto the viewer's right eye, the left eye image is projected onto the left eye, and the viewer can recognize the stereoscopic video. Note that the left and right shutter portions (lens portions) of the glasses 120 may function as shutters, and do not need to function as prescription lenses.

Hereinafter, the configuration of the display device 110 and the glasses 120 will be described with reference to FIGS.
The display device 110 is a transmissive liquid crystal display, and includes a backlight unit (not shown), a linearly polarizing element 111, a liquid crystal panel (liquid crystal cell) 112, a linearly polarizing element 113, a λ / 2 plate 118, and a λ / 4 plate. 114 are provided in this order from the back side. The linearly

polarizing elements

111 and 113 may be linearly polarizing plates.

The left and right shutter portions of the glasses 120 each include a λ / 4 plate 121, a liquid crystal panel (liquid crystal cell) 122, and a linearly polarizing element 123 in this order from the outside. The linearly polarizing element 123 may be a linearly polarizing plate.

In the system 100, the polarizing element 113, the λ / 2 plate 118 and the λ / 4 plate 114 of the display device 110, and the λ / 4 plate 121, the liquid crystal panel (liquid crystal cell) 122, and the polarizing element 123 of the glasses 120 provide a shutter function. It has gained. That is, the shutter function is exhibited only when the display area (display screen) of the display device 110 is observed. Therefore, when an area other than the display area (for example, a surrounding wall) is observed, the glasses 120 having one polarizing element 123 do not function as a shutter, and thus the observer does not feel flicker.

Further, the angle formed by the transmission axis 113t of the linear polarization element 113 and the in-plane slow axis 114s of the λ / 4 plate 114 is φ1, and the transmission axis 123t of the linear polarization element 123 and the in-plane of the λ / 4 plate 121 When the angle formed by the slow axis 121s is defined as φ2, the system 100 satisfies the following formulas (1) and (2) or (3) and (4).
40 ° ≦ φ1 ≦ 50 ° (1)
130 ° ≦ φ2 ≦ 140 ° (2)
130 ° ≦ φ1 ≦ 140 ° (3)
40 ° ≦ φ2 ≦ 50 ° (4)

Further, when the angle formed between the transmission axis 113t of the linearly polarizing element 113 and the in-plane slow axis 118s of the λ / 2 plate 118 is φ3, and the NZ coefficient of the λ / 2 plate 118 is defined as NZ, h, 100 satisfies the following formulas (5) and (6) or (7) and (8).
85 ° ≦ φ3 ≦ 95 ° (5)
0.7 ≦ NZ, h ≦ 0.8 (6)
-5 ° ≦ φ3 ≦ 5 ° (7)
0.2 ≦ NZ, h ≦ 0.3 (8)

However, φ1 is measured when viewed from the λ / 4 plate 114 side, and is measured to be positive in the counterclockwise direction with reference to the direction of the transmission axis 113t of the linearly polarizing element 113. φ2 is measured as viewed from the λ / 4 plate 121 side, and is measured to be positive in the counterclockwise direction with reference to the direction of the transmission axis 123t of the linearly polarizing element 123. φ3 is measured from the λ / 2 plate 118 side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis 113t of the linearly polarizing element 113.

For φ1, the preferred range is 42 ° ≦ φ1 ≦ 48 ° or 132 ° ≦ φ1 ≦ 138 °, the more preferred range is 44 ° ≦ φ1 ≦ 46 ° or 134 ° ≦ φ1 ≦ 136 °, For φ2, the preferred range is 42 ° ≦ φ2 ≦ 48 ° or 132 ° ≦ φ2 ≦ 138 °, the more preferred range is 44 ° ≦ φ2 ≦ 46 ° or 134 ° ≦ φ2 ≦ 136 °, For φ3, the preferred range is 87 ° ≦ φ3 ≦ 93 ° or −3 ° ≦ φ3 ≦ 3 °, and the more preferred range is 89 ° ≦ φ3 ≦ 91 ° or −1 ° ≦ φ3 ≦ 1 °. is there.

For NZ, h, a preferred range is 0.72 ≦ NZ, h ≦ 0.78 or 0.22 ≦ NZ, h ≦ 0.28, and a more preferred range is 0.74 ≦ NZ, h ≦ 0.76 or 0.24 ≦ NZ, h ≦ 0.26.

According to this embodiment, since the emitted light from the display device 110 can be circularly polarized, the above problems (1) and (2) can be solved. The principle will be specifically described below.

In the following description, the transmission axis 111t of the polarizing element 111 is set to 0 ° azimuth, the transmission axis 113t of the polarizing element 113 is set to 90 ° azimuth, and the in-plane slow axis 118s of the λ / 2 plate 118 is set to Set to 0 ° or 90 °, set NZ coefficient NZ, h of λ / 2 plate 118 to 0.75 or 0.25, and set in-plane slow axis 114s of λ / 4 plate 114 to 135 ° The in-plane slow axis 121s of the λ / 4 plate 121 is set to 45 ° azimuth, the transmission axis 123t of the polarizing element 123 is set to 0 ° azimuth, and the phase difference of the liquid crystal layer of the liquid crystal panel 122 is zero. The liquid crystal mode of the liquid crystal panel 122 is set so that the shutter light-shielding state can be obtained in this state. When the in-plane slow axis 118s is set to 0 ° azimuth, that is, when the in-plane slow axis 118s is orthogonal to the transmission axis 113t, NZ, h is set to 0.75. When the in-plane slow axis 118s is set in the 90 ° azimuth, that is, when the in-plane slow axis 118s is parallel to the transmission axis 113t, NZ, h is set to 0.25. As described above, the in-plane slow axis 118 s of the λ / 2 plate 118 is disposed orthogonally or parallel to the transmission axis 113 t of the polarizing element 113. Therefore, when viewed from the front, that is, when the display screen is observed in a state where the display screen of the display device 110 and the surface of the liquid crystal panel 122 of the glasses 120 are substantially parallel, the λ / 2 plate 118 is a polarizing element. 113 does not affect the phase difference of the polarized light transmitted through 113. Therefore, in the following description of the principle, the function of the λ / 2 plate 118 is not described.

First, the problem (1) will be described. The problem (1) occurs when the shutter is in a light-transmitting state when it should be in a light-blocking state. Therefore, in the following (i) and (ii), the phase difference of the liquid crystal layer of the liquid crystal panel 122 is zero.
(I) When the face is not tilted, the λ / 4

plates

114 and 121 are arranged between the polarizing element 113 and the polarizing element 123 in the crossed Nicols state so that the in-plane slow axes thereof are orthogonal to each other. Therefore, the effect of the λ / 4

plates

114 and 121 is substantially invalidated. Therefore, the shutter is shielded from light (see FIG. 4).
(Ii) When the face is tilted by 90 °, the polarizing element 123 is also tilted by 90 °, so the relationship between the polarizing element 113 and the polarizing element 123 is parallel Nicol. At the same time, the λ / 4 plate 121 is also inclined by 90 °, so that the in-plane slow axis 114 s of the λ / 4 plate 114 and the in-plane slow axis 121 s of the λ / 4 plate 121 are parallel to each other. Accordingly, the λ / 4

plates

114 and 121 substantially function as λ / 2 plates. Therefore, even if the face is tilted, the shutter is in a light shielding state (see FIG. 5).

Next, the problem (2) will be described. The problem (2) occurs when the shutter is in a light shielding state when it should be in a light transmitting state. Therefore, in the following (i) and (ii), the phase difference of the liquid crystal layer of the liquid crystal panel 122 is λ / 2.
(I) When the face is not tilted, the λ / 4

plates

114 and 121 is substantially invalidated. Therefore, only the liquid crystal layer (λ / 2) of the liquid crystal panel 122 exists between the polarizing element 113 and the polarizing element 123, and the shutter is in a light-transmitting state (see FIG. 6).
(Ii) When the face is tilted by 90 °, the polarizing element 123 is also tilted by 90 °, so the relationship between the polarizing element 113 and the polarizing element 123 is parallel Nicol. At the same time, the λ / 4 plate 121 is also inclined by 90 °, so that the in-plane slow axis 114 s of the λ / 4 plate 114 and the in-plane slow axis 121 s of the λ / 4 plate 121 are parallel to each other. Accordingly, the λ / 4

plates

114 and 121 substantially function as λ / 2 plates. The λ / 4

plates

114 and 121 that substantially function as λ / 2 plates and the liquid crystal layer (λ / 2) invalidate or add to each other's phase difference. That is, since only the

polarization elements

113 and 123 in a substantially parallel Nicol state are present, the shutter is in a translucent state (see FIG. 7).

As described above, the problems (1) and (2) are solved. However, these are phenomena when viewed from the front.

Therefore, this embodiment satisfies the above formulas (5) and (6) or (7) and (8). In the present embodiment, the above formula (1) or (3) is satisfied, and the NZ coefficient of the λ / 4 plate 114 is set to 1 or less (preferably less than 1). As a result, as shown in the simulation results described below, the polarization state of the light transmitted through the λ / 4 plate 114 can be made closer to circularly polarized light at an oblique viewing angle as compared with the system 1300 described above.

Particularly preferable setting conditions include the following. That is, the NZ coefficient of the λ / 4 plate 114 is set to 0.5, the angle formed between the in-plane slow axis 114s and the transmission axis 113t is set to 45 °, and the λ / 4 plate 121 is further moved to the surface. The inner slow axis 121s is arranged so as to be orthogonal to the in-plane slow axis 114s, and the following (a) or (b) is set.
(A) NZ and h are set to 0.75, and the in-plane slow axis 118s is orthogonal to the transmission axis 113t.
(B) NZ and h are set to 0.25, and the in-plane slow axis 118s is parallel to the transmission axis 113t.
As a result, the polarization state of the light transmitted through the λ / 4 plate 114 is always circularly polarized at an oblique viewing angle.

Here, the transition of the polarization state when the above-mentioned particularly preferable conditions are set will be specifically described with reference to FIGS. 8 and 9, the polarization state immediately after exiting the polarizing element 113 is point P0, the polarization state immediately after exiting the λ / 2 plate 118 is point P1, and the polarization state immediately after exiting the λ / 4 plate 114. Is indicated by a point P2.

At a polar angle of 60 ° and an azimuth angle of 0 °, the λ / 2 plate 118 does not affect the polarization state of the light transmitted through the polarizing element 113. Therefore, as shown in FIG. 8, at the polar angle of 60 ° and the azimuth angle of 0 °, the polarization state P1 immediately after exiting the λ / 2 plate 118 is the same as the polarization state P0 immediately after exiting the polarization element 113. . The light emitted from the λ / 2 plate 118 is converted to circularly polarized light by passing through the λ / 4 plate 114.

As shown in FIG. 9, at a polar angle of 60 ° and an azimuth angle of 45 °, first, the light emitted from the polarizing element 113 is converted into light in the polarization state P1 by passing through the λ / 2 plate 118. The light emitted from the λ / 2 plate 118 is converted to circularly polarized light by passing through the λ / 4 plate 114.

As described above, according to the present embodiment, it is possible to further reduce the transmittance when the shutter is shielded at an oblique viewing angle, as compared with the system 1300. Therefore, it is possible to further reduce the occurrence of crosstalk at the oblique viewing angle. Can do.

Further, in a general λ / 4 plate, that is, a uniaxially stretched film having an NZ coefficient of 1.0, the difference between the two in-plane main refractive indexes nx and ny was important. On the other hand, since the present embodiment also considers the characteristics of the λ / 4 plate 114 at an oblique viewing angle, the main refractive index nz in the thickness direction of the λ / 4 plate 114 is also an important parameter.

Unlike the λ / 4 plate 114, the λ / 4 plate 121 is almost always observed from the front when the glasses 120 are worn. Therefore, the in-plane retardation of the λ / 4 plate 121 only needs to satisfy the λ / 4 condition, and the NZ coefficient of the λ / 4 plate 121 can be set to an arbitrary value. This is because the NZ coefficient of the λ / 4 plate 121 does not depend on the transmittance.

The differences between the present embodiment and the technique described in Patent Document 2 are summarized as follows.
In the stereoscopic image recognition system, the viewing angle is used in two meanings.
(A) The viewing angle of the shutter function when the observer tilts his face while wearing the active shutter glasses and viewing the 3D display device from the front.
(B) The viewing angle of the shutter function when the observer moves in an oblique direction with respect to the screen of the 3D display device with the active shutter glasses on.
Patent Document 2 provides a solution to the viewing angle of (A). On the other hand, in this embodiment, not only the viewing angle of (A) but also the viewing angle of (B) can be improved as shown in FIG.

Hereinafter, the constituent members of this embodiment will be described in detail.

The

polarizing elements

111 and 113 are arranged in crossed Nicols. That is, the angle formed by the transmission axis 111t of the polarizing element 111 and the transmission axis 113t of the polarizing element 113 is set to approximately 90 ° (preferably 87 to 93 °, more preferably 89 to 91 °).

However, the arrangement relationship of the transmission axes of the

polarizing elements

111 and 113 can be appropriately set according to the liquid crystal mode of the liquid crystal panel 112, and may be parallel Nicols.

The transmission axis 113t of the polarizing element 113 is set so as to face substantially the vertical direction when the screen of the display device 110 is viewed from the front. More specifically, the transmission axis 113t is set in the range of 87 to 93 ° azimuth (preferably 89 to 91 ° azimuth).

The transmission axis 123t of the polarizing element 123 is set so as to face in the left-right direction when the observer wears the glasses 120. More specifically, the transmission axis 123t is set within a range of −3 to + 3 ° azimuth (preferably −1 to + 1 ° azimuth).

However, as long as the arrangement relationship of the polarizing element 123, the liquid crystal panel 122, and the λ / 4 plate 121 satisfies the above relationship, the arrangement direction of the transmission axis 123t of the polarizing element 123 is not particularly limited and can be set as appropriate. For example, the polarizing element 123, the liquid crystal panel 122, and the λ / 4 plate 121 may be appropriately rotated together from the state shown in FIG.

Examples of the linearly

polarizing elements

111, 113, and 123 typically include a material obtained by adsorbing and orienting an anisotropic material such as an iodine complex having dichroism on a polyvinyl alcohol (PVA) film. In order to ensure mechanical strength and heat-and-moisture resistance, a protective film such as a triacetyl cellulose (TAC) film may be laminated on both sides of the PVA film. Thus, the linearly

polarizing elements

111, 113, and 123 may be used as so-called polarizing plates.

Between the

polarizing elements

111 and 113, one or more birefringent layers (optical compensation films) may be provided as appropriate for the purpose of optical compensation. Thus, a back polarizing plate including the polarizing element 111 and the optical compensation film and a front polarizing plate including the polarizing element 113 and the optical compensation film may be used. Each optical compensation film may be directly bonded to the corresponding polarizing element, or may function as a protective film for the corresponding polarizing element.

Further, a surface treatment layer may be provided on the outermost surface of the display device 110 on the viewer side.

In addition, as a surface treatment layer, the following three things are mainly mentioned. First, a hard coat layer for preventing scratches, second, an AG (Anti Glare) layer for imparting antiglare properties, and third, an antireflection layer for reducing surface reflection.

Examples of the antireflection layer include an AR (Anti Reflection) layer having a low reflectance, an LR (Low Reflection) layer having a higher reflectance than the AR layer, and a moth-eye layer.

The surface treatment layer may be formed on the λ / 4 plate 114, or may be formed on another transparent base film (for example, a TAC film).

The materials of the λ / 4

plates

114 and 121 and the λ / 2 plate 118 are not particularly limited, and for example, a stretched polymer film can be used. Examples of the polymer include materials having a positive intrinsic birefringence, and more specifically, for example, polycarbonate, polysulfone, polyethersulfone, polyethylene terephthalate, polyethylene, polyvinyl alcohol, norbornene, triacetylcellulose, diacylcellulose, and the like. Is mentioned.

The method of forming the λ / 4

plates

114 and 121 is not particularly limited. However, when the NZ coefficient of the λ / 4

plates

114 and 121 satisfies 0 <NZ ≦ 1, for example, the λ / 4

plates

114 and 121 are manufactured by the method described in Patent Document 3 above. Can do. When NZ = 0 is satisfied, for example, the discotic liquid crystal can be prepared by aligning the optical axes so that the optical axis is perpendicular to the normal of the film surface. When NZ <0 is satisfied, a thermoplastic resin exhibiting negative intrinsic birefringence can be produced by a biaxial stretching method.

The method for forming the λ / 2 plate 118 is not particularly limited, but for example, it can be produced by the method described in JP-A-2007-219478.

The λ / 2 plate 118 is preferably adjacent to the polarizing element 113. That is, it is preferable that no birefringent layer is provided between the λ / 2 plate 118 and the polarizing element 113. However, an isotropic film may be disposed between the λ / 2 plate 118 and the polarizing element 113. Further, a protective film such as a TAC film as described later may be disposed between the λ / 2 plate 118 and the polarizing element 113. Further, a birefringent layer may be provided between the λ / 2 plate 118 and the polarizing element 113. In this case, the slow axis of the birefringent layer is substantially orthogonal to the transmission axis 113t of the polarizing element 113. Setting the direction substantially invalidates the birefringence function of the birefringent layer, and the same effect as when no birefringent layer is provided between the λ / 2 plate 118 and the polarizing element 113 is obtained. be able to. In this case, “substantially orthogonal” means that the angle formed by both axes is preferably in the range of 90 ° ± 3 °, and more preferably in the range of 90 ° ± 1 °.

The λ / 4 plate 114 is preferably adjacent to the λ / 2 plate 118. That is, it is preferable that a birefringent layer is not provided between the λ / 4 plate 114 and the λ / 2 plate 118. However, an isotropic film may be disposed between the λ / 4 plate 114 and the λ / 2 plate 118. Further, a protective film such as a TAC film may be disposed between the λ / 4 plate 114 and the λ / 2 plate 118.

The λ / 4 plate 121 is preferably adjacent to the liquid crystal panel 122. That is, it is preferable that no birefringent layer is provided between the λ / 4 plate 121 and the liquid crystal panel 122. However, an isotropic film may be disposed between the λ / 4 plate 121 and the liquid crystal panel 122. Further, a birefringent layer may be provided between the λ / 4 plate 121 and the liquid crystal panel 122. In this case, the slow axis of the birefringent layer is substantially parallel or substantially orthogonal to the transmission axis 123t of the polarizing element 123. Is set to a direction that substantially eliminates the birefringence function of the birefringent layer, and has the same effect as when no birefringent layer is provided between the λ / 4 plate 121 and the liquid crystal panel 122. Can be obtained. In this case, “substantially parallel” means that the angle formed by both axes is preferably in the range of 0 ° ± 3 °, more preferably in the range of 0 ° ± 1 °, The angle formed by both axes is preferably in the range of 90 ° ± 3 °, and more preferably in the range of 90 ° ± 1 °.

The liquid crystal mode (display mode) of the liquid crystal panel 112 is not particularly limited. For example, the vertical alignment (Vertical Alignment (VA)) mode, the in-plane switching (IPS) mode, the field fringe switching (Field Fringe Switching) Liquid crystal modes such as FFS)) mode. The liquid crystal panel 112 includes two transparent substrates, a liquid crystal layer sandwiched between the two substrates, and a transparent electrode formed on at least one of the two substrates. The driving method of the liquid crystal panel 112 is not particularly limited, and a simple matrix method (passive matrix method), a plasma addressing method, or the like may be used. Among them, a TFT method (active matrix method) is preferable.

The liquid crystal mode (display mode) of the liquid crystal panel 122 is not particularly limited as long as the pair of linearly polarizing elements in the crossed Nicols state can be used for black display. For example, VA mode, IPS mode, twisted nematic (twisted nematic (twisted nematic) TN)) mode, Super Twisted Nematic (STN) mode, Optically Compensated Birefringence (OCB) mode, and FFS mode. The liquid crystal panel 122 preferably has a response speed that can be synchronized with the frame rate of the display device 110. The liquid crystal panel 122 includes two transparent substrates, a liquid crystal layer sandwiched between the two substrates, and a transparent electrode formed on at least one of the two substrates.

Note that the optimum NZ coefficient of the λ / 4 plate 121 does not change depending on the liquid crystal mode of the liquid crystal panel 122.

The retardation Δn · d of the liquid crystal panel 122 is not particularly limited, and can be appropriately set in consideration of the transmittance at the time of transmitting through the shutter. Δn and d represent the birefringence anisotropy and the cell gap of the liquid crystal panel 122, respectively. Although the optimum Δn · d varies depending on the liquid crystal mode to be employed, the Δn · d of the liquid crystal panel 122 can usually be set in a range of 200 to 800 nm.

Note that the optimal NZ coefficient of the λ / 4 plate 121 does not change depending on Δn · d of the liquid crystal panel 122.

The backlight unit may be a direct type or an edge light type. The display device 110 may be a transflective or reflective liquid crystal display. In the case of a reflective type, the backlight unit can be omitted.

The display device 110 is not particularly limited to a liquid crystal display, but may be a plasma display, an organic or inorganic EL display, a CRT display, a projector, or the like. However, when these display devices are applied, it is necessary to provide the polarizing element 113 separately, which causes a cost increase. On the other hand, by applying a liquid crystal display as the display device 110, a linearly polarizing element included in a general surface polarizing plate can be used as the polarizing element 113. Therefore, the polarizing element 113 does not cause an increase in cost.

In addition, as long as the λ / 4 plate 114 and the λ / 2 plate 118 are arranged between the polarizing element 113 and the λ / 4 plate 121, the arrangement positions thereof are not particularly limited. For example, the stereoscopic image recognition system 100 of the present embodiment may further include a front plate (not shown), and the λ / 4 plate 114 and the λ / 2 plate 118 may be provided on the front plate.

The front plate is a transparent member disposed on the viewer side of the screen of the display device 110, that is, in front of the screen, and is disposed so as to cover the screen (display area) of the display device 110. The front plate includes a protective plate or a touch panel. The protective plate protects the display device 110 from various impacts. The above-mentioned surface treatment layer may be provided on the outermost surface of the front plate on the viewer side.

As a material for the protective plate, high transparency and high mechanical strength are preferred, and a resin made of tempered glass, polycarbonate, acrylic, or the like is suitable.

The touch panel is an input device for inputting various types of information, and information can be input while seeing through the screen of the display device 110 by touching (pressing) the surface of the touch panel. As described above, the touch panel can interactively and intuitively operate the display device 110 only by touching a predetermined portion on the screen with a finger, a pen, or the like.

The operation principle of the touch panel is not particularly limited, and includes a resistive film method, a capacitive coupling method, an infrared method, an ultrasonic method, an electromagnetic induction coupling method, etc. Among them, from the viewpoint of cost reduction, the resistive film method and A capacitive coupling method is preferable.

The configuration between the display device 110 and the front plate is not particularly limited as long as the polarization state of the light emitted from the display device 110 is not significantly changed. There may or may not be an air layer between them. Moreover, there may be a layer containing an adhesive or an adhesive. Furthermore, there may be an isotropic film.

The front plate may be a member that can be arbitrarily installed by an observer. As a result, the front panel can be removed when displaying a flat image, and the flat image can be viewed without using the front panel, so that the screen brightness when displaying a flat image can be improved.

(Embodiment 2)
A stereoscopic image recognition system according to the second embodiment will be described. The main differences between this embodiment and Embodiment 1 are as follows.

As shown in FIG. 11, the λ / 2 plate 118 is directly attached to the polarizing element 113 with an adhesive or an adhesive.

The λ / 4 plate 114 is attached to the λ / 2 plate 118 with an adhesive or an adhesive.

Optical compensation films

216 and 217 are provided between the liquid crystal panel 112 and the polarizing element 111 and between the liquid crystal panel 112 and the polarizing element 113 in order to compensate the viewing angle of the liquid crystal panel 112, respectively. The

optical compensation films

216 and 217 function as a birefringent layer.

Note that a protective film such as a TAC film may be provided instead of the

optical compensation films

216 and 217.

Further, an isotropic film may be attached to the surface of the λ / 4 plate 114 on the observer side, and a surface treatment layer may be provided on the surface of the isotropic film on the observer side. .

The surface treatment layer may be formed directly on the surface of the λ / 4 plate 114 on the viewer side.

The λ / 4 plate 121 is attached to the liquid crystal panel 122 with an adhesive or an adhesive.

A protective film (not shown) such as a TAC film is attached to both surfaces of the polarizing element 123 with an adhesive or an adhesive. Further, a protective film on the liquid crystal panel 122 side is attached to the liquid crystal panel 122 with an adhesive or an adhesive, whereby the polarizing element 123 is fixed to the liquid crystal panel 122.

Hereinafter, the result of simulating the effect of this embodiment will be described. As the simulation software, a liquid crystal simulator “LCD Master” was used.

The transmittance of the stereoscopic image recognition system can be calculated by the following formula (9) by calculating the Mueller matrix of the liquid crystal display and the active shutter glasses, respectively.

Further, since the observer wears active shutter glasses, the observer almost always looks at the liquid crystal panel of the active shutter glasses from the front. Therefore, the Mueller matrix M _glasses are limited to the Mueller matrix in the front direction. 2 and 3, since the shutter function is exhibited between the

polarizing elements

113 and 123, when evaluating the shutter function, the rear side (backlight side) of the polarizing element 113. The characteristics of these members need not be considered. That is, the transmittance S 'is in each viewing direction of the stereoscopic image recognition system, the Mueller matrix M _TV in each viewing direction of the liquid crystal display, multiplied by the Mueller matrix M _glasses in the front direction of the active shutter glasses further incident light ( It is obtained by multiplying the non-polarized) Stokes parameter S. The effect of the shutter function is confirmed by whether the shutter can sufficiently exhibit a light shielding state, that is, whether the transmittance is low in this verification.

The parameters of each member used for the simulation are shown below.
λ / 2 plate 118: in-plane retardation Re = 275 nm, NZ coefficient = 0.75, slow axis = 0 ° azimuth λ / 4 plate 114: in-plane retardation Re = 138 nm, NZ coefficient = 0.0, 0 .2, 0.5, 0.8 or 1.0, slow axis = 135 ° azimuth λ / 4 plate 121: in-plane retardation Re = 138 nm, NZ coefficient = 1.0, slow axis = 45 ° azimuth Polarizing elements 113 and 123: single transmittance = 42.9%, parallel transmittance = 36.8%, orthogonal transmittance = 0.005%
Polarizing element 113: Transmission axis = 90 ° azimuth Polarizing element 123: Transmission axis = 0 ° azimuth liquid crystal panel 122: Δn · d = 300 nm, VA mode

FIG. 12 shows the azimuth angle dependence of the transmittance in this embodiment. FIG. 12 shows the transmittance when the shutter is shielded, and shows the result at a polar angle of 60 °. FIG. 12 also shows the result of the configuration estimated from Patent Document 2 as a comparative example. This comparative example includes the same members as the present embodiment except that the λ / 2 plate 118 is not provided. However, the NZ coefficient of the λ / 4 plate 114 is set to 1.0. The transmittance at an azimuth angle of 180 ° to 360 ° exhibits the same behavior as the transmittance at an azimuth angle of 0 ° to 180 °.

As shown in FIG. 12, when the NZ coefficient of the λ / 4 plate 114 is in the range of 0 to 1, the transmittance when the shutter is shielded can be lowered compared to the comparative example.

When the NZ coefficient is 0.5, it can be said that the shutter function is most effectively exhibited because the transmittance when the shutter is shielded is particularly low in the azimuth angle range of 0 ° to 180 °. Therefore, in the present embodiment, it is particularly preferable that the NZ coefficient of the λ / 4 plate 114 is substantially 0.5.

Incidentally, there is a JEITA standard as a reference for determining the viewing angle. In this standard, a viewing angle range satisfying a contrast ratio of 10: 1 or more is defined as a viewing angle. This is because if the contrast ratio is about 10: 1, it is possible for a human to see the luminance ratio sufficiently. Therefore, also in this embodiment, if the contrast ratio between the light transmitting state and the light shielding state of the shutter is about 10: 1, it can be said that the shutter function is sufficiently exhibited.

In the configuration of this simulation, the transmittance at the time of shutter light transmission in the viewing angle direction with a polar angle of 60 ° and an azimuth angle of 45 ° is about 25%. Also, as shown in FIG. 12, the transmittance when the shutter is shielded is relatively large at an azimuth angle of about 45 °. Therefore, the contrast ratio becomes relatively low near the azimuth angle of 45 °. Therefore, from the viewpoint of satisfying the contrast ratio of 10: 1 or more when the polar angle is in the range of −60 ° to + 60 °, that is, the shutter function is sufficiently exhibited, the transmittance when the shutter is shielded is approximately 2.5% or less. I just need it.

Further, from the viewpoint of satisfying a contrast ratio of 10: 1 or more in a polar angle (viewing angle) range wider than the polar angle range of −60 ° to + 60 °, that is, from the viewpoint of sufficiently exhibiting the shutter function, the transmittance at the time of shutter light shielding. Is particularly preferably about 1% or less. Also from this viewpoint, in the present embodiment, the NZ coefficient of the λ / 4 plate 114 is preferably 0 or more and 1 or less.

Further, even when the NZ coefficient of the λ / 2 plate 118 is set to 0.25 and the in-plane slow axis of the λ / 2 plate 118 is set to 90 ° azimuth, the same result as the simulation result can be obtained. It was.

(Embodiment 3)
As shown in FIG. 13, the present embodiment is the same as the second embodiment except that a retardation film 315 that functions as a birefringent layer is provided on the viewer side of the λ / 4 plate 114.

The retardation film 315 is attached to the λ / 4 plate 114 with an adhesive or an adhesive.

The in-plane retardation of the retardation film 315 is 10 nm or less (preferably 5 nm or less), and the thickness direction retardation of the retardation film 315 is 20 nm or more and 80 nm or less (preferably 30 nm or more and 60 nm or less). is there. The retardation film 315 functions as a so-called negative C plate.

In addition, since the in-plane retardation of the retardation film 315 is as small as 10 nm or less, the direction of the in-plane slow axis of the retardation film 315 is not particularly limited and can be set as appropriate.

As a material of the retardation film 315, triacetyl cellulose (TAC) is suitable, and the retardation film 315 is preferably a TAC film.

In addition, an isotropic film may be affixed to the surface of the retardation film 315 on the viewer side, and a surface treatment layer may be provided on the surface of the isotropic film on the viewer side.

The surface treatment layer may be directly formed on the surface of the retardation film 315 on the viewer side.

Hereinafter, the result of simulating the effect of the present embodiment in the same manner as in the second embodiment will be described.

The parameters of each member used for the simulation are shown below.
λ / 4 plate 114: NZ coefficient = −0.6, −0.4, −0.2, 0.0, 0.2, 0.4, 0.5 or 0.6
Retardation film 315: in-plane retardation Re = 0 nm, thickness direction retardation Rth = 50 nm
Other than the parameters shown here, the parameters described in the second embodiment were used.

FIG. 14 shows the azimuth angle dependency of the transmittance in the present embodiment. FIG. 14 shows the transmittance when the shutter is shielded, and shows the result at a polar angle of 60 °. FIG. 14 also shows the results of the comparative example. Further, the transmittance at an azimuth angle of 180 ° to 360 ° shows the same behavior as the transmittance at an azimuth angle of 0 ° to 180 °.

As shown in FIG. 14, when the NZ coefficient of the λ / 4 plate 114 is in the range of −0.6 to 0.6, the transmittance when the shutter is shielded can be lowered as compared with the comparative example.

In addition, when the NZ coefficient = 0, it can be said that the transmittance when the shutter is shielded is particularly low in the range of the azimuth angle of 0 ° to 180 °, and the shutter function is most effectively exhibited. Therefore, in the present embodiment, it is particularly preferable that the NZ coefficient of the λ / 4 plate 114 is substantially zero.

Further, in the present embodiment, the NZ coefficient of the λ / 4 plate 114 is preferably −0.4 or more and 0.5 or less from the viewpoint of setting the transmittance when the shutter is shielded to about 1% or less. Accordingly, the shutter function can be sufficiently exhibited in a polar angle (viewing angle) range wider than the polar angle range of −60 ° to + 60 °.

(Embodiment 4)
As shown in FIG. 15, this embodiment is the same as Embodiment 2 except that a retardation film 415 that functions as a birefringent layer is provided between the λ / 2 plate 118 and the λ / 4 plate 114. is there.

The retardation film 415 is affixed to the λ / 2 plate 118 with an adhesive or an adhesive.

The in-plane retardation of the retardation film 415 is 10 nm or less (preferably 5 nm or less), and the thickness direction retardation of the retardation film 415 is 20 nm or more and 80 nm or less (preferably 30 nm or more and 60 nm or less). is there. The retardation film 415 functions as a so-called negative C plate.

In addition, since the in-plane retardation of the retardation film 415 is as small as 10 nm or less, the direction of the in-plane slow axis of the retardation film 415 is not particularly limited and can be set as appropriate.

As a material of the retardation film 415, triacetyl cellulose (TAC) is suitable, and the retardation film 415 is preferably a TAC film.

The λ / 4 plate 114 is attached to the retardation film 415 with an adhesive or an adhesive.

The parameters of each member used for the simulation are shown below.
λ / 4 plate 114: NZ coefficient = −0.6, −0.4, −0.2, 0.0, 0.2, 0.4 or 0.6
Retardation film 415: In-plane retardation Re = 0 nm, thickness direction retardation Rth = 50 nm
Other than the parameters shown here, the parameters described in the second embodiment were used.

FIG. 16 shows the azimuth angle dependency of the transmittance in this embodiment. FIG. 16 shows the transmittance when the shutter is shielded, and shows the result at a polar angle of 60 °. FIG. 16 also shows the results of the comparative example. Further, the transmittance at an azimuth angle of 180 ° to 360 ° shows the same behavior as the transmittance at an azimuth angle of 0 ° to 180 °.

As shown in FIG. 16, in the range where the NZ coefficient of the λ / 4 plate 114 is in the range of −0.6 to 0.6, the transmittance when the shutter is shielded can be lowered as compared with the comparative example.

In addition, when the NZ coefficient is 0.2, it can be said that the shutter function is most effectively exhibited because the transmittance when the shutter is shielded is particularly low in the range of the azimuth angle of 0 ° to 180 °. Therefore, in the present embodiment, it is particularly preferable that the NZ coefficient of the λ / 4 plate 114 is substantially 0.2.

Further, in the present embodiment, the NZ coefficient of the λ / 4 plate 114 is preferably −0.2 or more and 0.6 or less from the viewpoint of setting the transmittance when the shutter is shielded to about 1% or less. Accordingly, the shutter function can be sufficiently exhibited in a polar angle (viewing angle) range wider than the polar angle range of −60 ° to + 60 °.

The above-described embodiments may be combined as appropriate without departing from the scope of the present invention.

This application claims the priority based on the Paris Convention or the laws and regulations in the country of transition based on Japanese Patent Application No. 2011-1074559 filed on May 12, 2011. The contents of the application are hereby incorporated by reference in their entirety.

100: stereoscopic image recognition system 110:

video display devices

111, 113, 123: linearly polarizing

elements

111t, 113t, 123t: transmission axes 112, 122: liquid crystal panel (liquid crystal cell)
114, 121: λ / 4

plate

114s, 121s: in-plane slow axis 118: λ / 2 plate 118s: in-plane slow axis 120: active shutter glasses 315, 415: retardation film 216, 217: optical compensation film

Claims

An image display device having a first linearly polarizing element provided on the viewer side;
A λ / 2 plate provided on the viewer side of the first linearly polarizing element;
A first λ / 4 plate provided on the viewer side of the λ / 2 plate;
A second λ / 4 plate, a liquid crystal panel, and active shutter glasses having a second linearly polarizing element in this order from the outside,
The angle formed by the transmission axis of the first linearly polarizing element and the in-plane slow axis of the first λ / 4 plate is φ1, the transmission axis of the second linearly polarizing element, and the second λ / 4 When the angle formed by the in-plane slow axis of the plate is defined as φ2, the following formulas (1) and (2) or (3) and (4) are satisfied,
The NZ coefficient of the first λ / 4 plate is 1 or less,
When the angle formed between the transmission axis of the first linearly polarizing element and the in-plane slow axis of the λ / 2 plate is defined as φ3, and the NZ coefficient of the λ / 2 plate is defined as NZ, h, the following formula ( A stereoscopic image recognition system satisfying 5) and (6) or (7) and (8).
40 ° ≦ φ1 ≦ 50 ° (1)
130 ° ≦ φ2 ≦ 140 ° (2)
130 ° ≦ φ1 ≦ 140 ° (3)
40 ° ≦ φ2 ≦ 50 ° (4)
85 ° ≦ φ3 ≦ 95 ° (5)
0.7 ≦ NZ, h ≦ 0.8 (6)
-5 ° ≦ φ3 ≦ 5 ° (7)
0.2 ≦ NZ, h ≦ 0.3 (8)
However, φ1 is measured as viewed from the first λ / 4 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the first linearly polarizing element. φ2 is measured from the second λ / 4 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the second linearly polarizing element. φ3 is measured as viewed from the λ / 2 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the first linearly polarizing element.
The λ / 2 plate is affixed on the surface of the first linearly polarizing element on the viewer side,
The first λ / 4 plate is affixed on the observer side surface of the λ / 2 plate,
The stereoscopic image recognition system according to claim 1, wherein an NZ coefficient of the first λ / 4 plate is 0 or more and 1 or less.
The λ / 2 plate is affixed on the surface of the first linearly polarizing element on the viewer side,
The first λ / 4 plate is affixed on the observer side surface of the λ / 2 plate,
The stereoscopic image recognition system further includes a retardation film affixed on a viewer side surface of the first λ / 4 plate,
In-plane retardation of the retardation film is 10 nm or less,
The thickness direction retardation of the retardation film is 20 nm or more and 80 nm or less,
The 3D image recognition system according to claim 1, wherein the NZ coefficient of the first λ / 4 plate is not less than -0.4 and not more than 0.5.
The λ / 2 plate is affixed on the surface of the first linearly polarizing element on the viewer side,
The stereoscopic image recognition system further includes a retardation film affixed on the viewer side surface of the λ / 2 plate,
The first λ / 4 plate is affixed on the observer side surface of the retardation film,
In-plane retardation of the retardation film is 10 nm or less,
The thickness direction retardation of the retardation film is 20 nm or more and 80 nm or less,
The stereoscopic image recognition system according to claim 1, wherein the NZ coefficient of the first λ / 4 plate is not less than -0.2 and not more than 0.6.
The liquid crystal panel is a first liquid crystal panel;
The three-dimensional display according to any one of claims 1 to 4, wherein the video display device is a liquid crystal display and includes a third linearly polarizing element, a second liquid crystal panel, and the first linearly polarizing element in this order from the back side. Video recognition system.
A linearly polarizing element provided on the observer side;
A λ / 2 plate provided on the viewer side of the linearly polarizing element;
A λ / 4 plate provided on the viewer side of the λ / 2 plate,
When the angle formed by the transmission axis of the linearly polarizing element and the in-plane slow axis of the λ / 4 plate is defined as θ1, the following formula (I) or (II) is satisfied:
The NZ coefficient of the λ / 4 plate is 1 or less,
When the angle formed by the transmission axis of the linearly polarizing element and the in-plane slow axis of the λ / 2 plate is defined as θ2, and the NZ coefficient of the λ / 2 plate is defined as NZ, h, the following formula (III) and An image display device for a stereoscopic image recognition system that satisfies (IV) or (V) and (VI).
40 ° ≦ θ1 ≦ 50 ° (I)
130 ° ≦ θ1 ≦ 140 ° (II)
85 ° ≦ θ2 ≦ 95 ° (III)
0.7 ≦ NZ, h ≦ 0.8 (IV)
-5 ° ≦ θ2 ≦ 5 ° (V)
0.2 ≦ NZ, h ≦ 0.3 (VI)
However, θ1 is measured as viewed from the λ / 4 plate side, and is measured as positive in the counterclockwise direction with respect to the direction of the transmission axis of the linearly polarizing element. θ2 is measured as viewed from the λ / 2 plate side, and is measured as positive in the counterclockwise direction with reference to the direction of the transmission axis of the linearly polarizing element.
The λ / 2 plate is affixed on the observer-side surface of the linearly polarizing element,
The λ / 4 plate is affixed on the surface of the λ / 2 plate on the viewer side,
The video display device for a stereoscopic video recognition system according to claim 6, wherein the NZ coefficient of the λ / 4 plate is 0 or more and 1 or less.
The λ / 2 plate is affixed on the observer-side surface of the linearly polarizing element,
The λ / 4 plate is affixed on the surface of the λ / 2 plate on the viewer side,
The image display device for the stereoscopic image recognition system further includes a retardation film attached on the surface of the λ / 4 plate on the observer side,
In-plane retardation of the retardation film is 10 nm or less,
The thickness direction retardation of the retardation film is 20 nm or more and 80 nm or less,
The video display device for a stereoscopic video recognition system according to claim 6, wherein the NZ coefficient of the λ / 4 plate is not less than -0.4 and not more than 0.5.
The λ / 2 plate is affixed on the observer-side surface of the linearly polarizing element,
The image display device for the stereoscopic image recognition system further includes a retardation film attached on the surface of the λ / 2 plate on the viewer side,
The λ / 4 plate is affixed on the observer side surface of the retardation film,
In-plane retardation of the retardation film is 10 nm or less,
The thickness direction retardation of the retardation film is 20 nm or more and 80 nm or less,
The video display apparatus for a stereoscopic video recognition system according to claim 6, wherein the NZ coefficient of the λ / 4 plate is not less than -0.2 and not more than 0.6.
The linearly polarizing element is a first linearly polarizing element;
The video display device for a stereoscopic image recognition system is a liquid crystal display, and has a second linearly polarizing element, a liquid crystal panel, and the first linearly polarizing element in this order from the back side. Display device for 3D image recognition system.