An image display apparatus allows an image from a single image display device to be led to two eyes without using a half-mirror, thereby allowing observation of a bright image, and facilitates correction of various aberrations. A viewing optical system includes a left ocular part, a right ocular part, and an optical path distributing part for leading a light beam from a single image display device to the left and right ocular parts. The left and right ocular parts each have at least two reflecting surfaces. The optical path distributing part has at least one pair of reflecting surfaces for left and right optical paths. These reflecting surfaces are formed from rotationally asymmetric curved reflecting surfaces having the function of correcting decentration aberrations. The left and right optical paths of the viewing optical system are formed by optical surfaces arranged so that the left and right optical paths are not in plane symmetry with each other but in 180-degree rotational symmetry with respect to only a normal line passing through the center of the image display device.

This application claims benefit of Japanese Application No. 2000-239630 filed in Japan on Aug. 8, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to image display apparatus having a three-dimensionally decentered optical path. More particularly, the present invention relates to a head- or face-mounted image display apparatus that can be retained on an observer""s head or face and allows observation of the image of a single image display device with two eyes.
2. Discussion of Related Art
Image display apparatus designed to observe the image of a single image display device with two eyes have heretofore been known in Japanese Patent Application Unexamined Publication Nos. [hereinafter referred to as xe2x80x9cJP(A)xe2x80x9d] 6-110013, 7-287185, 9-61748, 9-181998, and 9-181999, Published Japanese Translation of PCT International Publication No. Hei 10-504115, etc.
Among them, the image display apparatus of JP(A) 6-110013 splits and folds light rays by using a prism in the shape of an isosceles triangular prism and a mirror. Therefore, correction of various aberrations is performed by using a lens placed in front of the pupil. This makes it difficult to correct aberrations, and at the same time, causes the apparatus to become large in size. JP(A) 7-287185 uses a plurality of mirrors and performs image formation with a single convex lens. Therefore, it is very difficult to perform assembly adjustment. In addition, appropriate performance cannot be attained. Although the image display device is placed three dimensionally, the optical systems for the left and right eyes are in bilateral symmetry with each other. Therefore, the images of the image display device that are displayed in the left and right eyes are in oppositely rotated relation to each other.
In JP(A) 9-61748, display light from an LCD (Liquid Crystal Display) is split by using a half-mirror so as to be observed with two eyes. Because the display light is distributed to the left and right eyeballs, the image for observation is weak in light intensity and hence dark. In JP(A) 9-181998 and 9-181999, optical paths for two eyes are provided sidewardly of the image display device. Therefore, the tilt angle of the principal rays with respect to the image display device is very large. Accordingly, these apparatus cannot use an ordinary LCD (Liquid Crystal Display) because the viewing angle thereof is not sufficiently wide.
The image display apparatus of Published Japanese Translation of PCT International Publication No. Hei 10-504115 splits display light by using a half-mirror. The image display apparatus has a very large number of components and requires a very complicated assembling operation.
Recently, with the achievement of small-sized image display devices, it has become necessary to reduce the focal length of the viewing optical system in order to ensure the same field angle. However, if the focal length is shortened, it becomes difficult to ensure the required back focus, and it becomes impossible to increase the optical path length within the prism. As a result, it becomes impossible to increase the number of reflecting surfaces and hence impossible to correct decentration aberrations satisfactorily.
Further, with the recent development of manufacturing techniques, image display devices are becoming higher in definition year by year.
The present invention was made in view of the above-described problems with the prior art.
Accordingly, an object of the present invention is to provide an image display apparatus, e.g. a head-mounted image display apparatus, in which an image from a single image display device is led to two eyes without using a half-mirror, thereby allowing observation of a bright image, and in which at least three curved reflecting surfaces are used to form an optical system, thereby allowing correction of various aberrations in conformity to recent compact and high-definition image display devices.
Another object of the present invention is to provide an image display apparatus favorably improved in terms of the tilt angle of the principal rays with respect to the image display device.
To attain the above-described objects, the present invention provides an image display apparatus having a three-dimensionally decentered optical path. The image display apparatus includes an image display device for forming an image for observation on an image display area. The image display apparatus further includes a viewing optical system for leading the image formed by the image display device to a pupil corresponding to a position where an eyeball of an observer is to be placed.
The image display device is a single image display device having a plurality of pixels juxtaposed on a single substrate.
Each pixel located at least in the central portion of the single image display device is arranged to emit an image light beam at such an exit angle that the light beam can be led to the left and right eyes of the observer.
The viewing optical system includes at least a left ocular part for leading the light beam to the left eye of the observer; a right ocular part for leading the light beam to the right eye of the observer; and an optical path distributing part for distributing the image light beam emitted from the image display device at the above-described exit angle to the left and right ocular parts.
The left ocular part has at least two reflecting surfaces. At least one of the at least two reflecting surfaces is formed from a rotationally asymmetric curved reflecting surface having the function of correcting decentration aberrations.
The right ocular part has at least two reflecting surfaces. At least one of the at least two reflecting surfaces is formed from a rotationally asymmetric curved reflecting surface having the function of correcting decentration aberrations.
The optical path distributing part has at least one pair of reflecting surfaces for left and right optical paths for the left and right eyes of the observer. The reflecting surfaces are each formed from a rotationally asymmetric curved reflecting surface having the function of correcting decentration aberrations.
The left and right optical paths of the viewing optical system are formed by optical surfaces arranged so that the left and right optical paths are not in plane symmetry with each other but in 180-degree rotational symmetry with respect to only a normal line passing through the center of the image display device.
The reasons for adopting the above-described arrangement in the present invention, together with the function thereof, will be described below.
FIG. 1 shows the left and right optical paths (for the left and right eyes) and optical surfaces of the viewing optical system in the image display apparatus according to Example 1 (described later). Part (a) of FIG. 1 is a plan view. Part (b) of FIG. 1 is a side view. In the figure, L and R are suffixed to reference symbols to distinguish between the left and right optical surfaces, axial principal rays and pupils. The reference symbols are put to the constituent elements in the order of backward ray tracing to match with the description of numerical data (shown later).
The viewing optical system includes a left ocular part 10L for leading a light beam to an observer""s left eye positioned at a left pupil 1L and a right ocular part 10R for leading a light beam to an observer""s right eye positioned at a right pupil 1R. The viewing optical system further includes an optical path distributing part (optical path distributing prism in Example 1, which is shown in FIG. 1) 20 for leading an image light beam emitted from an image display device 3 at a predetermined exit angle to the left and right ocular parts 10L and 10R.
The left and right ocular parts 10L and 10R each have at least two reflecting surfaces (back-coated mirrors 12L and 12R and totally reflecting surfaces 13L and 13R in the case of FIG. 1). At least one of the at least two reflecting surfaces is formed from a rotationally asymmetric curved reflecting surface having the function of correcting decentration aberrations.
In the present invention, a free-form surface is used as a typical example of a surface having a rotationally asymmetric curved surface configuration. A free-form surface is defined by the following equation. The Z-axis of the defining equation is the axis of a free-form surface.                     Z        =                              c                                      xe2x80x83                                                                  r                2                            /                              [                                  1                  +                                                            {                                              1                        -                                                                              (                                                          1                              +                              k                                                        )                                                                                c                            2                                                                                r                            2                                                                                }                                                                      ]                                              +                                    ∑                              j                =                2                            66                                                                  C                j                                                          X                m                                                          Y                n                                                                        (        a        )
In the equation (a), the first term is a spherical surface term, and the second term is a free-form surface term.
In the spherical surface term:
c: the curvature at the vertex
k: a conic constant
r={square root over ( )}(X2+Y2)
The free-form surface term is given by
            ∑              j        =        2            66                          C        j                          X        m                          Y        n              =                    C        2                  X        +                  C        3                  Y        +                  C        4                          X        2              +                  C        5                  X                    xe2x80x83                  Y        +                  C        6                          Y        2              +                  C        7                          X        3              +                  C        8                          X        2                  Y        +                  C        9                  X                    xe2x80x83                          Y        2              +                  C        10                          Y        3              +                  C        11                          X        4              +                  C        12                          X        3                  Y        +                  C        13                          X        2                          Y        2              +                  C        14                  X                    xe2x80x83                          Y        3              +                  C        15                          Y        4              +                  C        16                          X        5              +                  C        17                          X        4                  Y        +                  C        18                          X        3                          Y        2              +                  C        19                          X        2                          Y        3              +                  C        20                  X                    xe2x80x83                          Y        4              +                  C        21                          Y        5              +                  C        22                          X        6              +                  C        23                          X        5                  Y        +                  C        24                          X        4                          Y        2              +                  C        25                          X        3                          Y        3              +                  C        26                          X        2                          Y        4              +                  C        27                          XY        5              +                  C        28                          Y        6              +                  C        29                          Y        7              +                  C        30                          X        6                  Y        +                  C        31                          X        5                          Y        2              +                  C        32                          X        4                          Y        3              +                  C        33                          X        3                          Y        4              +                  C        34                          X        2                          Y        5              +                  C        35                          XY        6              +                  C        36                          Y        7
where Cj (j is an integer of 2 or higher) are coefficients.
In general, the above-described free-form surface does not have planes of symmetry in both the XZ- and YZ-planes. However, a free-form surface having only one plane of symmetry parallel to the YZ-plane is obtained by making all terms of odd-numbered degrees with respect to X zero. A free-form surface having only one plane of symmetry parallel to the XZ-plane is obtained by making all terms of odd-numbered degrees with respect to Y zero.
In addition, free-form surfaces as the above-described surfaces with a rotationally asymmetric curved surface configuration may be defined by Zernike polynomials. That is, the configuration of a free-form surface may be defined by the following equation (b). The Z-axis of the defining equation (b) is the axis of Zernike polynomial. A rotationally asymmetric surface is defined by polar coordinates of the height of the Z-axis with respect to the XY-plane. In the equation (b), R is the distance from the Z-axis in the XY-plane, and A is the azimuth angle about the Z-axis, which is expressed by the angle of rotation measured from the X-axis.
x=Rxc3x97cos (A)
y=Rxc3x97sin (A)                                                         Z              =                              xe2x80x83                                                                            D                  2                                +                                                      D                    3                                                      R                                                        xe2x80x83                                                      cos                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                      D                    4                                                      R                                                        xe2x80x83                                                      sin                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                      D                    5                                                                          R                    2                                                      cos                                                        xe2x80x83                                                                          (                                          2                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                    6                                                                          (                                                                  R                        2                                            -                      1                                        )                                                  +                                                      D                    7                                                                          R                    2                                                      sin                                                        xe2x80x83                                                                          (                                          2                                            A                                        )                                                  +                                                      D                    8                                                                          R                    3                                                      cos                                                        xe2x80x83                                                                          (                                          3                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                      9                                                                                (                                                                        3                                                                                R                            3                                                                          -                                                  2                                                    R                                                                    )                                                                          cos                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                                            D                      10                                                                                (                                                                        3                                                                                R                            3                                                                          -                                                  2                                                    R                                                                    )                                                                          sin                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                                                xe2x80x83                                                                                D                    11                                                                          R                    3                                                      sin                                                        xe2x80x83                                                                          (                                          3                                            A                                        )                                                  +                                                      D                    12                                                                          R                    4                                                                          cos                                                              (                                              4                                                A                                            )                                                                      +                                                                                xe2x80x83                                                                                D                      13                                                                                (                                                                        4                                                                                R                            4                                                                          -                                                  3                                                                                R                            2                                                                                )                                                                          cos                                                        xe2x80x83                                                                          (                                          2                                            A                                        )                                                  +                                                      D                    14                                                                          (                                                                  6                                                                          R                          4                                                                    -                                              6                                                                          R                          2                                                                    +                      1                                        )                                                  +                                                                                xe2x80x83                                                                                D                      15                                                                                (                                                                        4                                                                                R                            4                                                                          -                                                  3                                                                                R                            2                                                                                )                                                                          sin                                                        xe2x80x83                                                                          (                                          2                                            A                                        )                                                  +                                                      D                    16                                                                          R                    4                                                      sin                                                        xe2x80x83                                                                          (                                          4                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                    17                                                                          R                    5                                                      cos                                                        xe2x80x83                                                                          (                                          5                                            A                                        )                                                  +                                                                            D                      18                                                                                (                                                                        5                                                                                R                            5                                                                          -                                                  4                                                                                R                            3                                                                                )                                                                          cos                                                        xe2x80x83                                                                          (                                          3                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                      19                                                                                (                                                                        10                                                                                R                            5                                                                          -                                                  12                                                                                R                            3                                                                          +                                                  3                                                    R                                                                    )                                                                          cos                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                                                xe2x80x83                                                                                D                      20                                                                                (                                                                        10                                                                                R                            5                                                                          -                                                  12                                                                                R                            3                                                                          +                                                  3                                                    R                                                                    )                                                                          sin                                                        xe2x80x83                                                                          (                    A                    )                                                  +                                                                                xe2x80x83                                                                                D                      21                                                                                (                                                                        5                                                                                R                            5                                                                          -                                                  4                                                                                R                            3                                                                                )                                                                          sin                                                        xe2x80x83                                                                          (                                          3                                            A                                        )                                                  +                                                      D                    22                                                                          R                    5                                                      sin                                                        xe2x80x83                                                                          (                                          5                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                    23                                                                          R                    6                                                      cos                                                        xe2x80x83                                                                          (                                          6                                            A                                        )                                                  +                                                                            D                      24                                                                                (                                                                        6                                                                                R                            6                                                                          -                                                  5                                                                                R                            4                                                                                )                                                                          cos                                                        xe2x80x83                                                                          (                                          4                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                      25                                                                                (                                                                        15                                                                                R                            6                                                                          -                                                  20                                                                                R                            4                                                                          +                                                  6                                                                                R                            2                                                                                )                                                                          cos                                                        xe2x80x83                                                                          (                                          2                                            A                                        )                                                  +                                                                                xe2x80x83                                                                                D                    26                                                                          (                                                                  20                                                                          R                          6                                                                    -                                              30                                                                          R                          4                                                                    +                                              12                                                                          R                          2                                                                    -                      1                                        )                                                  +                                                      D                    27                                    (                                                            15                                                                    R                        6                                                              -                                          20                                                                    R                        4                                                              +                                                                                xe2x80x83                                                                          6                                                              R                      2                                                        )                                                sin                                                  xe2x80x83                                                                  (                                      2                                        A                                    )                                            +                                                                    D                    28                                                                          (                                                                  6                                                                          R                          6                                                                    -                                              5                                                                          R                          4                                                                                )                                                                  sin                                                  xe2x80x83                                                                  (                                      4                                        A                                    )                                            +                                                                                xe2x80x83                                                                            D                  29                                                                  R                  6                                                sin                                                  xe2x80x83                                                                  (                                      6                                        A                                    )                                                                                (        b        )
where Dm (m is an integer of 2 or higher) are coefficients.
It should be noted that to design an optical system symmetric with respect to the X-axis direction, D4, D5, D6, D10, D11, D12, D13, D14, D20, D21, D22 . . . should be used.
The above defining equations are shown to exemplify surfaces with a rotationally asymmetric curved surface configuration. Therefore, the same advantageous effects can be obtained for any other defining equation that expresses such a rotationally asymmetric curved surface configuration.
It should be noted that other examples of defining equations for free-form surfaces include the following defining equation (c):
Z=xcexa3xcexa3CnmXY
Assuming that k=7 (polynomial of degree 7), for example, a free-form surface is expressed by an expanded form of the above equation as follows:                                                         Z              =                              xe2x80x83                                                                            C                  2                                +                                                      C                    3                                                      Y                                +                                                      C                    4                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                      C                    5                                                                          Y                    2                                                  +                                                      C                    6                                                      Y                                                        "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                      C                    7                                                                          X                    2                                                  +                                                      C                    8                                                                          Y                    3                                                  +                                                                                xe2x80x83                                                                                C                    9                                                                          Y                    2                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                      C                    10                                                                          YX                    2                                                  +                                                      C                    11                                                                          "LeftBracketingBar"                                          X                      3                                        "RightBracketingBar"                                                  +                                                      C                    12                                                                          Y                    4                                                  +                                                      C                    13                                                                          Y                    3                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                                                xe2x80x83                                                                                C                    14                                                                          Y                    2                                                                          X                    2                                                  +                                                      C                    15                                                      Y                                                        "LeftBracketingBar"                                          X                      3                                        "RightBracketingBar"                                                  +                                                      C                    16                                                                          X                    4                                                  +                                                      C                    17                                                                          Y                    5                                                  +                                                      C                    18                                                                          Y                    4                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                                                xe2x80x83                                                                                C                    19                                                                          Y                    3                                                                          X                    2                                                  +                                                      C                    20                                                                          Y                    2                                                                          "LeftBracketingBar"                                          X                      3                                        "RightBracketingBar"                                                  +                                                      C                    21                                                                          YX                    4                                                  +                                                      C                    22                                                                          "LeftBracketingBar"                                          X                      5                                        "RightBracketingBar"                                                  +                                                      C                    23                                                                          Y                    6                                                  +                                                                                xe2x80x83                                                                                C                    24                                                                          Y                    5                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                      C                    25                                                                          Y                    4                                                                          X                    2                                                  +                                                      C                    26                                                                          Y                    3                                                                          "LeftBracketingBar"                                          X                      3                                        "RightBracketingBar"                                                  +                                                      C                    27                                                                          Y                    2                                                                          X                    4                                                  +                                                                                xe2x80x83                                                                                C                    28                                                      Y                                                        "LeftBracketingBar"                                          X                      5                                        "RightBracketingBar"                                                  +                                                      C                    29                                                                          X                    6                                                  +                                                      C                    30                                                                          Y                    7                                                  +                                                      C                    31                                                                          Y                    6                                                                          "LeftBracketingBar"                    X                    "RightBracketingBar"                                                  +                                                      C                    32                                                                          Y                    5                                                                          X                    2                                                  +                                                                                xe2x80x83                                                                                C                    33                                                                          Y                    4                                                                          "LeftBracketingBar"                                          X                      3                                        "RightBracketingBar"                                                  +                                                      C                    34                                                                          Y                    3                                                                          X                    4                                                  +                                                      C                    35                                                                          Y                    2                                                                          "LeftBracketingBar"                                          X                      5                                        "RightBracketingBar"                                                  +                                                      C                    36                                                                          YX                    6                                                  +                                                      C                    37                                                                          "LeftBracketingBar"                                          X                      7                                        "RightBracketingBar"                                                                                (        c        )
It should be noted that an anamorphic surface or a toric surface is also usable as a surface having a rotationally asymmetric curved surface configuration.
Referring to FIG. 1 again, the optical path distributing part 20 has at least one pair of reflecting surfaces for left and right optical paths (i.e. a pair of back-coated mirrors 22L and 22R and another pair of back-coated mirror 23L and 23R in the case of FIG. 1). These reflecting surfaces are formed from rotationally asymmetric curved reflecting surfaces having the function of correcting decentration aberrations.
The point of the image display apparatus having a three-dimensionally decentered optical path according to the present invention is as follows.
The left and right optical paths (for the left and right eyes) of the viewing optical system are formed by optical surfaces 11L to 14L, 21L to 23L, 24, 11R to 14R, 21R to 23R and 24 arranged so that the left and right optical paths are not in plane symmetry with each other but in 180-degree rotational symmetry with respect to only a normal line A-Axe2x80x2 passing through the center of the image display device 3. In Example 1, the refracting surface (entrance surface) 24 through which the image light beam first enters the optical path distributing prism 20 from the image display device 3 is a surface common to the left and right optical paths.
To form left and right optical paths that are in 180-degree rotational symmetry with each other as stated above, the decentered prisms 10L, 10R and 20 should be arranged as follows. Pairs of optical surfaces (left and right) 11L, 11R; 12L, 12R; 13L, 13R; 14L, 14R; 21L, 21R; 22L, 22R; and 23L, 23R; are arranged and the surface 24 common to the left and right optical paths is formed so that when the optical surfaces 11R to 14R, 21R to 23R and 24, which constitute the optical system for the right optical path, are rotated through 180 degrees about the normal line A-Axe2x80x2, these surfaces are coincident with the optical surfaces 11L to 14L, 21L to 23L and 24, which constitute the optical system for the left optical path.
It is desirable that the optical path distributing part 20 should have at least two pairs of reflecting surfaces (left and right) 22L, 22R; and 23L, 23R; and the two pairs of reflecting surfaces should have rotationally asymmetric curved reflecting surfaces having the function of correcting decentration aberrations, as in the case of the example shown in FIG. 1.
Further, the left and right optical paths for the left and right eyes should desirably be arranged so that a plane defined by the optical axis of the axial principal ray incident on the left first reflecting surface 23L closest to the image display device 3 among the left reflecting surfaces in the left optical path of the optical path distributing part 20 and the axial principal ray exiting the left first reflecting surface 23L is not identical with a plane defined by the optical axis of the axial principal ray incident on the right first reflecting surface 23R closest to the image display device 3 among the right reflecting surfaces in the right optical path of the optical path distributing part 20 and the axial principal ray exiting the right first reflecting surface 23R.
If the left and right optical paths for the left and right eyes are not arranged as stated above, the left and right first reflecting surfaces 23L and 23R undesirably interfere with each other. Accordingly, it actually becomes difficult to form left and right optical paths for leading a light beam from the single image display device 3 to the left and right eyes.
Further, it is desirable that the left first reflecting surface 23L closest to the image display device 3 among the reflecting surfaces in the left optical path of the optical path distributing part 20 and the right first reflecting surface 23R closest to the image display device 3 among the reflecting surfaces in the right optical path of the optical path distributing part 20 should be positioned to face the image display device 3 and should be disposed adjacent to each other in a direction [i.e. the X-direction, which is the vertical direction in part (b) of FIG. 1] perpendicular to a plane [i.e. the YZ-plane in part (a) of FIG. 1] containing the centers of the exit pupils 1L and 1R of the left and right optical paths of the viewing optical system and also containing the center of the image display device 3.
In this case, it is desirable that an anti-reflection member should be provided for an area including the boundary portion between the left first reflecting surface 23L and the right first reflecting surface 23R to prevent light rays emitted perpendicularly (in the Z-direction) from the central region of the image display device 3 from being reflected as ghost light, as will be described later.
It should be noted that the viewing optical system, which comprises the ocular parts 10L and 10R and the optical path distributing part 20 as stated above, may be formed from a combination of reflecting mirrors (in Example 5, only the optical path distributing part 20 is formed from a combination of reflecting mirrors). However, the viewing optical system may also be formed from a single prism member [corresponding to Example 4 (described later)] or a plurality of prism members [corresponding to Examples 1 to 3 and 6 (described later); in Example 5, only the ocular parts 10L and 10R are prism members]. In such a case, all of the reflecting surfaces may be back-coated reflecting surfaces formed on the surfaces of the prism members.
The viewing optical system may also be arranged to include, as shown in FIG. 1, an optical path distributing prism 20 constituting the optical path distributing part, and a combination of a left ocular prism 10L constituting the left ocular part and a right ocular prism 10R constituting the right ocular part. The left ocular prism 10L and the right ocular prism 10R are separated from the optical path distributing prism 20 by an air space.
In this case, the optical path distributing prism 20 may include at least the following surfaces. That is, as in the case of the example shown in FIG. 1, an entrance surface 24 is disposed to face the image display device 3 so that both an image light beam forming the left optical path for the left eye and an image light beam forming the right optical path for the right eye enter the optical path distributing prism 20 through the entrance surface 24. The optical path distributing prism 20 further includes a left exit surface 21L through which the light beam of the left optical path exits the optical path distributing prism 20. At least two left reflecting surfaces 23L and 22L are disposed in the optical path between the entrance surface 24 and the left exit surface 21L to reflect the light beam of the left optical path within the optical path distributing prism 20. The optical path distributing prism 20 further includes a right exit surface 21R through which the light beam of the right optical path exits the optical path distributing prism 20. At least two right reflecting surfaces 23R and 22R are disposed in the optical path between the entrance surface 24 and the right exit surface 21R to reflect the light beam of the right optical path within the optical path distributing prism 20. The reflecting surface 23L closest to the entrance surface 24 in the left optical path and the reflecting surface 23R closest to the entrance surface 24 in the right optical path are positioned so as to face both the image display device 3 and the entrance surface 24. Moreover, the reflecting surfaces 23L and 23R are disposed adjacent to each other in a direction [i.e. the X-direction, which is the vertical direction in part (b) of FIG. 1] perpendicular to a plane [i.e. the YZ-plane in part (a) of FIG. 1] containing the centers of the exit pupils 1L and 1R of the left and right optical paths of the viewing optical system and also containing the center of the image display device 3.
Further, it is desirable that a distributed light reinforcing member should be disposed between the image display device and the optical path distributing part so that the light intensity of an image light beam emitted at a predetermined exit angle from each pixel located at least in the central portion of the single image display device is made higher by the distributed light reinforcing member than the intensity of a light beam emitted in a direction perpendicular to the display surface of the image display device.
As shown in FIG. 1, the left and right ocular prisms 10L and 10R may be prisms 10 (suffixes xe2x80x9cLxe2x80x9d and xe2x80x9cRxe2x80x9d for distinction between left- and right-side constituent elements are omitted) each having a first surface 14, a second surface 12, and a third surface 11 (13). The first surface 14 is an entrance surface through which a light beam exiting the optical path distributing prism 20 enters the prism 10. The second surface 12 is a reflecting surface for reflecting the light beam entering through the first surface 14 and totally reflected from the third surface 11 (13) within the prism 10 so that the light beam reflected from the second surface 12 is incident on the third surface 11 (13) at an angle smaller than the total reflection critical angle. The third surface 11 (13) is arranged so that the light beam entering the prism 10 through the first surface 14 is incident on the third surface 11 (13) at an angle not smaller than the total reflection critical angle so as to be totally reflected therefrom, and, at the same time, the third surface 11 (13) is an exit surface through which the light beam reflected from the second surface 12 exits the prism 10. This configuration of the prism 10 corresponds to Examples 1 to 3 and 5 (described later).
In this case, the first surface 14 of each of the left and right ocular prisms 10L and 10R may be formed with a rotationally asymmetric curved surface configuration that corrects decentration aberrations. The second surface 12 may also be formed with a rotationally asymmetric curved surface configuration that corrects decentration aberrations.
In this case, it is desirable to arrange the left and right ocular prisms 10L and 10R so that the left axial principal ray exiting the optical path distributing prism 20 intersects, at a desired angle, a plane defined by the left axial principal ray exiting the left ocular prism 10L and the right axial principal ray exiting the right ocular prism 10R.
The left and right ocular prisms 10L and 10R may also be arranged as follows. As shown in Example 6 (described later), the left ocular prism is a prism having first to fourth surfaces. The first surface is an entrance surface through which a light beam exiting the optical path distributing prism enters the prism. The second surface is a reflecting surface for reflecting the light beam entering the prism through the first surface. The third surface is a reflecting surface for reflecting the reflected light beam from the second surface within the prism. The fourth surface is an exit surface through which the light beam reflected from the third surface exits the prism. The right ocular prism is a prism having first to fourth surfaces. The first surface is an entrance surface through which a light beam exiting the optical path distributing prism enters the prism. The second surface is a reflecting surface for reflecting the light beam entering the prism through the first surface. The third surface is a reflecting surface for reflecting the reflected light beam from the second surface within the prism. The fourth surface is an exit surface through which the light beam reflected from the third surface exits the prism. When the optical paths in the left and right ocular prisms are projected onto a plane containing the centers of the exit pupils of the left and right optical paths of the viewing optical system and also containing the center of the image display device, the optical path in each of the ocular prisms rotates within the prism in such a manner as to intersect itself.
In this case, the second surface of each of the left and right ocular prisms may be formed with a rotationally asymmetric curved surface configuration that corrects decentration aberrations. The third surface may also be formed with a rotationally asymmetric curved surface configuration that corrects decentration aberrations.
In this case, it is desirable to arrange the left and right ocular prisms so that the left axial principal ray and the right axial principal ray exiting the optical path distributing prism intersect, at a desired angle, a plane defined by the left axial principal ray exiting the left ocular prism and the right axial principal ray exiting the right ocular prism.
In the foregoing arrangement, it is desirable that the viewing optical system should form an intermediate image of the image displayed by the image display device in the right optical path and also form an intermediate image of the image displayed by the image display device in the left optical path.
The image display device may be rotated through a desired angle about the normal line passing through the center of the image display device as an axis of rotation so that the horizontal direction of the image display area of the image display device is at an angle to a plane containing the centers of the exit pupils of the left and right optical paths of the viewing optical system and also containing the center of the image display device.
In the viewing optical system of the present invention, the surface configuration of each surface of the left and right optical systems is determined so that the optical paths for the left and right eyes are in 180-degree rotational symmetry with respect to only the normal line A-Axe2x80x2 passing through the center of the image display device 3, as has been stated above. Accordingly, the left optical system extending from the entrance surface 24 of the optical path distributing part 20 to the exit surface 11L of the left ocular part 10L and the right optical system extending from the entrance surface 24 of the optical path distributing part 20 to the exit surface 11R of the right ocular part 10R are in 180-degree rotational symmetry about the normal line A-Axe2x80x2. Moreover, the left and right optical systems are three-dimensionally decentered reflecting optical systems. Therefore, the relay image (intermediate image) of the image displayed by the image display device 3 is generally rotated through the same angle in the same direction about each optical axis. Accordingly, an image naturally oriented with respect to both the horizontal and vertical directions cannot be observed unless the image display device 3 is rotated in the opposite direction to the direction of rotation of the relay image (intermediate image) through the same angle as the angle of rotation about the normal line A-Axe2x80x2 as an axis of rotation so that the horizontal direction of the image display area of the image display device 3 is at an angle to a plane containing the centers of the exit pupils 1L and 1R of the left and right optical paths of the viewing optical system and also containing the center of the image display device 3.
Incidentally, it is desirable to satisfy the following condition:
10xc2x0 less than xcex8 less than 120xc2x0xe2x80x83xe2x80x83(1)
where xcex8 is the angle formed between the axial principal rays 2L and 2R of left and right light beams led from each pixel located at least in the central portion of the image display device 3 to the left and right eyes of the observer.
The condition (1) needs to be satisfied in order to separate the image light beams for the two eyes appropriately. If xcex8 is not larger than the lower limit, i.e. 10xc2x0, the effective diameter portions of the left and right optical surfaces, particularly those of the left and right first reflecting surfaces 23L and 23R closest to the image display device 3 undesirably overlap each other. Accordingly, the optical system has to be increased in size in order to ensure the required effective diameter of each of the left and right first reflecting surfaces 23L and 23R and hence becomes unsuitable for use as the optical system of a head- or face-mounted image display apparatus. Conversely, if xcex8 is not smaller than the upper limit, i.e. 120xc2x0, an image display device having very wide viewing angle characteristics is needed to serve as the image display device 3. At the same time, the solid angle of the image light beam becomes small. As a result, it becomes impossible to observe a bright image. Regarding the angle xcex8, it is preferable to satisfy the following condition:
15xc2x0 less than xcex8 less than 100xc2x0xe2x80x83xe2x80x83(1-1)
The above-described image display apparatus can be used as an image pickup apparatus in which an image pickup device is provided in place of the image display device 3 in the above-described arrangement. In this case, the exit pupils 1L and 1R are arranged as entrance pupils through which a light beam from a subject passes, and a subject image is formed on the image pickup device.
Further, the image display apparatus can be used as a projection apparatus in which a projection object is provided in place of the image display device 3 in the foregoing arrangement. A screen is placed in front of the exit pupils 1L and 1R to form a projected image of the projection object on the screen.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

Image display apparatus having three-dimensionally decentered optical path


A processor identifies keypoints on a hand in a two-dimensional image that is captured by a camera. A three-dimensional pose of the hand is determined using locations of the keypoints to access lookup tables (LUTs) that represent potential poses of the hand as a function of the locations of the keypoints. In some embodiments, the keypoints include locations of tips of fingers and a thumb, joints that connect phalanxes of the fingers and the thumb, palm knuckles that represent a point of attachment of the fingers and the thumb to a palm, and a wrist location that indicates a point of attachment of the hand to a forearm. Some embodiments of the LUTs represent 2D coordinates of the fingers and the thumb in corresponding finger pose planes as a function of the locations of the tips of the fingers or thumb relative to the corresponding palm knuckles.

The location of human body parts, and especially human hands, in three-dimensional (3D) space is a useful driver of numerous applications. Virtual reality (VR), augmented reality (AR), or mixed reality (MR) applications use a representation of a user's hands to facilitate interaction with virtual objects, to select items from a virtual memory, to place objects in the user's virtual hand, to provide a user interface by drawing a menu on one hand and selecting elements of the menu with another hand, and the like. Gesture interactions add an additional modality of interaction with automated household assistants such as Google Home or Nest. Security or monitoring systems use 3D representations of human hands or other body parts to detect and signal anomalous situations. In general, a 3D representation of the location of human hands or other body parts provides an additional modality of interaction or detection that is used instead of or in addition to existing modalities such as voice communication, touchscreens, keyboards, computer mice, and the like. However, computer systems do not always implement 3D imaging devices. For example, devices such as smart phones, tablet computers, and head mounted devices (HMD) typically implement lightweight imaging devices such as two-dimensional (2D) cameras.

Hand skeleton learning, lifting, and denoising from 2D images


Apparatus, computer system, computer program and storage medium for determining intrathoracic blood volume (ITBV) and other cardio-vascular parameters of a patient by thermodilution measurements. The apparatus includes: temperature influencing means for introducing a traveling temperature deviation to a patient's blood stream, a temperature sensor device for measuring the local temperature of the patient's blood downstream of the temperature influencing means, a computer system adapted to: record local blood temperature measured as a function of time to determine a thermodilution curve, determine global enddiastolic blood volume (GEDV) and intrathoracic thermovolume (ITTV) from the thermodilution curve, determine intrathoracic blood volume (ITBV) as a function of GEDV, ITTV and the airway pressure inside the patient's lungs (P). By determining ITBV not only from GEDV but also a function of ITTV and P enhanced accuracy can be obtained, especially if the patient suffers from pulmonary edema and/or is mechanically ventilated.

The current state of the art in implementing transpulmonary thermodilution measurement are apparatus for injecting a bolus of thermal indicator into a patient's vena cava superior, and measuring the temperature response at a place of the patient's systemic circulation, e.g. patient's femoral artery to determine the thermodilution curve, i.e. the temperature response as a function of time. From the thermodilution curve, a schematic example of which is illustrated in FIG. 3, wherein the abscissa (time axis) 1 is linear and the ordinate (temperature difference axis) 2 is logarithmic, various cardio-vascular parameters can be derived by using computer systems running computer programs, which implement parameter calculations as disclosed in WO 93/21823, the contents of which are included herein by citation, and as set forth briefly below.
The Cardiac Output CO can be determined by algorithms based on the Stewart-Hamilton-equation:
  CO  =                              V          L                                  (                                    T              B                        -                          T              L                                )                                  K        1                          K        2                    ∫                                    T            B                                      Δ                                                        (            t            )                                                                              ⅆ          t                    where TB is the initial blood temperature, TL is the temperature of the liquid bolus, which is used as thermal indicator, VL is the thermal indicator volume, K1 and K2 are constants to consider the specific measurement setup, and ΔTB(t) is the blood temperature as a function of time with respect to the baseline blood temperature TB. Thermal indicator can either be colder or warmer with respect to blood temperature. To obtain cardiac output, the area under the thermodilution curve has to be determined by mathematical integration.
Other parameters that can be derived from the thermodilution curve 3 as schematically illustrated in FIG. 1 include the Exponential Decay or Downslope Time DST, i.e. the time the blood temperature difference ΔTB(t) takes to drop by the factor e−1, the Appearance Time AT, i.e. the time span between bolus injection IT and first appearance of a noticable temperature difference ΔTB(t) and the Mean Transit Time MTT.
The Intrathoracic Thermovolume ITTV and the Intrathoracic blood volume ITBV can be determined as follows:ITTV=CO·MTT ITBV=a′·GEDV+b′wherein a′ and b′ are species-specific constants and GEDV is the Global End-Diastolic Volume, which can be determined as follows:GEDV=CO·(MTT−DST)
An extravascular thermovolume estimate can be determined as the difference between Intrathoracic Thermovolume ITTV and the Intrathoric blood volume ITBVETV=ITTV−ITBV
Extravascular thermovolume correlates, if there is no significant perfusion defect in the lungs (e.g. massive pulmonary embolism or large single embolism), closely to the degree of Extravascular Lung Water.
Transpulmonary thermodilution has been shown to be a reliable technique for assessing cardiac output, cardiac preload and extravascular lung water (EVLW), i.e. to quantify pulmonary edema. The estimation of EVLW by the injection of a single thermal indicator is based on the above mentioned relationship ITBV=a′·GEDV+b′. This method has been shown to compare favorably with the double-indicator (thermo-dye) dilution technique and with the ex-vivo gravimetric methods.
However, for mechanically ventilated patients and patients suffering from severe pulmonary edema the results were not entirely satisfactory.
It is therefore an object of the present invention to provide a new apparatus, a new computer system and a new computer program allowing the determination of the intrathoracic blood volume by single indicator transpulmonary thermodilution with enhanced accuracy especially for patients suffering from severe pulmonary edema and/or for mechanically ventilated patients.

Apparatus, computer system and computer program for determining intrathoracic blood volume and other cardio-vascular parameters


The present invention relates to a cable bead, the method of constructing the cable bead and a tire constructed by a process incorporating the cable bead wherein the cable bead is formed with a bead core wound from a single filament of bead core wire having a rubber or elastomeric coating, first annular wrap of bead wrapping wire helically wound around the bead core, and a coating of lubricant or fatty acid disposed about the bead core.

A tire bead is that part of a tire which has a function of locating and fixing textile or steel cords of a carcass ply, determining the internal periphery of the tire, and anchoring the tire onto a wheel rim. The tire bead is essentially an annular, tensile member or inextensible hoop. Every tire has at least two tire beads which are located within the rubber or elastomeric matrix that makes up the radially inner-most circumference on each side of the tire. There are three primary conventional categories of tire beads, they are strap beads, single wire beads and cable beads.
Strap Beads
An example of a strap bead is disclosed in European Patent Application No. 655,354 wherein a bead core is constructed by winding a strip of wire-rubber matrix made of a row of several wires buried in rubber, as shown in FIG. 1 herein. The rubber keeps the bead together and prevents fretting of the wire into adjacent components of the tire. A strap bead is easy and economical to manufacture. There are, however, some drawbacks to strap beads. First, the inner and outer ends of the strap overlap and are spliced, wrapped or stapled together. The weakest region of this type of bead is at the overlap of the strap ends. Also, in the manufacture of a pneumatic tire incorporating strap beads, the rows and lines of the wire-rubber matrix tend to fall in disorder during the tire building and curing steps and it can adversely affect the uniformity of the tire.
Single Wire Beads
The single wire bead is constructed by wrapping a single strand of rubber coated bead wire into a bundle or hoop of a desired cross sectional shape. The cross-sectional shape can be defined as, but not limited to, hexagonal, triangular, square or pentagonal. The number of turns that the bead wire is wound depends upon the strength and/or cross-sectional area of the tire bead desired. For example, as shown in FIG. 2 herein, a single rubber-coated bead wire is wrapped nineteen (19) times into a cylindrical bundle or hoop that forms an hexagonal shaped bead. Note that the wraps begin on the inner row, left-hand corner, move to the right, then up and back toward the left, and then up and to the right. The free ends of the bead wire can be secured by a number of techniques including pushing them into the bundle, and/or stapling or taping them to the bundle. A single wire bead is the strongest of the conventional prior art beads described herein. The deficiencies of a single wire bead are a) since the single wire bead is wound of a single wire, the production time is often longer and therefore the single wire beads are generally more expensive to manufacture; and b) also, the free ends of the wound bead wire have a spring-back nature and sometimes come loose from the bundle causing tire misalignments, a protuberance from the tire, and/or some tire imbalance.
Cable Beads
A conventional cable bead typically consists of a core hoop formed of a single wire having its ends typically welded together. Then a cable, consisting of one or more filaments of wire, is helically wound around the core hoop. Next, one free end of each filament is connected to the opposite free end, typically by inserting the free ends into a ferrule and crimping the ferrule. The deficiencies in this cable bead construction generally include a) the core tending to break at the weld; b) the cable filament wire tending to break at the ferrule causing the free ends of the wound cable wire which have a spring-back nature to sometimes come loose from the bundle causing tire misalignments, a protuberance from the tire, and/or some tire imbalance. An example of this type of cable bead construction is set forth in G.B. 189,429 and U.S. Pat. No. 1,491,626.
Another prior art cable bead design, as disclosed in U.S. Pat. No. 1,715,302, can be constructed of a core hoop formed of a group of wires twisted together. The ends of the wires forming the core hoop can be secured to each other, typically by welding them together. Then, a cable consisting of one or more filaments of wire is helically wound around the core hoop. The ends of each filament of the cable are connected to each other, typically by inserting them into a ferrule and crimping the ferrule to secure the ends therein. When two or more cable layers are wound about the core, they are preferably wound in opposite directions to each other. The deficiencies in this cable bead construction include: a) the added time and expensive due to the core being formed of a group of twisted wires; and b) the cable filament(s) tending to break at the ferrule causing the free ends of the wound cable wire which have a spring-back nature to sometimes come loose from the bundle causing tire misalignments, a protuberance from the tire, and/or some tire imbalance.
Still another prior art cable bead design, as disclosed in U.S. Pat. No. 1,437,013 ('013), can be constructed of a core that "consists of three convolutions of wire laid side by side in such a relation as to form a triangular cross section the arrangement being such that two of the convolutions lie side by side and the third lies on the outer side of these two convolutions directly over their adjacent sides. The core so formed is of triangular cross section with one of its sides toward the inner side of the core and the inner side of the completed grommet and the apex of the triangle toward the outer side of the grommet" (page 1, lines 39-51). The three convolutions . . . are preferably formed from a continuous piece of wire . . . " (page 1, lines 100-102). The ends of the wire forming the core can be secured to each other, "as by welding them together" (page 1, lines 108-109). Then, "a plurality of convolutions of spirals are wound upon the core so formed with the spirals of several convolutions lying side by side and forming a complete layer or casing." (page 1, lines 52-56). "The end of the wire forming the surrounding casing may be secured in position in any suitable manner" (page 2, lines 12-14). When the surrounding casing of spirally formed wire has been completed, the grommet is substantially in the form indicated in FIG. 2 of the '013 patent, the spirals of the casing being arranged approximately in a circle about the triangular core.
The grommet so formed as an intermediate product of construction is then subjected to heavy pressure to expand it to the desired size. While so expanding the grommet, the casing of spirals assumes a configuration more or less approximating the cross-sectional shape of the core so that the completed grommet is substantially triangular in cross-section. The relation of the core wires and the wires of the spiral casing after the grommet has been so expanded is indicated in FIG. 3.
During the intermediate stage of construction, when the grommet is in the form as shown in FIG. 2, the spirals of the casing are arranged approximately in a circle about the triangular core. However, after the grommet has been formed into an intermediate article of manufacture, as previously discussed, the grommet is preferably stretched to enlarge it to the precise diameter desired for the completed grommet. The disclosure of expanding the grommet by heavy pressure from the size shown in FIG. 2 of the '013 patent up to the desired size as shown in FIG. 3 of that patent is not readily understandable. While the multiple convolutions of single wound wire forming the triangular core of the bead must have enough flexibility that the bead portions of the tire can be mounted on a rim, they must concurrently be stiff and strong enough that tire remains mounted on the rim during the stresses generated under normal operating conditions. Moreover, it seems likely that the wound wire would be stretched beyond its elastic limit and therefore be unable to return to its design shape. Therefore, it seems unlikely that the core would be unable to stretch from the diameter shown in FIG. 2 to the diameter shown in FIG. 3 while retaining its functional requirements due to the strength requirements of the grommet. This ability to stretch is even less likely in the bead design where the ends of the wire forming the core are joined together, as by welding. With this design, the core would have the tendency to break at the weld.
It is further not understood from the disclosure of the '013 patent how the surrounding casing or casings of spirally wound wires would shift from their initial circular configuration (shown in FIG. 2 of the '013 patent) to a triangular shape (shown in FIG. 3 of the '013 patent) corresponding to that of the enclosed triangular shaped core (a triangular shape with one of its sides toward the center of the grommet and its apex directed outwardly of the grommet). The spirally wound wire(s) are wound about the core so as to cross all of the core wires as they spiral along the length of the core from one end to the other. When a device (not shown) is inserted into the grommet to stretch it outwardly, the device would be forced to press the casing wires at spaced locations against the core wires which would in turn cause the casing wires to resist being stretched. And even if they could stretch, it is not understandable how they could stretch to a triangular shape since they would not be free to stretch evenly.
Another apparent structural contradiction in the '013 patent is that, similar to the triangular core, the convolutions of wound wire forming the casing of the bead must have enough flexibility that the bead portions of the tire can be mounted on a rim. They must concurrently be stiff and strong enough that tire remains mounted on the rim during the stresses generated under normal operating conditions. Moreover, it seems likely that the wound wire of the casing would be stretched beyond its elastic limit and therefore be unable to return to its design shape. Therefore, it seems unlikely that the casing would be able to stretch from the diameter shown in FIG. 2 of the '013 patent to the diameter shown in FIG. 3 of that patent while retaining its functional requirements due to the strength and stiffness requirements of the grommet needed for the bead to function properly in a tire.
Regarding the functionality of conventional cable beads, it is believed that the core of the prior art cable beads were primarily used as a mandrel to wrap the cabling around. When a prior art cable bead of the types described herein before is incorporated into a green tire carcass, the cable does not stick or attach itself to the green rubber of the ply when the ply ends are wrapped around the cable beads and pressed against the main body of the ply on the first stage tire building drum. Then, when the tire carcass is shaped into a toroidal cross section on the first stage tire building drum, the material around the cable tends to slip about the cable bead so that uniformity problems possibly caused by the bead being twisted (such as single wire or strap beads) are reduced. Then, after the tire is cured, the core is no longer needed and the strength of the bead is primarily derived from the cabling. The cabling of the prior art cable beads, while providing the primary strength of the bead, is also generally flexible. The flexibility of the prior art cable beads is advantageous in that the tire is easier to mount on a wheel. However, the flexibility has an important disadvantage. That is, the flexible nature of the prior art cable beads also causes them to more easily unseat from a wheel, especially during adverse load conditions such as with deflated or under-pressurized tires.
Another cable bead design as disclosed in Japanese Laid-Open Patent Application 55-1201 entitled BEAD WIRE discloses for example, a "composite bead wire, as shown in FIG. 4, a hard steel solid wire W14 coated with rubber coating R2 was sequentially wound in parallel so that they were in close contact with one another and stacked and wound, resulting in a formed bead wire main body with a hexagonal cross-section. With this as the cord ring, its peripheral surface was spirally wound with a hard steel wire W15 and the entire peripheral surface of the core ring was surrounded, resulting in a bead wire characterized by a circular cross-section." (See P. 15 of translation). In another embodiment, as shown in FIG. 5 of the 55-1201 Application, "a rubber coating R3a is applied to a single hard steel wire W16 using a rubber extruder, and that hard steel wire W16 is wound three times in parallel on a winder former to form a first layer." Using additional winders can be layered to form "a bead wire main body 1 whose cross-section shape is hexagonal."
"Next, a rubber coating R4 is applied to a hard steel wire W17 using a rubber extruder to make a rubber coated wire 2. Using the aforesaid bead wire main body 1 as a core ring, the rubber coated wire 2 is spirally wound . . . on its peripheral surface, and the entire peripheral surface of the bead wire main body 1 . . . " (See pages 15 and 16 of the translation). This patent application has a limitation in that the rubber coated wire forming the bead wire main body is in contact with the rubber coating the rubber coated wire disposed about the bead wire main body so that the surrounding wire and main bead wire have a tendency not to move with respect to each other during the manufacture of the tire prior to the molding process.
In a Japanese Laid-Open Patent Application 51-50106, there is disclosed a composite bead wire wherein a ring body B3 formed of a hard steel solid wire W11 with a rubber coating R2 has a hard steel wire W12 spirally wound about the peripheral surface at a suitable pitch. A rubber coating or a fabric coating can be applied to fill the gap between the ring body's B3 hexagonal cross-section and the circular cross-section of the peripheral spiral winding using the hard steel wire W12." This patent application can be distinguished from the present invention in that the application of a rubber coating or fabric coating between the ring body and the spiral winding would also prevent the movement of the spiral winding with respect to the ring body during the manufacture of the ring.
Thus, despite the existence of several types of beads in the prior art, there still exists a need for an improved tire bead construction that can reduce or eliminate the above-described difficulties.


A UE 100 is a UE 100 included in a D2D group (a terminal group) including a plurality of UEs 100 (a UE 100-1 and a UE 100-2) in a mobile communication system that supports D2D communication that is direct inter-terminal communication performed within the D2D group. The UE 100 performs UE-initiated scheduling of deciding allocation radio resources that are radio resources used for the D2D communication from among target radio resources reserved in a serving cell in which the D2D group exists and a neighboring cell adjacent to the serving cell when the D2D group is detected to be in a high-speed moving state.

In the 3rd Generation Partnership Project (3GPP) that is a mobile communication system standardization project, introduction of a device-to-device communication (D2D) into Release 12 as a new function is under review (see Non Patent Literature 1).
In the D2D communication, direct inter-terminal communication is performed within a terminal group including a plurality of nearby user terminals without intervention of a network. On the other hand, in cellular communication that is common communication of a mobile communication system, user terminals perform communication via a network.
In the D2D communication, radio communication can be performed between nearby user terminals at low transmission power, and thus power consumption of the user terminal and a load of the network can be reduced to be smaller than in the cellular communication.

Communication control method and user terminal


A plate-shaped footrest assembly for a chair; includes a footrest for support of the rear side of the legs of a user, and a footplate for placement of the feet of the user thereon, with the footplate being so linked to the footrest as to permit a pivoting between a stowed position when not being used and an unfolded position when in use. The footplate extends in the unfolded position at an inclination to the footrest. In stowed position, the footplate forms a major central area of the footrest while projecting in the unfolded position almost entirely across a useful support surface of the footrest.

The present invention generally relates to a plate-shaped footrest assembly for a chair, and more particularly to a footrest assembly including a footrest for support of the rear side of the legs of a user, and a footplate for placement of the feet of the user thereon, with the footplate being so linked to the footrest as to permit a pivoting about an axis oriented parallel to a plane of the footrest between a stowed position in which the footplate is not in use and extends in the plane of the footrest, and an unfolded position in which the footplate is in use and extends at an inclination to the footrest.
Plate-shaped footrests for chairs are known in a wide variety of designs. Normally, the footrest is mounted by a pantographic or telescoping scissors-type linkage mechanism to the frame of a chair for swinging from a stored position in which the footrest is located under the seat into an elevated position in which the support surface of the footrest extends approximately at seat level.
It is also known to provide footrests that are equipped with swingable footplates. In conventional footrests of this type, these footplates are relatively small and swingable about an axis that extends approximately in the middle of the footplate. Thus, when pivoting the footplate, only a slight area of the footplate projects upwardly beyond the support surface of the footrest while a same area is pivoted into a space underneath the support surface of the footrest. Such footplates have therefore only a relatively slight effectiveness.

Plate-shaped footrest assembly for a chair


A tiltable lift and a method for using it to aid the unloading of a pallet. The tiltable lift comprises a lift mounted atop a tiltable platform. A pallet load of pallet load elements, such as containers, cartons, boxes, trays, or bundles, deposited on the lift is tilted. A wall extending upward from the platform receives a side of the tilted pallet load, which is urged against the wall by gravity. The lift lifts the pallet load along the wall to position the topmost layer of the pallet load at a top end of the wall for easy access and removal of pallet load elements from the pallet.

The invention relates generally to lifts and tiltable supports and, more particularly, to lifts mounted on tiltable supports and associated methods for removing boxes, trays, bundles of articles, or other pallet load elements from a pallet.
A typical pallet load comprises a multi-layer array of containers, such as boxes or trays, stacked atop a pallet. The containers are often removed manually from the pallet one by one starting with the topmost layer. Containers in the topmost layer closest to the point of removal are easy to remove. But containers farther away from the point of removal are hard to reach.

Apparatus and methods for helping unload a pallet