Abstract:
A stereoscopic image display apparatus includes at least two linear image display devices which respectively display linear images in response to image signals. The two linear image display devices are periodically moved by a mechanical scan mechanism along a plurality of locus planes substantially parallel to each other. The mechanical scan mechanism may have a configuration which belt-drives the at least two linear image display devices fixed to a belt, or a configuration which rotationally drives the at least two linear image display devices provided on a disc. The stereoscopic image display apparatus can display a bright and extremely clear stereoscopic image without using a complicated optical system and a light transmissible display panel.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1) Field of the Invention  
           [0002]    The present invention relates to a stereoscopic image display apparatus.  
           [0003]    2) Description of the Related Art  
           [0004]    A stereoscopic image display apparatus for displaying a stereoscopic image having a three-dimensional impression on a two-dimensional screen is disclosed, for example, in Japanese Patent Kokai No. 2000-115812. As shown in FIG. 1 of the accompanied drawings, the stereoscopic image display apparatus disclosed in the above-mentioned Japanese Patent Kokai No. 2000-115812 uses liquid crystal panels  1  and  2 , and a half mirror  3 . As illustrated in FIG. 1, an observer can simultaneously observe a light beam  4  transmitted through the half mirror  3  and a light beam  5  reflected by the half mirror  3 . The light beam  4  is emitted from a displayed image on the liquid crystal panel  1 , and the light beam  5  is emitted from a displayed image on the liquid crystal panel  2 . Accordingly, the two displayed images can be observed by the observer as if those images are respectively positioned forward and backward. In this instance, when a brightness balance of the two liquid crystal panels is properly adjusted, the apparatus provides the observer with an image having a three-dimensional impression.  
           [0005]    Another technique, for example, shown in FIG. 2 of the accompanied drawings is also widely known in the art as an alternative technique of the conventional stereoscopic image display apparatus. The stereoscopic image display apparatus shown in FIG. 2 provides the observer with an image having a three-dimensional impression on the principle that two organic electroluminescence panels are combined as a front and a back panel, which thus synthesizes a light beam  9  from the front panel  7  having light transmissibility and a light beam  8  from the back panel  6 , thereby providing the observer with overlapped images which are respectively displayed on the panels.  
           [0006]    The technique shown in FIG. 1 requires an optical arrangement of the two display panels and the half mirror. This arrangement requires accurate positioning of the constituent elements to a level of a single pixel. Accordingly, the apparatus becomes complicated and large. The technique shown in FIG. 2 requires the front panel which is made from a material providing light transmissibility. Accordingly, a manufacturing method is complicated, which causes problems such as an increased manufacturing cost and a reduced product yield. Furthermore, a part of the light beam from the front panel may go toward the back panel, which causes a reflection of the display image of the front panel on the back panel.  
         SUMMARY OF THE INVENTION  
         [0007]    One object of the present invention is to provide a stereoscopic image display apparatus which displays a clear stereoscopic image without using a device such as a complicated optical system and an expensive light transmissible panel.  
           [0008]    According to one aspect of the present invention, there is provided an apparatus including at least two linear image display devices for respectively displaying linear images in response to image signals, and a moving mechanism section for periodically moving the linear image display devices along respective locus planes parallel to each other.  
           [0009]    The stereoscopic image display apparatus of the present invention thus displays a bright and extremely clear stereoscopic image without using the complicated optical system and the expensive light transmissible panel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic construction drawing showing a structure of a conventional stereoscopic image display apparatus;  
         [0011]    [0011]FIG. 2 is a schematic construction drawing showing a structure of another conventional stereoscopic image display apparatus;  
         [0012]    [0012]FIG. 3 is a schematic perspective view showing a structure of a stereoscopic image display apparatus according to a first embodiment of the present invention;  
         [0013]    [0013]FIG. 4 is a schematic top view showing a top view of the stereoscopic image display apparatus shown in FIG. 3;  
         [0014]    [0014]FIG. 5 illustrates an operation of the stereoscopic image display apparatus shown in FIG. 3;  
         [0015]    [0015]FIG. 6 is a block diagram showing a structure of an image signal supply section;  
         [0016]    [0016]FIG. 7 is a schematic perspective view showing a structure of a stereoscopic image display apparatus according to a second embodiment of the present invention;  
         [0017]    [0017]FIG. 8 is a schematic top view showing a top view of the stereoscopic image display apparatus shown in FIG. 7; and  
         [0018]    [0018]FIG. 9 illustrates an operation of the stereoscopic image display apparatus shown in FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    Referring to FIG. 3, a drive motor  10 , e.g., a servo motor, directly rotationally drives a belt-driven pulley  20  fixed to a rotating shaft of the motor  10  based on a control signal from a drive control circuit (not shown).  
         [0020]    The belt-driven pulley  20  transmits rotational movements of the drive motor  10  to a drive belt  30 .  
         [0021]    The drive belt  30  is used for transmitting motive power, and extends between two belt-driven pulleys  20 . The two belt-driven pulleys  20  are positioned to have a predetermined distance therebetween. The drive belt  30  is driven in a predetermined direction at a predetermined velocity by the drive motor  10  via the belt-driven pulleys  20 . It should be noted that a power transmitting mechanism in this embodiment is not limited to the belt-driven pulleys  20  and the drive belt  30  shown in FIG. 3. The power transmitting mechanism may use, for example, a gear and a chain. Alternatively, various power transmitting members may be combined to form the drive mechanism, provided that the drive mechanism can transmit rotational movements to horizontal directional movements.  
         [0022]    Two sets of mechanisms each including the belt-driven pulleys  20  and the drive belt  30  are respectively provided at an upper and a lower side of the apparatus in order to hold both ends of linear image display devices  40  and  50  (described below) so as to support the linear image display devices  40  and  50  in the vertical direction, i.e., longitudinal direction of the linear image display device.  
         [0023]    Upper ends of the linear image display devices  40  and  50  are attached to the upper drive belt  30  at predetermined locations of the upper drive belt and lower ends of the linear image display devices  40  and  50  are attached to the lower drive belt  30  at predetermined locations of the lower drive belt by means of predetermined fastening members. Accordingly, the drive belts  30  drive the linear image display devices in a direction perpendicular to display directions of the two linear image display devices, while keeping the positional relationship between the two linear image display devices.  
         [0024]    The linear image display devices  40  and  50  are, for example, LED arrays each having 120 independent LEDs aligned linearly in the longitudinal direction of the linear image display device. It should be noted that the number and the type of light emitting elements used for the linear image display devices are not limited to the above mentioned number and type. Each linear image display device may have a configuration using another light emitting elements such as light bulbs, organic electroluminescence devices, and electron emission devices for an FED (Field Emission Display). Alternatively, each linear image display device may have a configuration using one point source, which scans over the linear image display device in a longitudinal direction by the light emitted from the source.  
         [0025]    Although both of the linear image display devices have the same configuration with respect to each other, the linear image display device  40  is fixed to the drive belt  30  at a distance L1 apart from the belt surface by the fastening member attached to the drive belt  30 , whereas the linear image display device  50  is fixed to the drive belt  30  in a similar manner at a distance L2 apart from the belt surface.  
         [0026]    When viewing the apparatus from above, an antireflective device  60  is provided within the circle of the drive belt  30  which is stretched between the two pulleys. The antireflective device prevents reflection of the light coming from the linear image display devices  40  and  50 , or from the front of the stereoscopic image display apparatus. As shown in FIG. 4, a side of the stereoscopic image display apparatus facing the observer is defined as a front side, and a direction toward the observer is defined as a forward direction of the stereoscopic image display apparatus, which will be used in the following description.  
         [0027]    Referring to FIG. 4, a construction drawing of the linear image display device is shown which is viewed from above the device along the longitudinal direction. The purpose of FIG. 4 is to clarify the structure of the embodiment shown in FIG. 3 and to illustrate the positional relationship between the constituent elements thereof. It should be noted that a driving direction of the drive belt  30  is not limited to the direction shown by arrows in FIG. 4, and therefore an opposite direction may be acceptable.  
         [0028]    An operation of the display apparatus of the embodiment shown in FIGS. 3 and 4 will be hereinafter described.  
         [0029]    As the drive belt  30  is driven in one direction at a predetermined velocity by the drive motor  10  via the belt-driven pulley  20 , the linear image display devices  40  and  50  attached to the drive belt  30  are also driven at the predetermined velocity in a direction perpendicular to display directions of the devices. For example, when the velocity of the drive belt  30  is set in such a manner that the drive belt  30  makes a round of the two pulleys in {fraction (1/60)} seconds (approximately 16.7 mS), the linear image display devices  40  and  50  respectively cross the front side of the stereoscopic image display apparatus 60 times per second. It should be noted that the drive velocity of the linear image display devices  40  and  50  is not limited to the above velocity.  
         [0030]    As shown in FIG. 4, the two linear image display devices  40  and  50  are fixed to the drive belt  30  maintaining a predetermined positional relationship with respect to each other. Furthermore, as mentioned above, the linear image display device  40  is positioned at the distance L1 apart from the belt surface of the drive belt  30 , whereas the linear image display device  50  is positioned at the distance L2 apart from the belt surface of the drive belt  30 . Therefore, light emitted from either one of the linear image display devices is not intercepted by the other linear image display device. Moreover, no reflection of the emitted light occurs from either one of the linear image displaying devices on the other linear image display device.  
         [0031]    Accordingly, as shown in FIG. 5, by driving the linear image display devices  40  and  50  at the velocity of 60 rounds per second in the direction perpendicular to the display directions of the devices, afterimage planes  41  and  51  by an afterimage effect are independently formed on a front face of the stereoscopic image display apparatus.  
         [0032]    In this embodiment, each of the image planes displaying a stereoscopic image is divided into, for example, 160 regions such that the 160 regions are arranged in the horizontal direction. The divided regions where the linear image display devices respectively exist are detected by a location detecting means (not shown) such as a rotary encoder which is provided at the rotating shaft of the drive motor  10 . Pixel information of the region along the vertical direction of the image plane are supplied to each of the linear image display devices, when the linear image display device is on the region. The pixel information represents luminance data of the LEDs, in which each LED corresponding to a pixel.  
         [0033]    Specifically, in this embodiment, the display plane is divided into 120 (vertical direction)×160 (horizontal direction) pixels as an example of the operations. Therefore, during a scan time of {fraction (1/60)} seconds performed by the drive belt  30 , pixel data of all horizontally divided regions are supplied to the linear image display devices  40  and  50  region by region. The pixel data per each horizontally divided region includes 120 pixel data along the vertical direction. Consequently, the afterimage planes are generated.  
         [0034]    Several methods are considered to supply control data which changes luminance of each LED included in the linear image display devices  40  and  50 .  
         [0035]    For example, an image signal supply section  70  shown in a block diagram of FIG. 6 may be used to supply a drive current to the LEDs included in the linear image display devices  40  and  50  for controlling luminance of the LEDs. An outline of an operation of the image signal supply section  70  shown in FIG. 6 is hereinafter described.  
         [0036]    A timing generating circuit  71  including a microcomputer firstly receives a timing signal from an encoder (not shown) provided on the drive motor  10 . The timing generating circuit  71  then generates a memory address signal and a read control signal, which are supplied to an image data memory  72  based on the timing signal. In addition, the timing generating circuit  71  generates a shift signal and a load signal in synchronization with the memory address signal and the read control signal.  
         [0037]    In the image data memory  72 , which is a memory circuit formed by a storage medium such as a semiconductor memory, pixel data forming a predetermined display image is stored. The pixel data stored in a predetermined memory address is read from the memory and supplied to a shift register  73  in accordance with the memory address signal and the read control signal supplied from the timing generating circuit  71 .  
         [0038]    The shift register  73  functions as a buffer memory. The shift register  73  sequentially outputs the pixel data read from the image data memory  72  to a data latch circuit  74  at predetermined timings in synchronization with the shift signal supplied from the timing generating circuit  71 .  
         [0039]    The data latch circuit  74  holds the pixel data along the vertical direction in a single horizontally divided region during the scan on such region. The data held in the data latch circuit  74  is rewritten in accordance with the load signal supplied from the timing generating circuit  71 .  
         [0040]    An LED drive circuit  75  is formed by, for example, an IC for a current load drive. The LED drive circuit  75  controls luminance of each LED mounted on the linear image display devices  40  and  50  in accordance with the pixel data supplied from the data latch circuit  74 .  
         [0041]    Specific location of the image signal supply section  70  in the stereoscopic image display apparatus of this embodiment is a matter of design during the actual product assembly, and thus the location is not specifically limited. When, for example, the image signal supply section  70  is provided on the linear image display device, the apparatus may have a plurality of strip electrodes parallel to a surface of the drive belt  30  so as to supply the aforementioned timing signal and a power-supply voltage to the image signal supply section  70  via a brush-shaped electrode unit which slidably contacts the strip electrodes.  
         [0042]    In this embodiment, when displaying the afterimage plane  41  of the linear image display device  40  and the afterimage plane  51  of the linear image display device  50 , brightness of each plane is controlled. In this instance, a proper distribution of the luminance between the two planes can provides a stereoscopic image for the observer who simultaneously observes a light beam  42  from the afterimage plane  41  and a light beam  52  from the afterimage plane  51 .  
         [0043]    In this embodiment, the two afterimage planes are respectively generated by using the linear image display devices which are provided at different positions with each other on the drive belt as described above. Therefore, when the backward afterimage plane is displayed, no obstruction exists which disturbs the observation of the backward after image plane. When the forward afterimage plane is displayed, no reflection of the emitted light occurs from the forward plane on the backward plane. Furthermore, since the antireflective device  60  is provided behind the two afterimage planes, the two afterimage planes are displayed as a front and a back plane in front of a dark and gloomy background. Accordingly, a bright and extremely clear stereoscopic image can be obtained.  
         [0044]    A second embodiment of the present invention will be hereinafter described based on schematic construction drawings shown in FIGS. 7 and 8.  
         [0045]    Referring to FIGS. 7 and 8, a drive motor  110 , e.g., a servo motor, directly rotationally drives a disc base  130  fixed to a rotating shaft of the motor based on a control signal from a drive control circuit (not shown).  
         [0046]    On the disc base  130 , a linear image display device  140  is positioned at the distance L3 away from the center of the base, and a display direction of the device extends in a radial direction of the base. In a similar manner, a linear image display device  150  is positioned at the distance L4 away from the center of the base. An antireflective device  160  having a predetermined size is provided at a central area of the disc base  130 . Further descriptions regarding the linear image display devices  140  and  150 , and the antireflective device  160  are omitted, since they are similar to those describe in the first embodiment.  
         [0047]    It should be noted that, in FIG. 8, even though the linear image display devices  140  and  150  are positioned on a diameter of the disc base  130  so as to be aligned with each other, positional relationship between the two linear image display devices is not limited to the above relationship.  
         [0048]    An operation of the display apparatus of the second embodiment will be hereinafter described.  
         [0049]    As the disc base  130  is driven in one direction at a predetermined rotating speed by the drive motor  10 , the linear image display devices  140  and  150  provided on the disc base  130  are also driven at the same rotating speed. Since the display directions of the linear image display devices are directed to the radial direction of the disc base  130  as mentioned above, the linear image display devices  140  and  150  are driven in a direction perpendicular to the display directions of the devices. For example, when the rotating speed of the disc base  130  is set at 60 rotations per second, both of the linear image display devices  140  and  150  are also rotationally driven at velocities of 60 rotations per second. It should be noted that the rotating speed of the disc base  130  is not limited to the above number.  
         [0050]    As shown in FIG. 8, a positional relationship between the linear image display devices  140  and  150  is arranged on the disc base  130  in such a manner that neither one of the linear image display devices intercepts the display direction of the other linear image display device. Therefore, the light emitted from either one of the linear image display devices is not intercepted by the other linear image display device. Moreover, no reflection of the emitted light occurs from either one of the linear image display devices on the other linear image display device.  
         [0051]    Accordingly, by driving the linear image display devices  140  and  150  at the velocity of 60 rotations per second, afterimage planes  141  and  151  by an afterimage effect of the linear image display devices are independently formed on circumferences having radii L3 and L4, respectively. FIG.  9  illustrates this case. It should be noted that, in FIG. 9, a formation of the afterimage planes is shown only within a range having a predetermined visual field angle θ, which aims to limit the display image within an observer&#39;s visible range.  
         [0052]    Similar to the first embodiment, each of the image planes within the range having the predetermined visual field angle θ displaying a stereoscopic image is horizontally divided into a plurality of regions. The divided regions where the linear image display devices respectively exist are detected, and pixel information of the region along the vertical direction of the image plane are supplied to each of the linear image display devices when the linear image display device is on the region. The pixel information represents luminance data of the LEDs, in which each LED corresponding to a pixel.  
         [0053]    A proper distribution of the luminance between the images displayed on the two afterimage planes can provide a stereoscopic image for the observer who simultaneously observes a light beam  142  from the afterimage plane  141  and a light beam  152  from the afterimage plane  151 . Description of the driving method of the LEDs included in the linear image display devices is omitted, since it is similar to that described in the first embodiment.  
         [0054]    In the above embodiments, the two linear image display devices are utilized. However, the present invention is not limited to the above examples. For example, more than two linear image display devices may be utilized for displaying the stereoscopic image on condition that the afterimage plane displayed backward from the observer is not intercepted by the devices.  
         [0055]    Furthermore, a plurality of linear image display devices may be provided one after another such that these image display devices appear within the same after image plane in the horizontal direction so as to obtain a stereoscopic image having an increased luminance.  
         [0056]    This application is based on a Japanese patent application No. 2003-015934, the entire disclosure of which is incorporated herein by reference.