Abstract:
Provided is an inverted pendulum mobile vehicle such as a single-passenger coaxial two-wheel vehicle which is capable of turning with a small turning radius without causing discomfort to a rider or a vehicle occupant or causing a cargo or the like on the vehicle from shifting or falling off from the vehicle. The vehicle comprises a wheel supporting frame ( 12 ), a body frame ( 12 ) supported by the wheel supporting frame so as to be rotatable around a vertical axial line and carry a rider and or a cargo and a body coupler ( 52, 78, 70 ) that couples the body frame relative to the wheel supporting frame in a prescribed dynamic positional relationship. Thereby, even when the wheel supporting frame undergoes a rapid yaw movement either while traveling in a fore-and-aft direction or remaining stationary, the body frame that carries a vehicle occupant or a cargo is allowed to follow the yaw movement of the wheel supporting frame at a slower angular speed and/or acceleration/deceleration so that the vehicle occupant is prevented from experiencing discomfort and the cargo is prevented from shifting on the body frame or falling off from the vehicle.

Description:
TECHNICAL FIELD 
     The present invention relates to an inverted pendulum mobile vehicle, and in particular to an inverted pendulum mobile vehicle such as a single-passenger coaxial two-wheel vehicle which is capable of turning with a small turning radius. 
     BACKGROUND OF THE INVENTION 
     In a known single-passenger inverted pendulum mobile vehicle, a pair of drive wheels are provided on a same axial line so as to be actuated individually by separate electric motors, and the vehicle is enabled to travel while standing upright under an inverted pendulum control process (See Japanese patent laid open publication No. 2006-131115, for instance) 
     Such a coaxial two-wheel vehicle can turn as required by causing a difference between the rotational speeds of the two wheels, and can even turn around a fixed yaw axis by rotating the two wheels in mutually opposite directions at a same rotational speed. 
     However, according to such a two-wheel vehicle, because the rider stands on a platform which is integral with the vehicle frame rotatably supporting the wheels, the rider moves jointly with the vehicle frame and therefore experiences a yaw acceleration as the vehicle makes a turn. Typically, such a vehicle is capable of turning very quickly, the rider may experience some discomfort owing to rapid changes in the direction of the movement of the vehicle. When the vehicle carries a cargo, owing to a strong centrifugal force that may be applied to the cargo, there is a danger of the cargo to fall off or to shift from a prescribed position on the vehicle frame. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of such problems of the prior art, a primary object of the present invention is to provide an inverted pendulum mobile vehicle such as a single-passenger coaxial two-wheel vehicle which is capable of turning with a small turning radius without causing discomfort to a rider or a vehicle occupant or causing a cargo or the like on the vehicle from shifting or falling off from the vehicle. 
     A second object of the present invention is to provide such a vehicle without requiring a substantial increase in the cost and/or increasing the complexity of the control structure therefor. 
     According to the present invention, such an object can be accomplished at least partly by providing a mobile vehicle including at least one drive wheel and configured to be able to travel according to a principle of an inverted pendulum, comprising: a wheel supporting frame rotatably supporting the drive wheel; a drive actuator for actuating the drive wheel so as to cause the vehicle to travel in a fore-and-aft direction and to turn vehicle around a vertical axial line; a body frame supported by the wheel supporting frame so as to be rotatable around a vertical axial line and carry a rider and or a cargo; and a body coupler that couples the body frame relative to the wheel supporting frame in a prescribed dynamic positional relationship. 
     Thereby, even when the wheel supporting frame undergoes a rapid yaw movement either while traveling in a fore-and-aft direction or remaining stationary, the body frame that carries a vehicle occupant or a cargo is allowed to follow the yaw movement of the wheel supporting frame at a slower angular speed and/or acceleration/deceleration so that the vehicle occupant is prevented from experiencing discomfort and the cargo is prevented from shifting on the body frame or falling off from the vehicle. Typically, the vehicle has a vertically elongated dimension, and travels in an upright orientation so that the vehicle is enabled to travel freely in a limited space, and make highly tight turns. 
     If the body coupler comprises a yaw actuator that rotatively actuates the body frame relative to the wheel supporting frame, at least one sensor for detecting a dynamic state of the vehicle and a control device that provides a command signal for the yaw actuator according an output of the at least one sensor, the movement of the body frame can be controlled as desired, and the yaw movement of the body frame can be controlled in relation to the wheel supporting frame at will, and an optimum performance can be achieved. 
     Typically, the sensor detects a state of the actuator for actuating the drive wheel, and the control device provides a command signal for the yaw actuator so as to cause the body frame to follow a yaw movement of the wheel supporting member in a controlled manner. Thereby, the need for sensors and other control arrangements can be minimized. 
     According to a simplified embodiment of the present invention, the body coupler comprises a torsionally resilient member interposed between the body frame and wheel supporting frame. 
     The body coupler may further comprise a torsional damper interposed between the body frame and wheel supporting frame. 
     According to a preferred embodiment of the present invention, the vehicle comprises a pair of drive wheels which are coaxially disposed relative to each other so as to be rotated in an independent manner, and a pair of drive actuators that are configured to actuate the corresponding drive wheels individually. 
     In such a case, the body frame may comprise a pair of steps disposed on either side thereof to support corresponding feet of a rider and a pair of load sensors for detecting loads exerted on the steps by the corresponding feet of the rider, and the vehicle may further comprise a control device that causes the drive actuators to actuate the drive wheels in such a way that the vehicle makes a turn to a side of one of the steps on which a greater load is applied than the other. 
     Alternatively, the vehicle may further comprise a roll angle sensor mounted on the body frame and a control device that causes the drive actuators to actuate the drive wheels in such a way that the vehicle turns to a side toward which a roll angle of the body frame is detected by the roll angle sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Now the present invention is described in the following with reference to the appended drawings, in which: 
         FIG. 1  is a front view of a co-axial two-wheel vehicle embodying the present invention; 
         FIG. 2  is a see-through perspective view of an essential part of the vehicle illustrated in  FIG. 1 ; 
         FIG. 3  is a block diagram of the control arrangement for the co-axial two-wheel vehicle; 
         FIG. 4  is a diagram showing the time history of the yaw movement of the body frame following a given yaw movement of the wheel supporting frame; 
         FIG. 5  is a block diagram of an alternate control arrangement for the co-axial two-wheel vehicle; 
         FIG. 6  is a view similar to  FIG. 2  showing a second embodiment of the present invention; and 
         FIG. 7  is a simplified view of the torsion coupler used in the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a co-axial two-wheel vehicle  100  embodying the present invention comprise a pair of drive wheels  10 L and  10 R disposed coaxially on a same axial line one next to the other, a wheel supporting frame  12  rotatably supporting the drive wheels  10  and a body frame  14  extending upright from the wheel supporting frame  12 . 
     The body frame  14  comprises a vertically extending cylindrical column  16 , a skirt  18  formed in a lower part of the column  16  and covering the wheel supporting frame  12 , a pair of steps  20 L and  20 R extending laterally from either side of the skirt  18  to enable a rider to stand thereon and a grip bar  23  fixedly attached to the upper end of the column  16  and extending laterally so as to be held by the rider. The grip bar  23  extends horizontally toward either side in the same direction as the steps  20 L and  20 R extend. The wheel supporting frame  12  and body frame  14  jointly form a vehicle frame. 
     The column  16  is incorporated with a roll angle sensor  62  and a pitch angle sensor  64  which may consist of gyro sensors, for instance. The roll angle sensor  62  detects the roll angle or lateral tilting of the body frame  14 , and the pitch angle or fore-and-aft tilting of the body frame  14 . 
     As shown in  FIG. 2 , each step  20  comprises a step support member  42  extending in a corresponding direction, a foot load sensor  44  consisting of a six-axis load cell, for instance, attached to the upper surface of the corresponding step support member  42  and a step plate  46  mounted on the upper surface of the foot load sensor  44 . In  FIG. 2 , these components are denoted with numerals accompanied by letters R and L which indicate the corresponding parts are located on the right hand side and left hand side, respectively. 
     The drive wheels  10 L and  10 R are supported by the wheel supporting frame  12  via corresponding axle shafts  22 L and  22 R extending horizontally and coaxially to each other so that the two wheels may be spaced apart from each other by a prescribed distance and individually rotatable around a common center line of rotation. The wheel supporting frame  12  is additionally incorporated with electric motors  24 L and  24 R configured to drive the corresponding wheels  10 L and  10 R, respectively, in a mutually independent manner. 
     Each drive wheel  10  is fitted with a coaxial pulley  26 . An intermediate shaft  28  is rotatably supported by the wheel supporting frame  12  above each drive wheel  10  so as to be rotatable around an axial line in parallel with the rotational center line of the drive wheel  10 , and is coaxially fitted with a pair of pulleys  30  and  34 . An electric motor  24  is fixedly supported by the wheel supporting frame  12  adjacent to each drive wheel  10 , and has an output shaft  36  fitted with a pulley  38 . A first endless belt  32  is passed around the pulley  38  on the output shaft  36  of each electric motor  24  and one of the pulleys  34  on the corresponding intermediate shaft  28 . A second endless belt  40  is passed around the other pulley  30  on the intermediate shaft  28  and the pulley  26  on the corresponding drive wheel  10 . The numerals for various components illustrated in  FIG. 2  are accompanied by letters L and R to indicate on which side of the vehicle the corresponding components are located. Thus, the two wheels  10  can be actuated, in terms of both speed and rotational direction, individually or independently from each other. 
     Thus, when the two wheels are rotated in a same direction at a same rotational speed, the wheel supporting frame  12  travels straight ahead or back, depending on the direction of the rotation. When the two wheels are rotated at different rotational speeds, the wheel supporting frame  12  turns in a corresponding direction or undergoes a yaw movement as it travels. When the two wheels are rotated at a same sped but in mutually different direction, the wheel supporting frame  12  turns around a fixed yaw axis extending vertically through a middle point of the two wheels. 
     It should be noted that the body frame  14  is mounted on the wheel supporting frame  12  so as to be rotatable around a vertical axial line (yaw axis) via a vertical shaft  52 . In other words, the body frame  14  is connected to the wheel supporting frame  12  so as to be rotatable around a vertical axial line (yaw axis) via the vertical shaft  52 . 
     The vertical shaft  52  extends vertically and centrally from an upper part of the wheel supporting frame  12 . A lower part of the body frame  14  located between the column  16  and skirt  18  is provided with a support member  54  essentially consisting of a horizontal disk member which is integrally attached to the skirt  18 . The support member  54  is centrally provided with a bearing portion  56  that receives the vertical shaft  52  in a mutually rotatable manner with respect to a vertical center line of the vertical shaft  52 , and a yaw actuator  58  essentially consisting of an electric motor fitted with a brake so that the body frame  14  can be rotated with respect to the wheel supporting frame  12  as desired around the vertical axial line. 
     The mode of operation of the illustrated embodiment is described in the following. A rider places his feet upon the corresponding steps  46  and holds the two ends of the grip bar  23 . The drive wheels  20  are actuated so that the vehicle  100  stands still in an upright orientation according to the principle of the inverted pendulum vehicle. When the rider desires to travel ahead, he leans forward, causing the gravitational center of the rider to be shifted forward. Conversely, when the rider desires to travel backward, he leans back, causing the gravitational center of the rider to be shifted backward. Likewise, when the rider desires to make a turn, he leans laterally in the desired direction, and this causes the vehicle to turn in the desired direction. 
     The control system for this vehicle  100  is described in the following. Referring to  FIG. 3 , the control system comprises a control device  60  which essentially consists of a microcomputer. The control device  60  receives information on the roll angle of the body frame  14  from the roll angle sensor  62  and the pitch angle of the body frame  14  from the pitch angle sensor  64 , and controls the drive wheels  10  according to the principle of the inverted pendulum so as to cause the vehicle to move about while maintaining an upright orientation in a stable manner. Alternatively or additionally, the control device  60  may further receive output signals from the left foot load sensor  44 L and the right foot load sensor  44 R so that the shifting of the gravitational center of the rider may be detected, and individually controls the electric motors  24  and  58  that actuate the left wheel electric motor  24 L, right wheel electric motor  24 R and yaw electric motor  58  individually. 
     Based upon the control processes outlined in the following, the vehicle  100  can travel ahead or backward, and turn to the right or left as required.
     (1) When the loads acting on the right and left foot load sensors  44 L and  44 R are equal to each other, the electric motors  44 L and  44 R for actuating the corresponding drive wheels  10 L and  10 R are actuated in a same forward direction at a speed corresponding to the shift of the gravitation center of the rider in the forward direction as detected by the right and left foot load sensors  44 L and  44 R. Thereby, the vehicle  100  travels forward. Also, the greater the forward shift of the gravitational center is, the greater the speed of the forward travel of the vehicle is.   (2) When the loads acting on the right and left foot load sensors  44 L and  44 R are equal to each other, the electric motors  44 L and  44 R for actuating the corresponding drive wheels  10 L and  10 R are actuated in a same backward direction at a speed corresponding to the shift of the gravitation center of the rider in the backward direction as detected by the right and left foot load sensors  44 L and  44 R. Thereby, the vehicle  100  travels backward or rearward. Also, the greater the backward shift of the gravitational center is, the greater the speed of the backward travel of the vehicle is. The maximum speed of the backward travel of the vehicle is substantially lower than that of the forward travel of the vehicle.   (3) When the vehicle is traveling straight ahead, and load acting on the left foot load sensor  44 L is increased in relation to that acting on the right foot load sensor  44 R (it can be accomplished, for instance, by the rider leaning to the left), the electric motor  42 R for actuating the right drive wheel  10 R is actuated at a correspondingly higher speed in the forward direction than the electric motor  42 L for actuating the left drive wheel  10 L. Thereby, the vehicle  100  or the wheel supporting frame  12  makes a leftward turn while the vehicle  100  travels in forward direction.   (4) When the vehicle is traveling straight backward, and load acting on the left foot load sensor  44 L is increased in relation to that acting on the right foot load sensor  44 R (it can be accomplished, for instance, by the rider leaning to the left), the electric motor  42 R for actuating the right drive wheel  10 R is actuated at a correspondingly higher speed in the backward direction than the electric motor  42 L for actuating the left drive wheel  10 L. Thereby, the vehicle  100  or the wheel supporting frame  12  makes a leftward turn while the vehicle  100  travels in backward direction.   (5) When the vehicle is traveling straight ahead, and load acting on the right foot load sensor  44 R is increased in relation to that acting on the left foot load sensor  44 L (it can be accomplished, for instance, by the rider leaning to the right), the electric motor  42 L for actuating the left drive wheel  10 L is actuated at a correspondingly higher speed in the forward direction than the electric motor  42 R for actuating the right drive wheel  10 R. Thereby, the vehicle  100  or the wheel supporting frame  12  makes a rightward turn while the vehicle  100  travels in forward direction.   (6) When the vehicle is traveling straight backward, and load acting on the right foot load sensor  44 R is increased than that acting on the left foot load sensor  44 L (it can be accomplished, for instance, by the rider leaning to the right), the electric motor  42 L for actuating the left drive wheel  10 L is actuated at a correspondingly higher speed in the backward direction than the electric motor  42 R for actuating the right drive wheel  10 R. Thereby, the vehicle  100  or the wheel supporting frame  12  makes a rightward turn while the vehicle  100  travels in backward direction.   

     In the foregoing description, the foot load sensors  44  were used for determining the traveling direction of the vehicle, but it is also possible to use the roll angle sensor  62  and pitch angle sensor  64 , either additionally or alternatively, for determining the traveling direction of the vehicle. 
     When the vehicle  100  is making a turn such as in cases (3) to (6) above, the greater the difference in the rotational speeds of the two electric motors  24  is, the smaller the turning radius of the vehicle is, and the greater the yaw rate of the vehicle is. When one of the wheels is kept stationary while the other wheel is rotated in either direction, the vehicle turns around the stationary wheel, and the distance between the two wheels is given as the turning radius. When the two wheels are rotated at a same speed in opposite directions, the vehicle turns around a middle point between the two wheels, and one half of the distance between the two wheels is given as the turning radius. 
     When the vehicle is traveling either straight ahead or straight backward such as in cases (1) and (2), the body frame  14  and wheel supporting frame  12  are kept fixed or rotational fast to each other, for instance by applying brake to the yaw electric motor  58 , so that the grip bar  22  is kept in parallel with the central axial line of the two drive wheels  10 . In other words, there is no relative rotation between the body frame  14  and wheel supporting frame  12  in this case. 
     On the other hand, when the vehicle is making a turn such as in cases (3) to (6), as soon as a turning movement is initiated, the brake on the yaw electric motor  58  is disengaged, the control device computes the yaw angle and yaw rate of the vehicle, and actuates the yaw electric motor  58  to turn the body frame relative to the wheel supporting frame so as to achieve the same yaw angle as the wheel supporting frame at a yaw rate lower than that of the wheel supporting frame or with a certain time delay with respect to the yaw movement of the wheel supporting frame. 
     In other words, as the wheel supporting frame  12  make a turn, the body frame  14  follows the turning or yaw movement of the wheel supporting frame at a lower yaw rate or with a certain time delay, and is eventually oriented in the same direction as the wheel supporting frame. The yaw movement of the body frame can be effected in various ways, but it is preferred that the yaw acceleration of the body frame should be kept below a prescribed level so that the rider may not experience any discomfort. For the same reason, the yaw rate of the vehicle frame may be limited with respect to that of the wheel supporting frame. On the other hand, the response of the body frame is required to be fast enough for the maneuverability of the vehicle to be acceptable. 
       FIG. 4  shows an exemplary property of the yaw movement of the body frame  14  relative to the yaw movement of the wheel supporting frame  12 . In  FIG. 4 , letter A indicates the turning speed (yaw rate) of the wheel supporting frame  12 , and letter B indicates the turning speed (yaw rate) of the body frame  14 , with respect to the ground in each case. In this example, the turning movements of the both frames begin substantially at the same time at time T 1 . The angular acceleration of the body frame is smaller than that of the wheel supporting frame. The turning speed (yaw rate) of the wheel supporting frame then becomes constant (constant value Vw) at time T 2 , and the turning speed of the body frame reaches a constant value (Vb) (which is lower than value Vw) at time T 3  (which is somewhat later than time T 2 ). 
     The deceleration of the yaw movements of the wheel supporting frame and body frame occurs substantially at the same time at T 4 . During this deceleration process, the deceleration of the body frame is smaller than that of the wheel supporting frame. Thereafter, the turning movement of the wheel supporting frame  12  ends at time T 5 , and the turning movement of the body frame  14  ends at time T 6  which is later than time T 5 . 
     The wheel supporting frame  12  and body frame  14  were initially oriented in the same direction at time T 1 , and the turning of the body frame  14  follows the turning of the wheel supporting frame  12  with some time delay until they become oriented in the same direction once again at time T 6 . The body frame  14  thus turns at a lower angular speed and/or a lower acceleration/deceleration than the wheel supporting frame  12  during the turning maneuver of the vehicle. 
     Thus, the rider is prevented from being abruptly turned during a rapid turning maneuver, and can avoid discomfort. When a cargo is carried by the body frame or hung from the hand grip, such cargo is prevented from being excessively shifted or swung during a rapid turning maneuver, and this also contributes to the riding comfort of the vehicle. 
     The turning angle and turning speed of the yaw axis motor  58  were computed by the control device  60  according to the command signals for the electric motors for the right and left wheels in the illustrated embodiment. The signals may be obtained either from rotary encoders or the like incorporated in the electric motors or drive wheels, or from motor controllers that provide drive signals for the electric motors which typically consist of brushless motors. However, it is also possible to detect the yaw movement of the wheel supporting frame  12  by using a gyro sensor or the like, and use the thus detected yaw movement for the control of the yaw axis electric motor. 
       FIG. 3  illustrates a block diagram of such an embodiment. The system comprises a roll angle sensor  62  and a pitch angle sensor  64  consisting of gyro sensors or the like that are attached to suitable parts of the body frame  14 . Thereby, the control device  60  can control the electric motors  24  for actuating the drive wheels in such a manner that the turning control of the vehicle is conducted according to the roll angle of the body frame  14  as detected by the roll angle sensor  62 , and the forward/backward movement control of the vehicle is conducted according to the pitch angle of the body frame  14  as detected by the pitch angle sensor  64 . Typically, the vehicle makes a turn in the direction toward which the vehicle leans. 
     The part of the control device  60  responsible for the turning maneuver of the vehicle is described in greater detail with reference to  FIG. 5 . The system further comprises a yaw angle sensor  84  attached to the wheel supporting frame  12  and a differentiator  82  that differentiates the output from the roll angle sensor  62 . The control device  60  comprises a yaw angle command value computing unit  80  that receive inputs from the roll angle sensor  62 , yaw angle sensor  84  and differentiator  82  that provides a yaw rate of the wheel supporting frame  12 . The yaw angle command value computing unit  80  computes a yaw angle command value according to the inputs thereto. 
     An upper and a lower limit are set by a limiter  88  for the yaw angle command value provided by the yaw angle command unit  80 . The output of the limiter  88  is forwarded to a left wheel motor command value computing unit  90  and a right wheel motor command value computing unit  92 . The left wheel motor command value computing unit  90  computes a left wheel motor command value, and the right wheel motor command value computing unit  92  computes a right wheel motor command value, both according to the received yaw angle command value. 
     The electric motors  24 L and  24 R for the left and right drive wheels are actuated according to the command signals received from the left wheel motor command value computing unit  90  and right wheel motor command value computing unit  92 , respectively. Thereby, the wheel supporting frame  12  can turn according to the roll angle of the body frame  14 . 
     Additionally, the yaw angle command value computed by the yaw angle command value computing unit  80  is forwarded to a yaw angle electric motor command value computing unit  96  via a low pass filter  94 , and the yaw angle electric motor command value computing unit  96  computes a yaw angel electric motor command value according to the yaw angle command value received from the low pass filter  94 . The yaw angle electric motor  58  is actuated so as to turn the body frame  14  relative to the wheel supporting frame  12  according to the yaw angle electric motor command value provided by the yaw angle electric motor command value computing unit  96 . 
     The low pass filter  94  may consist of a first order delay circuit that can be represented by a transfer function 1/(1+Ts) so that the yaw angle electric motor  58  may turn the body frame  14  with a time delay given by a prescribed time constant relative to the turning movement of the wheel supporting frame  12  caused by the corresponding actuation of the electric motors for actuating the right and left wheels. Thereby, the turning of the body frame can be accomplished in such a way as to avoid any undue discomfort to the rider and to provide a favorable ride quality without imposing any computational load on the control system. 
     A second embodiment of the inverted pendulum mobile vehicle of the present invention is described in the following with reference to  FIGS. 6 and 7  in which the parts corresponding to those of the previous embodiment are denoted with like numerals. 
     In this embodiment, the vertical shaft  52  supported by the wheel supporting frame  12  is connected to a support member  54  integral with the body frame  14  via a torsional coupling  70 . The torsional coupling  70  includes a lower member  72  fixedly attached to the vertical shaft  52 , an upper member  76  fixedly attached to the support member  54  via a mounting member  74  and elastic members  78  made of rubber or other elastomeric material that join the lower member  72  and upper member  76  to each other. 
     The elastic member  78  is thus interposed between the wheel supporting frame  12  and body frame  14  so as to resiliently urge the two frames toward the mutually aligned position when the two frames are twisted relative to each other away from the mutually aligned position. 
     Therefore, as the wheel supporting frame  12  turns, in particular at a rapid rate, the elastic member  78  undergoes a resilient twisting deformation. This causes the lower member  72  to be twisted relative to the upper member  76  causing the upper member  76  to be stationary immediately thereafter, and the upper member  76  is allowed to follow the yaw movement of the lower member  72  with a certain time delay. In other words, the upper member  76  following the yaw movement of the lower part at a relatively slow angular speed (in particular, when the elastic member  78  is given with a damping factor which produces a damping force substantially proportional to the relative angular speed between the upper and lower members), and eventually aligns with the lower member  72 . 
     Thereby, the rider riding on the body frame  14  is prevented from being abruptly turned around a vertical axis, and this prevents the rider from experiencing discomfort. The torsional coupling  70  is not limited by the illustrated embodiment that uses elastic members made of rubber or the like such as shown in  FIGS. 6-7 , but may also consist of any other known arrangement including those using a torsional spring and an optional torsional damper. 
     Although the present invention has been described in terms of preferred embodiments thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims. For instance, the illustrated embodiments used a pair of coaxial drive wheels, but may also be other vehicles such as those disclosed in WO2008/139740, WO2008/132778 and WO2008/132779. 
     The contents of the original Japanese patent application on which the Paris Convention priority claim is made for the present application, as well as those of the prior art references mentioned in the present application, are incorporated in this application by reference.