Patent Publication Number: US-11027190-B2

Title: Game controller and game system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/295,290 filed Oct. 17, 2016 which is a continuation of U.S. patent application Ser. No. 14/950,578 filed Nov. 24, 2015 (now U.S. Pat. No. 9,498,709 issued Nov. 22, 2016) which is a continuation of U.S. patent application Ser. No. 14/585,318 filed Dec. 30, 2014 (now U.S. Pat. No. 9,227,138 issued Jan. 5, 2016) which is a continuation of U.S. patent application Ser. No. 14/330,403 filed Jul. 14, 2014 (now U.S. Pat. No. 9,044,671 issued Jun. 2, 2015) which is a continuation of U.S. application Ser. No. 12/285,812 filed Oct. 15, 2008 (now U.S. Pat. No. 8,834,271 issued Sep. 16, 2014), which is a divisional of U.S. application Ser. No. 11/504,086, filed 15 Aug. 2006, (now U.S. Pat. No. 8,267,786 issued Sep. 18, 2012), which in turn is a continuation-in-part of U.S. application Ser. No. 11/404,871, filed 17 Apr. 2006 (now U.S. Pat. No. 8,870,655 issued Oct. 28, 2014), which claims priority of JP 2005-242926, filed 24 Aug. 2005, JP 2006-122681, filed Apr. 26, 2006, and U.S. Application No. 60/714,862, filed 8 Sep. 2005, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a game controller and a game system, and more particularly to a game controller which includes two control units connected to each other by a flexible cable and is operated using the two control units and a game system including the game controller. 
     Description of the Background Art 
     For example, Japanese Laid-Open Patent Publication No. 2004-313492 (hereinafter, referred to as Patent Document 1) discloses a controller having its control units held by both hands of a player, respectively, so as to play a game. 
     The controller disclosed in Patent Document 1 is composed of an R unit to be held by a right hand of a player and an L unit to be held by a left hand of the player. The R unit and the L unit each has an operation button and a stick on the top surface and the side of a housing thereof. The R unit and the L unit can be physically coupled to each other so as to be used as a combined controller. 
     However, the controller disclosed in Patent Document 1 is constructed by simply separating a conventional game apparatus controller into right and left units. That is, although a player can place his or her right and left hands anywhere when the player holds the R and L units by his or her right and left hands, respectively, the player cannot control the controller itself with improved flexibility. For example, not only the combined controller but also the game apparatus controller separated into the right and the left units cannot realize a new operation. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a novel game controller and game system which realize a novel operation having enhanced flexibility by using a plurality of control units. 
     The present invention has the following features to attain the object mentioned above. The reference numerals and the like in the parentheses indicate the correspondence with the embodiment described below in order to aid in understanding the present invention and are not intended to limit, in any way, the scope of the present invention. 
     A first aspect of the present invention is directed to a game controller ( 7 ) for transmitting operation data to a computer ( 30 ) executing a game program. The game controller comprises: a first control unit ( 70 ); a second control unit ( 76 ); and a cable ( 79 ). The cable is flexible and electrically connects between the first control unit and the second control unit. The first control unit includes a first operation data generation section ( 74 ,  701 ). The first operation data generation section generates first operation data in accordance with a motion of a first control unit body included in the first control unit. The second control unit includes a second operation data generation section ( 78 ). The second operation data generation section generates second operation data in accordance with a direction input operation performed by a player. Further, one of the first control unit and the second control unit includes a transmission section ( 75 ). The transmission section transmits the first operation data and the second operation data to the computer at a predetermined timing. 
     In a second aspect based on the first aspect, the first operation data generation section includes an image pickup section ( 74 ). The image pickup section is fixed to the first control unit body and takes an image of a periphery along a predetermined direction from the first control unit body. The first operation data generation section outputs, as the first operation data, one selected from the group consisting of an image taken by the image pickup section and a result of subjecting the image taken by the image pickup section to a predetermined calculation. 
     In a third aspect based on the second aspect, the first operation data generation section further includes a positional information calculation section ( 744 ). The positional information calculation section calculates positional information indicating a position, in the image taken by the image pickup section, of at least one marker image which is included in the taken image and is used as an imaging target, when performing the predetermined calculation, and outputs the positional information as the first operation data. 
     In a fourth aspect based on the first aspect, the transmission section wirelessly transmits the first operation data and the second operation data to the computer. 
     In a fifth aspect based on the first aspect, the first operation data generation section has one of an acceleration sensor ( 701 ) and a gyro sensor included in the first control unit body. The first operation data generation section outputs data generated by the one of the acceleration sensor and the gyro sensor as the first operation data. 
     In a sixth aspect based on the first aspect, the cable is detachably connected to at least the first control unit. The transmission section is included in the first control unit. 
     In a seventh aspect based on the first aspect, the transmission section collects and transmits to the computer the first operation data and the second operation data at intervals shorter than 1/60 second. 
     In an eighth aspect based on the first aspect, the second operation data generation section includes a stick ( 78   a ) which has a tip projecting from a second control unit body included in the second control unit and is inclinable on the second control unit body. The second operation data generation section outputs data obtained in accordance with an inclining direction of the stick as the second operation data. 
     In a ninth aspect based on the first aspect, the second operation data generation section includes an operation button ( 78   f ) which has operation portions representing at least four directions and which is able to be pushed, by the operation portions, into a second control unit body included in the second control unit. The second operation data generation section outputs, as the second operation data, data corresponding to the operation portion at which the operation button is pushed. 
     In a tenth aspect based on the first aspect, the second operation data generation section includes a sliding member ( 78   g ) which has a top surface exposed from a second control unit body included in the second control unit and which is horizontally movable on the second control unit body. The second operation data generation section outputs data obtained in accordance with a horizontal moving direction of the sliding member as the second operation data. 
     In an eleventh aspect based on the first aspect, the second operation data generation section includes a touch pad ( 78   h ) on an outer surface of a second control unit body included in the second control unit. The second operation data generation section outputs, as the second operation data, data obtained in accordance with a position on the touch pad at which the touch pad is touched. 
     In a twelfth aspect based on the first aspect, the second operation data generation section includes at least four operation buttons ( 78   i ,  78   j ,  78   k ,  78   l ) which are able to be pushed into a second control unit body included in the second control unit. The second operation data generation section outputs data obtained in accordance with the pushed operation button as the second operation data. 
     In a thirteenth aspect based on the first aspect, the second control unit further includes one of an acceleration sensor ( 761 ) and a gyro sensor. One of the acceleration sensor and the gyro sensor is provided in a second control unit body included in the second control unit. The transmission section transmits, to the computer, data outputted by the one of the acceleration sensor and the gyro sensor as third operation data in addition to the first operation data and the second operation data. 
     In a fourteenth aspect based on the first aspect, at least one of the first control unit and the second control unit further includes a reception section ( 75 ), a speaker ( 706 ), and a sound control unit ( 707 ). The reception section receives transmission data transmitted from the computer. The sound control section generates a sound from the speaker using the transmission data having been received by the reception section. 
     A fifteenth aspect of the present invention is directed to a game controller for transmitting operation data to a computer executing a game program. The game controller comprises a first control unit, a second control unit, and a wireless connecting means. The wireless connecting means wirelessly connects between the first control unit and the second control unit. The first control unit includes a first operation data generation section. The first operation data generation section generates first operation data in accordance with a motion of a first control unit body included in the first control unit. The second control unit includes a second operation data generation section. The second operation data generation section generates second operation data in accordance with a direction input operation performed by a player. Further, one of the first control unit and the second control unit includes a transmission section. The transmission section transmits the first operation data and the second operation data to the computer at a predetermined timing. 
     In a sixteenth aspect based on the fifteenth aspect, the first operation data generation section includes an image pickup section. The image pickup section is fixed to the first control unit body and takes an image of a periphery along a predetermined direction from the first control unit body. The first operation data generation section outputs, as the first operation data, one selected from the group consisting of an image taken by the image pickup section and a result of subjecting the image taken by the image pickup section to a predetermined calculation. 
     In a seventeenth aspect based on the sixteenth aspect, the first operation data generation section further includes a positional information calculation section. The positional information calculation section calculates positional information indicating a position, in the image taken by the image pickup section, of at least one marker image which is included in the taken image and is used as an imaging target, when performing the predetermined calculation, and outputs the positional information as the first operation data. 
     In an eighteenth aspect based on the fifteenth aspect, the transmission section wirelessly transmits the first operation data and the second operation data to the computer. 
     In a nineteenth aspect based on the fifteenth aspect, the first operation data generation section has one of an acceleration sensor and a gyro sensor included in the first control unit body. The first operation data generation section outputs data generated by the one of the acceleration sensor and the gyro sensor as the first operation data. 
     In a twentieth aspect based on the fifteenth aspect, the transmission section collects and transmits to the computer the first operation data and the second operation data at intervals shorter than 1/60 second. 
     In a twenty-first aspect based on the fifteenth aspect, the second operation data generation section includes a stick which has a tip projecting from a second control unit body included in the second control unit and is inclinable on the second control unit body. The second operation data generation section outputs data obtained in accordance with an inclining direction of the stick as the second operation data. 
     In a twenty-second aspect based on the fifteenth aspect, the second operation data generation section includes an operation button ( 78   f ) which has operation portions representing at least four directions and which is able to be pushed, by the operation portions, into a second control unit body included in the second control unit. The second operation data generation section outputs, as the second operation data, data corresponding to the operation portion at which the operation button is pushed. 
     In a twenty-third aspect based on the fifteenth aspect, the second operation data generation section includes a sliding member which has a top surface exposed from a second control unit body included in the second control unit and which is horizontally movable on the second control unit body. The second operation data generation section outputs data obtained in accordance with a horizontal moving direction of the sliding member as the second operation data. 
     In a twenty-fourth aspect based on the fifteenth aspect, the second operation data generation section includes a touch pad on an outer surface of a second control unit body included in the second control unit. The second operation data generation section outputs, as the second operation data, data obtained in accordance with a position on the touch pad at which the touch pad is touched. 
     In a twenty-fifth aspect based on the fifteenth aspect, the second operation data generation section includes at least four operation buttons which are able to be pushed into a second control unit body included in the second control unit. The second operation data generation section outputs data obtained in accordance with the pushed operation button as the second operation data. 
     In a twenty-sixth aspect based on the fifteenth aspect, the second control unit further includes one of an acceleration sensor and a gyro sensor. One of the acceleration sensor and the gyro sensor is provided in a second control unit body included in the second control unit. The transmission section transmits, to the computer, data outputted by the one of the acceleration sensor and the gyro sensor as third operation data in addition to the first operation data and the second operation data. 
     In a twenty-seventh aspect based on the fifteenth aspect, at least one of the first control unit and the second control unit further includes a reception section ( 75 ), a speaker ( 706 ), and a sound control section ( 707 ). The reception section receives transmission data transmitted from the computer. The sound control section generates a sound from the speaker using the transmission data having been received by the reception section. 
     A twenty-eighth aspect of the present invention is directed to a game controller ( 7 ) for transmitting operation data to a computer ( 30 ) executing a game program. The game controller comprises: a first control unit ( 70 ); a second control unit ( 76 ); and a cable ( 79 ). The cable is flexible and electrically connects between the first control unit and the second control unit. The first control unit includes a first operation data generation section ( 74 ,  701 ). The first operation data generation section generates first operation data in accordance with a motion of a first control unit body included in the first control unit. The second control unit includes a second operation data generation section ( 761 ). The second operation data generation section generates second operation data in accordance with a motion of a second control unit body included in the second control unit. Further, one of the first control unit and the second control unit includes a transmission section ( 75 ). The transmission section transmits the first operation data and the second operation data to the computer at a predetermined timing. 
     In a twenty-ninth aspect based on the twenty-eighth aspect, the first operation data generation section has one of a first acceleration sensor ( 701 ) and a first gyro sensor included in the first control unit body. The first operation data generation section outputs data generated by the one of the first acceleration sensor and the first gyro sensor as the first operation data. The second operation data generation section has one of a second acceleration sensor ( 761 ) and a second gyro sensor included in the second control unit body. The second operation data generation section outputs data generated by the one of the second acceleration sensor and the second gyro sensor as the second operation data. 
     In a thirtieth aspect based on the twenty-ninth aspect, the first control unit further includes a first key ( 72 ). The first key, which is provided on the first control unit body, generates first key operation data in accordance with a player pressing the first key. The second control unit further includes a second key ( 78 ). The second key, which is provided on the second control unit body, generates second key operation data in accordance with the player pressing the second key. The transmission section transmits, to the computer, the first key operation data and the second key operation data in addition to the first operation data and the second operation data. 
     In a thirty-first aspect based on the twenty-eighth aspect, the first operation data generation section includes an image pickup section ( 74 ). The image pickup section is fixed to the first control unit body and takes an image of a periphery along a predetermined direction from the first control unit body. The first operation data generation section outputs, as the first operation data, one selected from the group consisting of an image taken by the image pickup section and a result of subjecting the image taken by the image pickup section to a predetermined calculation. The second operation data generation section has one of a first acceleration sensor ( 761 ) and a first gyro sensor. One of the first acceleration sensor and the first gyro sensor is provided in the second control unit body. The second operation data generation section outputs data generated by the one of the first acceleration sensor and the first gyro sensor as the second operation data. 
     In a thirty-second aspect based on the thirty-first aspect, the first control unit further includes one of a second acceleration sensor ( 701 ) and a second gyro sensor. One of the second acceleration sensor and the second gyro sensor is provided in the first control unit body. The transmission section transmits, to the computer, data outputted by the one of the second acceleration sensor and the second gyro sensor as third operation data in addition to the first operation data and the second operation data. 
     In a thirty-third aspect based on the twenty-eighth aspect, at least one of the first control unit and the second control unit further includes a reception section ( 75 ), a speaker ( 706 ), and a sound control section ( 707 ). The reception section receives transmission data transmitted from the computer. The sound control section generates a sound from the speaker using the transmission data having been received by the reception section. 
     A thirty-fourth aspect of the present invention is directed to a game system ( 1 ) comprising the game controller and a game apparatus ( 3 ). The game controller is described in the first aspect. The game apparatus is communicably connected to the game controller, and includes a computer for representing a virtual game world on a display screen ( 2 ) by executing a game program. The game apparatus performs a game process in accordance with at least one of the first operation data transmitted from the first control unit and the second operation data transmitted from the second control unit. 
     In a thirty-fifth aspect based on the thirty-fourth aspect, the game apparatus causes a player character appearing in the virtual game world to perform an action in accordance with at least one of the first operation data transmitted from the game controller and the second operation data transmitted from the game controller. 
     A thirty-sixth aspect of the present invention is directed to a game system comprising the game controller and a game apparatus. The game controller is described in the fifteenth aspect. The game apparatus is communicably connected to the game controller and includes a computer for representing a virtual game world on a display screen by executing a game program. The game apparatus performs a game process in accordance with at least one of the first operation data transmitted from the first control unit and the second operation data transmitted from the second control unit. 
     In a thirty-seventh aspect based on the thirty-sixth aspect, the game apparatus causes a player character appearing in the virtual game world to perform an action in accordance with at least one of the first operation data transmitted from the game controller and the second operation data transmitted from the game controller. 
     A thirty-eighth aspect of the present invention is directed to a game system comprising the game controller and a game apparatus. The game controller is described in the twenty-eighth aspect. The game apparatus is communicably connected to the game controller and includes a computer for representing a virtual game world on a display screen by executing a game program. The game apparatus performs a game process in accordance with at least one of the first operation data transmitted from the first control unit and the second operation data transmitted from the second control unit. 
     In a thirty-ninth aspect based on the thirty-eighth aspect, the game apparatus causes a player character appearing in the virtual game world to perform an action in accordance with at least one of the first operation data transmitted from the game controller and the second operation data transmitted from the game controller. 
     According to the first aspect, the first control unit generates operation data in accordance with a motion of a controller body included in the game controller, and the second control unit generates operation data in accordance with a direction input operation. Thereby, when the game controller is used in a game, a player can make an input with a finger of one hand as in the case of a conventional controller while moving the other hand. That is, the player can cause his or her right and left hands to perform respective separate operations, thereby providing a new operation, which cannot be conventionally performed. Further, by connecting two control units to each other by a cable, the game controller requires only one transmission section for a computer. 
     According to the thirteenth aspect, the first control unit generates operation data in accordance with a motion of a controller body included in the game controller, and the second control unit generates operation data in accordance with a direction input operation. Thereby, when the game controller is used in a game, a player can make an input with a finger of one hand as in the case of a conventional controller while moving the other hand. That is, the player can cause his or her right and left hands to perform respective separate operations, thereby providing a new operation, which cannot be conventionally performed. Further, two control units are completely separated from each other, thereby providing improved controllability and enabling two players to operate the game controller. 
     According to the second, third, sixteenth and seventeenth aspects, an image taken by the image pickup section fixed to the first control unit or information obtained from the taken image can be used as the operation data. For example, a direction and a position of the first control unit with respect to the imaging target can be calculated, whereby a game operation can be performed in accordance with the direction and the position of the unit. 
     According to the fourth or the eighteenth aspect, the game controller and the computer are wirelessly connected to each other, thereby providing improved controllability of the game controller. 
     According to the fifth or the nineteenth aspect, the acceleration sensor or the gyro sensor is used as the first operation data generation section, thereby reducing a cost. 
     According to the sixth aspect, the cable is eliminated from the first control unit, whereby the operation data can be transmitted to the computer using only the first control unit. 
     According to the seventh or the twentieth aspect, data can be collected and transmitted at intervals shorter than a typical game process cycle ( 1/60 second). 
     According to one of the eighth to the twelfth aspects, and the twenty-first to the twenty-fifth aspects, the second operation data generation section for outputting a signal in accordance with a direction input operation performed by a player can be realized by the inclinable stick, the button such as a cross key having portions to be pressed depending on a direction, the horizontally movable pad, the touch pad, the button representing each direction and the like. 
     According to the thirteenth aspect, each of the units outputs the operation data in accordance with the motion of the unit body. Therefore, a player can make an input with a finger of one hand as in the case of a conventional controller while moving the other hand, and further the player can hold the separate units with both hands, respectively, thereby moving both hands individually so as to make an input. 
     According to the fourteenth, twenty-seventh, and thirty-third aspects, the speaker included in one of the units outputs a sound in accordance with data from the computer, whereby the sound can be outputted near the hand with which the player holds the unit. 
     According to the twenty-eighth aspect, each of the first control unit and the second control unit generates operation data in accordance with a motion of the unit body. Therefore, when the game controller is used in a game, each of the units outputs the operation data in accordance with the motion of the unit body, whereby the player can hold the separate units with both hands, respectively, thereby moving both hands individually so as to make an input. That is, the player can cause his or her right and left hands to perform respective separate operations, thereby providing a new operation which cannot be conventionally performed. Further, by connecting two control units to each other by a cable, the game controller requires only one transmission section for a computer. 
     According to the twenty-ninth aspect, each of the units outputs the operation data in accordance with the tilt, attitude and the like of the unit body, and therefore the player holds separate units with both hands, respectively, thereby moving two hands individually so as to make an input. 
     According to the thirtieth aspect, each of the units not only outputs operation data in accordance with a tilt, an attitude and the like of the unit body but also outputs operation data in accordance with a player performing a key operation. Therefore, the player can hold the separate units with both hands, respectively, thereby moving both hands individually so as to make an input, and the player can also use his or her fingers of both hands so as to perform operations. 
     According to the thirty-first aspect, the first control unit can calculate a direction, a position and the like of the first control unit with respect to the imaging target, whereby an operation can be performed in accordance with the direction and the position of the first control unit with respect to the display device and the like. On the other hand, the second control unit can calculate a tilt, an attitude, a position and the like of the second control unit, whereby an operation can be performed in accordance with the attitude and the position of the second control unit. 
     According to the thirty-second aspect, the first control unit can also calculate a tilt, an attitude, a position and the like of the first control unit, whereby an operation can be performed in accordance with the attitude and the position of the first control unit. 
     Further, the game system according to the present invention can obtain the same effect as that of the aforementioned game controller. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view illustrating a game system  1  according to an embodiment of the present invention; 
         FIG. 2  is a functional block diagram of a game apparatus  3  shown in  FIG. 1 ; 
         FIG. 3  is a perspective view illustrating an outer appearance of a controller  7  shown in  FIG. 1 ; 
         FIG. 4  is a perspective view illustrating a state of a connecting cable  79  of the controller  7  shown in  FIG. 3  being connected to or disconnected from a core unit  70 ; 
         FIG. 5  is a perspective view of the core unit  70  shown in  FIG. 3  as seen from the top rear side thereof; 
         FIG. 6  is a perspective view of the core unit  70  shown in  FIG. 3  as seen from the bottom front side thereof; 
         FIG. 7  is a perspective view illustrating a state where an upper casing of the core unit  70  shown in  FIG. 3  is removed; 
         FIG. 8  is a perspective view illustrating a state where a lower casing of the core unit  70  shown in  FIG. 3  is removed; 
         FIG. 9  is a perspective view illustrating a first example of the subunit  76  shown in  FIG. 3 ; 
         FIG. 10  is a perspective view of a state where an upper casing of the subunit  76  shown in  FIG. 9  is removed; 
         FIGS. 11A, 11B, and 11C  are a top view, a bottom view and a left side view of a second example of the subunit  76  shown in  FIG. 3 , respectively; 
         FIG. 12  is a perspective view of the subunit  76  shown in  FIG. 3  as seen from the top front side thereof; 
         FIG. 13  is a top view illustrating an example of a first modification of the subunit  76  shown in  FIG. 3 ; 
         FIG. 14  is a top view illustrating an example of a second modification of the subunit  76  shown in  FIG. 3 ; 
         FIG. 15  is a top view illustrating an example of a third modification of the subunit  76  shown in  FIG. 3 ; 
         FIG. 16  is a top view illustrating an example of a fourth modification of the subunit  76  shown in  FIG. 3 ; 
         FIG. 17  is a block diagram illustrating a structure of the controller  7  shown in  FIG. 3 ; 
         FIG. 18  is a diagram illustrating a state of a game being generally controlled with the controller  7  shown in  FIG. 3 ; 
         FIG. 19  shows an exemplary state of a player holding the core unit  70  with a right hand as seen from the front surface side of the core unit  70 ; 
         FIG. 20  shows an exemplary state of a player holding the core unit  70  with a right hand as seen from the left side of the core unit  70 ; 
         FIG. 21  is a diagram illustrating a viewing angle of a LED module  8 L, a viewing angle of a LED module  8 R, and a viewing angle of an image pickup element  743 ; 
         FIG. 22  shows an exemplary state of a player holding the subunit  76  with a left hand as seen from the right side of the subunit  76 ; and 
         FIG. 23  shows an exemplary game image displayed on the monitor  2  when the game apparatus  3  executes a shooting game. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , a game system  1  according to one embodiment of the present invention will be described.  FIG. 1  is an external view illustrating the game system  1 . In the following description, the game system  1  according to the present invention includes a stationary game apparatus. 
     As shown in  FIG. 1 , the game system  1  includes a stationary game apparatus (hereinafter, referred to simply as a “game apparatus”)  3 , which is connected to a display (hereinafter, referred to as a “monitor”)  2  of a home-use television receiver or the like having a speaker  2   a  via a connection cord, and a controller  7  for giving operation information to the game apparatus  3 . The game apparatus  3  is connected to a receiving unit  6  via a connection terminal. The receiving unit  6  receives transmission data which is wirelessly transmitted from the controller  7 . The controller  7  and the game apparatus  3  are connected to each other by wireless communication. On the game apparatus  3 , an optical disc  4  as an example of an exchangeable information storage medium is detachably mounted. The game apparatus  3  includes a power ON/OFF switch, a game process reset switch, and an OPEN switch for opening a top lid of the game apparatus  3  on a top main surface of the game apparatus  3 . When a player presses the OPEN switch, the lid is opened, so that the optical disc  4  can be mounted or dismounted. 
     Further, on the game apparatus  3 , an external memory card  5  is detachably mounted when necessary. The external memory card  5  has a backup memory or the like mounted thereon for fixedly storing saved data or the like. The game apparatus  3  executes a game program or the like stored on the optical disc  4  and displays the result on the monitor  2  as a game image. The game apparatus  3  can also reproduce a state of a game played in the past using saved data stored in the external memory card  5  and display the game image on the monitor  2 . A player playing with the game apparatus  3  can enjoy the game by operating the controller  7  while watching the game image displayed on the monitor  2 . 
     The controller  7  wirelessly transmits the transmission data from a communication section  75  included therein (described later) to the game apparatus  3  connected to the receiving unit  6 , using the technology of, for example, Bluetooth (registered trademark). The controller  7  has two control units, a core unit  70  and a subunit  76 , connected to each other by a flexible connecting cable  79 . The controller  7  is an operation means for mainly operating a player object appearing in a game space displayed on the monitor  2 . The core unit  70  and the subunit  76  each includes an operation section such as a plurality of operation buttons, a key, a stick and the like. As described later in detail, the core unit  70  includes an imaging information calculation section  74  for taking an image viewed from the core unit  70 . As an example of an imaging target of the imaging information calculation section  74 , two LED modules  8 L and  8 R are provided in the vicinity of a display screen of the monitor  2 . The LED modules  8 L and  8 R each outputs infrared light forward from the monitor  2 . Although in the present embodiment the core unit  70  and the subunit  76  are connected to each other by the flexible cable, the subunit  76  may have a wireless unit, thereby eliminating the connecting cable  79 . For example, the subunit  76  has a Bluetooth (registered trademark) unit as the wireless unit, whereby the subunit  76  can transmit operation data to the core unit  70 . 
     Next, with reference to  FIG. 2 , a structure of the game apparatus  3  will be described.  FIG. 2  is a functional block diagram of the game apparatus  3 . 
     As shown in  FIG. 2 , the game apparatus  3  includes, for example, a RISC CPU (central processing unit)  30  for executing various types of programs. The CPU  30  executes a boot program stored in a boot ROM (not shown) to, for example, initialize memories including a main memory  33 , and then executes a game program stored on the optical disc  4  to perform game process or the like in accordance with the game program. The CPU  30  is connected to a GPU (Graphics Processing Unit)  32 , the main memory  33 , a DSP (Digital Signal Processor)  34 , and an ARAM (audio RAM)  35  via a memory controller  31 . The memory controller  31  is connected to a controller I/F (interface)  36 , a video I/F  37 , an external memory I/F  38 , an audio I/F  39 , and a disc I/F  41  via a predetermined bus. The controller I/F  36 , the video I/F  37 , the external memory I/F  38 , the audio I/F  39  and the disc I/F  41  are respectively connected to the receiving unit  6 , the monitor  2 , the external memory card  5 , the speaker  2   a , and a disc drive  40 . 
     The GPU  32  performs image processing based on an instruction from the CPU  30 . The GPU  32  includes, for example, a semiconductor chip for performing calculation process necessary for displaying 3D graphics. The GPU  32  performs the image process using a memory dedicated for image process (not shown) and a part of the storage area of the main memory  33 . The GPU  32  generates game image data and a movie to be displayed on the monitor  2  using such memories, and outputs the generated data or movie to the monitor  2  via the memory controller  31  and the video I/F  37  as necessary. 
     The main memory  33  is a storage area used by the CPU  30 , and stores a game program or the like necessary for processing performed by the CPU  30  as necessary. For example, the main memory  33  stores a game program read from the optical disc  4  by the CPU  30 , various types of data or the like. The game program, the various types of data or the like stored in the main memory  33  are executed by the CPU  30 . 
     The DSP  34  processes sound data or the like generated by the CPU  30  during the execution of the game program. The DSP  34  is connected to the ARAM  35  for storing the sound data or the like. The ARAM  35  is used when the DSP  34  performs a predetermined process (for example, storage of the game program or sound data already read). The DSP  34  reads the sound data stored in the ARAM  35 , and outputs the sound data to the speaker  2   a  included in the monitor  2  via the memory controller  31  and the audio I/F  39 . 
     The memory controller  31  comprehensively controls data transmission, and is connected to the various I/Fs described above. The controller I/F  36  includes, for example, four controller I/Fs  36   a ,  36   b ,  36   c  and  36   d , and communicably connects the game apparatus  3  to an external device which is engageable via connectors of the controller I/Fs  36   a ,  36   b ,  36   c  and  36   d . For example, the receiving unit  6  is engaged with such a connector and is connected to the game apparatus via the controller I/F  36 . As described above, the receiving unit  6  receives the transmission data from the controller  7  and outputs the transmission data to the CPU  30  via the controller I/F  36 . The video I/F  37  is connected to the monitor  2 . The external memory I/F  38  is connected to the external memory card  5  and is accessible to a backup memory or the like provided in the external memory card  5 . The audio I/F  39  is connected to the speaker  2   a  built in the monitor  2  such that the sound data read by the DSP  34  from the ARAM  35  or sound data directly outputted from the disc drive  40  can be outputted from the speaker  2   a . The disc I/F  41  is connected to the disc drive  40 . The disc drive  40  reads data stored at a predetermined reading position of the optical disc  4  and outputs the data to a bus of the game apparatus  3  or the audio I/F  39 . 
     Next, with reference to  FIGS. 3 and 4 , the controller  7  will be described.  FIG. 3  is a perspective view illustrating an outer appearance of the controller  7 .  FIG. 4  is a perspective view illustrating a state of the connecting cable  79  of the controller  7  shown in  FIG. 3  being connected to or disconnected from the core unit  70 . 
     As shown in  FIG. 3 , the controller  7  includes the core unit  70  and the subunit  76  connected to each other by the connecting cable  79 . The core unit  70  has a housing  71  including a plurality of operation sections  72 . The subunit has a housing  77  including a plurality of operation sections  78 . The core unit  70  and the subunit  76  are connected to each other by the connecting cable  79 . 
     As shown in  FIG. 4 , the connecting cable  79  has a connector  791  detachably connected to the connector  73  of the core unit  70  at one end thereof, and the connecting cable  79  is fixedly connected to the subunit  76  at the other end thereof. The connector  791  of the connecting cable  79  is engaged with the connector  73  provided at the rear surface of the core unit  70  so as to connect the core unit  70  and the subunit  76  to each other by the connecting cable  79 . 
     With reference to  FIGS. 5 and 6 , the core unit  70  will be described.  FIG. 5  is a perspective view of the core unit  70  as seen from the top rear side thereof.  FIG. 6  is a perspective view of the core unit  70  as seen from the bottom front side thereof. 
     As shown in  FIGS. 5 and 6 , the core unit  70  includes the housing  71  formed by plastic molding or the like. The housing  71  has a generally parallelepiped shape extending in a longitudinal direction from front to rear. The overall size of the housing  71  is small enough to be held by one hand of an adult or even a child. 
     At the center of a front part of a top surface of the housing  71 , a cross key  72   a  is provided. The cross key  72   a  is a cross-shaped four-direction push switch. The cross key  72   a  includes operation portions corresponding to the four directions (front, rear, right and left) represented by arrows, which are respectively located on cross-shaped projecting portions arranged at intervals of 90 degrees. The player selects one of the front, rear, right and left directions by pressing one of the operation portions of the cross key  72   a . Through an operation on the cross key  72   a , the player can, for example, instruct a direction in which a player character or the like appearing in a virtual game world is to move or a direction in which the cursor is to move. 
     Although the cross key  72   a  is an operation section for outputting an operation signal in accordance with the aforementioned direction input operation performed by the player, such an operation section may be provided in another form. For example, the cross key  72   a  may be replaced with a composite switch including a push switch including a ring-shaped four-direction operation section and a center switch provided at the center thereof. Alternatively, the cross key  72   a  may be replaced with an operation section which includes an inclinable stick projecting from the top surface of the housing  71  and outputs an operation signal in accordance with the inclining direction of the stick. Still alternatively, the cross key  72   a  may be replaced with an operation section which includes a disc-shaped member horizontally slidable and outputs an operation signal in accordance with the sliding direction of the disc-shaped member. Still alternatively, the cross key  72   a  may be replaced with a touch pad. Still alternatively, the cross key  72   a  may be replaced with an operation section which includes switches representing at least four directions (front, rear, right and left) and outputs an operation signal in accordance with the switch pressed by the player. 
     Behind the cross key  72   a  on the top surface of the housing  71 , a plurality of operation buttons  72   b ,  72   c ,  72   d ,  72   e ,  72   f  and  72   g  are provided. The operation buttons  72   b ,  72   c ,  72   d ,  72   e ,  72   f  and  72   g  are each an operation section for outputting a respective operation signal assigned to the operation buttons  72   b ,  72   c ,  72   d ,  72   e ,  72   f  or  72   g  when the player presses a head thereof. For example, the operation buttons  72   b ,  72   c , and  72   d  are assigned with functions of a first button, a second button, and an A button. Further, the operation buttons  72   e ,  72   f  and  72   g  are assigned with functions of a minus button, a home button and a plus button, for example. The operation buttons  72   b ,  72   c ,  72   d ,  72   e ,  72   f  and  72   g  are assigned with respective functions in accordance with the game program executed by the game apparatus  3 , but this will not be described in detail because the functions are not directly relevant to the present invention. In an exemplary arrangement shown in  FIG. 5 , the operation buttons  72   b ,  72   c  and  72   d  are arranged in a line at the center in the front-rear direction on the top surface of the housing  71 . The operation buttons  72   e ,  72   f  and  72   g  are arranged in a line in the left-right direction between the operation buttons  72   b  and  72   d  on the top surface of the housing  71 . The operation button  72   f  has a top surface thereof buried in the top surface of the housing  71 , so as not to be inadvertently pressed by the player. 
     In front of the cross key  72   a  on the top surface of the housing  71 , an operation button  72   h  is provided. The operation button  72   h  is a power switch for remote-controlling the power of the game apparatus  3  to be on or off. The operation button  72   h  also has a top surface thereof buried in the top surface of the housing  71 , so as not to be inadvertently pressed by the player. 
     Behind the operation button  72   c  on the top surface of the housing  71 , a plurality of LEDs  702  are provided. The controller  7  is assigned a controller type (number) so as to be distinguishable from the other controllers  7 . For example, the LEDs  702  are used for informing the player of the controller type which is currently set to controller  7  that he or she is using. Specifically, when the core unit  70  transmits the transmission data to the receiving unit  6 , one of the plurality of LEDs  702  corresponding to the controller type is lit up. 
     On the top surface of the housing  71 , a sound hole for externally outputting a sound from a speaker  706  shown in  FIG. 7 , which will be described below, is provided between the operation buttons  72   e ,  72   f , and  72   g  and the operation button  72   b.    
     On a bottom surface of the housing  71 , a recessed portion is formed. As described later in detail, the recessed portion is formed at a position at which an index finger or middle finger of the player is located when the player holds the core unit  70 . On a rear slope surface of the recessed portion, an operation button  72   i  is provided. The operation button  72   i  is an operation section acting as, for example, a B button. The operation button  72   i  is used, for example, as a trigger switch in a shooting game, or for attracting attention of a player object to a predetermined object. 
     On a front surface of the housing  71 , an image pickup element  743  included in the imaging information calculation section  74  is provided. The imaging information calculation section  74  is a system for analyzing image data taken by the core unit  70  and detecting for the centroid, the size and the like of an area having a high brightness in the image data. The imaging information calculation section  74  has, for example, a maximum sampling period of about 200 frames/sec., and therefore can trace and analyze even a relatively fast motion of the core unit  70 . The imaging information calculation section  74  will be described later in detail. On a rear surface of the housing  71 , the connector  73  is provided. The connector  73  is, for example, a 32-pin edge connector, and is used for engaging and connecting the core unit  70  with the connector  791  of the connecting cable  79 . 
     With reference to  FIGS. 7 and 8 , an internal structure of the core unit  70  will be described.  FIG. 7  is a perspective view illustrating, as seen from the rear side of the core unit  70 , a state where an upper casing (a part of the housing  71 ) of the core unit  70  is removed.  FIG. 8  is a perspective view illustrating, as seen from the front side of the core unit  70 , a state where a lower casing (a part of the housing  71 ) of the core unit  70  is removed.  FIG. 8  is a perspective view illustrating a reverse side of a substrate  700  shown in  FIG. 7 . 
     As shown in  FIG. 7 , the substrate  700  is fixed inside the housing  71 . On a top main surface of the substrate  700 , the operation buttons  72   a ,  72   b ,  72   c ,  72   d ,  72   e ,  72   f ,  72   g  and  72   h , an acceleration sensor  701 , the LEDs  702 , an antenna  754  and the like are provided. These elements are connected to a micro computer  751  (see  FIGS. 8 and 17 ) and the like via lines (not shown) formed on the substrate  700  and the like. The wireless module  753  not shown (see  FIG. 17 ) and the antenna  754  allow the core unit  70  to act as a wireless controller. The quartz oscillator  703  not shown, which is provided in the housing  71 , generates a reference clock of the micro computer  751  described later. On the top main surface of the substrate  700 , the speaker  706  and an amplifier  708  are provided. The acceleration sensor  701  is provided near the edge of the substrate  700  offset from the center thereof. Therefore, a change of a direction of the gravitational acceleration and an acceleration containing a centrifugal force component can be detected based on a rotation of the core unit  70  about the longitudinal direction thereof, so that a predetermined calculation is used to determine the rotation of the core unit  70  with favorable accuracy based on the acceleration data having been detected. 
     As shown in  FIG. 8 , at a front edge of a bottom main surface of the substrate  700 , the imaging information calculation section  74  is provided. The imaging information calculation section  74  includes an infrared filter  741 , a lens  742 , the image pickup element  743  and an image processing circuit  744  located in this order from the front surface of the core unit  70  on the bottom main surface of the substrate  700 . At a rear edge of the bottom main surface of the substrate  700 , the connector  73  is attached. Further, a sound IC  707  and the micro computer  751  are provided on the bottom main surface of the substrate  700 . The sound IC  707 , which is connected to the micro computer  751  and the amplifier  708  via lines formed on the substrate  700  and the like, outputs a sound signal to the speaker  706  via the amplifier  708  based on the sound data transmitted from the game apparatus  3 . On the bottom main surface of the substrate  700 , a vibrator  704  is provided. The vibrator  704  is, for example, a vibration motor or a solenoid. The core unit  70  is vibrated by an actuation of the vibrator  704 , and the vibration is conveyed to the player&#39;s hand holding the core unit  70 . Thus, a so-called vibration-feedback game is realized. The vibrator  704  is disposed slightly toward the front of the housing  71 , thereby allowing the housing  71  held by the player to strongly vibrate, that is, allowing the player to easily feel the vibration. 
     With reference to  FIGS. 9 to 12 , the subunit  76  will be described.  FIG. 9  is a perspective view illustrating a first example of the subunit  76 .  FIG. 10  is a perspective view illustrating a state where an upper casing (a part of the housing  77 ) of the subunit  76  shown in  FIG. 9  is removed.  FIG. 11A  is a top view illustrating a second example of the subunit  76 .  FIG. 11B  is a bottom view illustrating the second example of the subunit  76 .  FIG. 11C  is a left side view illustrating the second example of the subunit  76 .  FIG. 12  is a perspective view illustrating the second example of the subunit  76  as seen from the top front side thereof. 
     As shown in  FIG. 9 , the subunit  76  includes the housing  77  formed by, for example, plastic molding. The housing  77  extends in a longitudinal direction from front to rear, and has a streamline solid shape including a head which is a widest portion in the subunit  76 . The overall size of the subunit  76  is small enough to be held by one hand of an adult or even a child. 
     In the vicinity of the widest portion on the top surface of the housing  77 , a stick  78   a  is provided. The stick  78   a  is an operation section which includes an inclinable stick projecting from the top surface of the housing  77  and outputs an operation signal in accordance with the inclining direction of the stick. For example, a player can arbitrarily designate a direction and a position by inclining a tip of the stick in any direction of 360 degrees, whereby the player can instruct a direction in which a player character or the like appearing in a virtual game world is to move, or can instruct a direction in which a cursor is to move. 
     In front of the housing  77  of the subunit  76 , a plurality of operation buttons  78   d  and  78   e  are provided. The operation buttons  78   d  and  78   e  are each an operation section for outputting a respective operation signal assigned to the operation buttons  78   d  and  78   e  when the player presses a head thereof. For example, the operation buttons  78   d  and  78   e  are assigned with functions of an X button and a Y button, for example. Although the operation buttons  78   d  and  78   e  are assigned with respective functions in accordance with the game program executed by the game apparatus  3 , this will not be described in detail because the functions are not directly relevant to the present invention. In an exemplary arrangement shown in  FIG. 9 , the operation buttons  78   d  and  78   e  are aligned from the top to bottom on the front surface of the housing  77 . 
     In  FIG. 10 , a substrate is fixed in the housing  77 . The stick  78   a , an acceleration sensor  761  and the like are provided on the top main surface of the substrate. The stick  78   a , the acceleration sensor  761  and the like are connected to the connecting cable  79  via lines (not shown) formed on the substrate and the like. 
     As shown in  FIGS. 11A, 11B, 11C and 12 , the subunit  76  of the second example includes the housing  77 , the stick  78   a , the operation buttons  78   d  and  78   e  as in the case of the subunit  76  of the first example, and the subunit  76  of the second example has the operation buttons  78   b  and  78   c  on the top surface of the housing  77 . 
     Behind the stick  78   a  on the top surface of the housing  77 , the subunit  76  of the second example has a plurality of operation buttons  78   b  and  78   c . The operation buttons  78   b  and  78   c  are each an operation section for outputting a respective operation signal assigned to the operation buttons  78   b  and  78   c  when the player presses a head thereof. The operation buttons  78   b  and  78   c  are assigned with respective functions in accordance with the game program executed by the game apparatus  3 . However, this will not be described in detail because the functions are not directly relevant to the present invention. In an exemplary arrangement shown in  FIGS. 11A, 11B, 11C and 12 , the operation buttons  78   b  and  78   c  are arranged in a line at the center of the top surface of the housing  77  in the left-right direction. 
     Although the stick  78   a  is an operation section for outputting an operation signal in accordance with a direction input operation performed by the player as described above, such an operation section may be provided in another form. Hereinafter, with reference to  FIGS. 13 to 16 , a first through a fifth exemplary modifications, each of which includes the subunit  76  of the second example having an operation section for outputting an operation signal in accordance with the direction input operation, will be described. 
     As the first exemplary modification, as shown in  FIG. 13 , the subunit  76  may include a cross key  78   f  similar to the cross key  72   a  of the core unit  70  instead of the stick  78   a . As the second exemplary modification, as shown in  FIG. 14 , the subunit  76  may include a slide pad  78   g  which includes a disc-shaped member horizontally slidable and outputs an operation signal in accordance with the sliding direction of the disc-shaped member, instead of the stick  78   a . As the third exemplary modification, as shown in  FIG. 15 , the subunit  76  may include a touch pad  78   h  instead of the stick  78   a . As the fourth exemplary modification, as shown in  FIG. 16 , the subunit  76  may include an operation section which has buttons  78   i ,  78   j ,  78   k , and  78   l  representing at least four directions (front, rear, right and left), respectively, and outputs an operation signal in accordance with the button ( 78   i ,  78   j ,  78   k , or  78   l ) pressed by a player, instead of the stick  78   a . As the fifth exemplary modification, the subunit  76  may include a composite switch including a push switch having a ring-shaped four-direction operation section and a center switch provided at the center thereof, instead of the stick  78   a.    
     Next, with reference to  FIG. 17 , an internal structure of the controller  7  will be described.  FIG. 17  is a block diagram illustrating the structure of the controller  7 . 
     As shown in  FIG. 17 , the core unit  70  includes the communication section  75  in addition to the operation section  72 , the imaging information calculation section  74 , the acceleration sensor  701 , the speaker  706 , the sound IC  707 , and the amplifier  708  as described above. Further, the subunit  76 , which has the operation section  78  and the acceleration sensor  761  as described above, is connected to the micro computer  751  via the connecting cable  79  and the connectors  791  and  73 . 
     The imaging information calculation section  74  includes the infrared filter  741 , the lens  742 , the image pickup element  743  and the image processing circuit  744 . The infrared filter  741  allows only infrared light to pass therethrough, among light incident on the front surface of the core unit  70 . The lens  742  collects the infrared light which has passed through the infrared filter  741  and outputs the infrared light to the image pickup element  743 . The image pickup element  743  is a solid-state imaging device such as, for example, a CMOS sensor or a CCD. The image pickup element  743  takes an image of the infrared light collected by the lens  742 . Accordingly, the image pickup element  743  takes an image of only the infrared light which has passed through the infrared filter  741  and generates image data. The image data generated by the image pickup element  743  is processed by the image processing circuit  744 . Specifically, the image processing circuit  744  processes the image data obtained from the image pickup element  743 , identifies a spot thereof having a high brightness, and outputs process result data representing the identified position coordinates and size of the area to the communication section  75 . The imaging information calculation section  74  is fixed to the housing  71  of the core unit  70 . The imaging direction of the imaging information calculation section  74  can be changed by changing the direction of the housing  71 . The housing  71  is connected to the subunit  76  by the flexible connecting cable  79 , and therefore the imaging direction of the imaging information calculation section  74  is not changed by changing the direction and position of the subunit  76 . As described later in detail, a signal can be obtained in accordance with the position and the motion of the core unit  70  based on the process result data outputted by the imaging information calculation section  74 . 
     The core unit  70  preferably includes a three-axis acceleration sensor  701 . Further, the subunit  76  preferably includes a three-axis acceleration sensor  761 . The three axis acceleration sensors  701  and  761  each detects for a linear acceleration in three directions, i.e., the up/down direction, the left/right direction, and the forward/backward direction. Alternatively, a two axis acceleration detection means which detects for only a linear acceleration along each of the up/down and left/right directions (or other pair of directions) may be used in another embodiment depending on the type of control signals used in the game process. For example, the three axis acceleration sensors  701  and  761  or the two axis acceleration sensors  701  and  761  may be of the type available from Analog Devices, Inc. or STMicroelectronics N.V. Preferably, each of the acceleration sensors  701  and  761  is of an electrostatic capacitance (capacitance-coupling) type that is based on silicon micro-machined MEMS (Micro Electro Mechanical Systems) technology. However, any other suitable acceleration detection technology (e.g., piezoelectric type or piezoresistance type) now existing or later developed may be used to provide the three axis acceleration sensors  701  and  761  or two axis acceleration sensors  701  and  761 . 
     As one skilled in the art understands, the acceleration detection means, as used in the acceleration sensors  701  and  761 , are capable of detecting for only acceleration (linear acceleration) along a straight line corresponding to each axis of the acceleration sensor. In other words, each of the direct outputs of the acceleration sensors  701  and  761  is limited to signals indicative of linear acceleration (static or dynamic) along each of the two or three axes thereof. As a result, the acceleration sensors  701  and  761  cannot directly detect movement along a non-linear (e.g. arcuate) path, rotation, rotational movement, angular displacement, tilt, position, attitude or any other physical characteristic. 
     However, through additional processing of the acceleration signals output from each of the acceleration sensors  701  and  761 , additional information relating to the core unit  70  and the subunit  76  can be inferred or calculated, as one skilled in the art will readily understand from the description herein. For example, by detecting static acceleration (i.e., gravity), the outputs of the acceleration sensors  701  and  761  can be used to infer tilt of the object (core unit  70  or subunit  76 ) relative to the gravity vector by correlating tilt angles with detected acceleration. In this way, the acceleration sensors  701  and  761  can be used in combination with the micro computer  751  (or another processor) to determine tilts, attitudes or positions of the core unit  70  and the subunit  76 . Similarly, various movements and/or positions of the core unit  70  and the subunit  76  can be calculated or inferred through processing of the acceleration signals generated by the acceleration sensors  701  and  761  when the core unit  70  containing the acceleration sensor  701  or the subunit  76  containing the acceleration sensor  761  is subjected to dynamic accelerations by, for example, the hand of a user, as described herein. In another embodiment, each of the acceleration sensors  701  and  761  may include an embedded signal processor or other type of dedicated processor for performing any desired processing of the acceleration signals outputted from the acceleration detection means prior to outputting signals to micro computer  751 . For example, the embedded or dedicated processor could convert the detected acceleration signal to a corresponding tilt angle when the acceleration sensor is intended to detect static acceleration (i.e., gravity). Data representing the acceleration detected by each of the acceleration sensors  701  and  761  is outputted to the communication section  75 . 
     In another exemplary embodiment, at least one of the acceleration sensors  701  and  761  may be replaced with a gyro-sensor of any suitable technology incorporating, for example, a rotating or vibrating element. Exemplary MEMS gyro-sensors that may be used in this embodiment are available from Analog Devices, Inc. Unlike the acceleration sensors  701  and  761 , a gyro-sensor is capable of directly detecting rotation (or angular rate) around at least one axis defined by the gyroscopic element therein. Thus, due to the fundamental differences between a gyro-sensor and an acceleration sensor, corresponding changes need to be made to the processing operations that are performed on the output signals from these devices depending on which device is selected for a particular application. 
     More specifically, when the tilt or attitude is calculated using a gyro-sensor instead of the acceleration sensor, significant changes are necessary. Specifically, when using a gyro-sensor, the value of the tilt is initialized at the start of the detection. Then, data on the angular rate which is output from the gyro-sensor is integrated. Next, a change amount in tilt from the value of the tilt initialized is calculated. In this case, the calculated tilt corresponds to an angle. In contrast, when the acceleration sensor calculates the tilt, the tilt is calculated by comparing the value of the gravitational acceleration of each axial component with a predetermined reference. Therefore, the calculated tilt can be represented as a vector. Thus, without initialization, an absolute direction can be determined with an acceleration detection means. The type of the value calculated as the tilt is also very different between a gyro sensor and an acceleration sensor; i.e., the value is an angle when a gyro sensor is used and is a vector when an acceleration sensor is used. Therefore, when a gyro sensor is used instead of an acceleration sensor or vice versa, data on tilt also needs to be processed through a predetermined conversion taking into account the fundamental differences between these two devices. Due to the fact that the nature of gyroscopes is known to one skilled in the art, as well as the fundamental differences between the acceleration detection means and the gyroscope, further details are not provided herein. While a gyro-sensor is advantageous in that a rotation can be directly detected, an acceleration sensor is generally more cost effective when used in connection with the controller described herein. 
     The communication section  75  includes the micro computer  751 , a memory  752 , the wireless module  753  and the antenna  754 . The micro computer  751  controls the wireless module  753  for wirelessly transmitting the transmission data while using the memory  752  as a storage area during the process. Further, the micro computer  751  controls the sound IC  707  and the vibrator  704  based on data from the game apparatus  3  having been received by the wireless module  753  via the antenna  754 . The sound IC  707  processes sound data transmitted from the game apparatus  3  via the communication section  75 , and the like. 
     Data from the core unit  70  including an operation signal (core key data) from the operation section  72 , acceleration signals (core acceleration data) from the acceleration sensor  701 , and the process result data from the imaging information calculation section  74  are outputted to the micro computer  751 . An operation signal (sub key data) from the operation section  78  of the subunit  76  and acceleration signals (sub acceleration data) from the acceleration sensor  761  are outputted to the micro computer  751  via the connecting cable  79 . The micro computer  751  temporarily stores the input data (core key data, sub key data, core acceleration data, sub acceleration data, and process result data) in the memory  752  as the transmission data which is to be transmitted to the receiving unit  6 . The wireless transmission from the communication section  75  to the receiving unit  6  is performed periodically at a predetermined time interval. Since game process is generally performed at a cycle of 1/60 sec., data needs to be collected and transmitted at a cycle of a shorter time period. Specifically, the game process unit is 16.7 ms ( 1/60 sec.), and the transmission interval of the communication section  75  structured using the Bluetooth (registered trademark) technology is 5 ms. At the transmission timing to the receiving unit  6 , the micro computer  751  outputs the transmission data stored in the memory  752  as a series of operation information to the wireless module  753 . The wireless module  753  uses, for example, the Bluetooth (registered trademark) technology to modulate the operation information onto a carrier wave of a predetermined frequency, and radiates the low power radio wave signal from the antenna  754 . Thus, the core key data from the operation section  72  included in the core unit  70 , the sub key data from the operation section  78  included in the subunit  76 , the core acceleration data from the acceleration sensor  701  included in the core unit  70 , the sub acceleration data from the acceleration sensor  761  included in the subunit  76 , and the process result data from the imaging information calculation section  74  are modulated onto the low power radio wave signal by the wireless module  753  and radiated from the core unit  70 . The receiving unit  6  of the game apparatus  3  receives the low power radio wave signal, and the game apparatus  3  demodulates or decodes the low power radio wave signal to obtain the series of operation information (the core key data, the sub key data, the core acceleration data, the sub acceleration data and the process result data). Based on the obtained operation information and the game program, the CPU  30  of the game apparatus  3  performs the game process. In the case where the communication section  75  is structured using the Bluetooth (registered trademark) technology, the communication section  75  can have a function of receiving transmission data which is wirelessly transmitted from other devices. 
     As shown in  FIG. 18 , in order to play a game using the controller  7  with the game system  1 , a player holds the core unit  70  with one hand (for example, a right hand) (see  FIGS. 19 and 20 ), and holds the subunit  76  with the other hand (for example, a left hand) (see  FIG. 22 ). The player holds the core unit  70  so as to point the front surface of the core unit  70  (that is, a side having an entrance through which light is incident on the imaging information calculation section  74  taking an image of the light) to the monitor  2 . On the other hand, two LED modules  8 L and  8 R are provided in the vicinity of the display screen of the monitor  2 . The LED modules  8 L and  8 R each outputs infrared light forward from the monitor  2 . 
     When a player holds the core unit  70  so as to point the front surface thereof to the monitor  2 , infrared lights outputted by the two LED modules  8 L and  8 R are incident on the imaging information calculation section  74 . The image pickup element  743  takes images of the infrared lights incident through the infrared filter  741  and the lens  742 , and the image processing circuit  744  processes the taken images. The imaging information calculation section  74  detects infrared components outputted by the LED modules  8 L and  8 R so as to obtain positions and area information of the LED modules  8 L and  8 R. Specifically, the imaging information calculation section  74  analyzes image data taken by the image pickup element  743 , eliminates images which do not represent the infrared lights outputted by the LED modules  8 L and  8 R from the area information, and identifies points each having a high brightness as positions of the LED modules  8 L and  8 R. The imaging information calculation section  74  obtains position coordinates, coordinates of the centroid, and the like of each of the identified points having the high brightness and outputs the same as the process result data. When such process result data is transmitted to the game apparatus  3 , the game apparatus  3  can obtain, based on the position coordinates and the coordinates of the centroid, operation signals relating to the motion, attitude, position and the like of the imaging information calculation section  74 , that is, the core unit  70 , with respect to the LED modules  8 L and  8 R. Specifically, the position having a high brightness in the image obtained through the communication section  75  is changed in accordance with the motion of the core unit  70 , and therefore a direction input or coordinate input is performed in accordance with the position having the high brightness being changed, thereby enabling a direction input or a coordinate input to be performed along the moving direction of the core unit  70 . 
     Thus, the imaging information calculation section  74  of the core unit  70  takes images of stationary markers (infrared lights from the two LED modules  8 L and  8 R in the present embodiment), and therefore the game apparatus  3  can use the process result data relating to the motion, attitude, position and the like of the core unit  70  in the game process, whereby an operation input, which is different from an input made by pressing an operation button or using an operation key, is further intuitively performed. As described above, since the markers are provided in the vicinity of the display screen of the monitor  2 , the motion, attitude, position and the like of the core unit  70  with respect to the display screen of the monitor  2  can be easily calculated based on positions from the markers. That is, the process result data used for obtaining the motion, attitude, position and the like of the core unit  70  can be used as operation input immediately applied to the display screen of the monitor  2 . 
     With reference to  FIGS. 19 and 20 , a state of a player holding the core unit  70  with one hand will be described.  FIG. 19  shows an exemplary state of a player holding the core unit  70  with a right hand as seen from the front surface side of the core unit  70 .  FIG. 20  shows an exemplary state of a player holding the core unit  70  with a right hand as seen from the left side of the core unit  70 . 
     As shown in  FIGS. 19 and 20 , the overall size of the core unit  70  is small enough to be held by one hand of an adult or even a child. When the player puts a thumb on the top surface of the core unit  70  (for example, near the cross key  72   a ), and puts an index finger in the recessed portion on the bottom surface of the core unit  70  (for example, near the operation button  72   i ), the light entrance of the imaging information calculation section  74  on the front surface of the core unit  70  is exposed forward to the player. It should be understood that also when the player holds the core unit  70  with a left hand, the holding state is the same as that described for the right hand. 
     Thus, the core unit  70  allows a player to easily operate the operation section  72  such as the cross key  72   a  or the operation button  72   i  while holding the core unit  70  with one hand. Further, when the player holds the core unit  70  with one hand, the light entrance of the imaging information calculation section  74  on the front surface of the core unit  70  is exposed, whereby the light entrance can easily receive infrared lights from the aforementioned two LED modules  8 L and  8 R. That is, the player can hold the core unit  70  with one hand without preventing the imaging information calculation section  74  from functioning. That is, when the player moves his or her hand holding the core unit  70  with respect to the display screen, the core unit  70  can further perform an operation input enabling a motion of the player&#39;s hand to directly act on the display screen. 
     As shown in  FIG. 21 , the LED modules  8 L and  8 R each has a viewing angle θ 1 . The image pickup element  743  has a viewing angle θ 2 . For example, the viewing angle θ 1  of the LED modules  8 L and  8 R is 34 degrees (half-value angle), and the viewing angle θ 2  of the image pickup element  743  is 41 degrees. When both the LED modules  8 L and  8 R are in the viewing angle θ 2  of the image pickup element  743 , and the image pickup element  743  is in the viewing angle θ 1  of the LED module  8 L and the viewing angle θ 1  of the LED module  8 R, the game apparatus  3  determines a position of the core unit  70  using positional information relating to the point having high brightness of the two LED modules  8 L and  8 R. 
     When either the LED module  8 L or LED module  8 R is in the viewing angle θ 2  of the image pickup element  743 , or when the image pickup element  743  is in either the viewing angle θ 1  of the LED module  8 L or the viewing angle θ 1  of the LED module  8 R, the game apparatus  3  determines a position of the core unit  70  using the positional information relating to the point having high brightness of the LED module  8 L or the LED module  8 R. 
     As described above, the tilt, attitude or position of the core unit  70  can be determined based on the output (core acceleration data) from the acceleration sensor  701  of the core unit  70 . That is, the core unit  70  functions as an operation input means for performing an operation in accordance with a player moving a hand holding the core unit  70 , for example, upward, downward, leftward, or rightward. 
     Next, with reference to  FIG. 22 , a state of a player holding the subunit  76  with one hand will be described.  FIG. 22  shows an exemplary state of a player holding the subunit  76  with a left hand as seen from the right side of the subunit  76 . 
     As shown in  FIG. 22 , the overall size of the subunit  76  is small enough to be held by one hand of an adult or even a child. For example, a player can put a thumb on the top surface of the subunit  76  (for example, near the stick  78   a ), put an index finger on the front surface of the subunit  76  (for example, near the operation buttons  78   d  and  78   e ), and put a middle finger, a ring finger and a little finger on the bottom surface of the subunit  76  so as to hold the subunit  76 . It should be understood that also when the player holds the subunit  76  with a right hand, the holding state is similar to that described for the left hand. Thus, the subunit  76  allows the player to easily operate the operation section  78  such as the stick  78   a  and the operation buttons  78   d  and  78   e  while holding the subunit  76  with one hand. 
     As described above, the tilt, attitude or position of the subunit  76  can be determined based on the output (sub acceleration data) from the acceleration sensor  761  of the subunit  76 . That is, the subunit  76  functions as an operation input means for performing an operation in accordance with the player moving a hand holding the subunit  76 , for example, upward, downward, leftward, and rightward. 
     Here, an exemplary game played using the aforementioned controller  7  will be described. As a first example, a shooting game played using the controller  7  will be described.  FIG. 23  is a diagram illustrating an exemplary game image displayed on the monitor  2  when the game apparatus  3  executes the shooting game. 
     As shown in  FIG. 23 , a portion of a three-dimensional virtual game space S is displayed on the display screen of the monitor  2 . As a game object acting in accordance with an operation of the controller  7 , a portion of the player character P and a portion of a gun G held by the player character P are displayed on the display screen. Moreover, the virtual game space S displayed on the display screen represents a field of front vision of the player character P, and for example an opponent character E is displayed as a shooting target in  FIG. 23 . A target indicating a position at which the player character P shoots the gun G is displayed on the display screen as the target cursor T. 
     In the shooting game having such a game image displayed on the monitor  2 , a player operates the core unit  70  with one hand and operates the subunit  76  with the other hand as shown in  FIG. 18  so as to play the game. For example, when the player inclines the stick  78   a  (see  FIGS. 11A, 11B, 11C and 12 ) on the subunit  76 , the player character P is moved in the virtual game space S in accordance with the inclining direction. Further, when the player moves his or her hand holding the core unit  70  with respect to the display screen, the target cursor T is moved in accordance with the motion, attitude, position and the like of the core unit  70  with respect to the monitor  2  (LED modules  8 L and  8 R). When the player presses the operation button  72   i  (shown in  FIG. 6 ) on the core unit  70 , the player character P shoots the gun G at the target cursor T. 
     That is, while the player uses the stick  78   a  on the subunit  76  so as to instruct the player character P to move, the player can operate the core unit  70  as if the core unit  70  is a gun for the shooting game, thereby enhancing enjoyment in playing a shooting game. The player can perform an operation of moving the player character P and an operation of moving the target cursor T by using respective units held by different hands, whereby the player can perform the respective operations as independent ones. For example, since the virtual game space S displayed on the display screen is changed in accordance with the movement of the player character P, it is sometimes difficult to keep the target positioned near a position observed by the player in the virtual game space S because, for example, the player may be paying attention to the opponent character E suddenly jumping into the virtual game space S. However, while the player is moving the player character P with one hand (for example, a thumb of a left hand), the player can control a motion of the arm (for example, a right arm) which is not used for moving the player character P such that the core unit  70  has its front surface pointed to the observed position, thereby substantially enhancing flexibility for operating the controller  7  and increasing the reality of the shooting game. Further, in order to move the target cursor T, the player moves the controller. However, the operation of moving the controller does not hinder the player from performing a direction instruction operation for moving the player character P, thereby enabling the player to stably perform the two direction instruction operations. That is, by using the controller  7 , the player can freely use his or her left and right hands and can perform a new operation having increased flexibility, which cannot be achieved using a physically single controller. 
     In a second example, a player inclines the stick  78   a  on the subunit  76  so as to move the player character P in the virtual game space S in accordance with the inclining direction as in the first example. The player moves a hand holding the core unit  70  with respect to the display screen so as to move a sight point of a virtual camera in accordance with a position of the core unit  70  with respect to the monitor  2  (LED modules  8 L and  8 R). These operations allow the player to observe a position to which the core unit  70  is pointed in the virtual game space S while operating the stick  78   a  on the subunit  76  so as to instruct the player character P to move. 
     In the above description, the controller  7  and the game apparatus  3  are connected to each other by wireless communication. However, the controller  7  and the game apparatus  3  may be electrically connected to each other by a cable. In this case, the cable connected to the core unit  70  is connected to a connection terminal of the game apparatus  3 . 
     Moreover, in the present embodiment, only the core unit  70  among the core unit  70  and the subunit  76  of the controller  7  has the communication section  75 . However, the subunit  76  may have the communication section for wirelessly transmitting the transmission data to the receiving unit  6 . Further, both the core unit  70  and the subunit  76  may have the respective communication sections. For example, the respective communication sections included in the core unit  70  and the subunit  76  may wirelessly transmit the transmission data to the receiving unit  6 , or the communication section of the subunit  76  may wirelessly transmit the transmission data to the communication section  75  of the core unit  70 , and the communication section  75  of the core unit  70  may wirelessly transmit, to the receiving unit  6 , the received transmission data from the subunit  76  and the transmission data of the core unit  70 . In these cases, the connecting cable  79  for electrically connecting between the core unit  70  and the subunit  76  can be eliminated. 
     In the above description, the receiving unit  6  connected to the connection terminal of the game apparatus  3  is used as a receiving means for receiving transmission data which is wirelessly transmitted from the controller  7 . Alternatively, the receiving means may be a receiving module built in the game apparatus  3 . In this case, the transmission data received by the receiving module is outputted to the CPU  30  via a predetermined bus. 
     Although in the present embodiment the imaging information calculation section  74  included in the core unit  70  is described as an example of a determining section for outputting a signal (process result data) in accordance with a motion of the core unit  70  body, the imaging information calculation section  74  may be provided in another form. For example, the core unit  70  may include the acceleration sensor  701  as described above, or may include a gyro sensor. The acceleration sensor or the gyro sensor can be used to determine a motion or attitude of the core unit  70 , and, therefore, can be used as a determining section for outputting a signal in accordance with the motion of the core unit  70  body using the detection signal for the motion or attitude. In this case, the imaging information calculation section  74  may be eliminated from the core unit  70 , or sensor and the imaging information calculation section can be used in combination. 
     Further, although in the present embodiment only the core unit  70  includes the imaging information calculation section  74 , the subunit  76  may also include a similar imaging information calculation section. 
     Further, when the controller  7  includes a plurality of units, each of which may have a plurality of operation means such as the imaging information calculation section, the acceleration sensor, the gyro sensor, the stick, the cross key, and the operation button, various combination of the operation means can realize various controllers. Here, the operation means included in the core unit  70  and the subunit  76  are classified into an operation means A and an operation means B. The operation means A, such as the imaging information calculation section  74 , the acceleration sensors  701  and  761 , and the gyro sensor, outputs a signal in accordance with the movement of the unit body. The operation means B, such as the stick, the cross key, the operation button, the touch pad, outputs a signal in accordance with the player pressing a button, tilting a component or touching the same. 
     When the core unit  70  includes the operation means A and the subunit  76  includes the operation means B, the player can move one hand holding the core unit  70  while the player makes an input with a finger of the other hand holding the subunit  76  as in the case of a conventional controller. 
     That is, the player can perform different operations with a right and a left hands, respectively, thereby realizing a new operation which cannot be performed by a conventional controller. In this case, according to the present invention, operation data outputted by the operation means A corresponds to first operation data, and operation data outputted by the operation means B corresponds to second operation data. Further, the controller may be constructed such that the subunit  76  may include the operation means A, the core unit  70  may include the operation means A, and the subunit  76  may include the operation means A and the operation means B. In this manner, the player can move both hands individually, thereby realizing an increasingly improved operation. In this case, according to the present invention, operation data outputted by the operation means A of the subunit  76  corresponds to third operation data. 
     Further, when the core unit  70  and the subunit  76  each includes the operation means A, the player can move one hand holding the core unit  70  while the player can move the other hand holding the subunit  76  so as to make an input. That is, the player can move a right and a left hands individually, thereby realizing a new operation which cannot be performed by a conventional controller. In this case, according to the present invention, operation data outputted by the respective operation means A of the core unit  70  and the subunit  76  correspond to first operation data and second operation data. Further, each of the core unit  70  and the subunit  76  may include both the operation means A and the operation means B. In this manner, the player can perform operations by moving both hands and using fingers of both hands, thereby realizing a new operation. In this case, according to the present invention, operation data outputted by the operation means B of the core unit  70  corresponds to first key operation data, and operation data outputted by the operation means B of the subunit  76  corresponds to second key operation data. 
     Furthermore, when each of the core unit  70  and the subunit  76  includes the operation means A, one of the core unit  70  or the subunit  76  may include various types of operation means A. As described above, when the operation means A includes the imaging information calculation section, a direction, a position and the like of the unit with respect to the imaging target (marker) can be calculated, thereby enabling an operation based on the direction and the position of the unit with respect to the monitor  2 . On the other hand, when the operation means A includes the acceleration sensor or the gyro sensor, a tilt, an attitude, a position and the like of the unit itself can be calculated, thereby enabling an operation based on the attitude and the position of the unit. Accordingly, when the core unit  70  includes the imaging information calculation section and one of the acceleration sensor or the gyro sensor, and the subunit  76  includes the acceleration sensor or the gyro sensor, the core unit  70  can perform the aforementioned two operations. In this case, according to the present invention, operation data outputted by the imaging information calculation section of the core unit  70  corresponds to first operation data, operation data outputted by the acceleration sensor or the gyro sensor of the subunit  76  corresponds to second operation data, and operation data outputted by the acceleration sensor or the gyro sensor of the core unit  70  corresponds to third operation data. 
     In the present embodiment, image data taken by the image pickup element  743  is analyzed so as to obtain position coordinates and the like of an image of infrared lights from the LED modules  8 L and  8 R, and the core unit  70  generates process result data from the obtained coordinates and the like and transmits the process result data to the game apparatus  3 . However, the core unit  70  may transmit data obtained in another process step to the game apparatus  3 . For example, the core unit  70  transmits to the game apparatus  3  image data taken by the image pickup element  743 , and the CPU  30  may perform the aforementioned analysis so as to obtain process result data. In this case, the image processing circuit  744  can be eliminated from the core unit  70 . Alternatively, the core unit  70  may transmit, to the game apparatus  3 , the image data having been analyzed halfway. For example, the core unit  70  transmits to the game apparatus  3  data indicating a brightness, a position, an area size and the like obtained from the image data, and the CPU  30  may perform the remaining analysis so as to obtain process result data. 
     Although in the present embodiment infrared lights from the two LED modules  8 L and  8 R are used as imaging targets of the imaging information calculation section  74  in the core unit  70 , the imaging target is not restricted thereto. For example, infrared light from one LED module or infrared lights from at least three LED modules provided in the vicinity of the monitor  2  may be used as the imaging target of the imaging information calculation section  74 . Alternatively, the display screen of the monitor  2  or another emitter (room light or the like) can be used as the imaging target of the imaging information calculation section  74 . When the position of the core unit  70  with respect to the display screen is calculated based on the positional relationship between the imaging target and the display screen of the monitor  2 , various emitters can be used as the imaging target of the imaging information calculation section  74 . 
     The aforementioned shapes of the core unit  70  and the subunit  76  are merely examples. Further, the shape, the number, setting position and the like of each of the operation section  72  of the core unit  70  and the operation section  78  of the subunit  76  are merely examples. Needless to say, even when the shape, the number, the setting position and the like of each of the core unit  70 , the subunit  76 , the operation section  72 , and the operation section  78  are different from those described in the embodiment, the present invention can be realized. Further, the imaging information calculation section  74  (light entrance of the imaging information calculation section  74 ) of the core unit  70  may not be positioned on the front surface of the housing  71 . The imaging information calculation section  74  may be provided on another surface at which light can be received from the exterior of the housing  71 . 
     Further, although the speaker  706 , the sound IC  707 , and the amplifier  708  as described above are included in the core unit  70 , any devices at hand capable of outputting a sound may be included in either the subunit  76  or the core unit  70 . 
     Thus, the controller of the present invention allows a player to operate both the core unit  70  and the subunit  76  included therein so as to enjoy a game. For example, the core unit  70  has a function of outputting a signal in accordance with a motion of the unit body including the imaging information calculation section  74  and the accelerator sensor  701 , and the subunit  76  has a function of outputting a signal in accordance with a direction input operation performed by the player. For example, when used is a controller into which the core unit  70  and the subunit  76  are integrated, the whole controller has to be moved so as to output a signal in accordance with the motion of the unit body, thereby exerting some influence on the direction input operation. Further, the integration of the core unit  70  and the subunit  76  causes the opposite influence, that is, flexibility, which is realized by separation between the core unit  70  and the subunit  76 , is substantially reduced. As another example, the core unit  70  may have a function of outputting a signal in accordance with a motion of the unit body including the imaging information calculation section  74  and the acceleration sensor  701 , and the subunit  76  may have a function of outputting a signal in accordance with the motion of the unit body including the acceleration sensor  761 . Therefore, the player can move both hands holding the different units individually so as to make an input. Accordingly, the core unit  70  and the subunit  76  can be separated into a right unit and a left unit as in the case of a conventional controller for the game apparatus, and simultaneously the core unit  70  and the subunit  76  allow the player to freely use his or her right and left hands, thereby providing the player with a new operation, which cannot be performed by the integrated controller. Further, the controller can be operated with substantially enhanced flexibility, thereby providing a player with a game operation having increased reality. 
     The game controller and the game system according to the present invention can realize an operation having increased flexibility, and are useful as a game controller which includes two independent units and is operated by a player holding the two independent units, a game system including the game controller, and the like. 
     While the invention has been described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is understood that numerous other modifications and variations can be devised without departing from the scope of the invention.