GAME CONSOLE

Abstract

A portable, handheld game console includes a main body incorporating a touch-sensitive display screen and a variety of input devices. The input devices can include shoulder buttons located on a peripheral side surface of the main body, as well as input devices located on the main body adjacent the touch-sensitive display screen.

Claims

1-31. (canceled)

32. A handheld electronic gaming device, comprising: a housing; a display screen on a top surface of the housing; a directional input to the left of the display screen; a cross-shaped arrangement of four input buttons to the right of the display screen, wherein the directional input and the cross-shaped arrangement of four input buttons are arranged substantially symmetrically with respect to the display screen; a left shoulder button and a right shoulder button that are symmetrical with respect to the housing; a first speaker that is located towards the left side of the display screen; a second speaker is located towards the right side of the display screen; an audio interface configured to connect to an external audio output device; and image processing circuitry configured to cause three dimensional images to be displayed on the display screen, and the image processing circuitry is configured to cause three dimensional images to be displayed on a second display screen separate from the housing.

33. The handheld electronic gaming device according to claim 32, further comprising a power button on the housing.

34. The handheld electronic gaming device according to claim 32, further comprising an input device to the right of the display screen and between the cross-shaped arrangement of four input buttons and the right shoulder button.

35. The handheld electronic gaming device according to claim 32, further comprising a volume control on a side surface of the housing.

36. The handheld electronic gaming device according to claim 35, wherein the audio interface is on the side surface of the housing.

37. The handheld electronic gaming device according to claim 32, further comprising a game card slot with an opening on a side surface of the housing.

38. The handheld electronic gaming device according to claim 37, further comprising a memory card slot with an opening different from the opening of the game card slot.

39. The handheld electronic gaming device according to claim 37, wherein the game card slot is between the left shoulder button and the right shoulder button.

40. The handheld electronic gaming device according to claim 32, wherein the first speaker, the second speaker, the directional input and the cross-shaped arrangement of four input buttons are located such that when the user holds the gaming device with both hands in order to operate the directional input and the cross-shaped arrangement of four input buttons, the user's hands are not positioned in front of the first speak and the second speaker.

41. The handheld electronic gaming device according to claim 32, wherein the first speaker and the second speaker are located such that when the user holds the gaming device with both hands in order to operate the directional input and the cross-shaped arrangement of four input buttons, the user's hands do not block sounds emanating from the first speaker and the second speaker.

42. The handheld electronic gaming device according to claim 32, further comprising: a rechargeable battery; and a power port for charging the rechargeable battery on a peripheral surface of the housing.

43. A handheld electronic gaming device, comprising: a housing; a display screen on a top surface of the housing and that is centered on the top surface with respect to left and right sides of the housing; a directional input on the top surface of the housing to the left of the display screen; a cross-shaped arrangement of four input buttons on the top surface of the housing to the right of the display screen, wherein the directional input and the cross-shaped arrangement of four input buttons are arranged substantially symmetrically on the top surface of the housing with respect to the display screen; a left shoulder button and a right shoulder button on a side surface of the housing, wherein the left shoulder button and the right shoulder button are arranged symmetrically on the housing; a first speaker that is located to the left of the display screen; a second speaker is located to the right of the display screen; an audio interface configured to connect to an external audio output device; and image processing circuitry configured to cause three dimensional images to be displayed on the display screen, and the image processing circuitry is configured to cause three dimensional images to be displayed on a second display screen separate from the housing.

44. The handheld electronic gaming device according to claim 43, further comprising a power button on the housing.

45. The handheld electronic gaming device according to claim 43, further comprising an input device on the housing to the left of the display screen and between the directional input and the left shoulder button.

46. The handheld electronic gaming device according to claim 43, further comprising an input device on the housing to the right of the display screen and between the cross-shaped arrangement of four input buttons and the right shoulder button.

47. The handheld electronic gaming device according to claim 43, further comprising a volume control on a side surface of the housing.

48. The handheld electronic gaming device according to claim 43, further comprising a memory card slot with an opening between the left shoulder button and the right shoulder button.

49. The handheld electronic gaming device according to claim 43, wherein the first speaker, the second speaker, the directional input and the cross-shaped arrangement of four input buttons are located such that when the user holds the gaming device with both hands in order to operate the directional input and the cross-shaped arrangement of four input buttons, the user's hands are not positioned in front of the first speak and the second speaker.

50. The handheld electronic gaming device according to claim 43, wherein the first speaker and the second speaker are located such that when the user holds the gaming device with both hands in order to operate the directional input and the cross-shaped arrangement of four input buttons, the user's hands do not block sounds emanating from the first speaker and the second speaker.

51. The handheld electronic gaming device according to claim 43, further comprising: a rechargeable battery; and a power port for charging the rechargeable battery on the side surface of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a perspective view of the electronic game and communications device in accordance with an exemplary embodiment of the invention, with the device shown in an open, ready-to-use orientation;

[0018] FIG. 2 is a inverted perspective view of the game device shown in FIG. 1;

[0019] FIG. 3 is a front elevation of the device shown in FIG. 1, but with the game shown in a closed position;

[0020] FIG. 4 is a rear elevation of the device shown in FIG. 3;

[0021] FIG. 5 is a perspective view of a stylus for use with the game device shown in FIGS. 1-4;

[0022] FIG. 6 is a plan view of a game card for use with the game device shown in FIGS. 1-4;

[0023] FIG. 7 is a rear perspective view of the game card shown in FIG. 6;

[0024] FIG. 8 is an enlarged perspective view of a front, right corner of the card shown in FIG. 6;

[0025] FIG. 9 is an external view of a portable game machine according to a further illustrative embodiment of the present invention;

[0026] FIG. 10 is an illustration showing an internal configuration of a portable game machine;

[0027] FIG. 11 is an illustration showing an internal configuration of a GPU 222;

[0028] FIG. 12 is an illustration showing the operation of a portable game machine in an odd-numbered frame;

[0029] FIG. 13 is an illustration showing the operation of the portable game machine in an even-numbered frame;

[0030] FIG. 14 is an illustration showing one example of a virtual three-dimensional game space;

[0031] FIG. 15 is an illustration showing one example of a game screen displayed on a first display screen 11a and a second display screen 212a;

[0032] FIG. 16 is a flowchart showing the operation of an illustrative portable game machine;

[0033] FIG. 17 is a flowchart showing a flow of an odd-numbered frame rendering/displaying process;

[0034] FIG. 18 is a flowchart showing a flow of an even-numbered frame rendering/displaying process;

[0035] FIG. 19 is an illustration showing an original two-dimensional game image generating process to be performed by a two-dimensional image processing unit 37; and

[0036] FIG. 20 is an illustration showing an internal configuration of a GPU 22 according to an exemplary modification of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0037] Referring to FIGS. 1 and 2, in an illustrative embodiment the game device or console 10 includes a main body 12 and a cover body 14 hingedly connected to each other along an upper edge of the main body 12 and a lower edge of the cover body 14 (references herein to terms such as upper and lower and forward and rearward are for ease of understanding and are made relative to an orientation of the game device where the cover body 14 is in an open position and the game is being held by a user in a normal operating position). Hinge elements 16, 18 and 20 on the main body 12 mesh with hinge elements 22 and 24 on the cover body, with a hinge pin (not shown) extending through the aligned hinge elements in conventional fashion. Note that because hinge elements 16, 18 and 20 extend from the upper (or inner) face 26 of the main body 12, the cover body 14 overlies the upper face 26 when the cover body 14 is closed over the main body. When the cover body 14 is in its fully open position, it is substantially parallel to the main body 12 but lies in a substantially parallel, offset plane. The main body 12 also has a lower (or outer) face 28 (FIG. 2) and a peripheral edge 30.

[0038] A first display screen 32 is recessed within the upper face 26 of the main body 12 with dimensions of approximately 2 inches in length and 1 inches in width, yielding a diagonal screen dimension of 3 inches. The screen in the exemplary embodiment is a backlit, color liquid crystal display (LCD). This screen is touch sensitive and may be activated by a stylus, described further herein. A power button 34 is located in the upper left corner of face 26 and is used to turn the game on and off. A cross-shaped directional control button 36 is located adjacent and below the power button 34, and is used for game play control.

[0039] In the upper right corner of the main body 12, there are side-by-side start and select buttons 38, 40, respectively, with X/Y/A/B buttons 42 located adjacent and below the start and select buttons. Buttons 38, 40 and 42 are also used for game play control. A microphone 44 is located below the left edge of screen 32 for use with specially designed games having a microphone feature. A battery recharge indicator LED 46 and a power indicator LED 48 are also located on the upper face 26, adjacent the lower edge thereof, below the right edge of screen 32.

[0040] With reference now especially to FIG. 3, a lower or forward portion 50 of the peripheral edge 30 (closest to the user) is provided with a volume control slide 2 and headphone and microphone connectors 54, 56 on either side of a first game slot 58. Slot 58 is especially designed for larger game cartridges or cards originally designed for use with the assignee's Game Boy Advance game system.

[0041] As best seen in FIG. 2, an upper or rearward portion 60 of the peripheral edge 30 is provided with an external extension connector 62 that permits connection to an AC adapter for recharging the internal battery (not shown), or for operating the game using household power. A second game slot 64 in edge portion 60 is designed for receiving memory or game cards especially designed for this game device. The second game slot 64 is smaller than the first game slot 58, reflecting the different sizes of the game cards. Openings 66, 68 form an elbow-shaped through slot adapted for securing a wrist strap (not shown), thereby enabling the user to secure the game device to the body and thus minimize the potential for losing or misplacing the game. A stylus port or holder, in the form of a blind bore 70 is located adjacent the wrist-strap mount for holding a stylus 71 (FIG. 5) before or after use.

[0042] The stylus 71 is a plastic pencil-shaped device with a rounded tip 73 and is used to activate the touch screen 32.

[0043] A pair of left, right control buttons (or shoulder buttons) 72, 74 are located on the peripheral edge 30, at the corners where the upper portion 60 of the peripheral edge 30 meets the side portions 76, 78 of the peripheral edge. The location of these buttons and the location of previously described buttons 34, 36 and 42 facilitate manipulation game control by the user's thumbs and index fingers when the game is held with two hands in a natural and intuitive manner.

[0044] The lower (or outer) face 28 of the main body is provided with a battery cover 80 (FIG. 2) for accessing a rechargeable battery pack located within the main body.

[0045] The cover body 14 also has an upper (or inner) face 82 (FIG. 1) and a lower (or outer) face 84 (FIG. 2) connected by a peripheral edge 86. The upper face 60 incorporates a second display screen 88 of substantially the same dimensions as screen 32. Screen 88 is also a backlit color LCD. The cover body 14 also incorporates a pair of stereo speakers, with speaker grills 90, 92 located on opposite sides of the screen 88. Dimples or pads 94, 96 may be located above and laterally of screen 88. The dimples may be made of a compressible polymer or other suitable material and serve to dampen engagement of the inner surface 82 of the cover body 14 with the inner surface 26 of the main body 12 when the cover body is closed over the main body.

[0046] As already noted, the game card slot 58 is sized and adapted to receive a conventional game card designed for the by now well known Nintendo Gameboy Advance System. Accordingly, the game card per se for slot 58 does not form any part of this invention and need not be described further.

[0047] The new game or memory card 100 designed especially for use with this game device is shown in FIGS. 6, 7 and 8.

[0048] The game or memory card 100 is preferably of molded plastic construction and has substantially planar upper and lower surfaces 102, 104, respectively, a forward edge 106, rearward edge 108 and side edges 110, 112. The forward end of the upper surface 102 is formed with a rectangular recess 114 in which a plurality of terminal strips 116 are located, extending from a rear wall 118 of the recess to the forward edge 106 of the card. The rearward wall 115 of the recess is substantially perpendicular to the upper and lower surfaces 102, 104 but, as a practical matter, is sloped by no more than about 3 degrees simply to facilitate removal of the card from the mold during manufacture of the card. The terminal strips 116 are parallel to each other and are separated by raised ribs 120 that also extend from the rear wall 118 to the forward edge 106. The free ends 122 of the ribs 120 are chamfered as best seen in FIG. 8 to facilitate sliding entry of the card into the slot 58 in the main body 12. Ribs 120 also protect the terminal strips 116 from contact with the users' hands or other objects. The recess 114 and array of terminal strips 116 are not centered along the forward edge 106 of the card, but rather, are offset laterally toward the side edge 112 for a purpose explained in greater detail below.

[0049] An enlarged radius 124 is formed at forward corner 126 where the side edge 110 meets forward edge 106. A first notch 128 is formed in corner 126, defined by a vertical notch side wall 130, a vertical notch back wall 132 and a flat notch bottom wall 134. The latter is parallel to the upper and lower card surfaces 102, 104, while notch side wall 130 is parallel to side edges 110, 112, and notch back wall is perpendicular to the notch side wall 130 and parallel to the card forward edge 106. The depth of the notch is about half the approximate inch thickness of the card, and the length of the notch is about inch, which in turn, is about half the length of the recess 114. Rearwardly of the notch 128, along the card side edge 110, there is formed a second notch 136 that opens to the side of the card, defined by parallel side walls 140, 142 and a back wall 144. Side walls 140, 142 are parallel to forward and rearward card edges 106, 108 while back wall 144 is parallel to card side edges 110, 112. An angled surface 145 connects back wall 144 to the edge 110. Here again, the depth of the notch is about half the thickness of the card, and the length of the notch is about inch.

[0050] Notches 128 and 136 cooperate with components of a push-push mechanism inside the game slot 64 to provide controlled, spring-loaded movement of the game card during insertion and ejection.

[0051] The opposite forward corner 146 of the card where side edge 112 meets forward edge 106 is defined by a smaller radius than radius 124. Note that the forward surfaces 148, 150 of the card on either side of the recess 114 are also chamfered to substantially the same degree as the chamfer on ribs 120.

[0052] Side edge 112 is stepped along its entire length in the upper plane of the card only, as defined by horizontal shoulder 152 that is parallel to upper and lower surfaces 102, 104 and a recessed edge portion shoulder 154 that is parallel to the side edges 110, 112. This shoulder insures correct orientation of the card when inserted into a game console slot.

[0053] The rearward edge 108 of the card is substantially uniform in profile from side edge 110 to side edge 112, with both rearward corners 156, 158 rounded by a radii similar to the radius at corner 146.

[0054] The dimensions of the card are matched to the game machine entry slot, and in the exemplary embodiment, the card 100 is substantially square, with a length dimension (front-to-back) of 1, and a width dimension (side-to-side) of 1.

[0055] FIG. 9 is a further illustrative embodiment of a portable game machine 200. As with the prior embodiment, a further exemplary game machine physically including two display screens with one of the display screens being covered with a touch panel is exemplarily described. In the present embodiment, a game image is displayed on at least the display screen covered with the touch panel. Also, a non-portable video game machine, an arcade game machine, a portable terminal, a cellular phone, or a personal computer may be used as the game machine.

[0056] FIG. 9 is an external view of the portable game machine 200. As shown in FIG. 9, the portable game machine 200 includes two display screens, that is, a first display screen 211a and a second display screen 212a. The surface of the second display screen 212a is covered with a touch panel 213. Also, to the right of the second display screen 212a, the game machine includes an A button 214a, a B button 214b, and an R switch 214c, which are operable by the right hand of the player, and a loudspeaker 215 for producing game music. To the left of the second display screen 212a, the game machine includes a cross key 214d, a start button 214e, a select button 214f, and an L switch 214g, which are operable by the left hand of the player. Also, the portable game machine 200 includes a removable stylus 216 for input to the touch panel 213. Furthermore, the portable game machine 200 has, removably inserted therein, a cartridge 217, which is a storage medium having stored therein a game program of the illustrative embodiments. Note that, in the present embodiment, the touch panel 213 is exemplarily provided as an input unit, but this does not restrict the present invention.

[0057] FIG. 10 is a block diagram showing the portable game machine 200. It should be understood that the hardware/software and operational description which follows is applicable to the illustrative embodiment shown in FIGS. 1-8 as well as the illustrative embodiment shown in FIG. 9. As shown in FIG. 10, the portable game machine 200 includes a CPU (central processing unit) 223, which is an example of a computer for executing the game program, and other components. The CPU 223 includes a work RAM (working storage unit) 224, a GPU (graphic processing unit) 222, and a peripheral circuit I/F (interface) 225 that are electrically connected to one another. The work RAM 224 is a memory for temporarily storing, for example, the game program to be executed by the CPU 223 and calculation results of the CPU 223. The GPU 222 uses, in response to an instruction from the CPU 223, a VRAM 221 to generate a game image for display output to a first LCD (liquid crystal display unit) 211 and a second LCD 212, and causes the generated game image to be displayed on the first display screen 211a of the first LCD 211 and the second display screen 212a of the second LCD 212. The peripheral circuit I/F 225 is a circuit for transmitting and receiving data between external input/output units, such as the touch panel 213, the operation keys 214, and the loudspeaker 215, and the CPU 223. The touch panel 213 (including a device driver for the touch panel) outputs coordinate data corresponding to a position input (specified) with the stylus 216.

[0058] Furthermore, the CPU 223 is electrically connected to the external memory I/F 226, in which the cartridge 217 is inserted. The cartridge 217 is a storage medium for storing the game program and, specifically, includes a program ROM 217a for storing the game program and a backup RAM 217b for rewritably storing backup data. The game program stored in the program ROM 217a of the cartridge 217 is loaded to the work RAM 224 and is then executed by the CPU 223. In the present embodiment, an exemplary case is described in which the game program is supplied from an external storage medium to the portable game machine 200. However, the game program may be stored in a non-volatile memory incorporated in advance in the portable game machine 200, or may be supplied to the portable game machine 200 via a wired or wireless communication circuit.

[0059] FIG. 11 is a block diagram of the GPU 222. The GPU 222 includes two image processing units, that is, a three-dimensional image processing unit 231 and a two-dimensional image processing unit 237. The three-dimensional image processing unit 231 includes a geometry engine for calculating each vertex of a three-dimensional model based on three-dimensional model data and a rendering engine for generating a game image from the three-dimensional model disposed on a virtual three-dimensional game space. The two-dimensional image processing unit 237 includes a 2D rendering engine for generating a game image based on two-dimensional image data representing characters and two-dimensional image data representing backgrounds. More specifically, the two-dimensional image processing unit 237 disposes a two-dimensional image representing a character on a virtual screen called a sprite and a two-dimensional image representing a background on a virtual screen called a screen, and then synthesizes these virtual screens to generate a game image to be eventually displayed.

[0060] The three-dimensional image processing unit 231 is connected to the 3D line buffer 232. The 3D line buffer 232 is a buffer memory for temporarily retaining image data for one scanning line of the first LCD 211 (or the second LCD 212). The image data generated by the three-dimensional image processing unit 231 is stored in this 3D line buffer 232 sequentially by one line.

[0061] The 3D line buffer 232 is connected to a capture circuit 233 and an LCD selector (SEL LCD) 235. The capture circuit 233 sequentially reads image data for one line stored in the 3D line buffer 232 and then sequentially stores the read image data in the VRAM 221, which will be described further below, thereby capturing the game image generated by the three-dimensional image processing unit 231.

[0062] The capture circuit 233 is connected to a VRAM selector (SEL VRAM) 234. The VRAM 221 is provided with two VRAMs, that is, a first VRAM 221a and a second VRAM 221b. Instead of these two first and second VRAMs 221a and 221b, a single VRAM may be used with its two different storage areas being used as the first VRAM 221a and the second VRAM 221b. The VRAM selector 234 switches an output destination of the capture circuit 233 between the first VRAM 221a and the second VRAM 221b.

[0063] The first VRAM 221a and the second VRAM 221b are connected to a VRAM selector (SEL VRAM) 236. The VRAM selector 236 switches a source of data to the two-dimensional image processing unit 237 between the first VRAM 21a and the second VRAM 221b.

[0064] The two-dimensional image processing unit 237 is connected to a 2D line buffer 238. As with the 3D line buffer 232, the 2D line buffer 238 is a buffer memory for temporarily retaining image data for one scanning line of the second LCD 212. The image data generated by the two-dimensional image processing unit 237 is stored in this 2D line buffer 238 sequentially by one line.

[0065] The 2D line buffer 238 is connected to an LCD selector 235. The LCD selector 235 switches an output destination of the 3D line buffer 232 between the first LCD 211 and the second LCD 212, and an output destination of the 2D line buffer 238 between the first LCD 211 and the second LCD 212. In the present embodiment, the LCD selector 235 performs control such that, when the output of the 3D line buffer 232 is supplied to the first LCD 11, the output of the 2D line buffer 38 is supplied to the second LCD 212, and when the output of the 3D line buffer 232 is supplied to the second LCD 212, the output of the 2D line buffer 238 is supplied to the first LCD 211.

[0066] The portable game machine 200 has the above-described structure. Generally, the game image generated by the three-dimensional image processing unit 231 is supplied via the 3D line buffer 232 and the LCD selector 235 to the first LCD 211, while the game image generated by the two-dimensional image processing unit 237 is supplied via the 2D line buffer 238 and the LCD selector 235 to the second LCD 212. As a result, the three-dimensional game image generated by the three-dimensional image processing unit 231 is displayed on the first display screen 211a, while the two-dimensional game image generated by the two-dimensional image processing unit 237 is displayed on the second display screen 212a. However, the present embodiment has a feature in which the above-structured portable game machine 200 is used to display different three-dimensional game images on two display screens, that is, the first display screen 211a and the second display screen 212a. Hereinafter, the operation of the portable game machine 200 according to the present embodiment is described.

[0067] The portable game machine 200 alternately performs operations with periods of one frame. Hereinafter, the operation of the portable game machine 200 is described as being divided into a process in an odd-numbered frame and a process in an even-numbered frame. Note that the odd-numbered frame and the even-numbered frame are merely so called for convenience. In other words, if one frame is assumed to be an odd-numbered frame, frames before and after that frames are even-numbered frames. Conversely, if one frame is assumed to be an even-numbered frame, frames before and after that frames are odd-numbered frames.

[0068] FIG. 12 is an illustration showing the operation of the portable game machine 200 in an odd-numbered frame. As shown in FIG. 12, in the odd-numbered frame, the game image generated by the three-dimensional image processing unit 231 is supplied via the 3D line buffer 232 to the first LCD 211. Also, the output from the capture circuit 233 is supplied to the first VRAM 221a. That is, the game image supplied in this frame to the first LCD 211 is captured by the capture circuit 233, and is then stored in the first VRAM 221a. Also, the two-dimensional image processing unit 237 reads the game image stored in the second VRAM 221b (the game image captured in the immediately-preceding even-numbered frame by the capture circuit 233, as will be described further below). This game image is, as will be described further below, identical to the game image supplied in the immediately-preceding even-numbered frame to the second LCD 212. The game image read by the two-dimensional image processing unit 237 is supplied via the 2D line buffer 238 to the second LCD 212. As such, in the odd-numbered frame, the game image generated in this frame by the three-dimensional image processing unit 231 is supplied to the first LCD 211, while the game image generated in the immediately-preceding even-numbered frame by the three-dimensional image processing unit 231 is supplied to the second LCD 212.

[0069] FIG. 13 is an illustration showing the operation of the portable game machine 200 in an even-numbered frame. As shown in FIG. 13, in the even-numbered frame, the game image generated by the three-dimensional image processing unit 231 is supplied via the 3D line buffer 232 to the second LCD 212. Also, the output from the capture circuit 233 is supplied to the second VRAM 221b. That is, the game image supplied in this frame to the second LCD 212 is captured by the capture circuit 233, and is then stored in the second VRAM 221b. Also, the two-dimensional image processing unit 237 reads the game image stored in the first VRAM 221a (the game image captured in the immediately-preceding odd-numbered frame by the capture circuit 233, as will be described further below). This game image is identical to the game image supplied in the immediately-preceding odd-numbered frame to the first LCD 211. The game image read by the two-dimensional image processing unit 237 is supplied via the 2D line buffer 238 to the first LCD 211. As such, in the even-numbered frame, the game image generated in this frame by the three-dimensional image processing unit 231 is supplied to the second LCD 212, while the game image generated in the immediately-preceding odd-numbered frame by the three-dimensional image processing unit 231 is supplied to the first LCD 211.

[0070] In the present embodiment, the three-dimensional image processing unit 231 generates a game image representing a state in a virtual three-dimensional game space captured by virtual cameras different for odd-numbered and even-numbered frames. FIG. 14 is an illustration showing one example of the virtual three-dimensional game space. In FIG. 14, this virtual three-dimensional game space has disposed therein a first enemy character and a second enemy character as well as two virtual cameras, that is, a first virtual camera and a second virtual camera. In each odd-numbered frame, the three-dimensional image processing unit 231 generates a game image representing a state in a virtual three-dimensional game space captured by the first virtual camera. In each even-numbered frame, the three-dimensional image processing unit 231 generates a game image representing a state in a virtual three-dimensional game space captured by the second virtual camera. Alternatively, the three-dimensional image processing unit 231 may be provided with a plurality of virtual three-dimensional game spaces for generating, for odd-numbered and even-numbered frame, game images representing different states in the virtual three-dimensional game space.

[0071] Examples of the game screen displayed on the first display screen 211a and the second display screen 212a based on the above-described operation of the portable game machine 200 are illustrated in FIG. 15. As can be seen from FIG. 15, in each odd-numbered frame, a game image generated in that frame by the three-dimensional image processing unit 231 (such an image is hereinafter referred to as a real-time image) is displayed on the first display screen 211a, while a game image generated in the immediately-preceding frame by the three-dimensional image processing unit 231 then captured by the capture circuit 233 (such an image is hereinafter referred to as a captured image) is displayed on the second display screen 212a. On the other hand, in each even-numbered frame, a game image (real-time image) generated in that frame by the three-dimensional image processing unit 231 is displayed on the second display screen 212a, while a game image (captured image) generated in the immediately-preceding frame by the three-dimensional image processing unit 231 and then captured by the capture circuit 233 is displayed on the first display screen 211a.

[0072] As such, in the present embodiment, a real-time image and a captured image are alternately displayed on the first display screen 11a and the second display screen 212a. Then, on the first display screen 211a, a game image representing the state of the virtual three-dimensional game space captured by the first virtual camera is displayed, while on the second display screen 212a, a game image representing the state of the virtual three-dimensional game space captured by the second virtual camera is displayed. Note that, as evident from FIG. 15, game images are displayed for each frame on the first and second display screens 211a and 212a, thereby preventing flicker on the display screens.

[0073] With reference to FIGS. 16 through 18, the operation of the portable game machine 200 is described in more detail. Here, steps S11 through S17, S19 through S21, and S23 shown in FIG. 16 are described as process steps to be performed in the CPU 223 based on the game program stored in the program ROM 217a of the cartridge 217. However, any of these process steps may be achieved only by hardware.

[0074] In FIG. 16, the CPU 223 generates a virtual three-dimensional game space (S11). Specifically, in this process, world coordinates of each vertex of three-dimensional models, such as a player character and enemy characters, formed by a plurality of polygons are set at initial values. Next, based on operation key data output from the operation keys 214, the CPU 223 updates the coordinates of the player character in the virtual three-dimensional game space (S12), and then updates the coordinates of each enemy character in the virtual three-dimensional game space based on a predetermined algorithm (S13).

[0075] The CPU 223 then determines whether the current frame is an odd-numbered frame (S14).

[0076] When the current frame is an odd-numbered frame, the CPU 223 allocates the first LCD 211 as the output destination of the 3D line buffer 232 and the second LCD 212 as the output destination of the 2D line buffer 238 (S15). Furthermore, the CPU 223 allocates the first VRAM 221a as the output destination of the capture circuit 233 (S16), and the second VRAM 221b to the two-dimensional image processing unit 237 (S17). Thereafter, an odd-numbered frame rendering/displaying process (S18) is performed, and then the procedure goes to step S23. Details of the odd-numbered frame rendering/displaying process are described further below.

[0077] On the other hand, when the current frame is an even-numbered frame, the CPU 223 allocates the second LCD 212 as the output destination of the 3D line buffer 232 and the first LCD 211 as the output destination of the 2D line buffer 238 (S19). Furthermore, the CPU 223 allocates the second VRAM 221b as the output destination of the capture circuit (S20) and the first VRAM 221a to the two-dimensional image processing unit 237 (S21). Thereafter, an even-numbered frame rendering/displaying process (S22) is performed, and then the procedure goes to step S23. Details of the even-numbered frame rendering/displaying process are described further below.

[0078] In step S23, the CPU 223 determines whether the game is over. If the game continues, the procedure returns to step S12. If the game is over, the procedure ends.

[0079] Next, the details of the odd-numbered frame rendering/displaying process are described with reference to FIG. 17. The odd-numbered frame rendering/displaying process is performed by the GPU 222 based on instructions from the CPU 223.

[0080] First, the geometry engine of the three-dimensional image processing unit 231 converts vertex coordinates (in the world coordinate system) of each polygon in the virtual three-dimensional game space to the two-dimensional projection coordinate system (S32). When conversion of the vertex coordinates of each polygon is completed, an instruction for starting a display process is issued from the GPU 222 to the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional image processing unit (S33). Upon reception of this instruction, the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional processing unit concurrently perform their respective processes.

[0081] Upon reception of the display process starting instruction, the rendering engine of the three-dimensional image processing unit 231 generates image data for the first one line through a rendering process based on the results of conversions of the vertex coordinates of each polygon, and then stores the generated image data in the 3D line buffer 232 (S34). Then, the image data for one line stored in this 3D line buffer 232 is supplied to the first LCD 211, and is then displayed on the first display screen 211a (S35). Also, the image data for one line stored in the 3D line buffer 232 is stored in a predetermined area of the first VRAM 221a by the capture circuit 233 (S36). Then, after waiting for an H blank timing (horizontal blanking period) in order to establish horizontal synchronization (S37), the rendering engine performs a process similar to the above for the next line. That is, the rendering engine of the three-dimensional image processing unit 231 generates image data for the next one line, and then stores the generated image data in the 3D line buffer 232 (S34). Thereafter, until all lines have been completely processed (that is, until the entire screen has been completely processed), processes of steps S34 through S37 are repeated.

[0082] Upon reception of the display process starting instruction, the 2D rendering engine of the two-dimensional image processing unit 237 reads image data for the first one line of the game image stored in the second VRAM 221b, and then stores the read image data in the 2D line buffer 238 (S39). Then, the image data for one line stored in this 2D line buffer 238 is supplied to the second LCD 212, and is then displayed on the second display screen 212a (S40). Then, after waiting for an H blank timing (horizontal blanking period) in order to establish horizontal synchronization (S41), the 2D rendering engine performs a process similar to the above. That is, the 2D rendering engine of the two-dimensional image processing unit 237 reads image data for the next one line from the second VRAM 221b, and then stores the read image data in the 2D line buffer 238 (S39). Thereafter, until all lines have been completely processed (that is, until the entire screen has been completely processed), processes of steps S39 through S41 are repeated.

[0083] When all lines have been completely processed by the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional image processing unit 237, the odd-numbered frame rendering/displaying process ends.

[0084] Next, the details of the even-numbered frame rendering/displaying process are described with reference to FIG. 18. This even-numbered rendering/displaying process is performed by the GPU 222 based on instructions from the CPU 223.

[0085] First, the geometry engine of the three-dimensional image processing unit 231 converts vertex coordinates (in the world coordinate system) of each polygon in the virtual three-dimensional game space to the camera coordinate system (S51). Furthermore, the geometry engine of the three-dimensional image processing unit 231 converts these vertex coordinates (in the camera coordinate system) to the two-dimensional projection coordinate system (S52). When conversion of the vertex coordinates of each polygon is completed, an instruction for starting a display process is issued from the GPU 222 to the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional image processing unit (S53). Upon reception of this instruction, the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional processing unit concurrently perform their respective processes.

[0086] Upon reception of the display process starting instruction, the rendering engine of the three-dimensional image processing unit 231 generates image data for the first one line through a rendering process based on the results of conversions of the vertex coordinates of each polygon, and then stores the generated image data in the 3D line buffer 232 (S54). Then, the image data for one line stored in this 3D line buffer 232 is supplied to the second LCD 212, and is then displayed on the second display screen 212a (S55). Also, the image data for one line stored in the 3D line buffer 232 is stored in a predetermined area of the second VRAM 221b by the capture circuit 233 (S56). Then, after waiting for an H blank timing (horizontal blanking period) in order to establish horizontal synchronization (S57), the rendering engine performs a process similar to the above for the next line. That is, the rendering engine of the three-dimensional image processing unit 231 generates image data for the next one line, and then stores the generated image data in the 3D line buffer 232 (S54). Thereafter, until all lines have been completely processed (that is, until the entire screen has been completely processed), processes of steps S54 through S7 are repeated.

[0087] Upon reception of the display process starting instruction, the 2D rendering engine of the two-dimensional image processing unit 237 reads image data for the first one line of the game image stored in the first VRAM 221a, and then stores the read image data in the 2D line buffer 238 (S59). Then, the image data for one line stored in this 2D line buffer 238 is supplied to the first LCD 211, and is then displayed on the first display screen 211a (S60). Then, after waiting for an H blank timing (horizontal blanking period) in order to establish horizontal synchronization (S61), the 2D rendering engine performs a process similar to the above. That is, the 2D rendering engine of the two-dimensional image processing unit 237 reads image data for the next one line from the first VRAM 221a, and then stores the read image data in the 2D line buffer 238 (S59). Thereafter, until all lines have been completely processed (that is, until the entire screen has been completely processed), processes of steps S59 through S61 are repeated.

[0088] When all lines have been completely processed by the rendering engine of the three-dimensional image processing unit 231 and the 2D rendering engine of the two-dimensional image processing unit 237, the even-numbered frame rendering/displaying process ends.

[0089] As described above, according to the portable game machine 200 of the present embodiment, by using the single three-dimensional image processing unit 231, different three-dimensional game images can be simultaneously displayed on the first LCD 211 and the second LCD 212 without flicker on the display screens.

[0090] As described above, when generating a normal two-dimensional game image, the two-dimensional image processing unit 237 disposes a two-dimensional image representing a character on the virtual screen called a sprite and a two-dimensional image representing a background on the virtual screen called a screen, and then synthesizes these virtual screens to generate a game image to be eventually displayed. There might be the case where a plurality of screens are present. FIG. 19 shows an example in which five virtual screens, that is, a sprite and screens 0 through 3, are synthesized to form a two-dimensional game image. As an exemplary modification of the present embodiment, any two of these virtual screens can be used in place of the first VRAM 221a and the second VRAM 221b. The structure of the portable game machine 200 in that case is exemplarily shown in FIG. 20. In the example of FIG. 20, a sprite area 221c and a screen area 221d are used in place of the first VRAM 221a and the second VRAM 221b. Hereinafter, the operation in the exemplary modification is briefly described.

[0091] The capture circuit 233 stores the game image captured in each odd-numbered frame in the sprite area 221c of the VRAM 221 and the game image captured in each even-numbered frame in the screen area 221d of the VRAM 221. When generating a normal two-dimensional game image, the two-dimensional image processing unit 237 generates a two-dimensional game image formed by synthesizing the sprite and the screen and then outputs the generated image to the 2D line buffer 238. In the exemplary modification, however, in each odd-numbered frame, the two-dimensional image processing unit 237 generates a game image formed of only the screen, and then outputs the generated game image via the 2D line buffer 238 to the second LCD 212. In each even-numbered frame, the two-dimensional image processing unit 237 generates a game image formed of only the sprite, and then outputs the generated game image via the 2D line buffer 238 to the first LCD 211. As a result, game images similar to those shown in FIG. 15 are displayed on the first display screen 211a and the second display screen 212a.

[0092] As such, selecting a desired virtual screen from a plurality of virtual screens for display is a function originally provided to the two-dimensional image processing unit 237. Therefore, no special function has to be added to the two-dimensional image processing unit. Also, an additional storage area for temporarily storing the game image captured by the capture circuit 233 is not required, thereby suppressing cost required for the portable game machine 200.

[0093] As one embodiment of the present invention, the portable game machine having a hardware structure as shown in FIGS. 10 and 11 has been described. However, the present invention is applied not only to the portable game machine having such a hardware structure, but to the one having the above hardware structure achieved by the CPU and software. Also, the portable game machine according to the present embodiment can be emulated by a computer system, such as a personal computer or a portable information terminal. In this case, a game program that causes the computer system to achieve each hardware function of the portable game machine according to the present embodiment is supplied to the computer system. With this, the present invention can be applied also to a general-purpose computer system.

[0094] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.