Abstract:
A compact game controller incorporates an efficient and compact force feedback mechanism. Forces are generated at one of the controls of the controller in reaction to an action in a video game. The type of controller that can be held with two hands is limited in terms of size and internal space and in wireless versions is limited in terms of battery power. Efficient power consumption in the controller enables considerable usage time between battery replacement or recharging in wireless versions. The force feedback mechanism incorporates a double reduction gear system with a unique geometry which enables usage of a compact and energy efficient motor. The efficient force feedback mechanism and assembly can therefore be packaged within a compact ergonomic controller.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/806,396 filed Jun. 30, 2006 entitled “VIDEO GAME CONTROLLER WITH COMPACT AND EFFICIENT FORCE FEEDBACK MECHANISM” to David Neil McVicar et al. This application is incorporated in its entirety by reference as if fully set forth herein. 
    
    
     FIELD OF THE INVENTION 
     The present application is generally related to pointing devices, and specifically to a game controller that incorporates a mini joystick with force feedback. 
     BACKGROUND OF THE INVENTION 
     Many pointing devices incorporate a force feedback feature. Such devices are commonly used in an interactive system which typically displays a visual environment to a user on a display screen. The user can interact with the displayed environment to play a game through the use of a user manipulable object or user interface device, such as a joystick, joypad button controller, mouse, trackball, stylus and tablet, or the like. The interface device is connected to the computer system controlling the displayed environment. The computer updates the simulation or game in response to the user&#39;s manipulation of the user manipulable object, and provides feedback to the user. 
     Typically, motors or other actuators are coupled to the user manipulable object and are controlled by the computer system. Position sensors monitor the position of the user manipulable object and provide the measurement data to the computer system, which processes the data. Based on the data, the computer system generates control signals for controlling the motors to produce feedback forces to the user manipulable object, thereby conveying physical sensations in addition to visual stimulation to the user. 
     There are many challenges to incorporating force feedback into a small handheld game controller such as the type currently used with the various versions of the Sony PlayStation®, Microsoft Xbox® or the like. Among the greatest challenges are size, power, and weight constraints. Corded USB controllers are limited to the power supplied via the USB connection, which is about 500 milliamps. Cordless controllers rely on battery power and many force feedback systems consume a relatively large amount of power that would consume the battery life in relatively short time frame. 
     SUMMARY OF INVENTION 
     A compact game controller incorporates an efficient and compact force feedback mechanism. Forces are generated at one of the controls of the controller in reaction to an action in a video game. The type of controller that can be held with two hands is limited in terms of size and internal space and in wireless versions is limited in terms of battery power. Efficient power consumption in the controller enables considerable usage time between battery replacement or recharging in wireless versions. The force feedback mechanism incorporates a double reduction gear system with a unique geometry which enables usage of a compact and energy efficient motor. The efficient force feedback mechanism and assembly can therefore be packaged within a compact ergonomic controller. 
     One aspect of the present invention involves a method of providing force feedback in a game controller. The method comprises providing a motor assembly and a pinion gear on the shaft of the motor. The motor is located in a portion of the controller that is held within a hand during controller usage. The method also comprises converting the rotating force at the first pinion gear of the motor assembly into a feedback force produced as a function of a game. The feedback force is exerted upon a position manipulation device controlled by a thumb of the hand in which the portion of the controller is held. 
     Another aspect of the present invention relates to a game controller that comprises a body with a first and a second lobe, wherein a user of the controller may grip the first lobe with a first hand and the second lobe with a second hand. The controller also comprises a printed circuit board within the body that includes circuitry that operates the controller. A first set of controls accessible to the first hand and a second set of controls is accessible to the second hand. One of the first or second set of controls includes a force feedback mechanism that comprises a user manipulable object located on a first side of the printed circuit board and an actuator located on a second side of the printed circuit board. The actuator drives the user manipulable object in rotation around an axis. A gear system is coupled between the actuator and the user manipulable object and provides a gear reduction from the actuator to the user manipulable object. The gear system includes at least one annular gear which includes teeth on a concave side engaging teeth of a pinion for driving the annular gear. The gear system comprises a double reduction gear system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a top view of a prior art controller  10  with the top removed. 
         FIG. 1B  is an elevation of electromagnetic drive  14 A of prior art controller  10  shown in  FIG. 1A . 
         FIG. 2  is a perspective view of controller  100 , an embodiment of the present invention. 
         FIG. 3  is perspective view of some components of controller  100 . 
         FIG. 4  is a perspective view of assembly  102  that incorporates a force feedback mechanism. 
         FIG. 5  is an exploded view of assembly  102 . 
         FIG. 6  is a perspective view of thumb cap  136  in 3 positions as it is rotated about a left-right axis. 
         FIG. 7  is a perspective view of thumb cap  136  in 3 positions as it is rotated about a front-back axis. 
         FIG. 8  is a cut away view illustrating assembly  102  within the body of controller  100 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The current game controllers used with the various versions of the Sony PlayStation®, Microsoft Xbox® or other game systems have multiple sets of controls in one small form factor. These controllers are held with two hands and there are typically two different independent systems to control the action for each hand. In one example controller, there is a directional pad and a joystick available for the left hand, and a joystick and joypad (group of buttons) available for the right hand. A user may choose to play with whatever combination of controls he chooses. In addition, the controller is ergonomically shaped so that each hand can wrap around the controller and so that triggers can be pulled with the index finger of each hand. This requires a lobe for the palm of each hand to wrap around and grip. In wireless versions batteries must also be accommodated. Thus, there are space constraints not otherwise present in a stand alone joystick. 
     In many games, force feedback adds a new dimension to the experience. In particular, driving or other simulation type games that mimic situations with real world gravitational forces that a user is familiar with will enhance the user experience. For instance, gravitational forces acting on a vehicle as it corners or changes velocity can be simulated with the controller by providing resistance to the user&#39;s input at the controller. In the case of a joystick, the force feedback can make the joystick easier or more difficult to move in a particular direction based upon the action taking place in the game. 
       FIG. 1A  shows a prior game controller  10  that provides force feedback to directional pad  12  with a pair of electromagnetic drives  14 A and  14 B. As can be seen in the figure, the directional pad  12  and the associated electromagnetic drives  14  take up a very large portion of the overall controller  10 . As a rough approximation, directional pad  12  and the associated electromagnetic drives  14  occupy the left half of the controller while circuit board  16  occupies the right half of the controller. Above the circuit board, on the right side, are a group of game control buttons (not shown). Triggers (not shown) are also present on the underside of the controller. Thus, not including the triggers, controller  10  has two sets of game controls: the directional pad  12  on the left; and the joypad buttons on the right. 
     Each electromagnetic drive  14 (A or B) has two electromagnetic coils  18 . As can be seen in  FIG. 1B , coil  18 A is on the left and coil  18 B is on the right. Between the coils is a member that is driven based on the field generated by the coils. The member is coupled to the directional pad  12  and the force produced at the member by the coils is transmitted to pad  12 . Position sensor  22  detects the position of the member. The controller  10  utilizes a direct coupled electromagnetic drive to provide force feedback to the directional pad. By direct coupled, it is meant that the force produced at the member is coupled to the directional pad without usage of a gear system. While this electromagnetic drive produces relatively fluid feedback free from cogging problems that may be present in a direct drive motor or even a single reduction motor, the electromagnetic drives are large, heavy, and very power hungry. Each axis is controlled by a drive, and each drive requires about 300 mA at 4V. This power requirement renders it impractical for wireless solutions that must depend upon battery power of the controller. The batteries would be consumed in an unacceptably short time with such a system. In fact, with only 500 mA available from a USB connection, this solution is problematic even in a corded controller. In a dual axis force feedback system the 600 mA of current exceeds the 500 mA maximum of the USB standard. Furthermore, the electromagnetic drives are significantly more expensive than the solution provided by the present invention, which will be described with reference to  FIGS. 2-8 . 
       FIG. 2  illustrates game controller  100 , an embodiment of the present invention. Controller  100  comprises a body  106 . Both controller  100  and body  106  are meant to be held with two hands when playing a game and comprise a left lobe  10  and right lobe  112 . A player grips each of the lobes and then can manipulate the left set of controls  104  and the right set of controls, 108  with a thumb of each hand, and can pull a trigger  130  (not shown) with another finger such as an index finger. Each set of controls includes two or more different types of controls. The various types include the aforementioned directional pad, game control buttons also referred to as a joypad, and a thumb cap/joystick. 
       FIG. 3  illustrates a main printed circuit board  120  of the controller. Mounted on a first side, which can be referred to as the top side as it is adjacent the top of the controller, is a mini joystick  122 . In some preferred embodiments, motor  126  is mounted on the opposite side of the main circuit board  120 . On a shaft of motor  126  is a pinion  128 . One trigger  130  is also shown. 
       FIG. 4  is a perspective view, and  FIG. 5  is an exploded view of assembly  102  of controller  100 . Assembly  102  comprises a printed circuit board, which may be the main printed circuit board  120  or any other separate or additional printed circuit board. It also comprises motor  126 , pinion  128 , double reduction gear  132 , which itself comprises an intermediate pinion  133 , annular sector gear  134 , mini joystick thumb cap  136 , and joystick gimbal/potentiometer mechanism  138 . As best seen in  FIG. 5 , sub frame  140  has a shaft about which double reduction gear  132  rotates. Sub frame  140  also has a shaft about which annular sector gear  134  pivots. The sub frame extends through the circuit board from the top side of the circuit board to the bottom side, where the motor  126  mounts to the sub frame. In the particular embodiment illustrated, a cylindrical protrusion surrounding the output shaft fits within a circular hole of the sub frame. This assembly allows the motor to be placed where it can best be accommodated, on the underside of the main circuit board. As mentioned previously, the circuit board need not necessarily be the main circuit board but may be an auxiliary circuit board. In some embodiments, the motor extends into the lobes of the controller. In certain embodiments where a relatively large amount of torque and motor are required in comparison to the body size the body of controller  100 , the body may include a slight protrusion at the underside to accommodate the motor. 
     Torque produced by the gear system is multiplied by the combination of the various gears. This enables usage of a relatively small motor in order to produce a desired torque upon thumb cap  136 . Given that wireless embodiments of controller  100  with long battery life and play time are important, a smaller and more efficient motor is desirable. Furthermore, the smaller motor, and compact geometry of assembly  102  in general, allow for a smaller overall controller. As mentioned in the background, prior art controller  10  is rather large and heavy. This is likely a result of the rather large electromagnetic drive system. Furthermore, on a per axis basis, at 4 volts the prior art force feedback system draws 300 milliamps, whereas at the same voltage the force feedback system of assembly  102  draws only 50 milliamps. Thus the force feedback system of the present invention consumes about one sixth the power of the prior system: about 0.2 watts vs. 1.2 watts. In embodiments where the force feedback is provided on both the left-right and the front-back axes, this consumption difference is even more important. This is not only the case for wireless embodiments, but also for embodiments drawing power from a USB connection, which is specified to provide a maximum of 2.5 watts. 
     The ratio of the various gears in combination with the annular sector gear allows for a very compact assembly. Both the compact gear system and the compact motor make possible a smaller and lighter controller. This is an important advantage in a very competitive market where bulky controllers are not commercially successful. 
     One problem that is present in a direct coupled solution and to a lesser extent in single reduction gearing systems is known as “cogging.” The cogging occurs because the action of the motor produces a somewhat jerky or coarse feeling as the motor turns, which is transmitted to the user and makes the force feedback and the overall controller feel jerky or otherwise poorly actuated. This is, of course, undesirable in a game controller, and the double reduction gear system of the preferred embodiments reduces this to an un-noticeable level in addition to providing a compact and efficient solution for providing force feedback within a game controller. 
     For further information on the operation and geometry of a double reduction gear system, please refer to U.S. Pat. No. 6,573,885 to McVicar, which is hereby incorporated by reference in its entirety. 
       FIG. 6  illustrates the movement of assembly  102  along the left-right axis. Intermediate pinion  133  meshes with the teeth on the concave portion  135  of annular sector gear  134 . As the annular sector gear  134  and thumb cap  136  pivots, concave portion  135  travels from one end of the sector to another. A full size gear of the same diameter and/or ratio would be significantly larger and impractical for inclusion in a small controller. 
       FIG. 7  illustrates the movement of assembly  102  along the front-back axis. As no feedback is provided along this axis the gear system is stationary. Although single axis feedback has been illustrated in the pictured embodiments, other embodiments may include dual axis feedback. 
       FIG. 8  is a cut-away view of controller  100 . Assembly  102  is shown actuating one of the controls of the left lobe  110  of the controller. This feedback may, however, be provided at the left or right side controls. Although in the embodiment shown the motor is directly under the gimbal/potentiometer mechanism  138 , in other embodiments it extends outside of the footprint towards or into the lobes. 
     Although the various aspects of the present invention have been described with respect to exemplary embodiments thereof, it will be understood that the present invention is entitled to protection within the full scope of the appended claims.