Abstract:
Systems and methods involving reconfigurable rotating masses are disclosed. One embodiment may take the form of a system having a motor and coupled weights attached to the motor. Operation of the motor rotates the coupled weights and the weights are dynamically reconfigurable to change the location of the center of mass relative to an axis of rotation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to U.S. patent application Ser. No. 13/437,903, filed Apr. 2, 2012 and titled “Protecting an Electronic Device” and U.S. patent application Ser. No. 13/234,324, filed Sep. 16, 2011 and titled “Protective Mechanism for an Electronic Device,” the disclosures of which are hereby incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application is related to rotating, coupled masses and, more particularly to changing a center of mass of a rotating mass to achieve a desired effect. 
       BACKGROUND 
       [0003]    Haptic devices are generally designed to provide a tactile feedback to users of electronic devices. A commonly implemented haptic device is an eccentric weight that is rotated to cause vibration to occur. Generally, the stronger the vibrations, the more effective the haptic device. That is, a higher amplitude vibration will typically provide better feedback to a user than a low amplitude vibration. The amplitude may vary with several parameters; some of these are the frequency at which the weight rotates and the location of the center of mass relative to the axis of rotation, both of which are generally fixed parameters in conventional haptic devices. 
       SUMMARY 
       [0004]    Systems and techniques for operating a dynamic rotating mass are discussed herein. The dynamic rotating mass may be used to generate vibration and/or alter angular momentum of a falling device. In particular, a system is provided having a motor, a shaft extending from the motor, and a weight attached to the shaft. Operation of the motor rotates the shaft and the weight is dynamically reconfigurable when rotating to change the location of the center of mass relative to an axis of rotation. 
         [0005]    Another embodiment may take the form of a method of providing vibrations in an electronic device including operating a motor to rotate a shaft with a weight coupled to the shaft. The weight having an outer member and an inner member. The inner member is movable within a slot of the outer member. The method also includes changing a position of the inner weight within the slot to alter the center of mass of the weight. 
         [0006]    Yet another embodiment may take the form of an electronic device having a processor, a communication system coupled to the processor, a controller coupled to the processor, a motor operatively coupled to the controller and a shaft coupled to the motor and configured to be rotated by the motor. A set of coupled weights is coupled to the shaft and include a first weight encompassing a second weight. A center of mass of the set of coupled weights may be offset from an axis of rotation of the shaft and the second weight is displaceable within the first weight to alter the position of the center of mass relative to the axis of rotation. 
         [0007]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following Detailed Description. As will be realized, the embodiments are capable of modifications in various aspects, all without departing from the spirit and scope of the embodiments. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an isometric view of an example electronic device. 
           [0009]      FIG. 2  is a block diagram of an example electronic device. 
           [0010]      FIG. 3  illustrates an example of coupled weights. 
           [0011]      FIG. 4  illustrates the coupled weights of  FIG. 3  coupled to a shaft with a second weight in a resting position. 
           [0012]      FIG. 5  illustrates the coupled weights of  FIG. 3  rotating and the second weight being displaced from the resting position to alter a center of mass of the coupled weights. 
           [0013]      FIG. 6  illustrates the coupled weights of  FIG. 3  having a spring provide a restoring force to restore the second weight back to the resting position. 
           [0014]      FIG. 7  is a cross-sectional view taken along line VII-VII of the coupled weights of  FIG. 3  illustrating the second weight being attached at its base to the first weight in accordance with an alternative embodiment. 
           [0015]      FIG. 8  illustrates the coupled weights of  FIG. 3  including magnets to hold the second weight in a resting position. 
           [0016]      FIG. 9  illustrates the coupled weights of  FIG. 3  including detents to hold the second weight in a displaced position. 
       
    
    
       [0017]    The drawings are provided to help readers better understand the concepts discussed herein. They are not however intended to be limiting in any way. 
       DETAILED DESCRIPTION 
       [0018]    A system of coupled masses that can be driven at varying frequencies is provided. The masses may be coupled to a motor and have an axis of rotation such that some frequencies produce vibration while others produce a reduced vibration amplitude and still others may produce no vibration at all. In one embodiment, two coupled masses may be provided with one configured to be driven at various frequencies. The other mass may be passively attached or otherwise movably attached so that, in some embodiments, it may displace from a rest position due to centrifugal force as the first mass spins and a centripetal force (such as exerted by the first weight) may hold the second weight in the curved rotational path about the axis of rotation. 
         [0019]    In one embodiment, the first weight is driven on an axis that does not go through the center of the mass for the coupled masses, thus generating vibration when driven at low frequencies or any frequency. In another embodiment, the first weight may be driven on an axis near or through the center of the mass. Hence, at low rotational speed, the weight produces little or no vibration. The second weight may be displaced, thereby shifting the center of mass from being at or near the center of the axis of rotation to generate vibration. In some embodiments, the shifting of the second weight is caused by centrifugal force. For example, the second weight may be located at or near an axis of rotation and is pulled away from the center as the weights spin. In other embodiments, the shifting of the second mass may be prompted by other forces. For example, a magnetic force may push or pull the second mass to a displaced position. Additionally, a restorative force may return the second weight to its original or resting position. This force may be provided by a spring, by the second weight itself or by a magnet. 
         [0020]    The shifting of the center of mass of the coupled weights allows selective harmonic response of the vibration system to user input, alerts and so forth. That is, the weights may be configured to alter the center of mass at select frequencies to obtain a desired result. For example, the weights may reconfigure at a select frequency or over a range of frequencies that may alter an effect of the spinning weights. For example, the reconfigured weights may correspond to a high amplitude vibration output. 
         [0021]    Turning to the drawings and referring to  FIG. 1 , an isometric view of an example mobile electronic device  100  is illustrated. The mobile electronic device  100  may include one or more haptic devices that may serve as alerts to a user and/or function to alter angular momentum of the device to help reduce damage or likelihood of damage to the device  100  (or select components of the device  100 ) upon impact from a free-fall. It should be appreciated that the mobile electronic device  100  may take any suitable form, including but not limited to a digital music player (e.g., MP3 player), a digital camera, a smart phone (e.g., iPhone® by Apple, Inc.), a laptop computer, or tablet computer. 
         [0022]    The mobile electronic device  100  may include a display screen  102 , an enclosure  104 , and an input member  106 . Generally, the display screen  102  provides a visual output for the mobile computing device  100  and may take the form of a liquid crystal display screen, plasma screen, organic light emitting diode display, and so on. Additionally, in some embodiments the display screen  102  may provide both input and an output functionality. For example, the display screen  102  may include a capacitive input sensor so to receive input form a user upon the user touching the display screen with his or her finger. The enclosure  104  defines a structure that may at least partially enclose the various components of the mobile computing device  100 . The input member  106  permits a user to provide input to the mobile computing device  100 . The input member  106  may include one or more buttons, switches, or the like that may be pressed, flipped, or otherwise activated in order to provide an input to the mobile computing device  106 . For example, the input member  106  may be a button to alter the volume, return to a home screen, or the like. Additionally, the input member  106  may be any suitable size or shape, and may be located in any area of the mobile computing device  100 . Furthermore, the input member  106  may be combined with the display screen  102  as a capacitive touch screen. 
         [0023]      FIG. 2  is a block diagram of an embodiment of the mobile computing device  100  illustrating select electrical components. The mobile computing device  100  may include a processor  110 , sensors  112 , memory  114 , and a network/communication system interface  116 . The mobile computing device  100  may also include a controller  118 , a motor  120  and weights  122 . The controller  118  may be coupled to the processor  110  and configured to operate the motor  120 . The motor  120  may drive the weights  122  in order to generate a vibration alert, tactile feedback to a user, and/or to alter the angular momentum of the device  100  in the event of a free-fall. As such, the mobile device  100  may be configured to operate the motor  120  to provide an appropriate response to user input (e.g., via the sensors), to incoming data (e.g., an incoming text, call, email, and so forth via the network communication system interface  112 ), to a free-fall event (e.g., as sensed by one or more of an accelerometer, gyroscope, and so forth), or other events. The configuration of the device  100  may be performed at least in part by programming the device upon manufacture. Additionally, certain configurations may be performed by an end user. For example, and end user may be able to selectively configure alerts indicated by operation of the motor  120 . It should be appreciated that the device  100  may include more or fewer components and  FIG. 2  is intended to be exemplary only. 
         [0024]      FIG. 3A  illustrates an example of the weights  122 . The weights may  122  take the form of a coupled mass. Specifically, the weights  122  may include two or more distinct weight members that are coupled together or placed together so as to form a mass having a center of mass. As illustrated, for example, the weights  122  may include a first weight  130  and a second weight  132 . The first weight  130  may generally be larger than the second weight  132  and may have more mass than the second weight. Additionally, the first weight  130  may house the second weight  132 . That is, the second weight  132  may be located within the first weight  130 . In  FIG. 3A , for example, the second mass  132  may reside within a slot  134  of the first mass  130 . It should be appreciated that the weights  122  may be coupled together in a variety of different manners to achieve the desired purposes. That is, the second weight  132  and the first weight  130  may be coupled together in any suitable manner that allows for one or both of the weights to displace from a rest position relative to the other weight to change a center of mass for the weights  122 . 
         [0025]    The second weight  132  may be secured within the slot  134  of the first weight  130  in any suitable manner. For example, the second weight  132  may be coupled at its base within the slot  134  to allow displacement of the second weight through deflection or displacement of the second weight. In other embodiments, the slot  134  may be provided with retaining features (not shown) such as one or more tabs located about the edge of the slot and extending into the slot, to prevent the second weight from exiting the slot. In still other embodiments, the second weight may be formed from the first weight by removing material of the first weight to form the slot  134  and leaving the second weight 
         [0026]    In some embodiments, the first and second weights  130 ,  132  may be made of the same material. For example, in some embodiments, tungsten may be used for each weight. Further, one or more of the weights may be magnetic. In other embodiments, the first and second weights  130 ,  132  may be made from different materials. For example, the first weight  130  may be made from tungsten and the second weight  132  may be made from a magnetic material. Generally, the materials selected for use as the weights  122  will be dense materials so that they have a high weight to volume ratio. This allows for smaller sized weights while still providing a desired output vibration or effect upon angular momentum. Additionally, the weights  122  may take any suitable shape. As shown, the first and second weights  130 ,  132  are cylinders. However, other shapes may be implemented. Moreover, the first weight  130  and the second weight may take different shapes. 
         [0027]    A geometric center  136  of an end of the first weight  130  is illustrated at the intersection of the dashed cross-hairs. Additionally, a center of mass  137  is shown as being slightly offset to the left of the geometric center  136 . Due to the slot in the first weight  130  and the positioning of the second weight  132 , the geometric center may not correspond with a center of mass of the weights  122 . In some embodiments, the geometric center  136  may correspond to an axis of rotation. In other embodiments, the axis of rotation may correspond to a center of combined mass of the weights  122 . Further, in some embodiments, one or more of the center of mass, axis of rotation, and geometric center may coincide. 
         [0028]      FIGS. 3B-3F  illustrate several different alternative example embodiments of coupled weights. In each, first and second weights may displace relative to each other as the weights are spun. In each of  FIGS. 3B-C , an axis of rotation is perpendicular to the drawing (e.g., extends out from the sheet), whereas in  FIG. 3D  the axis of rotation is shown as being parallel to the drawing (e.g., runs left to right). In  FIG. 3B , second weight  200  is external to the first weight  202 . A geometric center  204  of the first weight  202  is shown as well as a center of mass  206  for the coupled weights. As the weights spin, the second weight  200  separates from the first weight  202  as shown by the arrows. 
         [0029]    In  FIG. 3C , the second weight  210  may be located within the first weight  212  while at rest and may exit or separate from the first weight when spun. In this embodiment, the center of mass and axis of rotation may each be near the geometric center  214  of the first weight  212 . In  FIG. 3D , the second weight  220  may be disposed within a slot  228  of the first weight  222  but may displace towards a geometric center  224  of the first weight  222  when the weights are spun. In this example, the axis of rotation may be at or near a center of the second weight when at rest. In some embodiments, the second weight&#39;s position may be actively controlled using magnets, for example. In  FIG. 3E , the second weight  230  may again be external to the first weight  232  and axis of rotation  238  may pass through one or both of the weights. As the weights are spun, the second weight  230  may displace along a surface of the first weight  230  to change the center of mass relative to the axis of rotation  238 . In still other embodiments, the first weight  242  may take an annular shape into which the second weight  240  is disposed, as shown in  FIG. 3F . 
         [0030]      FIG. 4  illustrates the weights  122  with the first weight  130  attached to a shaft  138 . In particular, the shaft  138  may be coupled the geographic center of the first weight  130 . The shaft  138  may also be coupled to the motor  120  and the motor may drive the shaft so that rotates about its longitudinal axis. As mentioned previously, the second weight  132  may be passively coupled to the first weight so that it may move relative to the first weight. In some embodiments, the second weight  132  is at rest at or near an inner position within the slot  134 . That is, a center of the second weight  132  may rest at or near the geometric center of the first weight. As shown in  FIG. 5 , as the shaft  138  and the first weight  130  rotate, centrifugal force may push the second weight  132  to an outer position within the slot  134 . 
         [0031]    The displacement of the second weight  132  causes a shift in the center of the mass of the coupled weights. As such, the center of mass is moved further away from the axis of rotation, thereby providing an output with an increased amplitude. Specifically, as the center of mass shifts due to the shifting of the second weight away from the axis of rotation, the angular velocity of the second weight and therefore the angular momentum of the second weight increases to increase the amplitude of vibration. The increased amplitude may better alert and obtain the attention of the user. Additionally, in embodiments, where the weights are utilized to alter the angular momentum of the falling device, the altered center of mass and increased amplitude output may help to better alter the angular momentum. 
         [0032]      FIG. 6  illustrates an embodiment that includes a spring  150  located within the slot  134  to hold the second weight  132  in the resting position. In particular, the spring  150  may be attached within the slot at or near an outer wall  152  of the slot. Although a single spring  150  is illustrated, multiple springs may be utilized some embodiments. Additionally, it should be appreciated that in other embodiments one or more springs may be located within the slot  134  at or near the inner wall in addition to or instead of the spring  150 . Generally, the springs may be configured to hold the second weight  132  in place until the centrifugal force exceeds, and thereby overcomes, the restraining force of the spring and the second weight is displaced. More particularly, the spring  150  may be configured to exert a force on the second weight hold it in its resting position until the centrifugal force exceeds the restoring force of the spring and the second weight displaces. It should be appreciated that as the spring is compressed, the force required to compress the spring increases, as such, the second weight may displace over a range of frequencies until the spring reaches a maximum compressed state that may correspond to a rotational frequency that produces a desired vibration. For example, the spring may be configured to hold the second weight in its rest position until a frequency is reached at which the weights  122  produce the desired vibrational amplitude in the device  100 . 
         [0033]      FIG. 7  is a cross-sectional view taken along line VII-VII in  FIG. 3  showing another embodiment. In particular, in  FIG. 7 , the second weight  132 ′ is shown as a deflecting beam. The second weight  132 ′ may be attached at its base  160  to an interior surface  162  of the slot  134  of the first weight  130 . The second weight may be hinged, or otherwise movably attached the interior surface  162 . For example, a spring hinge may be implemented to provide a restoring force. In some embodiments, ball and socket joint may movably attach the first and second weights. Alternatively, the second weight may be slideably attached to the interior surface  162 . In other embodiments, the second weight may be formed from the same block of material as the first weight. For example, the second weight may be formed as material is removed from the first weight to create the slot  134 . In embodiments where the first and second weights  130 ′,  132 ′ are made of the same material, this may be a more efficient way to manufacture the weights  122 . However, where the first and second weights are made of different materials, the second weight is attached within the slot  134 . 
         [0034]    As the weights are spun by the motor  120 , the second weight  132 ′ deflects within the slot  134  to move from its resting position to the outer position. Therefore, the slot  134  may be tapered in some embodiments and still accommodate displacement of the second weight. In other embodiments, the slot may have squared edges rather than tapered edges. As with the previous embodiment, the second weight  132 ′ may displace when the centrifugal force exceeds a restoring force that may correlates to a frequency that generates a desired result. In some embodiments, the second weight  132 ′ may act as a spring as it deflects and, as such, may be configured to deflect after a certain frequency of rotation is reached which generates centrifugal force that overcomes the force of the second weight  132 ′. 
         [0035]    Referring to  FIG. 8 , another embodiment is illustrated in which magnetic force is used to hold the second weight  132  in place or displace it. In  FIG. 8 , for example, the first weight  130 ″ may include a magnet  170  having north and south poles. The second weight  132 ″ may include a magnet  172  as well having north and south poles, but with the poles oriented oppositely from that of the magnet  170  of the first weight. As such, the south pole of magnet  170  may be oriented toward the north pole  172  so that the second weight is held in a resting position. Again, as the weights  122  spin centrifugal force will pull the second weight to a displaced position. However, the centrifugal force generally must exceed the magnetic force holding the second weight in the rest position before the second weight will move. 
         [0036]    The magnets  170 ,  172  may be embedded in the first and second weights  130 ″,  132 ″ or may be adhered or otherwise attached to a surface of the respective weights. Several alternative embodiments may be implemented as well. For example, in one embodiment, one or both of the first and second weights  130 ″,  132 ″ may be magnets. Alternatively, one of the weights may be a magnet and the other a magnetic material. In yet another embodiment, one or more weights may be an electromagnet that may be selectively magnetized to hold the second weight in a desired position. The controller may be used in some embodiments to control the magnetism of the weights. In some embodiments, the poles of the electromagnet may be reversed to repel the second weight to a displaced position. Additionally, the first weight may include magnets near the displaced position of the second weight to either hold or repel the second weight. 
         [0037]    Further, in some embodiments, the motor  120  may be used to provide the magnetism for the weights  122 .  FIG. 8B  illustrates the motor  120  generating magnetic flux lines which may influence the positioning of the second weight  132 ′″ located within the first weight  130 ′″. Magnetic flux lines  189  are illustrated to show how a magnetic field from operation of the motor  120  may reach the first and second weights. Further, a magnetic member  190  may be provided within the first member and which may be influenced by the magnetic field of the motor to either displace or hold the second weight  132 ′″ in a desired location. The weight spins in synchronization with the motor, and the motor&#39;s magnetic coils are driven in a pattern similar to a sinusoid. Therefore in the weight&#39;s rotating reference frame, the magnetic field from the motor is always in approximately the same direction, assuming the weight is attached directly without a gearbox. When the motor is off or driven at low power, the movable weight  132  will not shift, while the magnetic field will shift the weight when the motor is driven at a higher power. 
         [0038]      FIG. 9  illustrates yet another alternative embodiment in which detents are used to hold the second weight in a desired position. In particular, the slot  134  may include one or more detents  182  that correspond to apertures  180  in the second weight  132 ′″. In one embodiment, a detent may help secure the second weight in a rest position. In another embodiment, a detent may help secure the second weight in a displaced position. The detents may be made of any suitable material and in one embodiment may be made of the same material as one of the first or second weights. Additionally, the detents may take any suitable shape, such as triangular, square and so forth. 
         [0039]    The use of a detent in the resting position helps to hold the second weight in the rest position when the weights are spun at a relatively low frequency and up until some threshold frequency is reached. Upon reaching the threshold frequency, centrifugal force may displace the second weight. Similarly, the detent in the displaced position may be used to hold the second weight in the displaced position at lower frequencies. In particular, the motor may initially operate at a high frequency to displace the second weight, the motor may then reduce its frequency and the second weight may maintain its displaced position. This may be useful to help conserve power, as the motor may operate at lower speeds and still achieve a high amplitude output due to the displaced second weight. A spring or other device (not shown) may provide a restorative force to help return the second weight to its resting position once the motor stops. 
         [0040]    The foregoing describes some example embodiments of coupled masses used to generate vibration and/or alter angular momentum of a falling device. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the embodiments. Additionally, one or more of the embodiments may be combined together to achieve a desired performance. For example, a spring maybe implemented with an embodiment utilizing magnets to help hold and return the second weight to a resting position. Accordingly, the specific embodiments described herein should be understood as examples and not limiting the scope thereof.