Abstract:
A single-piece component rotatably supports a scroll wheel and includes an integral follower arm extending into a well within which the scroll wheel rotates. Formed on a circumferential surface of the scroll wheel are regularly spaced detents or other structures forming regularly spaced regions of alternating height. Located on an end of the follower arm is a follower which moves in and out of the detents as the scroll wheel rotates, with the arm biasing the follower against movement out of the detents. The carriage may also include pivots for relative movement of the carriage and scroll wheel assembly with respect to a housing, and a tab for actuating a switch.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to scroll wheels on mice, trackballs and other user input devices.  
       BACKGROUND OF THE INVENTION  
       [0002]     In many computers, user input (e.g., cursor control, screen scrolling, etc.) is often achieved by way of a pointing device such as a mouse or a trackball. A typical computer mouse  1  is shown in  FIG. 1 . Mouse  1  has a case  16  having a bottom case  20  and an upper case  18 . As a user slides mouse  1  across a planar (or substantially planar) surface, motion detectors and encoders within case  16  may convert the two-dimensional movement of the mouse across the surface into horizontal and vertical motion of a cursor, pointer, or other object on a computer screen. Mouse  1  has two buttons  8  and  12  which a user can “click” or “double click” to select something on a computer screen. Other mice may have fewer or additional buttons, or other features. Mouse  1  may be connected to a computer or other device by a cord  5  through which mouse  1  may receive power and communicate with a computer (or other device). Alternatively, mouse  1  could be battery powered and communicate via a wireless connection.  
         [0003]     Mouse  1  also has a scroll wheel  14 . Scroll wheel  14  is located such that the mouse user can comfortably turn the scroll wheel with a finger. The mouse and/or computer may be configured such that turning the wheel causes the screen image to scroll upwards or downwards. The scroll wheel may be configured to perform other functions, such as moving a screen object in a z direction; changing the zoom or other attributes of a screen image; scrolling horizontally; and innumerable other functions. A scroll wheel may also be configured to act as an additional button when pressed by the user.  
         [0004]     To prevent the scroll wheel from rotating undesirably (e.g., when the user is moving the mouse but not turning the wheel), to provide a desired tactile sensation for the user, and to provide a means of indexing wheel rotation into discrete increments, some type of restraint is typically imposed on scroll wheel rotation. A common restraint consists of a series of regularly-spaced ridges, detents or other structures on a surface of the wheel or its axis, and a follower biased into contact with the detents. As the wheel rotates, the follower is biased to resist movement out of a detent, and the torque necessary to continue rotating the wheel increases slightly. As the user increases the applied torque (i.e., continues to turn the wheel), the follower rides over a ridge (or other structure separating two detents), whereupon the needed torque decreases until the follower is biased into the next detent. In this way, the user can easily gauge (and make) relatively uniform scrolling movements.  
         [0005]     Existing mice scroll wheels restrain wheel rotation through a variety of configurations. U.S. Pat. No. 5,912,661, titled “Z-Encoder Mechanism” and owned by assignee of this invention, describes a configuration in which the detents are located on the axle of the scroll wheel. A metal spring attached to a printed circuit board within the mouse biases a follower into contact with the detents. An improvement upon this configuration is described in U.S. Pat. No. 6,353,429, titled “Detented Optical Encoder” and also owned by the assignee of this invention. Specifically, instead of a metal spring biased into contact with the axle detents, a plastic bracket contacts the axle near one of its rotational hubs and biases the axle upward so as to provide z-switch functionality. A follower, located within the portion of the bracket cradling the axle, is thereby simultaneously biased into contact with the detents. Further improvements are possible, however. For example, the configuration described in the &#39;429 patent requires assembly of at least 4 parts to provide indexed rotation. Because each of these parts (like all mechanical components) will have dimensional tolerances, a “tolerance stack-up” of the assembly results. This tolerance stack-up can potentially result in a rotational torque that may vary from mouse to mouse unless relatively small tolerances are maintained. This can increase manufacturing expense.  
         [0006]     In another configuration, regularly-spaced radially-extending indentations are molded into (or otherwise formed in) a side of a scroll wheel in a spoke-like arrangement. A follower piece is biased into contact with the spoke-like indentations on the side of the wheel. The follower piece may be a molded extension of a carriage or other structure supporting a wheel axle, or it may be a separate member that is attached to the carriage. A potential disadvantage of this configuration, however, is the variability in torque required to rotate the wheel in one direction versus the other. In the case of a separate member attached to the carriage, an additional part is required, resulting in additional assembly steps, cost and potential tolerance stacking problems. In yet another configuration, the indentations are not formed in the side of the wheel in a spoke-like arrangement. Instead, a series of ridges and/or depressions are formed on an inner circumference of the wheel. A follower is biased radially outward into contact with the ridges and/or depressions. However, known scroll wheels implementing this configuration utilize a separate biasing member that is not an integral part of the carriage supporting the wheel axle.  
         [0007]     A scroll wheel having circumferential detents that are acted upon by a biased follower integrally formed as part of the carriage would result in advantageous savings in assembly steps and expense. Such a design would also facilitate greater control over the fit of the components and allow greater performance consistency among the scroll wheels in different mice. For these and other reasons, advantages can be obtained from further refinements in scroll wheel design.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention improves upon existing scroll wheel designs by providing a single component that rotatably supports the scroll wheel, and which has an integral follower arm extending into a well within which the scroll wheel rotates. Formed on a circumferential surface of the scroll wheel are regularly spaced detents or other structures forming regularly spaced regions of alternating height. Located on an end of the follower arm is a follower which rests within the detents. As the scroll wheel rotates and the follower is pushed out of a detent, the follower arm biases the follower radially into the surface on which the detents are located. By integrally forming the follower and follower arm as part of the same component that houses and rotatably supports the scroll wheel, the number of components is reduced, reducing tolerance stack-up and providing other advantages. The carriage may further be pivotably attached to a mouse or other structure, and a tab formed on the carriage. In this manner, the scroll wheel can also function as an externally depressible button.  
         [0009]     In one embodiment, a modular scroll wheel assembly includes a scroll wheel sized for movement by a finger of a human user. The scroll wheel has a circumferential surface with regularly spaced regions of alternating height located on that surface. The modular scroll wheel assembly further includes a single-piece carriage that supports and rotatably holds the scroll wheel. The carriage has first and second sides that define a wheel well within which the scroll wheel rotates. An integral follower arm is disposed on the first side of the carriage; the follower arm has a follower in contact with the circumferential surface and is biased to resist deflection as the scroll wheel rotates.  
         [0010]     An embodiment of a computer mouse according to the invention includes a housing sized and configured for manual movement by a user across a surface so as to permit a corresponding movement of a screen object on a computer display. The housing has a bottom case and an upper case coupled to the bottom case, and at least two depressible buttons movably attached to the upper case. The mouse further includes a scroll wheel having a circumferential surface with regularly spaced regions of alternating height located around that circumferential surface. A single-piece carriage rotatably supports the scroll wheel such that a portion of the scroll wheel extends outside of the housing. The carriage includes first and second sides forming a wheel well within which the scroll wheel rotates, and an integral follower arm on the first side of the carriage. A follower on an end of the arm is in contact with the circumferential surface and is biased to resist deflection as the scroll wheel rotates.  
         [0011]     Other features and advantages of the invention are set forth below in the detailed description or will be apparent to persons skilled in the art in light of that description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is perspective outer view of a computer mouse having a scroll wheel.  
         [0013]      FIG. 2  is a front perspective view, with the upper case removed, of the mouse of  FIG. 1 .  
         [0014]      FIG. 3  is an exploded front perspective view of a scroll wheel, carriage and other internal components of the mouse of  FIG. 1 .  
         [0015]      FIG. 4  is an assembled front perspective view of a scroll wheel, carriage and other internal components of the mouse of  FIG. 1 .  
         [0016]      FIG. 5  is another assembled front perspective view of a scroll wheel, carriage and other internal components of the mouse of  FIG. 1 , but from a different angle than that of  FIG. 4 .  
         [0017]      FIG. 6  is another exploded front perspective view of a scroll wheel, carriage and other internal components of the mouse of  FIG. 1 , but from a different angle than that of  FIG. 3 .  
         [0018]      FIG. 7  is a top view of a scroll wheel, carriage and other internal components of the mouse of  FIG. 1 .  
         [0019]      FIG. 8  is a cut-away view taken along lines  8 - 8  of  FIG. 7 .  
         [0020]      FIG. 8A  is an enlarged view of a region of  FIG. 8  that has been rotated 90° counterclockwise.  
         [0021]      FIG. 9  is a perspective view of a scroll wheel carriage according to the invention.  
         [0022]      FIG. 10  is an enlarged perspective view of a region of  FIG. 9 .  
         [0023]      FIG. 11  is an enlarged top view of the follower arm and a portion of the carriage. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     An improved scroll wheel assembly according to the present invention is shown in  FIGS. 1-11 . With reference to  FIG. 2 , the upper case, as well as buttons  8  and  12 , have been removed for purposes of illustration. Located within mouse  1  and attached to lower case  20  is a printed circuit board  44 . Printed circuit board  44  electrically interconnects various mouse components, and also provides an internal structure to which other components may be attached. Scroll wheel  14  has an attached axle  22 . Axle  22  rotates within axle guides  58  (see  FIG. 3 ) defined within carriage  56 . The mouse of  FIGS. 1-11  is used only by way of example. Persons skilled in the art will appreciate that the invention is likewise applicable to other mouse designs. Such persons will also appreciate that the invention is likewise applicable to trackballs, keyboards and other input devices having (or capable of having) a scroll wheel.  
         [0025]      FIG. 3  is an “exploded” front perspective view of an embodiment of the improved scroll wheel assembly according to the present invention. The upper case of the mouse has been removed for clarity, and various circuit components also omitted for purposes of clarity. Most of the lower case of the mouse has also been removed, with portion  20 ′ representing a small part of the lower case  20 .  FIG. 4  is similar to  FIG. 3 , but in an assembled condition. Scroll wheel  14  may (but need not) include an outer surface  15  that is textured to allow for easier movement by the user. In the depicted embodiment, scroll wheel  14  includes a hub  49  that is substantially open on at least one face, and has an exposed inner circumferential surface  50  exposed by the opening in that face. Evenly spaced along inner circumferential surface  50  are a series of peaks and troughs forming detents  52 . Axle  22  is attached to wheel  14 , which attachment may be strengthened by spokes  54 . Wheel  14 , axle  22  and spokes  54  may be molded so as to form a single integral component.  
         [0026]     After assembly, a portion of scroll wheel  14  rests within carriage  56 . Carriage  56  is a single, integral piece which can be molded. Carriage  56  includes axle guides  58  on both sides of carriage  56 . Each axle guide  58  may be formed between a pair of uprights  60  extending from (and integral to) carriage  56 . Although both axle guides  58  are shown in the drawings as having a “snap-in” configuration formed by an angled inlet between uprights  60 , other axle guide configurations are possible. For example, one axle guide  58  could be an enclosed hole (e.g., without a gap between the uprights  60 ) into which one end of axle  22  is inserted, with the other end of axle  22  being snapped into the other axle guide. Each axle guide  58  supports axle  22  for rotation, and is slightly larger in diameter than the portion of axle  22  that fits therein so as to allow rotation of axle  22  and wheel  14 .  
         [0027]     Carriage  56  further has an integral follower arm  67  and follower  66 . Follower arm  67  projects inwardly towards scroll wheel  14  and is used to provide indexed wheel motion. After assembly, and as shown in  FIG. 4 , follower  66  (located on the inwardly projecting end of follower arm  67 ) is in contact with the inner circumferential surface  50 . As wheel  14  is rotated within the wheel well  57  formed by carriage  56 , follower  66  is alternatively forced out of, and allowed to descend into, detents  52 . As follower  66  is forced out of a detent  52 , it is pushed radially inward against a radially outward bias of the spring force of follower arm  67 . In this manner, indexed rotation of scroll wheel  14  is obtained, and scroll wheel  14  is prevented from rotating except when such rotation is desired.  
         [0028]      FIG. 9  is a perspective view of carriage  56  without scroll wheel  14 .  FIG. 10  is an enlarged view of the region  10  of  FIG. 9 , and shows exemplary dimensions for follower  66  and arm  67 . Dimensions may vary depending on material, scroll-wheel size, and other factors. As shown in  FIG. 11  (which is a top view of the region shown in perspective in  FIG. 10 ), the face  80  of arm  67  facing toward the detents may be straight when the follower  66  is centered within a trough (i.e., within a detent). As the dotted line shows, arm  67  flexes backward when force is exerted on follower  66   
         [0029]     As shown if  FIGS. 2-6 , carriage  56  may be mounted for pivotal movement within a mouse or other structure. Carriage  56  may include pivots  68 . Pivots  68  fit within pivot guides  70  formed in posts  72 , and are retained therein for pivotal movement. In the depicted embodiment, snap-fit pivot guides are shown; as with axle guides  58 , however, alternative arrangements are possible. Posts  72  are attached to (or formed as a part of) lower case  20 ′. Carriage  56  thereby pivots about an axis A passing through pivots  68  and pivot guides  70 . Located at the opposite end of carriage  56  is switch tab  74 . Switch tab  74  acts upon microswitch  76  when the user exerts downward force on wheel  14 ; switch tab  74  is thereby pressed against microswitch  76 , and actuates same. Microswitch  76  can be a self-biased switch such as a metallic beam switch, a metallic disc switch, or other type self-biasing switch which will support the carriage when not being pressed down by a user. As is known in the art, these types of switches are mechanically biased to an “off” state, and are only “on” when an external force is exerted on the switch. Although not shown, carriage  56  could alternatively be biased upward by a separate spring or resilient member. In such an alternative configuration switch  76  would not need to be self-biased.  
         [0030]      FIG. 6  is an exploded front perspective view of the mouse and scroll wheel from an opposite side of the mouse.  FIG. 5  is similar to  FIG. 6 , but in an assembled condition and showing additional components. Encoder wheel  24  is attached to (or formed as a part of) the end of axle  22 . After assembly, and as shown in  FIGS. 2 and 5 , encoder wheel  24  passes between a light emitting diode (LED)  42  and receptor(s)  46 . When scroll wheel  14  is rotated, the “spokes” of encoder wheel  24  alternatively allow and block light from LED  42  from reaching receptor(s)  46 , thereby facilitating detection of scroll wheel rotation. The details of such detection are known in the art, and are not critical to the present invention. The detents  52  could be configured such that, when the follower  66  rests within a detent, light from LED  42  reaches receptor(s)  46 . Alternatively, detents  52  could be configured so that, when the follower  66  rests within a detent, the encoder wheel  24  partially or completely blocks light from LED  42  from reaching receptor(s)  46 . LED  42  and receptor(s)  46  can be mounted upon a bracket  26 , which could in turn be mounted to circuit board  44 .  
         [0031]     In one embodiment, hub  49  of scroll wheel  14 , axle  22  and spokes  54  may be integrally formed from any desired plastic such as an acetyl resin (for example, DELRIN®, available from E.I. duPont de Nemours and Company of Wilmington, Del.). If desired, a rubber-like thermoplastic elastomer such as SANTOPRENE® (available from Advanced Elastomer Systems of Akron, Ohio) may be overmolded or otherwise used to form an outer surface  15  of wheel  14 . Carriage  56  may also be molded from a plastic, for example Acrylonitrile Butadiene Styrene (ABS). The described materials are exemplary, however, and other materials and combinations are with thin scope of the invention. A small amount of lubricant can be added to the connections between axles  22  and axle guides  58  and between follower  66  and detents  52 .  
         [0032]      FIG. 7  is a top view of one embodiment of the invention installed on a mouse circuit board  44 , with certain components omitted. Although shown in certain figures as located directly opposite the pivots  68 , switch tab  74  could be located elsewhere. For example, switch tab  74  could be on one side of carriage  56 , shown as item  74 ′ in  FIG. 7 . Circuit board  44  may also house components for tracking mouse movement across a surface, such as LED  91  and receptor  92 . Alternatively, mechanical encoder wheels and a captive rolling ball could be used, as could other motion tracking devices.  FIG. 8  is a cutaway view taken along the line of sight  8 - 8  of  FIG. 7 . Various components have been completely or partially removed so as to more clearly reveal detents  52  and follower  66 . As shown in  FIG. 8 , a scroll wheel in one embodiment of the invention may have eighteen (18) evenly-spaced detents  52  distributed on inner circumferential surface  50 .  FIG. 8A  is an enlarged view of region  8 A of  FIG. 8 , and has been rotated 90° counterclockwise for clarity.  FIG. 8A  shows dimensions for the embodiment of  FIG. 8 , but the dimensions, shapes and positioning of the components may vary as desired. Follower  66  has a shape generally matching the trough shape. Fatigue on follower  66  and the follower arm  67  may be reduced if there is substantially no preload upon the follower. In other words, when the scroll wheel is assembled and follower  66  is substantially centered within a detent  52 , no significant force is exerted on follower  66  or arm  67  by wheel  14 .  
         [0033]     As is clear from the above description, the invention provides numerous advantages over other scroll wheel configurations. Contained within a single part are the guides within which the scroll wheel axles rotate, the follower and the follower arm. Because there are a minimum number of parts, tolerances can be more easily and accurately maintained. This in turn enhances consistency in scroll wheel performance from mouse to mouse. Reducing the number of parts also reduces assembly time and expense. The invention further provides a consistent feel for a user rotating the scroll wheel in either direction. In other words, the forward and reverse rotational torque is more closely equal than is the case in other designs.  
         [0034]     Although an example of carrying out the invention has been described, those skilled in the art will appreciate that there are numerous variations and permutations of the above described device that fall within the spirit and scope of the invention as set forth in the appended claims. As but one example, the detents could alternatively be located on an inner circumferential surface that is on a portion of the scroll wheel axle inside of the wheel hub, with the follower facing radially inward. As another example, the detents could be molded (or otherwise formed) on the outermost surface of the scroll wheel, the carriage modified, and the follower oriented to face radially inward. As yet another example, the axle could alternatively be molded as two half axles extending from either side of the carriage into the wheel well, with depressions molded into the scroll wheel for those half axles. As set forth above, the scroll wheel of the invention can be incorporated into other mouse designs, into other pointing devices (e.g., trackballs), and other input devices (e.g., keyboards). These and other modifications are within the scope of the invention, which is to be limited only by the claims.