Abstract:
In a dual-concentric knob, an inner knob acts as a solid ergonomically functional knob for forces below a threshold and collapses into an outer knob for forces above the threshold. In some examples the inner knob also acts as a push button for forces below the threshold. 
     A hand-operated control is mounted on a hub for axial movement between a first position and a second position relative to the hub, a mechanism axially rigidly couples the control to the hub in the first position unless a force greater than a threshold is applied to the control, and a mechanism rotationally couples the control to the hub in both the first and the second positions.

Description:
BACKGROUND 
   This description relates to a control knob with a safety feature. 
   To reduce injury to passengers, vehicle safety standards require that control knobs and other devices that extend beyond a surrounding surface plane collapse to the level of that plane if forces on the knob exceed a specified threshold, as they might during a crash. 
   SUMMARY 
   In general, in one aspect, in a dual-concentric knob, an inner knob acts as a solid ergonomically functional knob for forces below a threshold and collapses into an outer knob for forces above the threshold. In some examples the inner knob also acts as a push button for forces below the threshold. 
   In general, in one aspect, a hand-operated control is mounted on a hub for axial movement between a first position and a second position relative to the hub, a mechanism axially rigidly couples the control to the hub in the first position unless a force greater than a threshold is applied to the control, and a mechanism rotationally couples the control to the hub in both the first and the second positions. 
   Implementations may include one or more of the following features. A resilient element applies force to the control toward the first axial position whenever the control is not in the first axial position. In the first axial position, a first portion of the first control extends beyond a plane. In the second axial position, the first portion of the first control does not extend beyond the plane. The first portion includes a material having a durometer greater than 50 shore A. A second portion of the first control extends beyond the plane in both the first and second axial positions. The second portion includes a material having a durometer less than 50 shore A. The plane is defined by a surface of a device that is controlled by the control. The plane is defined by a surface of a second control that surrounds the first control. The plane defined by the surface of the second control is about 9.75 mm from a surface of a device that is controlled by the first and second controls. The second control is included. The second control is coaxial with the first control. The second control includes a ring concentric with the first control. An encoder is coupled to the hub by a shaft. The encoder is configured to receive rotational input from the control by rotation of the shaft. The encoder is also configured to receive second rotational input from a second control coaxial with the first control by rotation of a second shaft coaxial with the first shaft. The encoder is configured to receive axial input from the control by axial movement of the shaft. The threshold is in the range of about 40 to about 378 newtons. The threshold is about 57 newtons. 
   In general, in one aspect, a first hand-operated control is mounted on a hub for axial movement between a first position and a second position relative to the hub, a mechanism axially rigidly couples the control to the hub in the first position unless a force greater than a threshold is applied to the control, and a second hand-operated control surrounds the first control. In the first axial position, a first portion of the first control extends beyond a plane defined by a surface of the second control. In the second axial position, the first portion of the first control does not extend beyond the plane. 
   Implementations may include one or more of the following features. The second control is coaxial with the first control. The second control includes a ring concentric with the first control. An encoder is coupled to the hub by a first shaft and is coupled to a hub of the second control by a second shaft coaxial with the first shaft. The encoder is configured to receive rotational input from the first control by rotation of the first shaft, and to receive rotational input from the second control by rotation of the second shaft. 
   In general, in one aspect, a first hand-operated control is mounted on a hub for axial movement between a first position and a second position relative to the hub. The control includes a first portion having a hardness greater than about 50 shore A and a second portion having a hardness less than about 50 shore A. A mechanism axially rigidly couples the control to the hub in the first position unless a force greater than about 57 newtons is applied to the control. A second hand-operated control includes a ring concentric with the first control. In the first axial position, the first portion of the first control extends beyond a plane defined by a surface of the second control. In the second axial position, the first portion of the first control does not extend beyond the plane. The second portion of the first control extends beyond the plane in both the first and second axial positions. 
   In general, in one aspect, a user interface device for use in automobiles includes a control knob for controlling at least one function of the device and mounted on a hub for axial movement between a first position and a second position relative to the hub, a mechanism that axially rigidly couples the control knob to the hub in the first position unless a force greater than a threshold is applied to the control knob, and a hand-operated control ring for controlling at least one second function of the device and that surrounds the control knob. In the first axial position, a first portion of the control knob extends beyond a plane defined by a surface of the control ring. In the second axial position, the first portion of the control knob does not extend beyond the plane. The user interface device may include one or a combination of a radio; a multimedia playback device; a navigation system; a control interface for a climate control system; a communications device; and a personal computer. 
   Advantages include the ability to provide a dual-concentric, three-function knob that acts as a solid, ergonomically functional control while meeting safety standards. The knob can still be used after the safety feature is activated and the parts separated. 
   Other features and advantages will be apparent from the description and the claims. 

   
     DESCRIPTION 
       FIG. 1  is a perspective view of a control panel. 
       FIG. 2A  is a side view of a control knob. 
       FIG. 2B  is a cross-sectional isometric view of a control knob. 
       FIG. 3A and 3B  are cross-sectional side views of a control knob. 
       FIG. 4A  is an exploded isometric view of a control knob. 
       FIGS. 4B-E  are isometric views of the assembly of a control knob. 
   

   Control panels in vehicles, for example, a control panel  100  for a radio, a navigation system, a DVD or other media player, a climate control system, a cellular telephone or other communications device, a personal computer, or some other device as shown in  FIG. 1 , sometimes include knobs  102  that extend outward from the face plane  101  of the control panel. If the vehicle makes a sudden stop, passengers may injure themselves on such knobs. Other controls such as buttons  103  and a display  105  are generally flush with the surface  101  or recessed below it and do not generally cause injury. The word knob includes, for example, buttons, dials, switches, and levers. 
   To reduce the chances of such injuries, knobs and other protrusions are required either to retract or to be less than a specified hardness. For example, under the European Convention Homologation rule 74/60/EEC ¶5.1.5, a protrusion that extends more than 9.75 mm from the surface behind it must collapse into that surface so that it protrudes less than 9.75 mm if a force greater than 378 N (84.98 lbf) is applied to it. Because materials having a hardness of less than 50 on the Shore A scale (referred to as “50 shore A”) are ignored when measuring dimensions and positions under this rule, the portions of the knobs made of such materials can extend beyond the specified limits. Other jurisdictions may specify other criteria, e.g., larger or smaller lengths, harder or softer materials. The criteria specified by any given jurisdiction may change over time, which may necessitate changes in the design of control features. 
   In some examples, as shown in  FIG. 2A , a knob  102  has two concentric rotational parts that can each rotate independently of one another, an outer ring  104  for controlling one set of functions, and an inner, taller knob  106  for controlling another set of functions. The inner knob  106  may also function as a push-button switch. In the example of  FIG. 2A , the outer ring  104  has a first texture  108  formed by knurling a band of material  203 , and the knob  106  has a second texture  110  formed of ridges. Other textures and surface finishes are possible. A dual-concentric knob of this design, with a push-button feature on the inner knob, provides at least three controls in a single package, allowing easy operation with minimal requirements for the user to take his eyes off the road to find the controls. In some examples, the outer knob could provide the push-button or both knobs could provide that feature. 
   As shown in  FIGS. 3A and 3B , the knob  106  and ring  104  are coupled to a rotational encoder  200  through hubs  207  and  206  and shafts  210  and  212 . In the example of the figures, the encoder  200  has a threaded outer extension  201  for attaching to the control panel  100  ( FIG. 1 ). The encoder  200  receives the rotational or push-button inputs of the ring  104  and knob  106  and converts them to electrical signals, which are in turn transmitted to appropriate electronics (not shown). Dual-encoder devices having a rotational encoder coupled to each of two concentric shafts and a push-button input coupled to at least one of the shafts are well-known, for example, the 62HY2222014 or 62HY2211001 dual-concentric encoders from Grayhill, Inc., of La Grange, Ill. 
   In some examples, the inner knob  106  may be composed of two or more materials having different hardnesses. An inner core  202  is composed of a relatively harder material, and an outer cover  204  is composed of a softer material. Similarly, the knurled portion  203  of the outer ring  104  can be formed of a softer material and the remainder  205  formed of a harder material. If the outer cover  204  is softer than  50  shore A, and the inner core  202  is harder than  50  shore A, then it is the dimensions of the inner core  202  that are considered for compliance with safety rules. Under the EEC rules, if the outer ring  104  takes up the 9.75 mm allowed for such a protrusion (distance L 1  in  FIG. 3A ), the inner knob  106  will be required to collapse into the outer ring  104  (i.e., it must collapse by distance L 2 ). When the knob  106  is collapsed, as shown in  FIG. 3B , the hard core  202  must be retracted fully into the outer ring  104 , but the softer cover  204  may continue to extend beyond it, provided it is less than 50 shore A in durometer. If the outer ring  104  were absent, the core  202  would need to retract to within 9.75 mm of the underlying surface  101  ( FIG. 1 ). The dimensions of the outer cover  204  and other components, including body  205  and knurled portion  203  of the outer ring  104 , can be selected to provide a size and shape that is needed for the knob  102  to be ergonomically functional, that is, to allow its user to grip the inner knob  106  or outer ring  104  and rotate each of them comfortably and effectively. 
   In some examples, the hub  206  and a spring  208  are configured to allow the knob  106  to collapse into the outer ring  104 . Clips  214  transfer force from the core  202  to the hub  206 , such that turning or pushing the knob  106  will turn or push the shaft  210 . In some examples, the clips  214  provide a rigid linkage between the core  202  and the hub  206 . In this way, pushing on the knob  106  will appear, to the user, to merely move it the small amount (e.g., 1 mm or less) needed to trigger the push-button mode of input. As long as the clips  214  are intact, the knob  106  will appear to the user to be a single rigid piece with the usual functionality and behavior expected of a non-collapsible knob. When a threshold force on the knob  106  is exceeded, the clips  214  will break or separate, and core  202  will move downward over the hub  206 , compressing the spring  208 , as shown in  FIG. 3B . In some examples, the clips  214  may have fingers that will ride up and down within grooves and therefore will continue to transfer rotational force from the knob  106  to the hub  206  in the collapsed position, allowing the knob to function as an input device even while collapsed. 
   In some examples, the lower surface  202   a  of the top wall of the core  202  contacts the top surface  206   a  of the hub to stop downward movement of the knob  106 , as shown in  FIG. 3B . In some examples, the bottom edge  202   b  of the core  202  contacts the top surface  205   a  of the bottom of the outer ring  104  to stop the knob  106 &#39;s movement (not shown). 
   After the collapsing force is removed, the spring  208  will push the knob  106  back to its nominal position, i.e., that shown in  FIG. 3A . In some examples, the clips  214  may be configured to re-attach the core  202  to the hub  206  when it is returned to its extended position. In some examples, the clips may not re-attach, in which case, the spring  208  will continue to hold the knob  106  in approximately its original extended position, but there will be no rigid linkage between the core  202  and hub  206 , or there may be only rotational linkage. In some examples, rotational linkage is maintained with reduced functionality, for example, the knob  106  may have a few degrees of play before rotation is transferred to the hub  206 . Pressing on the knob  106  will compress the spring, and may ultimately apply enough force to the hub  206  to activate the push-button function of the encoder  200 , but it may require the knob  106  to be pushed farther and with greater force than is normally required. Replacement of one or more parts (e.g., inner knob  106  and hub  206 , or the entire knob  102 ) may be required to restore the original rigid linkage. Replacement knobs can be supplied with the vehicle or to dealers and service centers. The collapsed knob can be replaced quickly and easily by reversing and then repeating the assembly process described below. 
   The knob  102  is assembled as shown in  FIGS. 4A-E . In some examples, the clips  214  have two parts, flanges  214   a  on the knob  106  and tabs  214   b  on the hub  206 . To attach the knob  106  to the hub  206 , the knob  106  is positioned so that its flanges  214   a  are rotationally aligned between the hub&#39;s tabs  214   b,  as shown in  FIG. 4C . The knob  106  is pressed onto the hub  206 , compressing spring  208  between them, until the flanges  214   a  are axially aligned with the tabs  214   b,  as shown in  FIG. 4D . As shown in  FIG. 4E , the knob  106  is then rotated (arrow  402 ) with a torque sufficient to engage the flanges  214   a  and tabs  214   b  (obscured by the flanges in  FIG. 4E ), engaging the clips  214 . At this point, notches  216   a  in the flanges  214   a  rotationally align with ridges  216   b  on the hub  206  to help control axial movement of the knob  106  when it collapses. In some examples, the design of notches  216   a  and ridges  216   b  allows the knob  106  to rotate the hub  206  even when the clips  214  are disengaged or broken and the knob  106  is in the compressed position. 
   Once engaged, the clips  214  will hold knob  106  and hub  206  together until an axial force exceeding the designed threshold is applied to the knob  106 , transferring any forces applied to the knob  106  to the hub  206 , as discussed above. In some cases, the clips are designed to withstand a force of around 53 N (12 lbf)—less than required by the EEC rule, but enough that the knob appears to the user to be solid. In some examples, the force could be in the range of about 40 N to the maximum allowed by regulation, for example, about 378 N. In some examples, the clips  214  are a cylindrical cantilevered snaps. The dimensions of such a clip can be selected by one of ordinary skill in the art to provide the desired resistance against separation. After the knob  106  and hub  206  are connected, the combination is attached to the shaft  210  by aligning hole  220  with the tip of the shaft  210  and pressing down on the knob  106 , with the outer ring  104  similarly positioned with its hub  207  on the outer shaft  212 , between the encoder  200  and the hub  206 . In some examples, the force required to insert the hub  206  onto the shaft  210  is less than the force required to separate the clips  214 . In some examples, the force required is greater, and the hub  206  is inserted onto the shaft  210  before the clips  214  are engaged. To replace a broken knob, the knob  106  is pressed in so that the flanges  214   a  are past the tabs  214   b  and ridges  216   b,  and then rotated to align the flanges  214   a  between the tabs  214   b.  The knob  106  can then be removed, leaving the hub  206  on the shaft  210 . A replacement knob  106  can be installed by reversing this procedure, and then rotating it to engage the clips  214 . In examples where the force to attach or remove the hub  206  from the shaft  210  are less than the forces required to engage or separate the clips  214 , the hub  206  may be removed from the shaft  210  and attached to the replacement knob  106  before being reinstalled onto the shaft  210 . In some examples, the hub  206  is replaced along with the knob  106 . Replacement parts supplied to dealers or customers may include a hub  206  and knob  106  already attached with the clips  214  engaged. The replacement part may differ in design or materials from the knob and hub originally supplied with the control panel  100 , for example, they may require installation forces other than those used on an assembly line. 
   In the examples illustrated, three clips  214  are spaced 120° apart. This provides stability to the knob  106 /hub  206  assembly without significantly complicating fabrication of the parts. More or fewer clips could be used, depending on considerations such as the forces required to operate or assemble the knob, the forces that the assembly must withstand before collapsing, and the cost to manufacture and assemble the parts. 
   In some examples, the strength of the spring  208  is selected to provide sufficient force to enable operation of the knob  102  after clips  214  are separated, but not such great force that it causes strain on the clips  214 , for example, by pushing the knob  106  outward when it is already at its fully extended position. In some examples, this is about 38 N (8.5 lbf) when the spring  208  is in its compressed (knob  106 collapsed) position. In some examples, other mechanisms are used to restore the knob  106  to its extended position, such as a compressible foam. 
   Other embodiments are within the scope of the following claims. For example, the outer ring  104  could also function as a push-button switch. The control could be something other than a knob, for example, a joystick.