Abstract:
A rotary knob device ( 1, 20 ) having a key function includes a key ( 5, 30 ) in a rotary knob ( 2, 23 ), which is operated separately from the rotary knob so that the key ( 5, 30 ) need not also be moved when the rotary knob ( 2, 23 ) is moved. In this regard, a holder ( 6, 24.1 ) is provided inside the rotary knob ( 2, 23 ), on which the rotary knob ( 2, 23 ) and the key ( 5, 30 ) are mounted to be thereby linked together structurally while functioning separately. The rotational control is transmitted by the rotary knob ( 2, 23 ), while key, linear movement, control is transmitted through the separate key ( 5, 30 ).

Description:
BACKGROUND OF THE INVENTION 
     This application claims a foreign priority date of German application 199 64 131.5, filed on Nov. 22, 1999, and the contents of that application is incorporated herein by reference. 
     This invention relates to a rotary knob device, or rotary switch, having a key function for manipulating control elements of a type including a hollow rotary knob which can be rotated to manipulate a first electrical control element and a key mounted in the rotary knob which can be linearly move within the rotary knob to manipulate a second electrical control element. 
     Rotary knob devices having a key function which are part of a rotary switch and/or a rotary controller are used in operating units, for example in automotive engineering. 
     Such a rotary knob is disclosed in German patent document 196 36 643 C1, where keying is performed at an end face of a top part of a rotary knob. The keying itself is performed centrally by additional switch mechanisms. When the rotary knob is rotated, the key is rotated as is a symbol on a top part of the key. This is a disadvantage, particularly when the symbol on the key should always remain horizontally in the same position. Another problem arises when central illumination of the function of the key is to be performed in addition to central contacting. 
     It is an object of this invention to provide a rotary knob device having a key in a rotary knob which remains horizontal even when the rotary knob is rotated. Another partial object is to provide a structure which allows a central illumination of the key along with central electrical contacting when keying. 
     SUMMARY OF THE INVENTION 
     According to principles of this invention, a rotary knob device having a key function includes a hollow rotary knob which can be rotated to manipulate a first electrical control element, a key mounted in the rotary knob which can be linearly move within the rotary knob to manipulate a second electrical control element and a holder which supports both the rotary knob and the key such that each can be moved on the holder separately from the other. 
     This invention is based on the idea of structuring a holder for supporting a rotary knob and a key in the rotary knob to be functionally separated from one another so that the key is not also rotated when the rotary knob is rotated. This holder is the structural connection between the rotary knob and the key. The rotational adjustment is transmitted through the rotary knob, while the key-function adjustment is carried out separately through the key. For central illumination and central contacting of the key at the same time, a flexible switch push member having a central bore is provided with electrical contacts mounted around it, preferably in a ring arrangement. Light needed for illumination can be introduced through the bore into the key. 
     Additional advantageous embodiments are also described. 
     Accordingly, a mating component of the rotary knob is movably mounted on the holder while the key is securely connected directly to the holder. The advantage here is that the key does not require additional alignment with a base plate or circuit board because the rotary switch can be designed as a compact individual part. A mounting of the rotary switch device in a panel may also be accomplished by the holder. 
     However, the holder may also be fixedly mounted on the mating component of the rotary knob in the rotary switch device or it may be part of the mating component. 
     The torque may be transmitted either directly or indirectly, with a variable-film potentiometer plate being mounted on the mating component of the rotary knob for direct transmission, while peripheral teeth are.provided on the mating component for an indirect transmission so that rotation is transmitted non-centrally to an electronic component. 
     Advantages of the proposed solution include, in addition to retaining the horizontal position of the key and the key symbol, the fact that a central homogeneous illumination of the key symbol and a central contacting beneath the key are accomplished independently of the rotational adjustment of the rotary knob of the rotary switch or the rotary control. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further benefits, characteristics and details of the invention are explained in more detail below using an embodiment shown in the drawings. The described and drawn features, can be used individually or in preferred combinations in other embodiments of the invention,. The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention, as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention in a clear manner. 
     FIG. 1 is a side sectional view of a rotary switch having a key function of this invention, 
     FIG. 2 is a side sectional view of a second embodiment rotary switch of this invention, 
     FIG. 2 a  is a top view of the rotary switch of FIG. 2, and 
     FIG. 3 is a side sectional view of a second embodiment rotary switch this invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a rotary controller  1 , in a structurally-compact form, including a hollow rotary knob  2  that cooperates with a rotary-knob substructure  3 . This rotary controller  1  is mounted in a cover panel  4 , for example a front panel of a motor vehicle dashboard. In addition, a key  5 , which is mechanically held by a holder  6 , is also integrated into the rotary knob  2 . The rotary-knob substructure  3  is loosely positioned on the holder  6 . The key  5  has perpendicular guide grooves  5 . 1  in which the holder  6  engages with its holding fingers  6 . 1 , thus joining the key  5  to the holder  6  in a twist-proof manner. For uniform keying, three guide grooves  5 . 1  are preferably provided. A key path here is limited by a depression  2 . 1  in the rotary knob  2  and a length of the guide groove(s)  5 . 1 . 
     The key  5  is preferably a hollow key element, so that holding fingers  6 . 1  engage inside the key. The key  5  also has an light guide  9 , one end of which preferably extends inside the key  5  and projects into a head area of the key  5  to illuminate a key symbol  10 . 
     In a preferred embodiment, when keying, the key  5  engages, via the light guide  9 , a contact dome  11 . 1  of a switch push member  11  having a central bore  11 . 2  for light of a light element  12  such as an LED. Via this contact dome  11 . 1 , contacts in the switch push member  11  and contacts of a circuit board  13  are centrally contacted. 
     For transmission of rotational information of the rotary switch  1  to an electronic component (not shown), the rotary-knob substructure  3  has a variable-film potentiometer plate  14  which contacts another contact element  15  of a circuit board  13 . The holder  6  itself prevents the key  5  from turning when the rotary knob  2  is turned, but it does not prevent movement of the variable-film potentiometer plate  14  relative to the contact element  15 , which thereby picks up different voltage values. 
     It is advantageous that the assembly of the individual elements is fixed in the panel  4  by the holder  6 . The holder  6  preferably has there for two U-shaped catch elements  6 . 2  which project away from an intermediate space between two holding fingers  6 . 1 , while leaving a free space to pick up the voltage value at contact element  15 . 
     FIG. 2 shows a rotary switch  20  having a key function. It can be integrated into a housing  24  as a mating piece for a hollow rotary knob  23  behind a cover panel  19  such as a front panel of an automotive operating unit (FIG. 2 a ). To illuminate the function symbol of the rotary switch  20 , that is a symbol  21 , a light panel  22  with activation is mounted beneath symbol(s)  21 . 
     The rotary switch  20  has a key  30  in the rotary knob  23 , which is mounted axially in the rotary knob  23  and in the housing  24  and which has a defined movement path with respect to the housing  24 . The key  30  is guided by a holder  24 . 1  of the housing  24  during keying. 
     A light guide strip  31 , for example, may be integrated into the key  30 , through which light of an LED  32  of a circuit board  25  is guided to a function display  33  which displays a function of the key  30 . A further symbol  34  serving as a function symbol of the key  30 , for example “circulating air” (FIG. 2 a ), is provided in a top part of the key  30  and is illuminated by another LED  35  of the circuit board  25 . Above the LED  35  there is a switch push member  36  having a central bore  36 . 1  with contacts arranged thereon, preferably in a circle. This switch push member  36  is provided with an additional lens system  38 , preferably above the central bore  36 . 1 . Through this lens system  38 , light of the LED  35  passes through a hollow part  39  of the key  30  to the symbol  34 . 
     Keying takes place aside from the rotary knob  23 . In this regard, the key  30  with the light guide strip  31  and the hollow part  39  is moved in the direction of the circuit board  25 , with the key  30 , via the lens system  38 , engaging a head part  37  of the switch push member  36 , which yields to pressure. Beneath the switch push member  36 , the contacts of the switch push member  36  come into contact with contacts of the circuit board  25 . The light guide strip  31  is moved in the direction of LED  32  at the same time, resulting in better light coupling for the function display  33 . 
     The rotary position of rotary knob  23  can be transmitted directly and centrally through a variable-film potentiometer plate (not shown in detail here) beneath rotary knob  23 . The Holder  24 . 1  is structured so that the key  30  remains in its starting position when the rotary knob top part  23  is turned. 
     An indirect non-centered transmission of the rotary adjustment to an electronic component, for example, a potentiometer  40  of the rotary switch  20 , is possible through gear teeth  26  on the rotary knob  23 . However, this potentiometer  40  may also be adjusted during keying, to which end the rotary switch  20  has a pinion  27  which is moved during keying. 
     This type of gear teeth may also be mounted on the rotary knob  2  of rotary switch  1  (not shown in detail here), which would also result in an non-centered transmission of the rotational adjustment. 
     In another embodiment (FIG.  3 ), based on related art, a variable-film potentiometer plate  38 ′ is connected with the hollow rotary knob  23 , for example a rotary resistor. The variable-film potentiometer plate  38  is preferably located beneath the light panel  22 , which is preferably integrated into the rotary knob  23 . Keying is accomplished as described above through the key  30 , and illumination of the key symbol  10  is accomplished through the bore  36 . 1  of the switch push member  36 . 
     Use of the rotary knob  2 ,  23  is not limited to automotive engineering. For example, the rotary knob  2 ,  23  may also be used in switch panels and control boards, etc.