Patent Publication Number: US-11385736-B2

Title: Control element, system, use and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of foreign priority to German Patent Application No. DE 10 2018 127 494.7, filed Nov. 5, 2018, which is hereby incorporated by reference in its entirety for all purposes. 
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates to a control element for a display unit, a system including such a control element and a display unit, a use of such a control element and a method for operating a display unit in conjunction with such a control element. 
     2. Related Art 
     Displays in vehicles and especially in dashboards are convenient utilities in modern vehicles. With the displays getting bigger, multiple information can be displayed in one display. In addition, the number of displays increases along with the increasing number of sources providing information for passengers especially for the driver. Rotary round push button, also commonly known as jog dials, have become one intuitive control for navigating through menus and making selections of menu items. However, with multiple information and multiple level of complexity, controlling displays with conventional jog dials can be cumbersome. 
     SUMMARY 
     In an aspect, schemes are provided which solve the complexity of menu navigation and item selection by providing an efficient approach for navigating through menus or making selections of menu items for the various types of displays in vehicles and at the same time are still easy and inexpensive to use and realize. 
     In an aspect, a control element for navigating through at least one menu of at least one display unit and/or for selecting of at least one menu item of the menu, includes: at least one housing body having at least one first housing part and at least one second housing part, whereby the second housing part is rotatable relative to the first housing part; at least one finger element, whereby the finger element rotates relative to the first housing part when the second housing part is rotated relative to the first housing part, whereby at least one bottom surface of the finger element lies at least in areas in at least one first plane; and at least one key element having at least one button element, and at least one selection element, whereby the button element is operatively connected to the selection element, whereby actuating the button element causes the selection element to move relative to the first housing part and/or the second housing part and to approach and/or to touch the first plane. 
     In one embodiment, a first direction is defined by at least one axial extension of the housing body especially in a direction parallel to a vector pointing from bottom to top of the control element. 
     In another embodiment, the control element further includes at least one wall element directly or indirectly connected to the second housing element, wherein the wall element rotates, especially around at least one central axis of the control element, relative to the first housing part when the second housing part is rotated relative to the first housing part, the wall element has at least in areas a hollow-cylindrical shape, the wall element is arranged at least in areas within the space enclosed by the housing element, by the first housing part and/or second housing part, and/or actuating the button element causes the selection element further to move relative to the wall element. 
     In yet another embodiment, the control element further includes at least one fastening element for fastening the control element on the display unit, especially on at least one position of a screen area included by the display unit, whereby preferably the fastening element is rotatably mounted in the housing body, especially in the first housing part and/or in the second housing part, relative to the first housing part and/or second housing part, the fastening element includes at least in areas, especially at at least one end and/or bottom surface of the fastening element, preferably the end and/or bottom surface pointing to the first plane, at least one first electrical conductive and/or magnetic material, especially for fastening the control element, the fastening element includes, especially at at least one end and/or bottom surface of the fastening element, preferably the end and/or bottom surface pointing to the first plane, at least one first electrical conductive and/or magnetic element, especially for fastening the control element, the fastening element includes at least one suction cup and/or at least one bottom surface of the fastening element lies at least in areas in the first plane. 
     In one embodiment the control element further includes at least one valve element, especially for supporting cancelling of a suction force built by the suction cup, having at least one valve body and at least one valve member moveable at least in sections inside the valve body, whereby the valve member is fixedly connected to the second housing part, whereby the valve body goes through the plate element and/or the valve body is fixedly connected to the first housing part and/or the suction cup. 
     In the two aforementioned embodiments it is also preferred that a suction force built by the suction cup is cancelable by pulling the second housing part away from the first housing part, especially along the first direction, the valve member can be moved from at least one first position to at least one second position, especially along the first direction, to establish a fluidal connection between at least one suction body included by the suction cup and the outside of the suction cup, preferably at least one space enclosed by the housing body, more preferably enclosed by the first housing part and/or enclosed by the second housing part, and/or the valve member can be moved from the second position to the first position, especially opposite the first direction, to interrupt the fluidal connection. 
     In another embodiment, the control element further includes at least one plate element, especially for increasing stability of the control element, wherein the plate element is directly or indirectly connected to the second housing element and/or directly or indirectly connected to the wall element, the plate element rotates around the central axis of the control element, relative to the first housing part when the second housing part is rotated relative to the first housing part, the plate element is arranged at least in areas within the space enclosed by the first housing part, the plate element includes at least one means, especially at least one hole, for guiding the key element, especially the selection element, along and/or opposite the first direction at least in sections and/or actuating the button element causes the selection element further to move relative to the plate element. 
     In one embodiment the second housing part has at least in areas a dome-like shape, especially for improving stability and/or usability of the control element, the first housing part, the second housing part, the plate element, the wall element, the valve element, especially the valve member and/or the valve body, and/or the suction cup are at least essentially arranged concentrically and/or the first housing part and the second housing part are stacked on each other at least in areas, especially along the first direction and/or in at least one cross-sectional plane, the plane preferably being perpendicular to the first direction. 
     In yet another embodiment, the first housing part has at least in areas a hollow-cylindrical shape, especially for allowing a compact design of the control element, the first housing part includes at least in areas, especially at at least one end of the first housing part, preferably the end pointing to the first plane, at least one second electrical conductive and/or magnetic material, especially for fastening the control element, the first housing part includes, especially at at least one end and/or bottom surface of the first housing part, preferably the end and/or bottom surface pointing to the first plane, at least one second electrical conductive and/or magnetic element, especially for fastening the control element, and/or the bottom surface of the first housing part lies at least in areas in the first plane. 
     In another embodiment, the finger element includes at least in areas, especially at at least one end and/or at the bottom surface of the finger element, preferably the end and/or bottom surface pointing to the first plane, at least one third electrical conductive and/or magnetic material, especially for allowing the finger element to be detected, includes, especially at at least one end and/or the bottom surface of the finger element, preferably the end and/or bottom surface pointing to and/or lying in the first plane, at least one third electrical conductive and/or magnetic element, especially for allowing the finger element to be detected, is arranged at least partly inside and/or outside the space enclosed by the housing body, especially enclosed by the first housing part and/or by the second housing part, and/or is fixedly connected to the second housing part and/or the wall element. 
     In yet another embodiment, actuating the button element includes and/or is represented by pressing the button element, the key element, especially the selection element and/or the button element, is movable, preferably along and/or opposite the first direction and/or against the preload of at least one spring element, especially at least one coil spring, the selection element and the button element are formed in one piece, at least one first end of the key element includes the selection element and/or at least one second end, preferably opposite to the first end, includes the button element, the key element, especially the selection element and/or the button element, rotates, especially around the central axis of the control element, relative to the first housing part when the second housing part is rotated relative to the first housing part and/or the button element is moveable at least in sections through the second housing part, especially in a direction parallel and/or opposite the first direction. 
     In one embodiment, the key element, especially the selection element, includes at least in areas, especially at at least one end of the key element, especially the selection element, preferably the end pointing to the first plane, at least one fourth electrical conductive and/or magnetic material, especially for allowing the key element to be detected, the key element, especially the selection element, includes, especially at at least one end and/or bottom surface of the key element, especially the selection element, preferably the end and/or bottom surface pointing to the first plane, at least one fourth electrical conductive and/or magnetic element, especially for allowing the key element to be detected, the selection element extends at least in sections in the space enclosed by the first housing part, the selection element is designed at least in areas cylindrically, the selection element is, especially moveable, arranged at the second housing part, the wall element and/or the plate element and/or is movable relative to at least the first housing part, the second housing part, the wall element and/or the plate element, especially along at least the first direction. 
     In another embodiment, the key element, especially the selection element and/or the button element, is arranged with an offset, especially for allowing to distinguish between different key elements, preferably by 90 degree, 180 degree or 270 degree, relative to the finger element, especially along an arc of a circle and/or in at least one cross sectional plane, preferably the plane being perpendicular to the first direction. 
     In yet another embodiment, the control element includes a plurality of key elements, preferably two, three, four, five, six, seven, eight, nine, ten and/or more than ten key elements, whereby preferably the offset between two adjacent key elements, especially along an arc of a circle and/or in at least one cross sectional plane, preferably the plane being perpendicular to the first direction, is identical to the offset between the finger element and at least one key element, especially the first key element on the arc of the circle arranged clockwise adjacent and/or anti-clockwise adjacent to the finger element. 
     In another aspect, a system includes at least one display unit and at least one control element, for navigating through at least one menu of the at least one display unit and/or for selecting of at least one menu item of the menu, according to at least one embodiment of the first aspect of the invention, whereby especially the display unit is included by at least one rear view device, to which preferably the control element is attached and/or attachable. 
     In one embodiment, the display unit includes at least in areas at least one magnetic and/or ferromagnetic material behind and/or in the screen area included by the display unit and/or at least one evaluation tool for detecting the presence and/or the location of magnetic fields and/or electrical conduciveness of objects approaching and/or touching the screen surface of the display unit and/or of a change in capacity due to objects approaching and/or touching the screen surface of the display unit. 
     In another aspect, a method of using a control element includes navigating through at least one menu of at least one display unit and/or selecting of at least one menu item of the menu. 
     In another aspect, a method for operating a display unit, especially in conjunction with a control element and/or a system includes: detecting the presence of the control element attached at a designated area of a display unit, especially by means of detecting the presence of a first electric conductive and/or magnetic member, preferably the fastening element, more preferably the first electric conductive and/or magnetic element, and/or the first housing part, more preferably the second electric conductive and/or magnetic element, on or near the display unit; and preferably displaying on the display unit the respective menu corresponding to the display unit, especially the area thereof, the control element is attached to and/or adapting the displayed menu to where the control element is located; calculating a first selection location based at least on detecting the position of a second electric conductive and/or magnetic member, preferably the finger element, more preferably the third electric conductive and/or magnetic element, relative to the position of the first electric conductive and/or magnetic member on or near the display unit; and preferably updating the display of the display unit dependent on the first selection; calculating a second selection location based at least on detecting the position of the second electric conductive and/or magnetic member, preferably the finger element, more preferably the third electric conductive and/or magnetic element, relative to the position of the first electric conductive and/or magnetic member on or near the display unit, preferably in reaction to detecting a rotation of the control element, especially a rotation of the second electric conductive and/or magnetic member; and preferably Updating the display of the display unit dependent on the first selection; identifying a third selection location, especially which key element was actuated, based at least on detecting the position of a third electric conductive and/or magnetic member, preferably the key element, more preferably the selection element, even more preferably the fourth electric conductive and/or magnetic element, relative to the position of the second electric conductive and/or magnetic member on or near the display unit, preferably in reaction to detecting an actuated key element; and preferably updating the display of the display unit and/or triggering a predefined action. 
     According to aspects of the present disclosure, by providing a free placement control element, especially in form of a rotary button, the complexity of the control element for menu navigation and menu item selection can be improved. The possibility to arrange the control element at different physical positions at the display unit especially at at least one screen included by the display unit provides a source of control information and an additional level of control on its own. This in turn allows to reduce the number of different elements required for the control element to a manageable number, hence, leading to a control element which is more intuitive to use. In addition, due to omitting the need for electronic components, the complexity of the entire system is further reduced. This in turn leads to a significant cost reduction concerning the components and also allows for a cheaper manufacturing of the control element. In addition weight is reduced. Furthermore, the control element is useable independent from any power sources, which increases the comfort to use it and decreases failure of the control element. 
     In this respect it has been found that navigation through the selection menu is possible by means of at least one finger element which can be tracked by a respective display unit the control element is attached to in that the finger element includes at least one electrical conductive and/or magnetic material and/or at least one respective element, especially a respective third material and/or third element. This allows the display unit to evaluate a flow of electrical current, a change in capacity and/or a magnetic field in order to detect the presence and/or position of the finger element. The respective detected location of the finger element, alternatively and/or in addition may preferably further be evaluated in conjunction with its relative position to the position of a fastening element (described in greater detail below), included by the control element for fastening it to the display unit, in order to better determine the menu selection. At least one bottom surface of the finger element lies at least in areas in a first plane. This first plane for example might be the top surface of the display unit, especially the surface of the screen. 
     Further, making a selection of a menu item can be accomplished by actuating a key element. The key element in turn includes a selection element which includes at least one electrical conductive and/or magnetic material and/or at least one respective element, especially a respective fourth material and/or fourth element. By actuating the key element, the fourth material and/or fourth element is approaching the first plane and may even in addition and/or alternatively touch the first plane. This means that when actuating the key element at least the finger element and at least one key element (especially its respective selection element) can be detected as being present in the first plane and/or approaching the first plane. This way, also for detecting the actuation of a key element can be realized in that the display unit (or a respective controller) evaluates a flow of electrical current, a change in capacity and/or a magnetic field in order to detect the presence and/or position of the key element. Advantageously, it has been found that if the position of the detected key element is evaluated relative to the position of the detected finger element, it is possible to support more than one key element since the relative position allows to discriminate between the different keys. This only requires that the plurality of key elements are arranged in a known manner relative to each other and/or relative the finger element. 
     The control element advantageously includes a fastening element, mentioned above, which at the same time allows to detect the presence of the control element at the display unit and the location it is arranged at. This in turn allows to control different appearances of the display of the display unit dependent on the position the control element is attached to the display unit. Especially if the fastening element includes at least one first electrical conductive and/or magnetic material and/or element this task can be accomplished in a quite easy and effective way. Evaluation of the presence and/or the position can be accomplished preferably as described before with respect to the finger element and the key element by a flow of electrical current, a change in capacity, and/or a magnetic field being evaluated. 
     Preferably the fastening element alternatively and/or in addition might include at least one suction cup. This allows a comfortable attachment of the control element at the display unit. In order to further allow an easy detachment of the suction cup (i.e. the control element) from the display unit the control element may include a valve element. In that the valve member is on the one hand moveable inside the valve body (between at least first and second positions) and on the other hand is fixedly connected to the second housing part, it is possible to achieve the establishment of a fluidal connection between the inside of the suction cup and the atmosphere when the second housing part is pulled, i.e. when the control element is pulled off the display unit, so that the suction force built by the suction cup is canceled. At the same time, when the control element is attached to the display unit, i.e. when the second housing part is pushed, the fluidal connection is interrupted. 
     In order to realize a safety function of the key element(s), a plate element may be provided which can be designed such that it guides the key element(s), especially by means of respective holes through which the key element(s), especially the selection element(s), goes. 
     The control element can be advantageously used in conjunction with a display unit. The control element preferably allows the display unit to identify the position where the control element has been attached to. For example, the touch screen display of the display unit may detect the location of the control element on the screen. Dependent on the physical location to which the control element is attached to at the display unit, especially the display screen, a location-dependent menu and/or navigation may be displayed by the display unit. This allows to simplify menu structures since the location is a further parameter which can be used as a preselection. 
     Alternatively or in addition, it may be acknowledged: 
     1. Placement and location detection: Touch sensor subsystem on display detects and locates the placement of rotating button on the screen. This then triggers the dedicated menu that displayed around the button based on location on the screen. 
     2. Rotation detection: One conductive body rotates with the rotating body. This triggers multitouch sensor on screen to detect the rotation displacement. 
     3. Selection Detection: When user pushes button, this make a conductive body touches the screen. Based on relative position of the rotating body, then the multitouch subsystem detects this action. 
     Further, it may be acknowledged alternatively or in addition: 
     1. Attachment mechanism to screen that not only keep the button in place but also trigger the location detection of touch sub-system: Can be done by magnet or (micro)suction that has electrical conduction characteristics. 
     2. Rotating conductive that follows the movement of rotating body so that the displacement of conductive gives enough capacitive change for the touch sensor to detect the rotation movement: This then trigger the pre-selection menu on the screen based on the rotation movement. 
     3. A secondary moving conductive that the position relative to surface of touch screen is change between contact to non-contact according the operation of “push button”: When the user pushes the button then the capacitive changes, which trigger “selection” action. This system may contain multiple buttons in one system. 
     4. Mechanism that triggers conductive pole movement along with button movement, and also mechanism to trigger conductive pole(s) to touch the display surface following button (s) press. 
     5. Identification of pressed button based on relative placement of “rotating conductive pole” and touching poles when a button is pressed. 
     6. Outer body material and its conductivity to internal conductive poles, that human body model can give enough capacitance discharge change of projected capacitive touch subsystem to detect conductive pole movement and conductive pole touch. 
     7. Rotation information is fetched by this displacement on the touch screen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration, certain examples of the present disclosure are shown in the drawings. It should be understood, however, that the present disclosure is not limited to the precise arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of system, apparatuses, and methods consistent with the present disclosure and, together with the detailed description, serve to explain advantages and principles consistent with the present disclosure, wherein: 
         FIGS. 1 a  and 1 b    show schematic representations of a control element according to a first embodiment; 
         FIGS. 2 a , 2 b , and 2 c    show schematic representations of the inside of a control element according to a second embodiment; 
         FIGS. 3 a  and 3 b    show schematic representations of a control element according to a third embodiment; 
         FIGS. 4 a , 4 b , and 4 c    show schematic representations of systems; 
         FIG. 5 a    shows an interior of a vehicle having multiple display units 
         FIG. 5 b    shows a schematic illustrations of displays of a display unit in  FIG. 5   a;    
         FIG. 6 a    shows a schematic illustration of a screen of a display unit; 
         FIG. 6 b    shows a schematic illustration of a bottom view on a control element; 
         FIG. 6 c    shows schematic illustrations of a system with actuated key elements; 
         FIG. 7 a    shows schematic illustrations of different menu selections; 
         FIG. 7 b    shows schematic illustrations of different menu item selections; 
         FIG. 8  shows a flow chart; and 
         FIG. 9  shows a flow chart of a method. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
     It is to be understood that the phraseology and terminology employed herein are for the purpose of describing the present disclosure and should not be regarded as limiting. For example, the use of a singular term, such as, “a” is not intended as limiting of the number of items. Also the use of relational terms, such as but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” are used in the description for clarity and are not intended to limit the scope of the present disclosure or the appended claims. Further, it should be understood that any one of the features can be used separately or in combination with other features. Other systems, methods, features, and advantages of the present disclosure will be or become apparent to those skilled in the art upon examination of the description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. 
       FIG. 1 a    shows a control element  1  in a perspective top view including a housing body  3  having a first housing part  5  and a second housing part  7 . The second housing part  7  can be rotated relative to the first housing part  5 . A first direction D is defined by the axial extension of the housing body  3  in a direction parallel to a vector pointing from bottom to top of the control element  1 . The second housing part  7  has at least in areas a dome-like shape. The control element  1  further includes a single key element having a button element  9 . The button element is movable through the second housing part  7  in a direction parallel and/or opposite the first direction D. 
       FIG. 1 b    shows the control element  1  in a perspective bottom view. The key element further has a selection element  11 . The selection element includes at least one fourth electrical conductive and/or magnetic element  12 . The control element  1  further includes a fasting element  13  for fastening the control element  1  on a display unit. The fastening element  13 , therefore, includes a first electrical conductive and/or magnetic element  15 . The control element  1  further includes a finger element  17 . The finger element  17  includes a third electrical conductive and/or magnetic element  19 . The bottom surface of the finger element  17  shown in  FIG. 16  lies in a first plane (not explicitly shown in  FIG. 1 b   ). 
     As can be seen in  FIG. 1 b    the first housing part  5  has at least in areas a hollow-cylindrical shape and at least one bottom surface  21  of the first housing part  5  also lies in the first plane. Further, the bottom surface of the fastening element  13  lies in the first plane. This preferably allows to arrange the control element  1  at a display unit, especially at the respective screen display, whereby the bottom surfaces of, respectively, the first housing part  5 , the fastening element  13  and the finger element  17  commonly touches the screen surface. 
     The control element  1  further includes a plate element  23  which includes at least one hole  25  for guiding the selection element  11  along the first direction D at least in sections. 
     The button element  9  is operatively connected to the selection element  11 , whereby actuating the button element  9  causes the selection element  11  to move relative to the first housing part  5 , the second housing part  7  and the plate element  23  and to approach and/or touch the first plane. Actually the selection element  11  is movable along and/or opposite the first direction D. By approaching and/or touching the first plane a further electrical conductive and/or magnetic material/element (i.e. the fourth material and/or element) can be detected in and/or near the first plane. 
     Thus, control element  1  uses one key element for selection and a second housing part  7  that extends to half of the housing body  3 . 
     The finger element  17 , the key element, especially the button element  9  and the selection element  11 , and the plate element  23  rotate, especially all together and/or around the central axis X of the control element, relative to the first housing part  5  when the second housing part  7  is rotated relative to the first housing part  5 . 
     As the finger element  17  rotates along with the second housing part  7  a selection of menu can be calculated based on the position of the finger element  17 , especially the third electrical conductive and/or magnetic element  19 , relative to the fastening element  13 . 
     When the button element  9  is actuated, especially pressed, the selection element  12  moves lower so that it makes a contact with this screen of the display unit, especially a touch panel surface. The subsystem of the display unit then triggers a “selection” action based on this pressed button element  9 , as will be described later in greater detail. 
     The first housing part  5  may be made of magnetic material for attachment mechanism but also can be made of electrical conductive material or even electric nonconductive material. 
     The material chosen for the fastening element  13  may be an electrical conductive material and/or magnetic material. The touch panel subsystem then detects this material characteristics (electrical conductive/magnetic) as the fastening element  13  is placed on the screen. At the same time the fastening element  13  behaves as attachment mechanism. Therefore, the material may be a magnetic one. 
     Of course, another design may have a second housing part that is separated from the key element, which makes the key element stays on its place during rotation of the second housing part relative to the first housing part. 
       FIGS. 2 a -2 c    show as schematic representation of the inside of a control element  1 ′ according to a second embodiment of the first aspect of the invention in a partly explosion representation. Elements which functionally correspond as far as possible to those of control element  1  shown in  FIG. 1 a    and  FIG. 1 b    are provided with the same reference signs, however, single dashed. 
     In  FIG. 2 a    a finger element  17 ′ is arranged at a wall element  27 ′ which is directly connected to a second housing part (not shown in  FIG. 2 a   ), whereby the wall element  27 ′, hence the finger element  17 ′, rotates relative to a first housing part (not shown in  FIG. 2 a   ) when the second housing part is rotated relative to the first housing part. The wall element  27 ′ is arranged within the space enclosed by the first housing part. Further the control element  1 ′ includes three key elements, of which the respective three selection elements  11 ′ are shown in  FIG. 2 a   . The control element  1 ′ further includes a fastening element  13 ′ which in turn includes a first electrical conductive and/or magnetic element  15 ′. 
       FIG. 2 b    shows the elements of  FIG. 2 a    in their final position. 
       FIG. 2 c    shows two bottom views of the arrangement shown in  FIG. 2 b   . The bottom view on the left-hand side of  FIG. 2 c    shows the control element  1 ′ with the finger element  17 ′ being at the 12 o&#39;clock position and the three selection elements  11 ′ being at the, respectively, 3 o&#39;clock position, 6 o&#39;clock position and 9 o&#39;clock position. The bottom view on the right-hand side of  FIG. 2 c    shows the control element  1 ′ with the finger element  17 ′ being at the 3 o&#39;clock position and the three selection elements  11 ′ being at the, respectively, 6 o&#39;clock position, 9 o&#39;clock position at the 12 o&#39;clock position. From this representation it can be especially taken that the offset between two adjacent selection elements  11 ′ along an arc of a circle in at least one cross-sectional plane perpendicular to the first direction D′ is identical to the offset between the finger element  17 ′ and the first selection element  11  on the arc of the circle arranged clockwise adjacent to the finger element  17 ′. In other words the finger element  17 ′ and the selection elements  11 ′ are arranged with an offset of 90° in a clockwise direction. 
     From  FIGS. 2 a -2 c   , it is evident that the control element  1 ′ includes only passive components, hence, it has low manufacturing and component costs, has zero risk of power outage during operation and has low weight. 
     In total, the control element  1 ′ includes at least four at least in areas electrical conductive and/or magnetic elements: One for rotation detection (i.e. the finger element) and three for selection detection (i.e. the selection elements). The selection elements  11 ′ rotate with the second housing part and touches the display surface when the buttons are actuated. The finger element  17 ′ rotates with the second housing part and is always in contact with the display surface. 
       FIGS. 3 a -3 b    show as schematic representation of a control element  1 ″ according to a third embodiment of the first aspect of the invention. Elements which functionally correspond as far as possible to those of control element  1  shown in  FIG. 1 a    and  FIG. 1 b    or to the control element  1 ′ shown in  FIGS. 2 a -2 c    are provided with the same reference signs, however, doubled dashed. 
     In  FIG. 3 a   , a perspective bottom view of the control element  1 ″ is shown. The fastening element  13 ″ included by control element  1 ″ includes a suction cup  29 ″ in form of a suction body. The suction cup  29 ″ may preferably use conductive material for on-screen placement detection. Preferably the control element  1 ″ instead may include two finger elements  17 ″, hence also two third electrical conductive and/or magnetic elements  19 ″ are present which always have contact with a screen of the display unit where the control element  1 ″ is attached to. 
     In  FIG. 3 b   , a perspective and partly cross-sectional side view of the control element  1 ″ is shown. The control element  1 ″ further includes a valve element  31 ″ having a valve body  33 ″ and a valve member  35 ″ moveable at least in sections inside the valve body  33 ″. The valve member  35 ″ is fixedly connected to the second housing part  7 ″. The valve body  33 ″ goes through the plate element  23 ″ and is fixedly connected to the suction cup  29 ″. When the upper part of the housing body  3 ″, i.e. the second housing part  7 ″, is pulled, the valve element  31 ″ is released and air can flow into the suction cup  29 ″. In other words the valve body  33 ″ moves along with the second housing part  7 ″ in a direction along the first direction D″ when pulled, and let air flows into the suction cup  29 ″. As consequence, the pull action then will cancel the suction force and release the control element  1 ″ from the display unit the control element  1 ″ is arranged at. 
       FIG. 4 a -4 c    show schematic representations of a system  37 ′″ including a control element  1 ′″ according to the first aspect of the invention and a display unit  39 ′″ to which the control element  1 ′″ is attached and/or attachable. Elements which functionally correspond as far as possible to those of control element  1  shown in  FIG. 1 a    and  FIG. 1 b   , to the control element  1 ′ shown in  FIGS. 2 a -2 c   , or to the control element  1 ″ shown in  FIG. 3 a -3 b    are provided with the same reference signs, however, tripled dashed. 
       FIG. 4 a    shows the system  37 ′″ in a perspective view. 
       FIG. 4 b    shows the system  37 ′″ with a first fastening mechanism. The first housing part of the control element  1 ′″ includes a second electrical conductive and/or magnetic element  41 ′″ which is arranged at the bottom surface of the first housing part. The second electrical conductive and/or magnetic element  41 ′″ may be provided alternatively and/or in addition to a fastening element. Especially the second electrical conductive and/or magnetic element  41 ′″ may be used to reinforce the attachment force. For this configuration the display unit  39 ′″ includes at least in areas a magnetic and/or ferromagnetic material  43 ″″ behind and/or in at least one screen area. This is a quite simple design of the control element  1 ′″ and does not require cleaning of the display unit  39 ′″. 
       FIG. 4 c    shows the system  37 ″′ with a second fastening mechanism. The control element  1 ′″ is attached to the display unit  39 ′″ by means of a suction cup  29 ′″. Thus, no need for additional electrical and/or magnetic structures on the display are required which leads to lower cost. 
       FIG. 5 a    shows an interior of a vehicle having multiple display units  39 ″″.  FIG. 5 b    shows schematic illustrations of displays of the respective display units  39 ″″ dependent on which of the three display units  39 ″″ a control element according to the first aspect of the invention is attached to. As can be taken from  FIG. 5 b   , if the control element is arranged on the left-side display unit  39 ″″ a basic car control navigation menu is shown on the respective display unit  39 ″″. If the control element is arranged on the middle display unit  39 ″″ a navigation control navigation menu is shown on the respective display unit  39 ″″. If the control element is arranged on the right-side display unit  39 ″″ a multimedia control navigation menu is shown on the respective display unit  39 ″″. 
       FIG. 6 a    shows a schematic illustration of a screen in form of a touch sensor pattern of the display unit to which the control element according to the first aspect of the invention can be attached to with annotations regarding principal values. The figure is with respect to considerations of projective capacitive touch sensor design to each conductive body distance. Wmin and Dmin depending on the attached performance specifications, which are influenced by the conductive material, the sensor pattern, the cover material thickness and the touch controller IC performance. For example Wmin and Dmin may be 1.5 times of the sensor pitch. This in turn means that for sensor pattern which has for example 5 mm pitch, both, Wmin and Dmin usually needs to be bigger than 7.5 mm. 
       FIG. 6 b    shows a schematic illustration of a bottom view of a control element according to the first aspect of the invention, such as the one from the left-hand side of  FIG. 2 c   , especially the control element  1 ′, with annotations regarding principal values in conjunction with  FIG. 6 a   . If dmin is the minimum finger separation distance then d 1 , d 2 , d 3 , d 4 , d 5 &gt;=dmin. If Wmin is the minimum metal slug diameter for touch subsystem to detect then Wpole&gt;=Wmin. 
       FIG. 6 c    shows in the top row schematic illustrations of bottom views of a control element according to the first aspect of the invention, especially the control element  1 ′, in two different rotation configurations as already known from  FIG. 2 c   . In the bottom row  FIG. 6 c    shows schematic illustrations of the side views of the respective control elements with different key elements actuated. In the left column (finger element  17 ′ at 12 o&#39;clock position) the key element at 6 o&#39;clock is actuated, i.e. the respective button element is pressed and the respective selection element touches the screen of a display unit  39   a . In the right column (finger element  17 ′ at 3 o&#39;clock position) the key element at 6 o&#39;clock (which in the left column was the key element at the 3 o&#39;clock position) is actuated, i.e. the respective button element and the respective selection element is pressed. 
       FIG. 7 a    shows a schematic illustration of different menu selections, i.e. different rotation positions of a finger element, for example finger element  17 ′, on a display unit  39   b . Or in other words  FIG. 7 a    illustrates rotation detection of a control element placed on the screen of the display unit  39   b . The touch sensor may preferably detect that the control element is placed by detecting its “preregistered shape”. For example, it is outer round body (first housing part), inner round pillar (fastening element) and rotating pillar (finger element).  FIG. 7 a    shows how the touch sensor identifies the rotation: 12 O&#39;clock selection, 1 O&#39;clock, 4 O&#39;clock, 9 O&#39;clock selection respectively, especially by comparing the relative position of the finger element, especially finger element  17 ′, and the fastening element, especially fastening element  15 ′. The “on screen menus” can be placed accordingly, considering the “minimum displacement/movement” of touch sensor characteristics. 
       FIG. 7 b    shows a schematic illustration of different key elements actuated, for example by means of the different selection elements  11 ′. Actuating a key element (i.e. pressing the button element) is detected by the touch subsystem of the display unit  39   b , e.g. by identifying “additional touching object(s)” within the preset area of “Rotating button”, and its relative position to “rotating pillar” (finger element) that always touches the surface of touch screen. In the left view of  FIG. 7 b    the key element with offset of 90° with respect to the finger element is pressed. In the middle view of  FIG. 7 b    the key element with offset of 270° with respect to the finger element is pressed. In the right view of  FIG. 7 b    the key element with offset of 180° with respect to the finger element is pressed. 
     It is acknowledged that the pattern of the display unit  39   a  and  39   b  may be understood as that touch sensor pattern X and Y. 
       FIG. 8  shows a flowchart  100  regarding a system block diagram for illustration of how a control element according to the first aspect of the invention works in conjunction with a display unit, especially changing the content of the display dependent on control element actions. In a step  101  a control element is rotated, i.e. a second housing part is rotated relative to a first housing part. In a step  103  projected capacitive touch sensors are provided which changes the capacitive when conductive touches the surface of the touch screen. In a step  105  touch control IC is provided which calculates based on capacitive change of the touch sensor at least one size of the conductive body, at least one location and at least one a displacement of them. In a central processing unit the information from the touch controller IC on touch information is received in a step  107  and based on this content in a step  109  change of a display unit is performed and/or a predefined action is executed. 
       FIG. 8  shows a flowchart  200  of a method according to the fourth aspect of the invention. 
     In a step  201  the presence of a control element is detected at the designated area of a display unit. When the control element is placed on the display unit, the touch screen sensor identifies the control element by its bottom electric conductive and/or magnetic characteristics (like size of the circular), to prevent mis-detection of “finger touch”. 
     In a step  203 , as the placement is detected, the menu surrounding the control element is displayed based on location of the button (e.g. if it placed on navigation area it will display the navigation menu, etc.). 
     In a step  205  the location of selection is then calculated by relative calculating the placement of the rotating conductive (i.e. finger element) to the central conductive (i.e. fastening element). 
     In steps  207  through  211  as a rotation of the control element, especially a rotation of the second housing part relative to the first housing part, is detected by the touch sensor, the menu of current pre-selection is updated. 
     In steps  213  through  215  when actuated key element is detected (e.g. as third touch in addition of central and rotating conductive) the system then calculates the relative position of this contact to determine which button is pressed. 
     In a step  217  the menu based on this detection is updated. 
     In a step  219  a pre-defined action is triggered. 
     Preferably the steps of methods disclosed in this application are proceeded in the order as mentioned. However, alternatively every other sequence of the single steps may be possible. 
     The features disclosed in the claims, the specification, and the drawings maybe essential for different embodiments of the claimed invention, both separately or in any combination with each other. 
     REFERENCE SIGNS 
     
         
           1 ,  1 ′,  1 ″,  1 ′″ Control element 
           3 ,  3 ″ Housing body 
           5 ,  5 ″ Housing part 
           7 ,  7 ″ Housing part 
           9  Button element 
           11 ,  11 ′,  11 ″ Selection element 
           12 ,  12 ″ Element 
           13 ,  13 ′,  13 ″ Fastening element 
           15 ,  15 ′ Element 
           17 ,  17 ′,  17 ″ Finger element 
           19 ,  19 ″ Element 
           21 ,  21 ″ Surface 
           23 ,  23 ″ Plate element 
           25 ,  25 ′,  25 ″ Hole 
           27 ′ Wall element 
           29 ″,  29 ′″ Suction cup 
           31 ″ Valve element 
           33 ″ Valve body 
           35 ″ Valve member 
           37 ″ cc System 
           39 ′″,  39 ″″ Display unit 
           39   a ,  39   b  Display unit 
           41 ′″ Element 
           43 ′″ Material 
           100  Flow chart 
           101 - 109  Step 
           200  Flow chart 
           201 - 219  Step 
         D, D′, D″ Direction 
         X, X″ Axis