Abstract:
A memory unit mounting module is provided for an on-board vehicle navigation device. The memory unit mounting module includes a memory unit and a support plate inside a housing of the navigation device and absorbing means arranged between the support plate and the memory unit for protecting the memory unit against shock and/or vibration, The absorbing means includes at least one spring element that may support the memory unit, and at least one damping element for absorbing shock and/or vibration of the memory unit.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of European Patent Application Serial Number 04 027 113.2 filed Nov. 15, 2004, titled NAVIGATION DEVICE OF A VEHICLE AND MEMORY UNIT MOUNTING SYSTEM, which is incorporated by reference in this application in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a memory unit mounting module and, in particular, a memory unit mounting module for use with a vehicle navigation device. 
     2. Related Art 
     Computer-based navigation devices are available for on-board use in vehicles. These navigation devices provide end-users, such as drivers of vehicles in which the navigation devices are installed, with various navigation functions and features. Navigation devices are able to determine a route from a present vehicle position to a selected vehicle destination. To provide the navigation function, some navigation devices access and use a detailed database that includes data representing physical features in a geographic region. Some detailed databases include data representing road and intersection locations and information about the roads, such as turn restrictions, speed limits, address ranges and further route mapping and planning information. For example, some detailed data bases include information related to points of interest (POI), such as factual information regarding monuments, sightseeing places, restaurants, and other types of vehicle travel destinations. 
     Given the relatively large electronic memory capacity needed for such detailed data bases for on-board navigation devices, geographic and other data are often stored on a memory unit such as a CD-rom disk. The demand for on-board access in vehicle navigation devices to ever increasing volumes of data has resulted in efforts to include hard disks and similar electronic memory units in these devices. When a hard disk is used in an on-board navigation device in a vehicle, several problems arise. The navigation device needs to be able to accurately read data from the hard disk while the vehicle is in motion, in spite of exposure of the hard disk to shocks and vibrations. Some navigation devices have addressed these problems by securing a memory unit to a housing of the navigation device. The memory unit cannot be assured in all normal driving circumstances to properly read data in such a navigation device, as shocks or vibrations due to the road surface on which the vehicle is moving can disturb the reading of the data. 
     Damping elements are used in combination with disk drives for portable computers such as laptops, as a shock protective mechanism to reduce damage in such computers from motion shocks. However, in these applications, the disk drive is locked during transportation of the computer. The damping elements are also mechanically locked during transportation because the damping elements could be destroyed or displaced within the shock protective mechanism by exposure to a strong shock, such as the shock experienced by a portable computer or other portable electronic device, including the disk drive, when the computer falls or is dropped. 
     Therefore, a need exists for a memory unit mounting module for use with an on-board vehicle navigation device that is able to protect an electronic memory unit, such as a hard disk, from vibrations and/or shocks and that will properly function when the vehicle, in which the navigation device is installed, is moving. 
     SUMMARY 
     A memory unit mounting module for an on-board vehicle navigation device is provided. The memory unit mounting module may include a memory unit and a support plate, at least one spring element supporting the memory unit, and at least one damping element for absorbing shock and/or vibration of the memory unit. 
     Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is a perspective view of an example of one implementation of a navigation device that includes a memory unit mounting module. 
         FIG. 2  is a perspective view of the memory unit mounting module of  FIG. 1  removed from the navigation device, with its support plate positioned downward. 
         FIG. 3  is a rear view of the memory unit mounting module of  FIG. 2 . 
         FIG. 4  is a side view of the memory unit mounting module of  FIG. 2 . 
         FIG. 5  is a cross-sectional view of an example of a damping element of a memory unit mounting module. 
         FIG. 6  is a plan perspective view of the support plate of the memory unit mounting module of  FIG. 2 . 
         FIG. 7  is a perspective view of the frame for the memory unit mounting module of  FIG. 2 . 
         FIG. 8  is an enlarged cut-away view of a retention element attached to the frame of  FIG. 7 . 
         FIG. 9  is a perspective view of the cover and fixing strip of the memory unit mounting module of  FIG. 2 . 
         FIG. 10  is a perspective view of an example of a memory unit mounting module include vertically disposed resilient extensions. 
         FIG. 11  is an exploded perspective view of the memory unit mounting module of  FIG. 10 . 
         FIG. 12  is a rear perspective view of the memory unit mounting module of  FIG. 10  with the support plate removed. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an example of one implementation of a navigation device  100  that includes a memory unit mounting module  118 . The navigation device  100  may be installed in a housing  102 , the housing  102  having a bottom side  104  and two lateral sides  106  and  108 . On a front side  110  of the housing  102 , an operation module (not shown) may be installed and utilized to control the navigation device  100 . It is understood that the navigation device  100  may not be limited to utilization, together with such an electronic operation module, as a vehicle navigation module. As an example, the navigation device  100  may be part of a multi-media module that may be located in the housing  102 , including any combination of other modules such as an audio module, a radio module and a telecommunication module. The housing  102  may, as an example, have a plurality of pins, such as the two pins  112  and  114 , that may help to locate and position the housing  102  in corresponding recesses (not shown) provided in a vehicle dashboard. The housing  102  may then be connected to the vehicle dashboard using, as an example, the fixing elements  116 . It is understood that one or more fixing elements having a different structure and mode of operation than the fixing elements  116  shown in  FIG. 1  may be utilized. 
     The navigation device  100  may further include a memory unit mounting module  118 , in which a hard disk or other electronic memory unit for storing all the data necessary to guide the user of the vehicle from a present position to a predetermined destination location may be installed. The memory unit mounting module  118  may include a support plate  120 . The memory unit mounting module  118  as shown in  FIG. 1  has not been completely installed into the housing  102 . The memory unit mounting module  118  may be introduced for such installation into a recess  122  provided in the bottom side  104  of the housing  102  having a shape suited for accommodation of the memory unit mounting module  118 . Mounting tabs  124 , shown also in  FIG. 6 , may be inserted into corresponding slots (not shown) in the bottom side  104 . The memory unit mounting module  118  may then be pivoted to a position where the support plate  120  may be flush with the bottom side  104  of the housing  102 . The support plate  120  may have laterally extending arms  126  and  128  located for alignment, upon such installation, with lateral grooves in the bottom side  104 . As an example, the lateral groove  130  is shown in  FIG. 1 . 
     When the memory unit mounting module  118  is fully installed in the navigation device  100 , the bottom surface  132  of the support plate  120  may form a part of the bottom side  104  of the housing  102 . As an example, if an electronic memory unit forming part of the memory unit mounting module  118  in the navigation device  100  needs to be replaced or repaired, the memory unit mounting module  118  may be easily removed from the navigation device  100 . The housing  102  may further include cut-outs in the housing  102  that may help to dissipate heat produced by operation of electronic components of the navigation device  100 . As an example, the housing  102  may have a plurality of circular cutouts  134  and a plurality of elongated cutouts  136 . 
       FIG. 2  is a perspective view of the memory unit mounting module  118  of  FIG. 1  removed from the navigation device, with its support plate  120  positioned downward. The memory unit mounting module  118  is positioned in  FIG. 2  consistent with an orientation that the memory unit mounting module  118  may have when the navigation device  100  is installed in the dashboard of a vehicle with the bottom side  104  facing downward. The support plate  120  of the memory unit mounting module  118  may as an example have four spring elements  202 , only two of which are visible in  FIG. 2 . The four spring elements  202  may support a frame  204 . The frame  204  may carry a cover  206 , in which an electronic memory unit  208  may be installed. The electronic memory unit  208  is a medium capable of storing data in electronic form and reading electronic data, including, but not limited to, a hard disk memory drive. The electronic memory unit  208  may, as an example, store for retrieval the data needed for the navigation device  100  to calculate a route to a predetermined destination location for a vehicle. The electronic memory unit  208  may include an array of contact pins  210 . A corresponding connector (not shown) may be connected with the contact pins  210  in order to enable a data exchange by the electronic memory unit  208  with other components of the navigation device  100 . The frame  204  may have two vertically upstanding arms  212  that may facilitate correct fitting of the corresponding connector onto the contact pins  210 . As another example (not shown), the electronic memory unit  208  may serve the functions of the frame  204  and the frame  204  may be omitted. 
     The electronic memory unit  208  may itself emit electromagnetic radiation or generate an electrostatic charge. Where the electronic memory unit  208  is installed in a navigation device  100  for a vehicle, such electromagnetic radiation and electrostatic charges may potentially interfere with the operation of other electronic components of the navigation device  100  unless the other components are adequately shielded from the radiation. The cover  206  accordingly may, as an example, have an electrically conducting outer surface  214  to shield the other components of the navigation device  100  from potential electromagnetic or electrostatic interference that may be generated by the electronic memory unit  208 . As examples, the electrically conducting outer surface  214  may include aluminum, steel, precious metals, a conductive plastic, or any other electrically conducting material. In an example, the electrically conducting outer surface  214  may be formed of a light weight electrically conducting material. The cover  206  may include an electrically insulating inner surface (not shown) that may prevent electrical contact between the electronic memory unit  208  and the cover  206 . As an example, the electrically insulating inner surface may be formed as a coating of an electrically insulating material. As an example, the electrically insulating material may be a dielectric polymer layer, sheet or film. In an example, the material may include polyethylene terephthalate. The electronic memory unit  208  may be attached to the cover  206 . The attachment may be, as examples, mechanical or adhesive. As an example, the electronic memory unit  208  may have protrusions  216  that may engage recesses  218  in the cover  206 . 
     The combined weight of the frame  204 , the cover  206  and the electronic memory unit  208  may be carried by the four spring elements  202  when the memory unit mounting module  118  is in a “resting position”, meaning that the module  118  is not being subjected to external motion forces such as vibrations or shocks. The spring elements  202  may vertically extend across the distance between and be attached to the frame  204  and the support plate  120 . The vertical extension of the spring elements  202  in a resting position may be determined by selection of the overall dimensions and compressive strength of the spring elements  202 , and consideration of the combined weight of the frame  204 , the cover  206 , and the electronic memory unit  208 . The spring elements  202  may help to absorb shocks applied, by any external motion forces exerted on the memory unit mounting module  118 , to the cover  206  or the electronic memory unit  208  in a direction between the frame  204  and the support plate  120 . 
     The memory unit mounting module  118  may further include damping elements  220  interposed between the frame  204  and the support plate  120 . The damping elements  220  may as an example be attached to the frame  204  but not be attached to the support plate  120 . The vertical extension of the spring elements  202  spanning the distance between the frame  204  and the support plate  120  in a resting position may be longer than a height of the damping elements  220  partially extending in the same direction from the frame  204  toward the support plate  120 . The damping elements  220  may accordingly be spaced apart from the support plate  120  when the memory unit mounting module  118  is in a resting position. The damping elements  220  accordingly may not be under any compression between the frame  204  and the support plate  120  at such a resting position, as the combined weight of the frame  204 , the cover  206  and the electronic memory unit  208  may then be carried solely by the spring elements  202 . As an example, the damping elements  220  may as shown in  FIG. 2  be in mutual alignment with the spring elements  202  in a direction spanning the distance between the frame  204  and the support plate  120 . In another example (not shown), the damping elements may be attached to the support plate  120  but not be attached to the frame  204 . As a further example (not shown) the damping elements may not be in mutual alignment with the spring elements  202 . 
     In an additional example (not shown), the damping elements  220  may be replaced by a resilient pad (not shown). The resilient pad may be made of a resilient material that may become deformed when a force is applied. The resiliency and the shape of the resilient pad may determine the force-absorbing characteristics of the resilient pad. The resilient pad may be interposed between the frame  204  and the support plate  120 . 
     Movement of a vehicle in which the navigation device  100  is installed may, as an example, generate an external motion force applied to the navigation device  100 . The external motion force may then, as an example, move the electronic memory unit  208  toward the support plate  120 . This movement of the electronic memory unit  208  may be initially decelerated by compression of the spring elements  202 . If as an example the external motion then moves the memory unit  208  still further toward the support plate  120 , the damping elements  220  may make contact with the support plate  120 . The damping elements  220  may then be deformed in proportion with the amount of such external motion force that is applied to the memory unit  208 . As an example, the damping elements  220  may not be deformed at all when the memory unit mounting module  118  is in a resting position as explained above. An external motion force may then cause the damping elements  220  to make contact with the support plate  120 . The damping elements  220  may in that case more effectively decelerate further movement of the electronic memory unit  208  toward the support plate  120  than if the damping elements  220  were arranged to themselves support a portion or all of the combined weight of the frame  204 , the cover  206  and the electronic memory unit  208  when the memory unit mounting module  118  is in a resting position. 
     The memory unit mounting module  118  may include a fixing strip  222 . The fixing strip  222  may help to maintain the support plate  120 , the frame  204  and the cover  206  in relative alignment with each other as shown in  FIG. 2 . The fixing strip  222  may, as an example, have an adhesive inner surface (not shown), that may be a self-adhesive surface. The fixing strip  222  may be attached to the bottom surface  132  of the support plate  120  by a first end  138  also shown in  FIG. 1 . The fixing strip  222  may pass through a first cut-out section  226  provided in the frame  204 . The fixing strip  222  may wrap around the cover  206  so that the adhesive inner surface fixes the cover  206  and the fixing strip  222  relative to each other. The fixing strip  222  may pass through a second cut-out section  228  that may be provided in the frame  204 , and may be located as indicated in  FIG. 3  discussed next below. A second end  140  of the fixing strip  222 , shown in  FIG. 1 , may also be attached to the bottom surface  132  of the support plate  120 . 
       FIG. 3  is a rear view of the memory unit mounting module  118  of  FIG. 2 .  FIG. 4  is a side view of the memory unit mounting module  118  of  FIG. 2 . The fixing strip  222  may help to keep the electronic memory unit  208  in alignment with the memory unit mounting module  118 . The fixing strip  222  may help to limit the movement of the frame  204 , the cover  206  and the electronic memory unit  208  in the +X and −X directions opposite to the support plate  120 , as indicated by the arrow  302 . The fixing strip  222  may help to limit the movement of the frame  204 , the cover  206  and the electronic memory unit  208  laterally to the support plate  120  in the +Y and −Y directions as indicated by the arrow  304 . The fixing strip  222  may help to limit the movement of the frame  204 , the cover  206  and the electronic memory unit  208  laterally to the support plate  120  in the +Z and −Z directions as indicated by the arrow  402 . The fixing strip  222  may be positioned in relation to the support plate  120  and the cover  206  so that movement of the frame  204 , the cover  206  and the electronic memory unit  208  in each of the +X, −X, +Y, −Y, +Z and −Z directions may be limited to one or more selected distances. As an example, each of the selected distances may be about 2 millimeters or less. As an example, the fixing strip  222  may be formed of a material having adequate tensile strength to endure repeated extensions by force applied in the +X, +Y, −Y, +Z and −Z directions without becoming unduly stretched or breaking, yet having adequate flexibility to permit movement by the frame  204 , the cover  206  and the electronic memory unit  208  in the +X, +Y, −Y, +Z and −Z directions. The fixing strip  222  may ensure that the spring elements  202  and the damping elements  220  may remain aligned in the memory unit mounting module  118  even when the navigation device  100  or the module  118  is held in different orientations. As examples, the fixing strip  222  may be made of a plastic or rubber sheet or fabric, or a textile fabric. In an example, the fixing strip may be a polytetrafluoroethylene fabric. 
     The fixing strip  222  may not influence the collective movement of the frame  204 , the cover  206 , and the electronic memory unit  208  in the −X direction, as that movement may be controlled by the spring elements  202  and the damping elements  220 . The influence of the fixing strip  222  by limiting movement of the frame  204 , cover  206  and electronic memory unit  208  in the +X, +Y, −Y, +Z and −Z directions may, however, help to avoid dislocation of the spring elements  202  from alignment in the memory unit mounting module  118 . During manufacture of the memory unit mounting module  118 , transportation of the module  118 , manufacture of the navigation device  100 , and utilization of the navigation device  100  in a vehicle, the spring elements  202  may need to remain in alignment so that external motion forces applied to the memory unit mounting module  118  may be controlled and dampened when the module  118  is ultimately installed in a navigation device  100 . If, as an example, the spring elements  202  were to jump and then remain out of alignment with the support plate  120  or the frame  204  or both, the damping elements  220  might have to carry all or a portion of the collective weight of the frame  204 , the cover  206 , and the electronic memory unit  208  in a resting position. In that case, the capability of the memory unit mounting module  118  to provide damping and control over its movement relative to the support plate  120 , as induced by external motion forces, might be considerably deteriorated. 
     As an example, the memory unit mounting module  118  may be manufactured as a separate module or sub-assembly of the navigation device  100 . As a consequence, the memory unit mounting module  118  may be separately transported as a sub-assembly. During this transport or during the process of manufacturing the navigation device  100 , the memory unit mounting module  118  may not be maintained in the same orientation as when incorporated into the navigation device  100 . The orientation of the memory unit mounting module  118  in various navigation devices  100  may also vary. As an example, the memory unit mounting module  118  may not be positioned with the support plate  120  facing downward when the navigation device  100  is installed in a vehicle. In that case, gravity may not induce the spring elements  202  to support the combined weight of the frame  204 , the cover  206  and the electronic memory unit  208 . In spite of such an orientation, the memory unit mounting module  118  may still ensure that such collective weight is supported by the spring elements  202  and that the spring elements  202  and damping elements  220  remain in alignment in the memory unit mounting module  118 . 
     Referring further to  FIGS. 3 and 4 , the frame  204  may include a projection  306  attached to a lower surface  404  of the frame  204 , including a vertically positioned section  308 . As an example, the projection  306  may be L-shaped and include a horizontally positioned end section  406 . The horizontally positioned end section  406  may be, as an example, oriented substantially parallel to the frame  204 . The horizontally positioned end section  406  may include two horizontally oriented sections  310  and  312  separated by a gap  314 . A projecting tab  316  may be secured to the support plate  120  and positioned in alignment with the gap  314  in between the two horizontally oriented sections  310  and  312  of the projection  306 . The two horizontally oriented sections  310  and  312  of the projection  306  may limit movement of the projection  306 , relative to the projecting tab  316  between them, in the +Y and −Y directions indicated by the arrow  304 . The two horizontally oriented sections  310  and  312  of the projection  306  may further limit movement of the projection  306 , relative to the projecting tab  316  between them, in the +Z direction indicated by the arrow  402 . As an example (not shown), the two horizontally oriented sections  310  and  312  of the projection  306  may fully encircle the projecting tab  316  leaving space between the horizontally oriented sections and the projection  306  in a resting position at one or more selected distances. In this case, the two horizontally oriented sections  310  and  312  of the projection  306  may also limit movement of the projection  306  relative to the projecting tab  316  between them in the −Z direction. These limitations on movement of the projection  306  relative to the projecting tab  316  correspondingly limit movements of the frame  204 , the cover  206  and the electronic memory unit  208  relative to the support plate  120 . 
     Alignment and retention of the spring elements  202  and the damping elements  220  within the memory unit mounting module  118  and the operations of these elements are now discussed in further detail. Referring to  FIGS. 3 and 4 , the spring elements  202  may each at one end meet with an upper surface  318  of the support plate  120  and may at the other end meet with a retention element  320 . The retention elements  320  may be attached to the frame  204  by suitable fasteners such as, for example, screws  322 .  FIGS. 3 and 4  show that although the damping elements  220  may be fixedly connected by the retention elements  320  to the frame  204 , the damping elements  220  may not come in contact with the support plate  120 , when the memory unit mounting module is in a resting position. 
     It is understood that the respective functions of the support plate  120  and the frame  204  and the various elements of the memory unit support module  118  that are attached to the frame and support plate may be reversed, for example, as illustrated within the break out section  324  of  FIG. 3 , where the projection  306  is shown reversed and extending from the support plate  120  and the projecting tab  316  is shown reversed and extending from the frame  204 . As an additional example, the damping elements  220  may be attached to the support plate  120  but not be attached to the frame  204 . Each of the upper surface  318  of the support plate  120  and the lower surface  404  of the frame  204  constitute interchangeable platforms in this regard. 
       FIG. 5  is a cross-sectional view of an example of a damping element  220  of a memory unit mounting module positioned in a retention element  320 . The retention element  320  may be secured to the frame  204  by inserting screws  322  shown in  FIGS. 3 and 4  into a through-hole  502  in the retention element  320 . The retention element  320  may have a recess  504 , that may partially or completely enclose a flange  506  on a first part  508  of the damping element  220 . The first part  508  of the damping element  220  may be formed from a material selected to have a greater rigidity than a selected rigidity of a second part  510  of the damping element  220 . As an example, the first part  508  of the damping element  220  may be formed of a natural or synthetic polymer material having a relatively rigid structure. 
     The second part  510  of the damping element  220  may be configured as an elastomeric bellows. As an example, the second part  510  of the damping element  220  may be formed of a natural or synthetic polymer material having a relatively flexible structure. In an example, the first part  508  and the second part  510  of the damping element  220  may be integrally formed by a suitable molding process, or may be separately formed and bonded by adhesive or mechanically interlocking elements such as threads or tabs and slots. The second part  510  of the damping element  220  may include an S-shaped resilient region  512 . The second part  510  of the damping element  220  may include a recessed region  514  in the form of a cavity. A guiding pin  516  attached to and projecting from the support plate  120  toward the frame  204 , as discussed further below in connection with  FIG. 6 , may be introduced into the recessed region  514 . The damping element  220  may include a reservoir  518 . The reservoir  518  may be filled with a compressible fluid. As an example, a liquid having a volume substantially independent of temperatures in a range that may prevail in the memory unit mounting module  118  during use may be selected. As an example, a silicone oil may be utilized. 
     When an external motion force is applied to the memory unit mounting module  118 , the frame  204 , the cover  206  and the electronic memory unit  208  may move the damping element  220  in the −X direction indicated by the arrow  302  shown in  FIG. 3 , toward the support plate  120 . When a tip  520  of the damping element  220  is accordingly brought into contact with the support plate  120 , the S-shaped resilient region  512  of the damping element  220  may be deformed by the guiding pin  516 . The S-shaped resilient region  512  of the damping element  220  may accordingly be moved by the guiding pin  516  in the direction +X towards the retention element  320  shown in  FIGS. 3 and 4  until a lower surface  522  of the recessed region  514  may come into contact with an upper surface  524  of the retention element  320 . The movement of the damping element  220  in the +X direction may be arrested when the lower surface  522  of the recessed region  514  comes into such contact with the upper surface  524  of the retention element  320 . As an example, when the memory unit mounting module  118  is in a resting position, the damping element  220  may be shaped as shown in  FIG. 5 . When the memory unit mounting module  118  is exposed to external motion forces, a resulting collective movement of the frame  204 , the cover  206  and the electronic memory unit  208  in the direction −X, as an example, may first be decelerated by the spring elements  202 . If such resulting movement is sufficiently strong to move the tip  520  of the damping element  220  into contact with the support plate  120 , then the damping element  220  may further decelerate this collective movement. 
       FIG. 6  shows the upper surface  318  of the support plate  120  in further detail. The support plate  120  may include guiding pins  516 . As an example, the guiding pins  516  may be press-fitted into through-holes (not shown) in the support plate  120 . The guiding pins  516  may help to guide movement of the damping elements  220  generally in the +X and −X directions shown in  FIG. 3 . In an example where the damping elements  220  may be positioned inside the spring elements  202  as shown in  FIGS. 3 and 4 , the guiding pins  516  accordingly may also help to guide movement of the spring elements  202  generally in the +X and −X directions. The support plate  120  may include one or more laterally extending arms  126  and  128 . As an example, the laterally extending arms may include fastener holes  602  and  604 , in which suitable fasteners (not shown) may be introduced to securely attach the support plate  120  to the housing  102  of the navigation device  100 , as shown in  FIG. 1 . The support plate  120  may include vertically arranged extensions  606  and  608 , which may as an example have curved ends  610  and  612 , respectively. The vertically arranged extensions  606  and  608  may guide an outboard end  142  of the memory unit mounting module  118  into place as the module is installed in the navigation device  100  as shown in  FIG. 1 . The curved ends  610  and  612  on the vertically arranged extensions  606  and  608  may then lock the memory unit mounting module  118  into place in the navigation device  100  at a position flush with the bottom side  104  of the housing  102 , as shown in  FIG. 1 . 
       FIG. 7  shows the lower surface  404  of the frame  204  in further detail. The retention elements  320  may be attached to the lower surface  404  of the frame  204  using the screws  322 . The damping elements  220  may be attached to the retention elements  320 .  FIG. 8  shows a retention element  320  attached to the lower surface  404  of the frame  204  in further detail. The frame  204  may include an eyelet  802  directed in a vertical direction. As an example, the eyelet  802  may be a deformed partial cutout of the frame  204 . A first end  804  of the retention element  320  may be inserted into the eyelet  802  in order to attach the first end  804  to the frame  204 . A second end  806  of the retention element  320  may include a thread hole  502 , into which a screw  322  may be introduced to attach the second end  806  to the frame  204 , so that the retention element  320  may be secured to the frame  204 . 
       FIG. 9  shows the cover  206  and the fixing strip  222  in further detail. The fixing strip  222  is wrapped around an upper surface  902  of the cover  206 . The electronic memory unit  208  (not shown) may be introduced into a front opening  904  of the cover  206 . The fixing strip  222  may include openings  144  and  146  also shown in  FIG. 1 . The openings  144  and  146  may be located so that when the fixing strip  222  is wrapped around the support plate  120 , and the support plate  120  is completely installed into the housing  102  of the navigation device  100  as indicated in  FIG. 1 , edge portions  232  of the support plate  120  as shown in  FIG. 3  are exposed. The exposed edge portions  232  of the support plate may make electrical contact with the bottom side  104  of the housing  102 . This electrical contact may reduce any potential escape of electromagnetic radiation or of an electrostatic charge from the navigation device  100 . 
       FIG. 10  is a perspective view of an example of a memory unit mounting module including vertically disposed resilient extensions.  FIG. 11  is an exploded perspective view of the memory unit mounting module of  FIG. 10 .  FIG. 12  is a bottom perspective view of the memory unit mounting module of  FIG. 10  with the support plate removed. 
       FIG. 10  shows the memory unit mounting module  118  from a perspective with the support plate  120  facing downward. As an example, two vertically disposed resilient extensions  1002  also shown in  FIG. 12  may be attached to or integrally formed with the cover  206 . The vertically disposed extensions  1002  may each include one or more resilient arms  1004 . The vertically disposed resilient extensions  1002  and the resilient arms  1004  may have an undulated or sinuous form, the undulation providing or adding to the resilient properties of the extensions and arms. As an example, the vertically disposed extensions  1002  may be made of a flexible material as discussed in connection with the fixing strip  222 . Each resilient arm  1004  may include an opening  1006 , shown in  FIG. 11 , near the end  1008  of the resilient arm. A hook  614 , as an example either attached to or cut out from the support plate  120  and also shown in  FIG. 6 , may be engaged with the opening  1006 . The vertically disposed extensions  1002  may help to limit the movement of the frame  204 , cover  206  and electronic memory unit  208  with respect to the memory unit mounting module  118  in the +X, +Y, −Y, +Z and −Z directions as earlier discussed in connection with the fixing strip  222 . The vertically disposed extensions  1002  may pass through cut-outs sections  226  and  228  of the frame  204 , as already explained in connection with  FIG. 2 .  FIG. 11  shows an exploded view of the navigation device  100  modified as discussed in connection with  FIG. 10 .  FIG. 12  shows a bottom view of the navigation device  100  modified as discussed in connection with  FIG. 10 . The vertically disposed extensions  1002  may pass the cut-outs  226  and  228  in the frame  204 . As an example, the frame  204  may be connected with the cover  206  and the electronic memory unit  208  using screws  1202 . 
     The navigation device  100  and the memory unit mounting module  118  may reduce adverse effects of external motion forces such as shocks and vibrations on the operation of an electronic memory unit  208  in such a navigation device installed in a vehicle. The electronic memory unit  208  may be able as a result to properly function even in environments where it may be exposed to strong vibrations or shocks. 
     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.