Abstract:
The image correction method and system for navigation device with portable navigation unit converts an image based on projection to a first display into a suitable image on a second display such that the area of the second display is used economically and efficiently while maintaining some elements of the image in substantially common aspect ratio between the images on the first display and on the second display. The image correction method determines the ratio of the second display, determines if image correction is required, and checks a correction table and performs image correction according to correction rules to generate the corrected image for projecting on the second display.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application No. 60/755,553 filed Dec. 31, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to an image correction method and system for navigation device with portable navigation unit, and more particularly, to an image correction method and system that converts an image from the portable navigation unit to an external display so as to give aesthetic appearance and map elements that is close to the original image even when the display size, shape and aspect ratio of the external display are different from the display of the portable device.  
       BACKGROUND OF THE INVENTION  
       [0003]     A navigation system performs travel guidance for enabling a user to easily and quickly reach the selected destination. A typical example is a vehicle navigation system where a vehicle is equipped with a navigation function to guide a driver to a destination through a calculated route. In recent years, the use of both mobile media and navigation systems in a vehicle has become increasingly more common. Because of data storage requirements, such systems were initially somewhat bulky and required that the systems be permanently installed in the vehicle. However, more recently developed devices are sufficiently compact to allow them to be personally portable and be temporarily mounted within the vehicle. This gives the user the option to use the device both inside and outside of the vehicle.  
         [0004]     To have the navigation display visible to the driver when such devices are used within a vehicle, the portable device is either, held by the driver or a passenger, propped up against the interior structure of the vehicle, or otherwise attached to a device mount. Such a device mount typically is further secured to a portion of the interior of the vehicle at a position such that the display is visible by the driver. An example of the attachment of such a device mount to the interior of the vehicle is via a suction cup portion to the front windshield.  
         [0005]     To increase the portability of such navigation devices it is desirable to reduce or minimize the overall physical size of the device as much as possible. Of course, the reduction of the overall size of such navigation devices has resulted in a similar reduction in the size of the device components, including the display and the controls. While being used as a portable device, the smaller display and controls tend not to be a problem for the user as the portable device is held relatively close and the user can concentrate primarily on the operation and display of the navigation device.  
         [0006]     However, when such a portable navigation device is mounted in a vehicle, the smaller display and controls present certain problems for the driver. One such problems includes being difficult to read or otherwise observe the information on the small display of the portable device, especially given that the driver&#39;s primary attention and concentration needs to be directed towards the operation of the vehicle and the road ahead, and not on the navigation display. This problem is compounded by the fact that when attached to a device mount, the navigation device is typically held much further away from the user than if it was held in hand in a portable mode.  
         [0007]     Another problem of in-vehicle use is that the controls such as keys and touch panel of the portable navigation device are also positioned relatively far away and are small in size. Yet another problem is that the sounds generated by the portable navigation device, such as directional call-outs, street names and the like, may not be heard by the driver especially due to the distant positioning of the navigation device and the effect of other sources of sound, such as the car audio system.  
         [0008]     A portable navigation device may be used in a vehicle in conjunction with an external (second) display device such as a head unit of the vehicle audio/video system. The external display device in general has a larger display size compared to the display size of the portable navigation device. Moreover, the external display device may also be positioned in such a way that the user is able to reach and read or observe the information on the display with ease. Thus, it would be advantageous to connect the portable navigation device to the external display. However, an aspect ratio of the external display may be different from that of the portable navigation device.  
         [0009]     Therefore, a need exists for a navigation device which includes a removable navigational unit, which while used in the vehicle, provides for an improved operation of the navigation device within the vehicle. Moreover, there is a need for a method and apparatus of image correction to display image effectively to an external display that takes account of the possible display shape and aspect ration difference.  
       SUMMARY OF THE INVENTION  
       [0010]     It is therefore, an object of the invention to provide a method and system for navigation device with portable navigation unit, and more particularly, to an image correction method and system that converts an image from the portable navigation unit to an external display so as to give aesthetic appearance and map elements that is close to the original image even when the display size, shape and aspect ratio of the external display are different from the display of the portable device.  
         [0011]     In at least one embodiment, the present invention is an image correction system which can operate with a navigation system. The navigation system having a portable navigation device, a display screen, controls, at least one speaker, a GPS antenna and a vehicle data generator. The portable navigation device is removable or otherwise detachable from the navigation system and when detached can be operated on its own using a built-in display, controls speaker and GPS antenna. When the portable navigation device is attached to the remaining, fixed or in-vehicle portions of the navigation system then the portable navigation device operates with these components as a complete navigation system. Specifically, when attached to the remainder of the system the portable navigation device switches its display from its integral display to the in-vehicle display screen, its control inputs to the in-vehicle controls, its sound generation to the in-vehicle speakers, and its GPS signal input to the in-vehicle GPS antenna. In addition, the portable navigation device can add an input from the vehicle generator to further facilitate the generation of navigation data.  
         [0012]     When used with the in-vehicle components of the navigation system, the in-vehicle functioning of the portable navigation may be improved. Namely, the portable navigation device may be made easier to use and function better in a vehicle, since the in-vehicle display screen can be larger than that of the integral screen, the controls may be bigger and better positioned for the user, the sound can be louder, clearer and easier to control, the GPS signal reception may be improved and the accuracy of the navigation can also be increased.  
         [0013]     With some in-vehicle displays and portable displays the aspect ratio of each of the displays is different from the other. For example an in-vehicle display may have an aspect ratio of 16:9 and the portable display is 4:3. Projecting the display of the either to the other, e.g. the image of the portable display to the in-vehicle display will cause a certain amount of distortion of the image.  
         [0014]     In embodiments, the present invention provides a system and/or method for correcting the distortion of an image projected to another display having a different aspect ratio. In order to save processing resources this correction is done only on certain define image elements that are deemed as being of the greatest or highest importance in providing the best possible final image. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1A  is a perspective view showing a vehicle interior which includes a navigation system established by a portable navigation unit and in-vehicle components in accordance with at least one embodiment of the present invention.  
         [0016]      FIG. 1B  is a perspective view showing an example of overall structure of the navigation system established by the portable navigation unit and the in-vehicle components in accordance with at least one embodiment of the present invention.  
         [0017]      FIG. 1C  is a perspective view of a portion of a navigation system including the portable navigation unit and a navigation interface in accordance with at least one embodiment of the present invention.  
         [0018]      FIG. 1D  is a perspective view of a portion of a navigation system including the portable navigation unit and a navigation interface in accordance with at least one embodiment of the present invention.  
         [0019]      FIG. 1E  is a perspective view showing a front portion of the portable navigation unit which is a main component of the navigation system in accordance with at least one embodiment of the present invention.  
         [0020]      FIG. 1F  is a perspective view showing a rear portion of the portable navigation unit which is a main component of the navigation system in accordance with at least one embodiment of the present invention.  
         [0021]      FIG. 1G  is a perspective view showing another example of overall structure of the navigation system in accordance with at least one embodiment of the present invention where the portable navigation unit is disconnected.  
         [0022]      FIG. 1H  is a perspective view showing an overall structure of the navigation system in accordance with at least one embodiment of the present invention where the portable navigation unit and the in-vehicle components are illustrated separately.  
         [0023]      FIG. 2  is a schematic diagram showing a basic concept of the navigation system in accordance with at least one embodiment of the present invention.  
         [0024]      FIG. 3  is a table showing an example of pin assignment for the navigation system in accordance with at least one embodiment of the present invention.  
         [0025]      FIG. 4  is a perspective view of a portion of the navigation system including the portable navigation unit and the in-vehicle display in accordance with at least one embodiment of the present invention.  
         [0026]      FIG. 5A  is a schematic diagram showing a situation where the display of the portable navigation unit and the in-vehicle display have different aspect ratios in accordance with at least one embodiment of the present invention.  
         [0027]      FIG. 5B  is a schematic diagram showing a situation where the image data from the portable navigation unit is displayed on the in-vehicle display without compensating difference of aspect ratios.  
         [0028]      FIG. 5C  is a schematic diagram showing a situation where the image data from the portable navigation unit is displayed on the in-vehicle display while shapes of selected elements on the image are corrected to compensate the difference of aspect ratios.  
         [0029]      FIG. 6  is a schematic block diagram showing the data table and correction rule for selectively correcting the elements in the map data for the case of  FIG. 5C .  
         [0030]      FIG. 7  is a flow chart showing an example of basic operational steps of the present invention for displaying an image on the in-vehicle display based on the image data from the portable navigation unit. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     In at least one embodiment, the present invention includes a navigation system having both of a portion that is mounted in a vehicle (in-vehicle portion) and a portion that is removable and/or portable (portable navigation unit). The removable portion, i.e, the portable navigation unit, is capable of operating on its own, and separate from the remaining in-vehicle components of the navigation system.  
         [0032]     Further, depending on the embodiment, the in-vehicle portion of the navigation system may be capable of operating and performing certain functions on its own separately from the removable portion (portable navigation unit). However, with the removable portion of the system received by and operating with the in-vehicle portion, each portion is capable of operating with additional functionality. Typically, the portable navigation unit has not only a navigation function but other functions, such as a digital audio player, an FM transceiver, etc., as well.  
         [0033]     One embodiment is shown in  FIGS. 1A and 1B , the navigation system  100  includes an in-vehicle portion  110  (also referred to as “in-vehicle components”) and a removable or portable portion  170  (also referred to as a “portable navigation unit”).  FIG. 1A  shows the embodiment example of the condition wherein the navigation system  100  is installed to a vehicle. Actual placement, shape and size of parts of the navigation system  100  in the vehicle may differ from the view in  FIG. 1A  when the navigation system  100  is actually applied to a vehicle.  
         [0034]      FIG. 1B  is a perspective view showing an example of overall structure of the navigation system established by the portable navigation unit and the in-vehicle components in accordance with at least one embodiment of the present invention. In this example, the navigation system  100  is separated from the vehicle to clearly show the overall components associated with the system. The in-vehicle portion  110  includes an in-vehicle display  120  which is typically a head unit of a vehicle audio/video system, speaker or speakers  130 , a GPS (navigation) antenna  140 , a vehicle data generator  150 , a navigation interface  160  and a vehicle power source (battery)  168 . The removal portion  170  includes a portable navigation unit  180 .  
         [0035]     With the navigation system  100 , the user can either use the portable navigation unit  180  within the vehicle or away from the vehicle as a portable device (hand-held navigation device, digital audio player, etc). As shown in  FIGS. 1E and 1F , the portable navigation unit  180  includes integral components including an interface or connector  181  for electrical connection with a device mount or cradle (not shown), a display  182 , controls  184  such as keys and buttons, a speaker  185 , a GPS or navigation antenna  186 , and a power source (battery)  188 . The portable navigation unit  180  has a self-contained operation such that the user can carry and use the unit separately and independently from the rest of the navigation system  100  and the vehicle in which the in-vehicle portion  110  is contained.  
         [0036]     The portable navigation unit  180  can be connected to the in-vehicle portion  110  of the navigation system  100  by any of a variety of means. This connection between the portable navigation unit  180  and the in-vehicle portion  110  enables transmitting signals therebetween for communication. These signals can include data such as navigation images, call-outs transmitted from the portable navigation unit  180  to the in-vehicle portion  110  and GPS signals, vehicle information (e.g. speed pulses), control inputs, transmitted from the in-vehicle portion  110  to the portable navigation unit  180 .  
         [0037]     In some embodiments, the connection includes direct electrical communication between the portable navigation unit  180  and the in-vehicle portion  110 . The direct communication can include two or more electrical connectors or pads in direct physical contact, allowing an electrical connection to be made. In the embodiment of  FIGS. 1E and 1F , the direct electrical connection to the portable navigation unit  180  can be established through an interface (electrical connector)  181 . The interface  181  can be any of a variety of different configurations, including a plug or receptacle, with the in-vehicle portion  110  having a matching cooperating plug or receptacle in the navigation interface  160 .  
         [0038]     In some embodiments, the connection between the portable navigation unit  180  and the in-vehicle portion  110  is made by means other than a direct electrical connection. For example, the connection can be by wireless means, such as a WiFi, Bluetooth, FM transmission, or the like. Such a wireless communication allows the portable navigation unit  180  to operate with the in-vehicle portion  110  without the need of directly connecting the portable navigation unit  180  to the in-vehicle portion  110 , which in turn allow for easier use and less exposed wires in the vehicle.  
         [0039]     In some embodiments, the display  182  functions to display the navigational data and information when the portable navigation unit  180  is used in its portable mode of operations. The navigational data can show or display images  183  such as maps, symbols, turn indicators, routes, points of interests or POIs, various icons, and the like. The display  182  can be any of a variety of commercially available display screens including a color LCD device, plasma display device, etc. Many other displays, commercially available or not, can also be used for the display  182 .  
         [0040]     As the portable navigation unit  180  is connected to, or otherwise in communication with the in-vehicle portion  110  of the navigation system  100 , in the embodiments, the portable navigation unit  180  is placed into a mode where the display  182  is turned off. In this mode, the associated data is transmitted to the in-vehicle portion  110  so that the image  183  is reproduced on the in-vehicle display screen  120 , as shown in  FIGS. 1A and 1B . In this manner, the display  182  can be off when it is not required to show navigation data on the portable navigation unit  180 .  
         [0041]     In other embodiments of the present invention, the display  182  continues to remain on when the portable navigation unit  180  is connected to the in-vehicle portion  110  of the navigation system  100 . Such embodiments may be used to allow other occupants of the vehicle to be able to view the navigation data on the portable navigation unit  180 . One example of such an embodiment would include positioning the portable navigation unit  180  connected to the in-vehicle portion so that the rear seat passengers can see the image  183  on the display  182 . As noted below with respect to certain embodiments, the display  182  may be a touch screen which has the capability to incorporate some or all of the controls  184 .  
         [0042]     In the embodiment shown in  FIGS. 1E and 1F , the controls  184  are set on the exterior of the portable navigation unit  180  and are generally adjacent to the display  182 . The controls  184  allow the user to operate the various functions of the portable navigation unit  180 , such as moving through menu screen and selecting items or operations. The specific size, shape, location and operation of the controls  184  can vary depending on the particular embodiment.  
         [0043]     As noted above, in some embodiments, some or all of the controls  184  are integrated into the display  182 . This integration can be performed by any of a variety of means including using a touch screen for the display  182  with a displayed image which shows a button, switch, slider or other representation of control. This allows the controls displayed to be changed and tailored to the particular condition and operation of the portable navigation unit  180 .  
         [0044]     In some embodiments, the operation of some or all of the controls  184  are disabled when the portable navigation unit  180  is connected to the in-vehicle portion  110  as shown in  FIGS. 1A-1C . In this configuration, the portable navigation unit  180  is capable of being controlled by in-vehicle controls incorporated in the in-vehicle portion  110  as further described herein. An example of such in-vehicle controls can include the in-vehicle display  120  having a touch sensitive screen which shows various keys and menu bars and transmits control inputs through the interface  160  to the portable navigation unit  180 .  
         [0045]     Disabling the controls  184  can protect the operation of the navigation system  100  from an accidental or stray control input being entered directly into the portable navigation unit  180 . This aspect can be beneficial if the portable navigation unit  180 , when connected to the in-vehicle portion  110 , is positioned such that it is easily and/or unintentionally bumped or otherwise contacted by the occupants of the vehicle.  
         [0046]     In other embodiments, the operation of some or all of the controls  184  are kept active when the portable navigation unit  180  is connected to the in-vehicle portion  110 . This arrangement may be useful to allow a remote vehicle occupant (e.g. the rear seat passenger) to separately operate the navigation system  100 .  
         [0047]     As shown in  FIG. 1F , the speaker  185  can be used to transmit audio information related to the navigation operations of the portable navigation unit  180 . This audio information can include call outs for turns, street names, POIs, arrival indications, and the like. The audio information may also include music, songs, dramas, news, etc., when the portable navigation unit  180  is used as a digital audio player or an FM receiver. The use of audio in addition to a visual display can greatly aid the driver and minimize driver distraction.  
         [0048]     As shown in  FIGS. 1A, 1B  and  1 F, in some embodiments, when the portable navigation unit  180  is connected to the in-vehicle portion  110 , the speaker  185  can be turned off and the sound is sent via the interface  160  to the in-vehicle speakers  130 . The use of the larger and sometime higher quality in-vehicle speakers  130  instead of the smaller integral speaker  185 , can provide a better and clearer audio presentation for the user.  
         [0049]     An additional benefit of using the in-vehicle speakers  130  is that, in some embodiments, the in-vehicle portion  110  of the navigation system  100  can automatically mute or lower the volume of other media being played over the in-vehicle portion  110  (non-essential sound) when a call out or other announcement is made by the navigation system  100 . In this way, the user will not miss or not hear a call out by the navigation system  100  while the in-vehicle portion  110  is broadcasting other media (e.g. playing a song).  
         [0050]     As shown in  FIGS. 1E and 1F , the navigation antenna  186  functions to receive navigation signals transmitted from an external source or sources, such as orbiting satellites. In certain embodiments, the navigation signals received by the navigation antenna  186  are GPS signals and the antenna is a GPS antenna. In other embodiments, the signals received by the navigation antenna  186  also include other information such as traffic reports, weather conditions and the like.  
         [0051]     The navigation antenna  186  shown in  FIG. 1F  is in a closed position where the antenna is folded down while the navigation antenna  186  shown in  FIG. 1E  is in an open position where the antenna is oriented in a horizontal direction. The navigation antenna  186 ′ shown in the dotted lines of  FIG. 1F  indicates the antenna in the open position like the antenna  186  shown in  FIG. 1E .  
         [0052]     When the portable navigation unit  180  is used separately from the in-vehicle portion  110  in a portable mode, the navigation antenna  186  is capable of receiving navigation (GPS) signals. Based on the GPS signals, the portable navigation unit  180  is able to determine the current position of the user as well as other navigation related information (speed, compass heading, etc.). The portable navigation unit  180  is also able to reproduce music or other audible sounds when used as a digital audio player or an FM receiver.  
         [0053]     With the portable navigation unit  180  connected to the in-vehicle portion  110 , in some embodiments, the integral GPS antenna  186  is no longer used and instead the navigation signals are received by the portable navigation unit  180  via the in-vehicle portion  110 . Specifically, as shown in  FIGS. 1A and 1B , the navigation signals can be received from the in-vehicle antenna  140  when the portable navigation unit  180  is connected to the in-vehicle portion  110 . The navigation signal reception can be greatly improved by using the vehicle mounted antenna  140  instead of the integral antenna  186  because typically the in-vehicle antenna  140  can be formed larger in size using superior components than that of the integral antenna  186 .  
         [0054]     Another reason is that because metal and other components of the vehicle can block, interfere or otherwise degrade the navigation signal reception within the vehicle, and the in-vehicle antenna  140  can be mounted in a location on the vehicle where this degradation is minimized or non-existent. For example, the in-vehicle antenna  140  can be mounted under the front or rear windshields, or even on the outside of the vehicle on the roof or the trunk. In contrast, for convenience and ease of use, the portable navigation unit  180  will typically be mounted within the interior structure of the vehicle, which can adversely affect its ability to receive the navigation signal.  
         [0055]     Other embodiments of the navigation system  100  may use the integral navigation antenna  186  to receive the GPS signals even when the portable navigation unit  180  is connected to the in-vehicle portion  110 . Thus, in such embodiments, the in-vehicle antenna  140  can be omitted. This may be done to reduce an overall cost and/or complexity of the navigation system  100 .  
         [0056]     The power source  188  functions to provide electric power to operate the portable navigation unit  180  separately from any external power source. Depending on the embodiment, the power source  188  can be any of a variety of available batteries or the like. For example the power source  188  can be one or more rechargeable batteries. In some embodiments, when the portable navigation unit  180  is connected to the in-vehicle portion  110 , such as that shown in  FIGS. 1A, 1B  and  1 C, the power source  188  is recharged by the vehicle through the interface  140 .  
         [0057]     As shown in  FIGS. 1A and 1B , and as noted above, the in-vehicle portion  110  of the navigation system  100  includes the in-vehicle display  120 , the controls  125 , the speaker  130 , the navigation antenna  140 , the vehicle data generator  150 , the device interface  160  and the vehicle power source  168 . Different embodiments will contain different variations of the above listed items in the particular in-vehicle portion of the navigation system. For example, in some embodiments, only the display  120  is included in the in-vehicle portion  110 . In this manner, the user is provided with a larger fixed screen to view the navigation information, but all other operations and functions occur at or within the portable navigation unit  180 . In other embodiments, a wireless device interface  160  is provided to transmit a signal to a set of speakers  130  and none of the other components listed above are included.  
         [0058]     While the in-vehicle portion  110  of the system can function with the portable navigation unit  180 , as noted above, in embodiments, it may also function on its own and separately from the portable navigation unit  180 . In this regard, the in-vehicle portion  110  may also include a media or information source  190  which is capable of providing images and/or audio data to the display  120  and the speakers  130 , respectfully. This allows the in-vehicle portion  110  to be operated independently of any connection to the portable navigation unit  180 .  
         [0059]     One example of the media (information) source  190  can be an FM radio which receives traffic incident information, weather forecast, sports and other event information, etc. Another example of the information source  190  can be a trip computer which uses input from the vehicle data generator  150  to calculate trip and status information of a vehicle and present it on the display  120 . Many other such configurations of the in-vehicle portion  110  are possible.  
         [0060]     Some embodiments of the navigation system  100  may also include a microphone for voice commands. The microphones may be included in either the portable portion  170  or the in-vehicle portion  110 . When the portable navigation unit  180  is connected to the in-vehicle portion  110 , then either of a microphone on the portable navigation unit  180  or in the in-vehicle portion  110 , or the both microphones can be used. The advantages of using an in-vehicle microphone can include an improved quality and an improved sensitivity for a directional microphone to pick up user&#39;s voice command.  
         [0061]     As shown in  FIGS. 1A and 1B , the in-vehicle display  120  can, in embodiments, be a mounted or in-dash display which is positioned to be viewable by the driver. The in-vehicle display  120  can be a flat panel LCD display, a plasma display, a projection display, a CRT, or any other similar such display. While the specific size and shape of the display  120  can vary, to aid the driver in operating the vehicle and to reduce driver distraction, the display  120  is typically significantly larger than the display  182  of the portable navigation unit  180 .  
         [0062]     Such a larger display allows the driver to obtain more navigational information quickly in an efficient manner than is possible with a smaller display, especially if the smaller display is positioned further away from the driver. In some embodiments, the in-vehicle display  120  also incorporates some or all of the controls  125  through its touch screen as further described below. The display  120  can project an image  122  which can be generated either by an in-vehicle device such as the media source  190  or by the portable navigation unit  180  connected thereto.  
         [0063]     In embodiments where the aspect ratio of the in-vehicle display  120  and that of the display  182  of the portable navigation unit  180  differ, either the in-vehicle portion  110  and/or the portable portion  170  may also include a display generator (not shown). Such a display generator can sense or otherwise determine the difference in the aspect ratios and then automatically adjust the image to properly fit the image to the display to which it is projected. In some embodiments only certain elements of the image are resized and/or reshaped for projection on the display having a different aspect ratio. Limiting the reconfiguration of the image to specific elements allows for a reduced use of processing power and thus a quicker image rendering.  
         [0064]     In some embodiments, the determination of the display&#39;s aspect ratio is done by a signal sent through the interface  160 . Such an embodiment is set forth in  FIGS. 3 and 4  showing that a cable has a line and pin dedicated to the status of the display aspect ratio. As shown in  FIG. 4 , pin No. 11 allows for transmission of the status of the display&#39;s aspect ratio. In this case, if the display&#39;s aspect ratio is 16:9, a high level signal is sent, and if the aspect ratio is 4:3 a low level signal is sent.  
         [0065]     Certain embodiments do not include the in-vehicle display  120  of  FIGS. 1A and 1B , and instead use the display  182  of the portable navigation unit  180  to show the navigation information. In such embodiments, the portable navigation unit  180  may be preferably positioned in a location different from that shown to better enable the driver to view the display  182 .  
         [0066]     As shown in  FIGS. 1A, 1B  and  1 G, the in-vehicle controls  125  can function to either control the in-vehicle devices such as a media (information) source  190  and/or to control the operation of the portable navigation unit  180 . Using the in-vehicle controls  125  to operate the portable navigation unit  180  instead of the potentially smaller and harder to reach integrated controls  184 , it can aid the driver in the operation of the vehicle to reduce the likelihood of driver distraction problems.  
         [0067]     Depending on the embodiment, the in-vehicle controls  125  can be physical controls, such as buttons, switches, sliders, etc., and/or virtual controls set forth on a touch sensitive screen or similar display. While the size and positioning of the controls  125  can vary, typically they will be larger than the integrated controls  184  on the portable navigation unit  180  and positioned relatively close to be easily accessible by the driver. The in-vehicle controls  125  can operate the portable navigation unit  180  via a signal transmitted through the interface  160 , either by a direct electrical connection or by wireless connection.  
         [0068]     In some embodiments, the controls are set in a remote controller (not shown) which transmits a signal to either the in-vehicle portion  110  or directly to the portable navigation unit  180 . Certain embodiments can locate the in-vehicle controls  125  in more convenient locations to the driver such as on the steering wheel, or the like. Some embodiments of the navigation system  100  do not include the in-vehicle controls at all.  
         [0069]     The in-vehicle speaker  130  can function to transmit or broadcast both sounds generated by in-vehicle devices and sounds generated by the portable navigation unit  180 . The sound signals from the portable navigation unit  180  to the in-vehicle portion  110  can be transmitted via the interface  160 . The speakers  130  can be one or more speakers of varying size, shape, arrangement, configuration, etc. To improve the quality and/or volume of the sound which the driver hears, in embodiments, the speakers  130  are significantly larger than the integral speaker  185  of the portable navigation unit  180 . In addition, the number of speakers  130  can be much greater than that of the portable navigation unit  180 . Improving the quality and/or volume of the sound used in navigation can aid the driver&#39;s operation of the vehicle and potentially reduce driver distraction. Certain embodiments do not include the in-vehicle speakers  130  and instead utilize the integral speaker  185  as the sole source of sound or have no sound source at all.  
         [0070]     The in-vehicle navigation antenna  140  functions to receive navigation signals from external sources. In some embodiments, the antenna  140  is a GPS antenna which receives signals from orbiting GPS satellites. Since the reception of such GPS signals can be adversely affected by obstructions such as the metal bodywork of a vehicle, in some embodiments, the antenna  140  is positioned to have a relatively unobstructed view of the sky. Examples of such positioning can include internal positioning under the front or rear windshield, external positioning on the vehicle&#39;s roof or trunk area, or the like.  
         [0071]     As noted above, with the integral antenna  186  of the portable navigation unit  180  being positioned within the passenger compartment of the vehicle, improved reception typically will be available from the antenna  140  positioned in the manner noted above. Of course, in certain embodiments the navigation system  100  does not include an in-vehicle antenna  140  and receives the navigation signal from the integral antenna  186  of the portable navigation unit  180 .  
         [0072]     The in-vehicle data generator  150  functions to provide the navigation system  100  with one or more types of data from the vehicle. The amount and type of data provided can vary by embodiments and can include data which facilitates the navigation functions. For example, the data generator  150  can provide vehicle speed pulse data to be used to determine vehicle speed and distance of travel separately and potentially more accurately than by GPS alone. The data generator  150  can transmit its data to the portable navigation unit  180  via the interface  160 .  
         [0073]     The interface  160  functions as a connection or data link between the portable navigation unit  180  and the in-vehicle portion  110  of the navigation system  100 . As noted above, in some embodiments, the interface  160  can provide two-way communications between the in-vehicle portion  110  and the portable navigation unit  180 . Data such as speed pulses, GPS signals, control inputs and the like, can be sent to the portable navigation unit  180  from the in-vehicle portion  110 , and data such as the map images, turn indicator images, audio call-outs, and the like can be sent to the in-vehicle portion  110  from the portable navigation unit  180  via the interface  160 . It should be noted that the specific types of data transferred between the devices can vary depending on the embodiment of the invention.  
         [0074]     In at least one embodiment, as shown in  FIGS. 1C and 1D , the interface  160  includes a cradle, receptacle, dock or docking station  162  and a cable  166 . The cradle  162  functions to receive the portable navigation unit  180  and in so doing make electrical connections between the interface  160  and the portable navigation unit  180 . As shown, the cradle  162  also includes a connector  164  which functions to make electrical connections with the connector  181  ( FIG. 1F ) of the portable navigation unit  180 . The connector  164  can be any of a variety of different configurations, including a plug or a receptacle, a USB connector that fits with the connector  181 .  
         [0075]     The connector  164  on the cradle  162  and the connector  181  ( FIG. 1F ) of the portable navigation unit  180  can together be any of a variety of cooperating structures, for example an interlocking male-female multi-pin connector. The connector  164  and the connector  181  may be similar to those commonly found on electronic devices such as PDAs, cameras, cell phones and the like. Depending on the embodiment, the particular electrical connections between the connector  164  and the connector  181  can be any of a wide variety. Examples of the connections can include audio, video, power including battery power, AC power for battery charge, audio output, audio mute, illumination inputs, vehicle status inputs, external GPS inputs, car data bus inputs, USB device or other auxiliary or PC device connector, etc.  
         [0076]     An embodiment of a navigation system  200  includes a docking station  262  as set forth in  FIG. 2 , showing the interface  260  including a set or series of connections, including a 13-pin cable  266  connection and an AV Out  267  set between the docking station  262  and a display  220  (via a hide-away box  268 ), a cable  242  to the in-vehicle GPS antenna  240  and power harness  269 . Shown in the table of  FIG. 3  is an example of layout and pin assignment of a-13 pin connector with each of its pin and/or lines in the cable identified by pin number, pin name, use, I/O, specification and relevant notes.  
         [0077]     Referring back to  FIGS. 1A and 1B , in other embodiments, the interface  160  can be a wireless connection between the in-vehicle portion  110  and the portable navigation unit  180 . Any known wireless connection can be used including WiFi, Bluetooth, FM transmission, IR (infrared ray) and the like.  
         [0078]     The vehicle power source  168  includes a means of delivering power generated by, or otherwise within, the vehicle to each of components of the navigation system  100 , including to the portable navigation unit  180  through the interface  160 . With the power supplied to the portable navigation unit  180  from an external source, the navigation unit  180  can prevent or limit any loss of charge of its internal or integral power source  188  ( FIGS. 1E and 1F ). As noted above, the power source  188  may be a battery, and specifically a rechargeable battery. In addition, the external supply of power can be used to recharge the battery  188  as the portable navigation unit  180  is connected to the in-vehicle portion  110 . An example of a power connection cable for a docking station embodiment is set forth in the power harness  269  of  FIG. 2 .  
         [0079]     It should be noted that in some embodiments of the system  100 , the portable navigation unit  180  can further include components such as a processor, an image display generator or controller, a database, a memory, a system bus, general purpose inputs (such as for push-button switches, trigger switches, etc.) and outputs (e.g. to trigger illumination lights on the device, sound a buzzer or beeper, etc.), audio outputs, video outputs, wireless information transceiver such as two-way (e.g. cellular, WiFi, Bluetooth, infrared ray, etc.) or one-way (e.g. pager, FM RDS receiver, etc.) communication, and the like.  
         [0080]      FIG. 1H  is a schematic view showing an example of the components of the navigation system  100 . The navigation system  100  is comprised mainly of the in-vehicle portion  110  and the separate removable or portable portion  170 . The in-vehicle portion  110  has a plurality of components as described above. The portable portion  170  has the portable navigation unit  180 .  
         [0081]     In some embodiments of the invention, the portable navigation unit and/or the in-vehicle components can also receive and potentially transmit therebetween, traffic, weather, stock, movies, event information or similar information received from an external source. This external source can transmit its data via radio frequencies, such as by a local FM signal, or from orbiting satellites, or the like. Such transmissions can be received by an additional component in either the portable device and/or the in-vehicle portion of the system. Such traffic information can be displayed on either the portable device display and/or the in-vehicle display.  
         [0082]      FIG. 4  shows another embodiment of the present invention. The navigation system  400  includes an in-vehicle portion  410  and a removable or portable portion  470 . The in-vehicle portion  410  includes a display unit or head unit  420  having a fold down or rotatable display  422 , a receptacle  424 , and controls  426 . The rotatable display  422  is able to open or close as shown by the arrow C in  FIG. 4 . The portable portion  470  includes a portable navigation unit  480  having a display  482  and controls  484 . The backside  480 ′ of the portable navigation unit  480  is also shown in  FIG. 4 .  
         [0083]     The portable navigation unit  480  can be inserted into and received by the receptacle  424 , as shown by the arrow A. Likewise, the portable navigation unit  480  can be inserted into and received by the receptacle  424 , with the display  482  facing the inside (backward) of the head unit  420 , as shown by the arrow B. With the portable navigation unit  480  received in the display unit  620 , the system can function as set forth herein for the navigation system  100 ,  200  and the like noted above. That is, the navigation system  400  differs from the other systems set forth herein in that the portable navigation unit  480  is received by and retained in the display unit  420 .  
         [0084]     In embodiments, once the portable navigation unit  480  is received by the display unit  420 , the navigation images can be displayed on the rotatable display  422  and the portable navigation unit  480  can be operated by the controls  426 . Other in-vehicles components, such as speakers, navigation antenna, microphone and the like, can also be used with the display unit  420  although not shown in  FIG. 4 .  
         [0085]     Another embodiment of the present invention includes a system or method which adjusts certain screen elements to compensate for the difference between aspect ratios of the display of the portable navigation unit and the in-vehicle display. This compensation or correction of image elements can be critical for specific applications where the shape of the displayed image carries a certain meaning which would otherwise be lost due to a distortion of the element in a redisplayed image.  
         [0086]     For example, in a navigation application, the image of a circle on a map can carry the meaning of a destination point while the image of an oval can a completely different meaning of a highway sign. Obviously, with an uncorrected redisplay of an image of circle as an oval element, the meaning of the circle element is lost and the confusion of the meaning of the oval element will most likely result. The correction of image elements can also provide the benefit of increasing the aesthetics and/or uniformity of the redisplayed image.  
         [0087]     As shown in  FIG. 5A , in embodiments, an integral display (first display)  512  of a portable navigation unit  510  has a shape and an aspect ratio which is different from the shape and aspect ratio of the display  522  (second display) of an in-vehicle display unit  520 . As shown, the display  512  is generally square in shape, for example, having an aspect ratio of 4:3, whereas the display  522  is more elongated horizontally, for example, having an aspect ratio of 16:9 or so. Of course, other differing display shapes may also be used in various other embodiments.  
         [0088]     In the embodiments, when the portable navigation unit  510  detects, via an interface cable  516 , that the portable navigation unit  510  is connected to the in-vehicle display unit  520 , an image controller or generator  514  in the portable navigation unit  510  will redirect the projection of the image from the integral display  512  to the in-vehicle display  522 . In some embodiments, the image generator  514  will continue to project an image to the integral display  512  while transmitting and projecting a second image to the in-vehicle display  522 .  
         [0089]     In at least one embodiment, the image is transmitted to the in-vehicle display  522  without any correction or manipulation. As shown in  FIG. 5B , in such embodiments, an image  530  shown on the integral display  512  will result in a deformed image on the in-vehicle display  522  with regard to the aspect ratio. For example, with the image being initially generated for a first display having an aspect ratio of 4:3, redirecting or transmitting the image to a second display having an aspect ratio of 16:9 without correction will result in a new image which has been elongated or stretched along the longer side (horizontal direction in  FIG. 5B ) of the second display.  
         [0090]     As shown, the initial image  530  is projected onto the display  512  of the portable navigation unit  510  and then when connected to the in-vehicle display  522 , the redisplayed image  535  is displayed. The original image  530  can include various same elements, symbols, icons, text, fonts or other information and the redisplayed image also contains certain elements, symbols, icons, text, fonts or other information. Depending on the embodiment, the displayed elements, symbols, icons or other information can include navigational or map features, such as roads, intersections, lakes, mountains, points of interests or POIs, turn indicators, control buttons or sliders, as well as textual information such as street names, city names, menu items, and the like.  
         [0091]     While in this embodiment, the redisplayed image  535  will still contain all the same elements, symbols, icons, text, fonts, information and the like, as the original display image, the elements, symbols, icons, text, font, information, etc. will be distorted to a certain degree. That is, the aspect ratio of each displayed item will be changed to match or reflect the difference in aspect ratios of the two displays. As shown, the image elements  535  are horizontally elongated relative to the original image  530 . For example, a circular element  533  in the original image  530  is shown redisplayed as an oval or elliptical shaped element  538  and a rectangular element  534  is shown redisplayed also as a rectangular element  539  except being longer on the side which has been stretched.  
         [0092]     In contrast, in at least one embodiment, the redisplayed image is processed so that every redisplayed element, symbol, icon, text, font or the like is reshaped so that each item retains its original aspect ratio and/or shape. However, while doing an all inclusive correction provides an improved image, depending on the processing power and speed of the portable device, the speed of the image rendering can be adversely affected.  
         [0093]     To provide sufficiently fast image rendering and to save a graphics storage space, while retaining a desired image quality, embodiments of the present invention perform image correction on only certain selected elements, symbols, icons, text, fonts or other information. The selection of which items to correct and which items not to correct can vary depending on any of a variety of factors including the amount and type of distortion of uncorrected items, the assigned or inherent meaning of the shape of the items, the processing power of the device creating the image, the importance of the item relative to other displayed items, the function of the displayed image, and the like.  
         [0094]     An embodiment shown in  FIG. 5C  is a set of displays of different aspect ratios, where the integral display  512  has an image  540  which is partially corrected and transferred to the in-vehicle display  522  having an image  545 . The image  540  can display any of a variety of elements, symbols, icons, text, font or other information, however, for clarity, a simple image  540  is shown. The image  540  has items including a circular shaped element  543  and a rectangular shaped element  544 . In this example, the image  540  is transferred to, and redisplayed on the in-vehicle display  522  as a partially corrected image.  
         [0095]     As shown, the image  545  has items including a corrected circular shaped element  548  and an uncorrected or elongated rectangular shaped element  549 . In this embodiment, the image of the circular shaped element  543  was selectively corrected such that the redisplayed image element  548  would remain circular in shape. In contrast, the rectangular shaped element  544  was selectively not corrected such that the redisplayed image element  549  was still a rectangular shaped element, although elongated and/or stretched.  
         [0096]     Selectively choosing the circular element to correct and not correct the rectangular element allows the circular element to retain its meaning as a circle and not be viewed as an oval, which may have a separate meaning, while reducing processing time by not correcting the rectangular element which in the redisplay maintains any meaning assigned as it is still a rectangle.  
         [0097]     In at least one embodiment of the present invention, the image that is produced by the portable navigation unit is comprised of map images rendered from a navigation database and a separate set of image elements referenced by one or more look-up tables. The image elements can include points of interests, street names, city names, destination markers, turn and route indicators and the like. As the complete image is created, the map image is rendered with the image elements laid over the map image.  
         [0098]     In such embodiments, to facilitate the correction of the images between the portable display and the in-vehicle display, the image generator or operating system chooses not to correct the map image and to correct some or all of the image elements. In at least one embodiment, the choice of which elements to correct and the correction of the image elements can be accomplished by means of a corrected element look-up table. This corrected element look-up table can be substituted for the original or uncorrected look-up table upon the detection of the connection with the in-vehicle display. Within the corrected image table, all or only selected elements can have a different shape or form from their original shape or form.  
         [0099]     When viewed on the in-vehicle display, the corrected images may retain their aspect ratios to the display of their uncorrected images on the first or original display. Of course, if the corrected images are displayed on the first or original display, they will be accordingly distorted, compressed or compacted. For example, a corrected rectangle if displayed on the original display could be shown as a square shaped image.  
         [0100]      FIG. 6  is a schematic block diagram showing the data tables and correction rules for map data in converting the map data for the external (in-vehicle or second) display. As shown, the map data has various map elements and their images. In the case where changes in the aspect ratio are required for displaying the map image to the external display such as an in-vehicle display, the aspect ratio of map image in the map data is changed to an appropriate aspect ratio according to the correction rule  607 .  
         [0101]     The correction rule  607  in  FIG. 6  is a set of formulas to be used to correct the map image and some map elements for viewing in the external display. Generally, the image elements table  603  is used to display such map elements on the display of the portable navigation unit. In the case where the in-vehicle display is used, the corrected image elements table  605 , which stores images for different aspect ratios, is used to display an image on the in-vehicle display. Some map elements such as the rectangular shape noted above may be drawn without using the corrected image elements table but by the correction rule  607 .  
         [0102]      FIG. 7  is a flow chart showing the steps of displaying an image to the external (in-vehicle) display such as shown in  FIG. 5C  with image correction for aesthetic appearance and ease of viewing or correctly recognizing map elements. First, whether the portable navigation unit is connected to an external display is determined in the step  701 . If it is established that the external display has been connected to the portable navigation unit, it will be determined whether the aspect ratio and shape of the display of the external display in the step  702 .  
         [0103]     Next, it is determined whether the image correction as described above with reference to  FIGS. 5B and 5C  is needed in the step  703 . Several factors may be taken into consideration as noted above. If the difference between the aspect ratios of the portable display and the external display is minimum, the image correction may not be performed. Even when there is some differences in the aspect ratio between those two displays, the portable navigation unit may be set not to generate corrected images in order to save computational resources. The user may also set his/her preference as to whether the image correction is to be performed.  
         [0104]     If the image correction is deemed necessary, in the step  704 , the portable navigation unit will check the correction table to determine which elements are to be corrected for the external display. The pre-compiled image that has been stored in the image correction table such as shown in  FIG. 6  may be used for generating corrected image data. The navigation system may also use correction rules to calculate and generate an image to be displayed.  
         [0105]     Based on the images stored in the map database and the correction table, an image for the external display is generated in the step  705 . Finally, the portable navigation unit will transmit the generated image data to the external display so that the external display can display the corrected image in the step  706 .  
         [0106]     Although the invention is described herein with reference to the preferred embodiment, one skilled in the art will readily appreciate that various modifications and variations may be made without departing from the spirit and scope of the present invention. Such modifications and variations are considered to be within the purview and scope of the appended claims and their equivalents.