Abstract:
An on-vehicle information processing unit includes a central processing unit; a device connected to the central processing unit; a device-dependent driver for driving only the device; an operating-system-standard (OS-standard) driver enabling an application to drive different devices; a device-dependent application for using the device through the device-dependent driver; and an OS-dependent application for using the device through the OS-standard driver. The central processing unit can include a switch for enabling the OS-dependent application only when using an Internet function, and for operating the device-dependent application in a normal mode. This makes it possible to solve a problem of a conventional on-vehicle information processing unit in that it is necessary for a general-purpose application to use a dedicated device driver for interfacing between the device and the general-purpose application, and hence it is difficult for the general-purpose application to make effective use of its functions because of man-hours required to develop the dedicated driver.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an on-vehicle information processing unit that meets the requirement of high-speed processing such as map drawing.  
           [0003]    2. Description of Related Art  
           [0004]    [0004]FIG. 16 is a block diagram showing a hierarchical configuration of a conventional navigation system. In FIG. 16, the reference numeral  101  designates navigation hardware including a DVD-ROM drive, a display monitor, a GPS receiver, a vehicle speed pulse counter, a gyroscope and the like. The reference numeral  102  designates a navigation OS (operating system) including basic functions such as memory management of programs, process management and thread management in conjunction with a function of controlling navigation hardware  101 . The reference numeral  103  designates a graphic-chip-only device driver for directly controlling a graphic chip of the navigation hardware  101 ;  104  designates a navigation application; and  105  designates an Internet browser for carrying out program communications with the navigation application  104  via an external interface (I/F)  104   a.    
           [0005]    Next, the operation of the conventional navigation system will be described.  
           [0006]    Starting its operation, the navigation application  104  commands the graphic chip  101   a  to execute a display operation through the graphic-chip-only device driver  103 , thereby carrying out high-speed drawing. In the display state, the navigation application  104  starts the Internet browser  105  through the external I/F  104   a  to display an Internet browser screen on the graphic chip  101   a.    
           [0007]    With the foregoing configuration, the conventional on-vehicle information processing unit executes a program using the dedicated driver (graphic-chip-only device driver  103 ) to achieve the best performance of the device (graphic chip  101   a ) without using drivers installed in the operating system (OS). Accordingly, a general-purpose application, which is designed to operate using the drivers prepared in the OS, cannot work without change. To enable its operation, it is necessary for the general-purpose application like an Internet browser to use a device driver specifically designed for the application in accordance with the rule proper to the device driver. Thus, the dedicated device driver suitable for the general-purpose application must be developed. This presents a problem of requiring great man-hours to develop it, making it difficult to utilize the available resources of the general-purpose application.  
           [0008]    For example, when a system is configured such that it operates the navigation application (device-dependent application) on the Windows CE by using a dedicated device driver, a problem arises that the system cannot make use of the general-purpose applications like an Internet browser, so-called Windows applications, which utilize GDI (graphics device interface) compatible device drivers that employ a common interface, and hence adapt to different drawing devices.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention is implemented to solve the foregoing problem. It is therefore an object of the present invention to provide an on-vehicle information processing unit capable of extending its applications and implementing high-speed processing at the same time.  
           [0010]    According to one aspect of the present invention, there is provided an on-vehicle information processing unit comprising: a central processing unit; a device connected to the central processing unit; a device-dependent driver for driving only the device; an operating-system-standard (OS-standard) driver enabling an application to drive different devices; a device-dependent application for using the device through the device-dependent driver; and an operating-system-dependent (OS-dependent) application for using the device through the OS-standard driver.  
           [0011]    Here, the central processing unit may comprise switching means for enabling the OS-dependent application only when using an Internet function, and for operating the device-dependent application in a normal mode.  
           [0012]    The device-dependent driver may further comprise driver switching means for switching between the device-dependent driver and the OS-standard driver.  
           [0013]    The device-dependent application may control the driver switching means by carrying out inter-program communication with the OS-dependent application.  
           [0014]    The on-vehicle information processing unit may further comprise a device driver switching module for enabling the device-dependent driver in response to a request of the device-dependent application, and for enabling the OS-dependent driver in response to a request of the OS-dependent application.  
           [0015]    The device driver switching module may enable one of the device-dependent driver and OS-dependent driver in response to an operation of a manual switch.  
           [0016]    The central processing unit may further comprise a program managing module for controlling execution of the device-dependent application and the OS-dependent application, and the device driver switching module switches the device drivers in response to a request of the program managing module.  
           [0017]    The device may be a display device having multi-display layers, and display an image associated with the device-dependent application on an upper layer, and an image associated with the OS-dependent application on a lower layer.  
           [0018]    The device may simultaneously display images associated with both the device-dependent application and the OS-dependent application by limiting at least one of display areas of the upper display layer and the lower display layer.  
           [0019]    The OS-dependent application may operate on a virtual machine.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a block diagram showing a hardware configuration of an on-vehicle information processing unit in accordance with the present invention;  
         [0021]    [0021]FIG. 2 is a block diagram showing a hierarchical configuration of an embodiment  1  of the navigation system in accordance with the present invention;  
         [0022]    FIGS.  3 ( a ) and  3 ( b ) are diagrams illustrating display examples in the embodiment 1 of the navigation system in accordance with the present invention;  
         [0023]    [0023]FIG. 4 is a block diagram showing a hierarchical configuration of an embodiment 2 of the navigation system in accordance with the present invention;  
         [0024]    [0024]FIG. 5 is a block diagram showing a hierarchical configuration of an embodiment 4 of the navigation system in accordance with the present invention;  
         [0025]    [0025]FIG. 6 is a block diagram showing a hierarchical configuration of an embodiment 5 of the navigation system in accordance with the present invention;  
         [0026]    [0026]FIG. 7 is a block diagram showing a hierarchical configuration of an embodiment 6 of the navigation system in accordance with the present invention;  
         [0027]    [0027]FIG. 8 is a block diagram showing a hierarchical configuration of an embodiment 7 of the navigation system in accordance with the present invention;  
         [0028]    [0028]FIG. 9 is a block diagram showing a hierarchical configuration of an embodiment 8 of the navigation system in accordance with the present invention;  
         [0029]    FIGS.  10 ( a )- 10 ( d ) are diagrams illustrating display examples in the embodiment 8 of the navigation system in accordance with the present invention;  
         [0030]    [0030]FIG. 11 is a block diagram showing a hierarchical configuration of an embodiment 9 of the navigation system in accordance with the present invention;  
         [0031]    FIGS.  12 ( a )- 12 ( e ) are diagrams illustrating display examples in the embodiment 9 of the navigation system in accordance with the present invention;  
         [0032]    [0032]FIG. 13 is a block diagram showing a hierarchical configuration of an embodiment 11 of the navigation system in accordance with the present invention;  
         [0033]    FIGS.  14 ( a )- 14 ( e ) are diagrams illustrating display examples in the embodiment 11 of the navigation system in accordance with the present invention;  
         [0034]    [0034]FIG. 15 is a block diagram showing a hierarchical configuration of an embodiment 12 of the navigation system in accordance with the present invention; and  
         [0035]    [0035]FIG. 16 is a block diagram showing a hierarchical configuration of a conventional navigation system.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    The invention will now be described with reference to the accompanying drawings.  
       Embodiment 1  
       [0037]    [0037]FIG. 1 is a block diagram showing a hardware configuration of an on-vehicle information processing unit in accordance with the present invention. In FIG. 1, the reference numeral  11  designates a ROM prestoring programs such as a navigation OS, device drivers and navigation applications;  10  designates a microprocessor (central processing unit) for executing those programs; and  12  designates a RAM for storing these programs and data when executing the programs.  
         [0038]    The reference numeral  18  designates a DVD-ROM drive for driving a DVD (Digital Versatile Disk)-ROM  19  to read data; and  17  designates a DVD-ROM interface for transferring data between the DVD-ROM drive  18  and the microprocessor  10 . The reference numeral  21  designates a graphic controller (graphic chip) for writing image data to a frame buffer  20  when the microprocessor  10  outputs the image data or an image processing instruction, and for drawing an image corresponding to the image data to a display monitor  22  like a liquid crystal display. The reference numeral  23  designates a mobile phone for connecting the microprocessor  10  to the Internet.  
         [0039]    The reference numeral  16  designates a GPS receiver for receiving radio waves from GPS satellites;  15  designates a vehicle speed pulse counter mounted on an axle of a vehicle for measuring its speed;  14  designates a gyroscope for detecting the bearing of the vehicle; and  13  designates a peripheral interface for transferring data between the microprocessor  10  and the GPS receiver  16 , vehicle speed pulse counter  15  and gyroscope  14 .  
         [0040]    The reference numeral  19  designates the DVD-ROM for prestoring a map database and the like. In addition to these components, there are installed a speaker for outputting voice guidance, a driver of the speaker, an FM multiplexed broadcasting transceiver for communicating with external infrastructure, a radio/optical beacon receiver and the like.  
         [0041]    Incidentally, a recording medium such as a DVD-ROM can be used instead of the ROM  11  to record the navigation OS, device drivers, navigation applications and the like so that these programs are read out of it to be used.  
         [0042]    [0042]FIG. 2 is a block diagram showing a hierarchical configuration of the embodiment 1 of the navigation system in accordance with the present invention. In FIG. 2, the reference numeral  31  designates navigation hardware including the DVD-ROM drive  18 , the display monitor  22 , the GPS receiver  16 , the vehicle speed pulse counter  15 , the gyroscope  14  and the like. It includes a graphic chip  31   a  that corresponds to the graphic chip  21  of FIG. 1 as one of the devices. The reference numeral  32  designates a navigation OS including basic functions such as memory management of programs, process management and thread management in conjunction with a function of controlling navigation hardware  31 . The reference numeral  33  designates a graphic-chip-only device driver for directly controlling the graphic chip  31   a  in the navigation hardware  31 . It includes a driver switching means  33   a.  The reference numeral  34  designates a GDI-based device driver (OS-standard driver) activated by a start instruction fed from the driver switching means  33   a  in the graphic-chip-only device driver  33 .  
         [0043]    The reference numeral  35  designates a navigation application module (device-dependent application) consisting of application programs for implementing navigation services such as calculation of the current position, searching for a path, and path guidance. The reference numeral  36  designates a general purpose Internet browser (OS-dependent application) coded to use the GDI for carrying out inter-program communications with the navigation application  35  through the external interface (I/F)  35   a.    
         [0044]    Next, the operation of the present embodiment 1 will be described.  
         [0045]    Starting its operation, the navigation application  35  commands the graphic chip  31   a  to execute display operation through the graphic-chip-only device driver  33 , thereby carrying out high-speed drawing as shown in FIG. 3( a ). In the display state, in response to the depression of the Internet button on the screen, the navigation application  35  starts the Internet browser  36  through the external I/F  35   a,  and enables the GDI-based device driver  34  by the start instruction sent from the driver switching means  33   a  in the graphic-chip-only device driver  33 . Since the Internet browser  36  is coded to use the GDI, it controls the graphic chip  31   a  from the GDI through the GDI-based device driver  34 , thereby displaying the Internet browser screen as shown in FIG. 3( b ) instead of the display as shown in FIG. 3( a ).  
         [0046]    Once the Internet browser  36  has been started, an end message is sent to the navigation application  35 . Receiving the end message, the navigation application  35  commands the graphic-chip-only device driver  33  to carry out switching to disable the GDI-based device driver  34  and to enable the graphic-chip-only device driver  33  by using the driver switching means  33   a,  thereby enabling the graphic chip  31   a  to display the navigation screen as shown in FIG. 3( a ), again. Thus, the navigation application  35  can coexist with the Internet browser  36 .  
         [0047]    As described above, the present embodiment 1 can execute both the OS-dependent general-purpose program and device-dependent high-speed processing program.  
       Embodiment 2  
       [0048]    Although the Internet browser  36  is independent of the navigation application  35  in the foregoing embodiment 1, the Internet function can be incorporated into the navigation application  35  as shown in FIG. 4 which shows a configuration of the present embodiment 2. Since the remaining configuration is the same as that of the embodiment 1, the description thereof is omitted here.  
         [0049]    Next, the operation of the present embodiment 2 will be described.  
         [0050]    The navigation application  35  operates as in the embodiment 1. Only when using the Internet function, the navigation application  35  commands the graphic-chip-only device driver  33  to carry out switching to disable the graphic-chip-only device driver  33  and to enable the GDI-based device driver  34  by using the driver switching means  33   a,  thereby executing the display as shown in FIG. 3( b ).  
         [0051]    According to the present embodiment 2, incorporating the Internet function into the navigation application can simplify its configuration as compared with that of the embodiment 1.  
       Embodiment 3  
       [0052]    Although switching is carried out between the graphic-chip-only device driver  33  and the GDI-based device driver  34  to connect one of them to the graphic chip  31   a  in the foregoing embodiments, this is not essential. For example, another device such as a voice device can be used instead of the GDI-based device driver  34  to be switched. This offers an advantage of being able to make effective use of OS-standard applications using voice.  
       Embodiment 4  
       [0053]    [0053]FIG. 5 is a block diagram showing a hierarchical configuration of an embodiment 4 of the navigation system in accordance with the present invention. The present embodiment 4 is configured such that it operates the Internet browser  36  on a virtual machine (VM)  50 . The Internet browser  36  carries out inter-program communications with the navigation application  35  as in the foregoing embodiment 1. Since the remaining configuration and operation, and hence the advantage are the same as those of the embodiment 1, the description thereof is omitted here to avoid duplication.  
       Embodiment 5  
       [0054]    [0054]FIG. 6 is a block diagram showing a hierarchical configuration of an embodiment 5 of the navigation system in accordance with the present invention. The present embodiment 5 comprises a device driver switching module  37  between the navigation application  35  and the Internet browser  36 . The device driver switching module  37  controls the graphic-chip-only device driver  33  to carry out switching to enable the GDI-based device driver  34  through the driver switching means  33   a.  Since the remaining configuration is the same as that of the foregoing embodiment 1, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0055]    Next, the operation of the present embodiment 5 will be described.  
         [0056]    When the navigation application  35  starts its operation with requesting the device driver switching module  37  to use the graphic-chip-only device driver  33 , the device driver switching module  37  enables the graphic-chip-only device driver  33  to carry out the display as shown in FIG. 3( a ).  
         [0057]    In the display state, in response to the depression of the Internet button on the screen, the navigation application  35  starts the Internet browser  36  through the external I/F  35   a.  In response to a driver switching request from the Internet browser  36 , the device driver switching module  37  commands the graphic-chip-only device driver  33  to carry out switching to enable the GDI-based device driver  34  by sending the start instruction from the driver switching means  33   a  in the graphic-chip-only device driver  33 . Since the Internet browser  36  is coded to use the GDI, it controls the graphic chip  31   a  through the GDI in the navigation OS  32  and the GDI-based device driver  34 , thereby enabling the graphic chip  31   a  to display the Internet browser screen as shown in FIG. 3( b ) instead of the display as shown in FIG. 3( a ).  
         [0058]    Once the Internet browser  36  has been started, it sends an end message to the navigation application  35 . Receiving the end message, the navigation application  35  issues a switching request to the device driver switching module  37 . In response to the switching request, the device driver switching module  37  commands the graphic-chip-only device driver  33  to carry out switching to disable the GDI-based device driver  34  and to enable the graphic-chip-only device driver  33  by using the driver switching means  33   a,  thereby enabling the graphic chip  31   a  to display the navigation screen as shown in FIG. 3( a ), again.  
         [0059]    Since the present embodiment 5 includes the dedicated module for carrying out device driver switching, it offers an advantage of being able to simplify programs, facilitating producing the programs.  
       Embodiment 6  
       [0060]    [0060]FIG. 7 is a block diagram showing a hierarchical configuration of an embodiment 6 of the navigation system in accordance with the present invention. The present embodiment  6  comprises a manual switch  38  in the navigation hardware  31 , and a switch-input driver  39  that operates in response to a switching signal from the manual switch  38  to enable the device driver switching module  37  to carry out its switching operation. Since the remaining configuration is the same as that of the foregoing embodiment 5, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0061]    Next, the operation of the present embodiment 6 will be described.  
         [0062]    When a user issues a request to the switch-input driver  39  by operating the manual switch  38  to use the graphic-chip-only device driver  33 , the device driver switching module  37 , receiving the control signal from the switch-input driver  39 , enables the graphic-chip-only device driver  33  to carry out the display as shown in FIG. 3( a ).  
         [0063]    In this display state, in response to a request from the manual switch  38  to use the GDI-based device driver  34 , the switch-input driver  39  outputs the control signal. Receiving the control signal from the switch-input driver  39 , the device driver switching module  37  disables the graphic-chip-only device driver  33  and enables the GDI-based device driver  34 . Since the Internet browser  36  is coded to use the GDI, it controls the graphic chip  31   a  through the GDI in the navigation OS  32  and the GDI-based device driver  34 , thereby enabling the graphic chip  31   a  to display the Internet browser screen as shown in FIG. 3( b ) instead of the navigation screen as shown in FIG. 3( a ).  
         [0064]    Once the Internet browser  36  has been started, and a request to use the graphic-chip-only device driver  33  is sent from the manual switch  38  to the switch-input driver  39 , the switch-input driver  39  outputs the control signal. Receiving the control signal, the device driver switching module  37  enables the graphic-chip-only device driver  33  to carry out the display as shown in FIG. 3( a ), again.  
         [0065]    According to the present embodiment 6, a user can freely select one of the OS-dependent general-purpose program and the device-dependent high-speed processing program as in the foregoing embodiment 1 by operating the manual switch  38 .  
       Embodiment 7  
       [0066]    [0066]FIG. 8 is a block diagram showing a hierarchical configuration of an embodiment 7 of the navigation system in accordance with the present invention. The present embodiment 7 comprises a manual switch  38  in the navigation hardware  31 ; a switch-input driver  39  operating in response to a switching signal from the manual switch  38 ; and an application switching module  40  for carrying out switching operation in response to the output of the switch-input driver  39 . The application switching module  40  controls the execution of the navigation application  35  and the Internet browser  36 , and the display switching of the device driver switching module  37 . Since the remaining configuration is the same as that of the foregoing embodiment 6, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0067]    Next, the operation of the present embodiment 7 will be described.  
         [0068]    When a user operates the manual switch  38  to provide the switch-input driver  39  with a request to switch the application, to use the navigation application  35 , for example, the application switching module  40 , receiving the control signal from the switch-input driver  39 , enables through the device driver switching module  37  the navigation application  35  and the graphic-chip-only device driver  33  to carry out the display as shown in FIG. 3( a ).  
         [0069]    In this display state, when the user operates the manual switch  38  to request the switch-input driver  39  to carry out the application switching, to use the Internet browser  36 , for example, the application switching module  40 , receiving the control signal from the switch-input driver  39 , enables the Internet browser  36 , and disables the graphic-chip-only device driver  33  using the control signal from the device driver switching module  37 . In the course of this, the graphic-chip-only device driver  33  enables the GDI-based device driver  34  using the control signal from the driver switching means  33   a.  Since the Internet browser  36  is coded to use the GDI, it controls the graphic chip  31   a  through the GDI in the navigation OS  32  and the GDI-based device driver  34 , thereby enabling the graphic chip  31   a  to display the Internet browser screen as shown in FIG. 3( b ) instead of the navigation screen as shown in FIG. 3( a ).  
         [0070]    When the user issues a request to use the navigation application  35  to the switch-input driver  39  by operating the manual switch  38 , the switch-input driver  39  outputs the control signal. Receiving the control signal, the application switching module  40  enables the navigation application  35  and the graphic-chip-only device driver  33  through the device driver switching module  37  to carry out the display as shown in FIG. 3( a ), again.  
         [0071]    According to the present embodiment 7, the inter-application communications become unnecessary, which offers an advantage of being able to make the operation of the applications easier.  
       Embodiment 8  
       [0072]    [0072]FIG. 9 is a block diagram showing a hierarchical configuration of an embodiment 8 of the navigation system in accordance with the present invention. The present embodiment 8 comprises a graphic chip  31   a  with multi-display layers so that the display of the navigation application  35  is carried out on the upper layer of the graphic chip  31   a,  and the display of the Internet browser  36  is carried out on the lower layer of the graphic chip  31   a.  Since the remaining configuration is the same as that of the foregoing embodiment 1, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0073]    Next, the operation of the present embodiment 8 will be described.  
         [0074]    When the navigation application  35  is activated, it performs its display on the upper layer of the graphic chip  31   a  using the graphic-chip-only device driver  33 , thereby carrying out the high-speed drawing as shown in FIG. 10( a ). In this display state, in response to the depression of the Internet button on the screen, the navigation application  35  actives the Internet browser  36  through the external I/F  35   a,  and enables the GDI-based device driver  34  through the graphic-chip-only device driver  33 . Thus, the display as shown in FIG. 10( a ) disappears, and the screen of the Internet browser  36  is displayed in the lower layer of the graphic chip  31   a  as shown in FIG. 10( d ).  
         [0075]    On the other hand, when the navigation application  35  issues a display area limit instruction, the upper layer display as shown in FIG. 10 ( a ) is changed to the display as shown in FIG. 10( b ). Thus, superimposing the lower layer upon the upper layer will produce the display as shown in FIG. 10( c ). In this display state, when an Internet browser end message is issued, the upper layer display area returns to its primary screen as shown in FIG. 10( a ).  
         [0076]    As described above, the present embodiment 8 can display the images of both the applications. Accordingly, when the Internet provides display information linking with the function of the navigation like sightseeing information with spot information, for example, the present embodiment 8 can display the sightseeing spot along with the images of the navigation application, thereby implementing a system with improved usability. In addition, it offers an advantage of being able to eliminate screen flickering involved in the device driver switching because of obviating it.  
       Embodiment 9  
       [0077]    [0077]FIG. 11 is a block diagram showing a hierarchical configuration of an embodiment 9 of the navigation system in accordance with the present invention. It comprise a multi-display layer graphic chip  31   a;  and three applications including the Internet browser  36 , a spreadsheet application  41  and a scheduling application  42  as the OS-dependent application. Since the remaining configuration is the same as that of the foregoing embodiment 8, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0078]    Next, the operation of the present embodiment 9 will be described.  
         [0079]    When the navigation application  35  is activated, it performs its display on the upper layer of the graphic chip  31   a  using the graphic-chip-only device driver  33 , thereby carrying out the high-speed drawing as shown in FIG. 12( a ). In this display state, in response to the depression of the utility-on button on the screen, the display as shown in FIG. 12( a ) disappears, and the icons of the Internet browser  36 , spreadsheet application  41  and scheduling application  42  are displayed in the lower layer of the graphic chip  31   a  as shown in FIG. 12( d ).  
         [0080]    On the other hand, when the navigation application  35  issues a display area limit instruction, the upper layer display as shown in FIG. 12( a ) is changed to the display as shown in FIG. 12( b ). Thus, superimposing the lower layer upon the upper layer will produce the display as shown in FIG. 12( c ). In this display state, when one of the icons is depressed, the display becomes as shown in FIG. 12( e ).  
         [0081]    In this display state, in response to the depression of the OFF button on the screen, the display of the upper layer is returned to its primary screen as shown in FIG. 12( a ). In this case, the navigation application  35  completes the operation of the Internet browser  36 , the spreadsheet application  41  or the scheduling application  42 .  
         [0082]    As described above, the present embodiment 9 can display the images of both the device-dependent application and OS-dependent application at the same time. Accordingly, it offers an advantage of being able to implement a system with improved usability.  
       Embodiment 10  
       [0083]    Although not shown in a drawing, the present embodiment 10 differs from the foregoing embodiments 8 and 9 in that it displays the images of the OS-dependent application in the upper layer of the graphic chip  31   a,  and the images of the navigation application in the lower layer of the graphic chip  31   a,  offering a similar advantage. Although it depends on the performance of the display unit, the foregoing embodiments 8 and 9 can usually achieve better results with a device that accomplishes higher performance in displaying high-speed images in the upper layer, whereas the present embodiment 10 can obtain better result in the opposite case.  
       Embodiment 11  
       [0084]    [0084]FIG. 13 is a block diagram showing a hierarchical configuration of an embodiment 11 of the navigation system in accordance with the present invention. It comprises a display area control application  43  instead of the scheduling application  42  in the embodiment 9 as shown FIG. 11. The display area control application  43  controls the display area of the graphic-chip-only device driver  33 . Since the remaining configuration is the same as that of the foregoing embodiment 9, the description thereof is omitted here by designating the same components by the same reference numerals.  
         [0085]    Next, the operation of the present embodiment 11 will be described.  
         [0086]    When the navigation application  35  is activated, it carries out the display operation in the upper layer of the graphic chip  31   a  using the graphic-chip-only device driver  33 , first. Its initial screen is as shown in FIG. 14( a ). The screen of the lower layer is as shown in FIG. 14( d ), resulting in the screen as shown in FIG. 14( b ).  
         [0087]    In this display state, in response to the depression of a utility button on the screen, the display area control application  43  narrows the upper layer (increasing the display area of the lower layer), displaying the icons as shown in FIG. 14( c ). In response to the depression of a selected icon, the display area control application  43  detects the activation of the Internet browser  36 , for example, and further reduces the upper layer display area, resulting in the display as shown in FIG. 14( e ). In this display state, in response to the depression of the OFF button, the display area control application  43  returns the display area, providing the screen as shown in FIG. 14( b ). Thus, controlling the size of the display area to be changes in accordance with the applications can make effective use of the screen resources.  
       Embodiment 12  
       [0088]    [0088]FIG. 15 is a block diagram showing a hierarchical configuration of an embodiment 12 of the navigation system in accordance with the present invention. It comprises a class library layer  44  for making the graphic-chip-only device driver  33  as thought it were the GDI-based device driver  34  when seen from the navigation application  35 . The remaining configuration and operation are the same as those of the foregoing embodiments.  
         [0089]    As described above, the present embodiment 12 can facilitate the production of the navigation application.