On-vehicle information processor with map data and map data...

Details On-vehicle information processor with map data and map data... On-vehicle information processor with map data and map data...

2000-11-29

2002-05-28

Cuchlinski, Jr., William A. (Department: 3661)

Data processing: vehicles, navigation, and relative location

Navigation

Employing position determining equipment

C701S206000, C701S207000, C340S995190

Reexamination Certificate

active

06397144

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to on-vehicle information processors for providing map information based on map data and, more particularly, to an on-vehicle information processor in which a large volume of map data and associated map management data is managed efficiently.
2. Description of the Related Art
FIG. 10
is a block diagram showing a construction of an on-vehicle information processor disclosed in Japanese Laid-Open Patent Application No. 10-253367. Referring to
FIG. 10
, the on-vehicle information processor comprises applications
101
-
103
for providing services to a user by processing map data and the like; an operating system
104
for providing basic functions related to a recording medium
105
for storing map data and the like and a memory
106
for temporarily storing map data when the application is executed; a cache
111
for caching the map data and the like; and a device driver
121
for directly controlling the recording medium
105
. The applications
101
-
103
and the operating system
104
are stored in, for example, a read-only memory (ROM) and executed by a microprocessor after being developed in a random access memory (RAM) or the like.
A description will now be given of the operation according to the related art.
FIG. 11
shows an example of how a cache is used in the related-art on-vehicle information processor.
When any of the applications
101
-
103
reads out the map data from the recording medium
105
via the operating system
104
, the map data is stored in the cache
111
and retained therein according to a predetermined caching system. When the cache
111
becomes full, the data is discarded appropriately. When any of the applications
101
-
103
accesses the data stored in the cache
111
, accessed data, for example, data items
111
-
1
-
111
-
3
, are locked so that the other applications are prevented from accessing the data
111
-
1
-
111
-
3
. In this way, the integrity of the cache
111
is maintained.
The applications
101
-
103
provide to the user based on the map data thus read out. For example, the application displays a road map on a display.
As described, in the related-art on-vehicle information processor, the data is locked so that applications other than the initially accessing application are prevented from accessing that data. Therefore, accessing from a plurality of applications the same data in the cache is not permitted. Accordingly, improvement in the processing speed cannot be hoped for.
SUMMARY OF THE INVENTION
Accordingly, a general object of the present invention is to provide an on-vehicle information processor in which the aforementioned drawback is eliminated.
Another and more specific object is to provide an on-vehicle information processor in which the processing speed is improved by allowing a plurality of applications to access the same map data temporarily stored in a map data cache.
Still another object of the present invention is to provide an on-vehicle information processor in which map data and map management data read out by a data reading unit are managed independently such that the map data and the map management data are read out from a data managing unit when required, so that the efficiency in processing an application is improved.
The aforementioned objects can be achieved by an on-vehicle information processor for providing map information based on map data, comprising: application processing means for providing predetermined map information based on map data and map management data; a data reading unit for reading the map data and the map management data from a recording medium; a data management unit for managing the map data and the map management data independently; and a request analyzing unit for responding to a request from the application processing means to permit access from the application processing means to the map data and the map management data managed by the data management unit.
The data management unit may acquire the map management data provided initially to the application means, so as to manage the acquired map management data; the request analyzing unit reads out the map management data from the recording medium via the data reading unit so as to supply the map management data thus read out to the application means, when the map management data is initially required by the application means; and the request analyzing unit may supply the map management data managed by the data management unit to the application means when the map management data is subsequently required by the application means.
The data management unit may be provided with a map data cache and a control unit for controlling the map data cache.
The control unit in the data management unit may control the total size of map data stored in the map data cache to be smaller than a predetermined upper limit.
The request analyzing unit may grant access from a plurality of application means to the same map data stored in the map data cache.
The map data cache may store count information indicating a number of application means accessing a storage area storing the map data, and the control unit may determine the map data stored in the map data cache that should be discarded, based on the count information stored in the map data cache.
The map data cache may store information relating to chronological sequence of storage of the map data or information indicating time of access to the map data, and the control unit may determine the map data stored in the map data cache that should be discarded, based on the information stored in the map data cache.


REFERENCES:
patent: 6047280 (2000-04-01), Ashby et al.
patent: 6308177 (2001-10-01), Israni et al.
patent: 2001/0002457 (2001-05-01), Umezu et al.
patent: 10-253367 (1998-09-01), None
patent: 411311941 (1999-11-01), None

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