U.S. patent application number 09/793990 was filed with the patent office on 2001-09-13 for navigation device.
Invention is credited to Ata, Teruaki, Hamada, Hiroyuki, Ogawa, Isao, Sakamoto, Kiyomi, Ueyama, Yoshiki, Yamashita, Atsushi.
Application Number | 20010021894 09/793990 |
Document ID | / |
Family ID | 18577100 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021894 |
Kind Code |
A1 |
Sakamoto, Kiyomi ; et
al. |
September 13, 2001 |
Navigation device
Abstract
A navigation device N.sub.1 at least includes a CPU 11 and a
detector 19 generating a detection signal S.sub.2 for determining
whether a main device 1 is used inside a vehicle or not. If
determining, based on the detection signal S.sub.2 from the
detector 19, that the main device 1 is used inside the vehicle, the
CPU 11 operates in on-vehicle mode to carry out first navigation
(present position estimation and route search) suitable for
vehicles. Otherwise, the CPU 11 operates in off-vehicle mode to
carry out second navigation (present position estimation and route
search) suitable for pedestrians. Thus, the navigation device
N.sub.1 can automatically switch its operation mode between
on-vehicle mode and off-vehicle mode.
Inventors: |
Sakamoto, Kiyomi; (Ikoma,
JP) ; Hamada, Hiroyuki; (Yawata, JP) ; Ata,
Teruaki; (Osaka, JP) ; Yamashita, Atsushi;
(Osaka, JP) ; Ueyama, Yoshiki; (Sakai, JP)
; Ogawa, Isao; (Yokohama, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18577100 |
Appl. No.: |
09/793990 |
Filed: |
February 28, 2001 |
Current U.S.
Class: |
701/410 ;
340/995.1 |
Current CPC
Class: |
G01C 21/3688 20130101;
G01C 21/26 20130101 |
Class at
Publication: |
701/209 ;
340/995 |
International
Class: |
G01C 021/34 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2000 |
JP |
2000-56081 |
Claims
What is claimed is:
1. A navigation device usable inside and outside a vehicle,
comprising: a determination part for determining whether said
navigation device is used inside or outside the vehicle; and a
navigation processing part, wherein if said determination part
determines that said navigation device is used inside the vehicle,
said navigation processing part carries out first navigation
suitable for vehicles, and if said determination part determines
that said navigation device is used outside the vehicle, said
navigation processing part carries out second navigation suitable
for pedestrians.
2. The navigation device according to claim 1, wherein said
navigation processing part uses a first cartographic file
representing a relatively large area in said first navigation, and
uses a second cartographic file representing a relatively small
area in said second navigation.
3. The navigation device according to claim 1, further comprising a
memory for storing road network data indicating a connecting
relation among roads, wherein if said determination part determines
that said navigation device is used inside the vehicle, said
navigation processing part searches for a first route for guiding
the vehicle from a starting point to a destination point, based on
the road network data stored in said memory, and if said
determination part determines that said navigation device is used
outside the vehicle, said navigation processing part searches for a
second route for guiding a pedestrian from the starting point to
the destination point, based on the road network data stored in
said memory.
4. The navigation device according to claim 3, wherein said road
network data includes a record indicating a traffic regulation
provided for each of the roads, and said navigation processing part
searches for the first route abiding by the traffic regulation for
said vehicle by referring to said record.
5. The navigation device according to claim 1, further comprising:
a main device accommodating said determination part and said
navigation processing part; and a holder mounted on said vehicle
and removably holding said main device, wherein said main device
further comprises a detector for detecting whether said holder
holds said main device or not, and said determination part
determines whether said navigation device is used inside or outside
the vehicle, based on a detection result by said detector.
6. The navigation device according to claim 4, wherein said
navigation processing unit starts said second navigation while
carrying out said first navigation if said determination part
determines that said navigation device is used outside the vehicle,
and said navigation processing unit starts said first navigation
while carrying out said second navigation if said determination
part determines that said navigation device is used inside the
vehicle.
7. The navigation device according to claim 5, further comprising
an external storage provided outside said main device for storing
data required for said first navigation and said second
navigation.
8. The navigation device according to claim 7, wherein said main
device further includes an internal storage smaller and lighter
than said external storage unit, and said navigation processing
part reads, while carrying out said first navigation, data required
for said second navigation from said external storage to said
internal storage.
9. The navigation device according to claim 1, further comprising:
a terminal for connecting to a device which is fixed to said
vehicle and is capable of specifying whether the vehicle is driven
or parked; and a detector for detecting whether said vehicle is
driven or parked by monitoring a state of said terminal, wherein
said determination part determines whether said navigation device
is used inside or outside the vehicle, based on a detection result
by said detector.
10. The navigation device according to claim 9, wherein said
navigation processing part starts said second navigation while
carrying out said first navigation if said determination part
determines that said navigation device is used outside the vehicle,
and said navigation processing unit starts said first navigation
while carrying out said second navigation if said determination
part determines that said navigation device is used inside the
vehicle.
11. The navigation device according to claim 9, further comprising:
a main device accommodating said determination part and said
navigation processing part; and an external storage provided
outside said main device for storing data required for said first
navigation and said second navigation.
12. The navigation device according to claim 11 wherein said main
device further includes an internal storage smaller and lighter
than said external storage unit, and said navigation processing
part reads, while carrying out said first navigation, data required
for said second navigation from said external storage to said
internal storage.
13. The navigation device according to claim 1, further comprising
an input part for at least generating, in response to an operation
by a user, an operation signal indicating a point where a user gets
on or off the vehicle, wherein said determination part determines
whether the navigation device is used inside or outside the
vehicle, based on the operation signal from said input part.
14. The navigation device according to claim 13, further
comprising: a terminal for connecting to a device which is fixed to
said vehicle and is capable of specifying whether the vehicle is
driven or parked; and a detector for detecting whether said vehicle
is driven or parked by monitoring a state of said terminal, wherein
said determination part determines whether said navigation device
is used inside or outside the vehicle, based on the operation
signal from said input part and a detection result by said
detector.
15. The navigation device according to claim 13, wherein said
navigation processing part starts said second navigation while
carrying out said first navigation if said determination part
determines that said navigation device is used outside the vehicle,
and said navigation processing unit starts said first navigation
while carrying out said second navigation if said determination
part determines that said navigation device is used inside the
vehicle.
16. The navigation device according to claim 13, further
comprising: a main device accommodating said determination part and
said navigation processing part; and an external storage provided
outside said main device for storing data required for said first
navigation and said second navigation.
17. The navigation device according to claim 16, wherein said main
device further includes an internal storage smaller and lighter
than said external storage unit, and said navigation processing
part reads, while carrying out said first navigation, data required
for said second navigation from said external storage to said
internal storage.
18. The navigation device according to claim 1, further comprising
an input part for at least generating, in response to an operation
by a user, an operation signal indicating timing where a user gets
on or off the vehicle, wherein said determination part determines
whether the navigation device is used inside or outside the vehicle
based on the operation signal from said input part.
19. The navigation device according to claim 18, wherein said
navigation processing part starts said second navigation while
carrying out said first navigation if said determination part
determines that said navigation device is used outside the vehicle,
and said navigation processing unit starts said first navigation
while carrying out said second navigation if said determination
part determines that said navigation device is used inside the
vehicle.
20. The navigation device according to claim 18, further
comprising: a main device accommodating said determination part and
said navigation processing part; and an external storage provided
outside said main device for storing data required for said first
navigation and said second navigation.
21. The navigation device according to claim 20, wherein said main
device further includes an internal storage smaller and lighter
than said external storage unit; and said navigation processing
part reads, while carrying out said first navigation, data required
for said second navigation from said external storage to said
internal storage.
22. The navigation device according to claim 1, further comprising:
a main device accommodating said determination part and said
navigation processing part; and an external communications
controller provided outside said main device and fixed to the
vehicle for communicating with the main device, wherein said main
device further comprises an internal communications controller for
generating a notification signal indicating whether communications
are possible with said external communications controller, and said
determination part determines whether the navigation device is used
inside or outside the vehicle, based on the notification signal
from said internal communications controller,.
23. The navigation device according to claim 22, wherein said
navigation processing part starts said second navigation while
carrying out said first navigation if said determination part
determines that said navigation device is used outside the vehicle,
and said navigation processing unit starts said first navigation
while carrying out said second navigation if said determination
part determines that said navigation device is used inside the
vehicle.
24. The navigation device according to claim 22, further
comprising: an external storage provided outside said main device
for storing data required for said first navigation and said second
navigation.
25. The navigation device according to claim 24, wherein said main
device further includes an internal storage smaller and lighter
than said external storage unit; and said navigation processing
part reads, while carrying out said first navigation, data required
for said second navigation from said external storage to said
internal storage.
26. The navigation device according to claim 22, wherein said
external communications controller transmits a radio wave with
electric power substantially covering inside the vehicle to
communicate with said internal communications controller.
27. A navigation method used in a computer device operable inside
and outside a vehicle, the method comprising the steps of:
determining whether the navigation device is used inside or outside
the vehicle; carrying out first navigation suitable for vehicles if
it is determined in said determining step that the navigation
device is used inside the vehicle; and carrying out second
navigation suitable for pedestrians if it is determined in said
determining step that the navigation device is used outside the
vehicle.
28. A recording medium on which a program to be run on a computer
device usable inside and outside a vehicle is recorded for
realizing navigation, said program comprising the steps of:
determining whether the navigation device is used inside or outside
the vehicle; carrying out first navigation suitable for vehicles if
it is determined in said determining step that the navigation
device is used inside the vehicle; and carrying out second
navigation suitable for pedestrians if it is determined in said
determining step that the navigation device is used outside the
vehicle.
29. A program to be run on a computer device usable inside and
outside a vehicle for realizing navigation, said program comprising
the steps of: determining whether the navigation device is used
inside or outside the vehicle; carrying out first navigation
suitable for vehicles if it is determined in said determining step
that the navigation device is used inside the vehicle; and carrying
out second navigation suitable for pedestrians if it is determined
in said determining step that the navigation device is used outside
the vehicle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to navigation devices and,
more specifically, to a navigation device structured as usable both
inside and outside a vehicle.
[0003] 2. Description of the Background Art
[0004] Conventional vehicle navigation devices display a map and a
present position of a vehicle on the map, and search for an optimal
route from a starting point to a destination point for guiding a
driver. Such vehicle navigation device is usually mounted fixedly
inside the vehicle, and therefore the user cannot use the device
outside the vehicle or inside another vehicle. To avoid such
inconvenience, research and development has been carried out on
navigation devices removable from the vehicle for portable use both
inside and outside the vehicle. Such navigation device is
exemplarily disclosed in Japanese Patent Laid-Open Publication No.
10-318763, which is described below with reference to FIGS. 24a and
24b.
[0005] In FIG. 24a, a navigation device N.sub.c is structured by a
main device 101, a GPS (Global Positioning System) antenna 102, and
an autonomous navigation sensor 103. The main device 103 is
removably mounted on an arm stand 104 fixed in the vicinity of a
driver's seat of a vehicle for various operations required for
navigating the user. When used inside the vehicle, the navigation
device N.sub.c is typically mounted on a dashboard. On the other
hand, when used outside the vehicle, the antenna 102 is mounted on
an antenna mounting portion 105. Provided on the antenna mounting
portion 105 is a micro switch 106 that turns on when the antenna
102 is mounted.
[0006] When the above-structured navigation device N.sub.c is used
inside the vehicle, the main device 101 is fixedly mounted on the
arm stand 104, and supplied with power by a battery provided in the
vehicle through a power cable, cigarette socket or others.
Moreover, the main device 101 makes a connection with the
autonomous navigation sensor 103. Thus, the main device 101 carries
out various operations required for user's navigation, which are
similar to the conventional ones.
[0007] When the navigation device N.sub.c is used outside the
vehicle, the user first removes the power cable and autonomous
navigation sensor 103 from the main device 101. When the power
cable is removed, the main device 101 is automatically supplied
with electric power by an internal battery. The user also removes
the antenna 102 from the dashboard, and then mounts it on the
antenna mounting portion 105. The user then removes the main device
101 from the arm stand 104. Once the antenna 102 is mounted on the
antenna mounting portion 105, the micro switch 106 is ON. The state
of the micro switch is always monitored by a controller (not shown)
of the main device 101. When the micro switch is ON, the controller
determines that the main device has been out of the vehicle, and
the operation mode is changed to portable mode as shown in a flow
chart of FIG. 24b.
[0008] In portable mode, the controller stores the present position
and the present time when the main device 101 was out of the
vehicle, as the present position of the vehicle and the time. The
controller also stores cartographic data that has been used until
the main device 101 was removed. The cartographic data represents a
map covering an area adjacent to the present position of the
vehicle (step S101).
[0009] Next, the controller waits for a predetermined time (step
S1002), and then detects the present position of the user based on
a signal from a GPS satellite (step S1003). The controller further
checks whether the detected present position of the user is within
a predetermined range of distance (step S1004). If within the
range, the procedure goes to step S1005. Otherwise, the procedure
goes to step S1006.
[0010] In step S1005, the controller checks whether the micro
switch is ON, that is, whether the antenna 102 has been removed
from the antenna mounting portion 105. If the antenna 102 has been
removed, the controller determines that the user came back inside
the vehicle, and ends the portable mode. If the micro switch is ON
in step S1005, the controller determines that the user is around
the vehicle within the predetermined range of distance therefrom,
and the procedure goes to step S1006.
[0011] In step S1006, the controller checks whether the present
position of the user is at a predetermined distance (100 meters,
for example) or more from the position previously stored. If the
present position is within the predetermined distance, the
procedure returns to step S1002 to repeat the process. If, on the
other hand, the present position is at 100 meters or more away from
the stored position, the controller chronologically stores a set of
the present position and the present time (step S1007). Then, the
procedure returns to step S1002 to repeat the process.
[0012] As described above, the navigation device N.sub.c stores the
position when the main device 101 was out of the vehicle as the
position of the vehicle. Then, as the user travels the
predetermined distance or more, the main device 101 stores the
position of the user and the time of the movement. In other words,
the controller stores a path of the traveling user. Then, in
response to an operation by the user, the controller makes the map,
with the path of traveling overlaid thereon, displayed on a screen
of the main device 101. Thus, the user can recognize his/her own
path of traveling, and come back to the vehicle along the path.
Moreover, with an operation by the user, the controller searches
for a route from the present position of the user to the vehicle
position, and guides the user to the vehicle along the route.
[0013] In portable mode, the conventional navigation device N.sub.c
guides the vehicle and the user outside the vehicle. On the other
hand, the conventional navigation device N.sub.c guides the vehicle
as such when the main device 101 is mounted on the arm stand 104.
There is a big difference, however, between guiding users and
guiding vehicles. For example, the user can only travel within an
area much smaller than that the vehicle can. Therefore, the
navigation device N.sub.c can preferably display a relatively small
area in detail in portable mode, while displaying a relatively
large area when guiding the vehicle. However, even in portable
mode, the navigation device N.sub.c uses cartographic data used for
guiding the vehicle and displays a map covering a larger area with
the path of the traveling user overlaid thereon.
[0014] Furthermore, different traffic regulations are applied to
pedestrians and vehicles. Therefore, the navigation device N.sub.c
searches for a route for guiding the user to the vehicle with a
help of the map used for guiding the vehicle, but the found route
is not necessarily optimal for the user as a pedestrian.
[0015] As is evident from the above, the navigation device N.sub.c
carries out the same operation when used both inside and outside
the vehicle, and therefore cannot provide guidance suitable for
pedestrians.
SUMMARY OF THE INVENTION
[0016] Therefore, an object of the present invention is to provide
a navigation device that can automatically determine whether it is
used inside or outside a vehicle, and operate in an appropriate
mode.
[0017] To achieve the object above, the present invention is
directed to a navigation device that can be used inside and outside
a vehicle, the device comprising a determination part for
determining whether the device is used inside or outside the
vehicle, and a navigation processing unit. When the determination
unit determines that the device is used inside the vehicle, the
navigation unit carries out first navigation suitable for vehicles.
When the determination unit determines that the device is used
outside the vehicle, the navigation unit carries out second
navigation suitable for pedestrians.
[0018] These and other objects, features, aspects and advantages of
the present invention will become more apparent from the following
detailed description of the present invention when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a block diagram showing the whole structure of a
navigation device N.sub.1;
[0020] FIG. 2 is a diagram showing one example of data structure of
road network data D.sub.NET;
[0021] FIG. 3 is a diagram demonstrating the road network data
D.sub.NET in further detail;
[0022] FIG. 4 is a flow chart showing a mode setting procedure
executed by the navigation device N.sub.1;
[0023] FIG. 5 is a flow chart showing a present position estimation
procedure executed by the navigation device N.sub.1;
[0024] FIG. 6 is a flow chart showing a route search/guide
procedure executed by the navigation device N.sub.1;
[0025] FIG. 7 is a flow chart showing a detailed procedure for
route search (step S63 in FIG. 6) in on-vehicle mode;
[0026] FIG. 8 is a flow chart showing a detailed procedure for
route search (step S66 in FIG. 6) in off-vehicle mode;
[0027] FIGS. 9a and 9b are diagrams each showing one example of an
optimal route found by the navigation device N.sub.1;
[0028] FIG. 10 is a flow chart showing a route search/guide
procedure executed by a navigation device N.sub.2;
[0029] FIG. 11 is a diagram demonstrating one of technical effects
of the navigation device N.sub.2;
[0030] FIG. 12 is a block diagram showing the whole structure of a
navigation device N.sub.3;
[0031] FIG. 13 is a flow chart showing a present position
estimation procedure executed by the navigation device N.sub.3;
[0032] FIG. 14 is a flow chart showing a route search/guide
procedure executed by the navigation device N.sub.3;
[0033] FIG. 15 is a block diagram showing the whole structure of a
navigation device N.sub.4;
[0034] FIG. 16 is a flow chart showing a present position
estimation procedure executed by the navigation device N.sub.4;
[0035] FIG. 17 is a flow chart showing a route search/guide
procedure executed by the navigation device N.sub.4;
[0036] FIG. 18 is a block diagram showing the whole structure of a
navigation device N.sub.5;
[0037] FIG. 19 is a flow chart showing a present position
estimation procedure executed by the navigation device N.sub.5;
[0038] FIG. 20 is a flow chart showing a route search/guide
procedure executed by the navigation device N.sub.5;
[0039] FIG. 21 is a block diagram showing the whole structure of a
navigation device N.sub.6;
[0040] FIG. 22 is a flow chart showing a present position
estimation procedure executed by the navigation device N.sub.6;
[0041] FIG. 23 is a flow chart showing a route search/guide
procedure executed by the navigation device N.sub.6;
[0042] FIG. 24a is a diagram showing the structure of a
conventional navigation device N.sub.c; and
[0043] FIG. 24b is a flow chart showing one operation of the
conventional navigation device N.sub.c.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] FIG. 1 is a block diagram showing the whole structure of a
navigation device N.sub.1 according to a first embodiment of the
present invention. In FIG. 1, the navigation device N.sub.1 mainly
includes a main device 1, a holder 2, and a sensor 3.
[0045] The main device 1 accommodates a CPU 11, ROM 12, RAM 13, a
storage 14, an input unit 15, an output unit 16, a receiver 17, a
first terminal 18, and a detector 19, all communicably
interconnected with one another. The CPU 11 is communicably
connected to the sensor 3 though a first terminal 18 of the main
device 1 and a second terminal 21 of the holder 2.
[0046] The CPU 11 operates by following a program previously stored
in the ROM 12, and uses the RAM as a working area to execute
operations required for navigation suitable for vehicles and
pedestrians. Such operations typically include present position
estimation, route search, and route guide.
[0047] The storage 14 is typically implemented by a CD drive, DVD
drive, or hard disk drive, storing various data required for
navigation. Normally, the storage 14 stores in advance cartographic
database DB.sub.CART and road network data D.sub.NET.
[0048] In the present embodiment, the cartographic database
DB.sub.CART is constructed by a plurality of cartographic files
F.sub.CART each representing a map of a different scaling factor
SF. Here, the scaling factor SF is a rate of reduction of a map.
Therefore, if the scaling factor SF is larger, the cartographic
file F.sub.CART represents a map of a wider area. Such cartographic
file F.sub.CART is mainly used for displaying a map.
[0049] The road network data D.sub.NET is mainly used for searching
for a route, and defines, by nodes and links, connections among
intersections and roads on the map represented by each cartographic
file F.sub.CART. Furthermore, the road network data D.sub.NET also
includes, as required, data about coordinates, shapes, and
attributes, and traffic regulations of both intersections and
roads.
[0050] FIG. 2 shows one example of data structure of the road
network data D.sub.NET. In FIG. 2, the road network data D.sub.NET
is constructed mainly by a node list NL, a link list LL, and a
traffic regulation list RL.
[0051] The node list NL is composed of records NR.sub.0 to NR.sub.i
of nodes #0 to #i included in a road network.
[0052] The record NR.sub.0 is composed of coordinates of the node
#0 (generally defined by latitude and longitude of that node), the
number of connecting links to the node #0, a pointer specifying a
recording location for a record LR of one link, the number of
traffic regulations, and a pointer specifying a recording location
for a record RR of one traffic regulation. Other records NR.sub.1
to NR.sub.i are composed similarly.
[0053] The link list LL is composed of records LR.sub.0 to LR.sub.j
of links #0 to #j included in the road network. The record LR.sub.0
is composed of node numbers of the nodes located at both ends of
the link #0, link distance, road type, road width, and one-way
traffic information. Other records LR.sub.1 to LR.sub.j are
composed similarly.
[0054] The traffic regulation list RL is composed of records
RR.sub.0 to RR.sub.k of all traffic regulations #0 to #k provided
for the nodes #0 to #i. The record RR.sub.0 is composed of an enter
link number, exist link number, and traffic regulation information.
Other records RR.sub.1 to RR.sub.k are composed similarly. In the
present embodiment, it is assumed for convenience that the traffic
regulation list RL only includes regulations for vehicles.
[0055] With reference to FIG. 3, the above road network data
D.sub.NET is more specifically described. In FIG. 3, assume that
one ends of the links #0, #1, and #2 are connected at one node #0.
The other ends of those links are the nodes #1, #2, and #3,
respectively. Also assume that, when entering the node #0 from the
link #1, a vehicle is allowed by a traffic regulation to exit only
to the link #0. Under such assumption, in the record NR.sub.0, the
number of connecting links indicates "3", and the pointer specifies
recording locations of the records LR.sub.0 to LR.sub.2. The number
of traffic regulations is "1", and the pointer specifies, for
example, the recording location of the record RR.sub.0.
[0056] Also, in the record LR.sub.2, the node numbers are "#3" and
"#0". The exemplary one-way traffic regulation is "#3".fwdarw.#"0",
representing that the vehicle can go only from the node #3 to the
node #0.
[0057] Also in the record RR.sub.0, the enter link number is "#1",
the exit link number is "#0", and the traffic regulation
information indicates that the vehicle can make only a left
turn.
[0058] Referring back to FIG. 1, the input unit 15 is typically
implemented by a remote controller, touch sensor, key board, mouse,
and a combination of two or more among these devices. The user
operates the input unit 15 to select a function of the navigation
device N.sub.1, switch the map to be displayed, or set various
points that the user designates. The input unit 15 typically
produces an operation signal S.sub.1 indicating the operation by
the user, and transmits it to the CPU 11.
[0059] The output device 16 is typically implemented by a liquid
crystal display device and a loudspeaker, displaying a map on a
screen based on the cartographic file F.sub.CART, displaying a
route based on route data D.sub.R required for route guidance, and
producing sounds as required.
[0060] The receiver 17 is typically implemented by a GPS receiver,
calculating the present position of the main device 1 based on the
information transmitted from an artificial satellite and
transmitting calculation results to the CPU 11 as positional data
D.sub.P. Note that the receiver 17 is not restricted to such GPS
receiver, but may be any receiver as long as it can calculates the
present position of the main device 1 to realize so-called
heteronomous navigation that is an antonym of autonomous
navigation. In heteronomous navigation, the present position of the
main device 1 is derived not from a detection result by a sensor
incorporated in a vehicle as in autonomous navigation, but from
information received from a positioning system such as GPS.
[0061] The first terminal 18 is provided on the main device 1 and
makes a contact to the second terminal 21, electrically connecting
the CPU 11 and the sensor 3 together.
[0062] The detector 19 monitors a state of the first terminal 18 to
detect whether the main device 1 is removed from or mounted on the
holder 2, and transmits a detection signal S.sub.2 indicating the
detection result to the CPU 1.
[0063] The holder 2 is structured so as to removably hold the main
device 1, and is fixed to the vicinity of a driver's seat. When the
user drives the vehicle, the main device 1 is mounted on the holder
2, thereby allowing the user to easily view the screen of the
output device 16. And the main device 1 is removed from the holder
2, thereby allowing the user to use the main device outside the
vehicle. Such holder 2 includes at least the second terminal 21 and
a wiring 22.
[0064] The second terminal 21 is a terminal for electrically
connecting the CPU 11 etc. of the main device 1 and the holder 2
together. When the main device 1 is mounted on the holder 2, the
second terminal 21 makes a contact to the first terminal 18. Thus
the holder 2 is electrically connected to the main device 1.
[0065] One end of the wiring 22 is connected to the second terminal
21, while the other is to the sensor 3.
[0066] The sensor 3 typically includes an azimuth sensor
(typically, a gyro-compass) and a vehicle speed sensor, directly
mounted on the vehicle and on remote to both of the main device 1
and the holder 2. When the main device 1 and the holder 2 are
connected together, the sensor 3 detects an azimuth and a vehicle
speed at predetermined intervals, and transmits a detection signal
S.sub.3 indicating the detection result to the CPU 11. Note that,
other than the azimuth sensor and the vehicle speed sensor, the
sensor 3 may include any components as long as it can detect
parameters unique to the vehicle to achieve so-called autonomous
navigation. As stated above, autonomous navigation is a technique
for deriving the present position of the main device 1 from the
detection result by the sensor 3 mounted on the vehicle.
[0067] The operation of the navigation device N.sub.1 is described
below. When the navigation device N.sub.1 is powered on, the CPU 11
operates by following a program stored in the ROM 12, and executes
first a mode setting process shown in FIG. 4. In FIG. 4, the CPU 11
receives the detection signal S.sub.2 from the detector 19 (step
S41). Then, the CPU 11 determines, based on the received detection
signal S.sub.2, whether the main device 1 is mounted on the holder
2 or not (step S42).
[0068] If determining that the main device 1 is mounted on the
holder 2, the CPU 11 sets an operation mode required for estimation
of the present position (refer to FIG. 5) and route search/guide
(refer to FIG. 6, etc.) as "on-vehicle mode" (step S43). If
determining otherwise, the CPU 11 sets the operation mode as
"off-vehicle mode" (step S44). More specifically, in step S43 or
S44, the CPU 11 exemplarily sets a flag indicating "on-vehicle
mode" or "off-vehicle mode" in a recording area of the RAM 13.
After setting the operation mode, the CPU 11 ends the mode setting
process shown in FIG. 4.
[0069] After ending the mode setting process, the navigation device
N.sub.1 carries out estimation of the present position as shown in
FIG. 5. In FIG. 5, the CPU 11 first carries out initialization
(step S51). For example, in step S51, the cartographic file
F.sub.CART that has been used until previous power-off or that
includes the present position of the main device 1 is read from the
storage 14 into the RAM 13, and a working area required for
estimation of the present position is allocated. If the position of
the main device 1 when powered on is close to that when powered off
last time, the accumulated results (refer to step S53) used until
the main device 1 was powered off last time may be read into the
RAM 13.
[0070] After step S51, the CPU 11 operates as a determination part
in Claims, determining whether the operation mode is "on-vehicle
mode" or not (step S52). In the present embodiment, the operation
mode is defined by the flag. Therefore, the CPU 11 checks in step
S52 whether the flag indicates "on-vehicle mode" or "off-vehicle
mode".
[0071] If the operation mode is "on-vehicle mode", the CPU 11 finds
that the main device 1 is used inside the vehicle, and accumulates
the values of the azimuth and vehicle speed based on the detection
signal S.sub.3 from the sensor 3 (step S53). Then, the CPU 11
determines in step S54 whether a predetermined time has passed
after previous estimation (refer to step S55). In step S54, the CPU
11 may determine whether the vehicle has traveled a predetermined
distance from the previously estimated position. If the
predetermined time has not passed yet, the procedure returns to
step S53 to repeatedly accumulate the values the azimuth and
vehicle speed.
[0072] On the other hand, if determining in step S54 that the
predetermined time has passed or the vehicle has traveled the
predetermined distance, the CPU 11 receives the positional data
D.sub.P from the receiver 17. Also, the CPU 11 estimates the
present position of the main device 1 based on the accumulated
results as to the azimuth and vehicle speed and the position
specified by the positional data D.sub.P. In other words,
estimation of the present position is carried out by a combination
of autonomous and heteronomous navigation techniques. Then, the CPU
11 performs map matching based on the cartographic file F.sub.CART
for matching the estimated present position on the road in the map
represented by the cartographic file F.sub.CART read in the RAM
13(step S55).
[0073] Note that the cartographic file F.sub.CART used in step S55
may be read from the storage 14 into the RAM 13 anytime during
estimation of the present position, more specifically, after once
step S55 executed. Also note that the cartographic file F.sub.CART
read at one time preferably covers an area larger than that
displayable on the screen of the output device 16 at one time.
Thus, the number of times the cartographic file F.sub.CART has to
be transferred from the storage 14 into the RAM 13 can be
reduced.
[0074] The scaling factor SF.sub.1 of the read cartographic file
F.sub.CART for on-vehicle mode is predetermined. In most cases, the
vehicle speed is higher than the walking speed of the user.
Therefore, the scaling factor SF.sub.1 is selected so as to be at
least larger in value than the scaling factor SF.sub.2 for
off-vehicle mode. With such scaling factor SF.sub.1, the output
unit 16 can display a map covering a relatively large area on the
screen.
[0075] After step S55, the CPU 11 operates as one example of a
navigation processing part in Claims, making the output unit 16
display the estimated present position and its adjacent area map
represented by the cartographic file F.sub.CART (scaling factor
SF.sub.1) (step S56). Thus, the user can visually recognize the
present position of the vehicle. Normally, the output unit 16
displays the map with the scaling factor SF.sub.1, but can also
display the map with another scaling factor based on an operation
of the input unit 15 by the user. In on-vehicle mode, the above
steps S52 through S56 are repeated.
[0076] Referring back to step S52, when determining that the
operation mode is not "on-vehicle mode", the CPU 11 regards that
the user has removed the main device 1 from the holder 2 and
carries it for use outside the vehicle. In this case, the CPU 11
cannot receive the detection signal S.sub.3, and therefore receives
only the positional data D.sub.P from the receiver 17. Further, for
map matching, the CPU 11 uses the cartographic file F.sub.CART
representing the area adjacent to the present position specified by
the positional data D.sub.P. Thus, the CPU 11 carries out matching
of the estimated present position on a road represented by the
cartographic file F.sub.CART (step S57).
[0077] Note that the cartographic file F.sub.CART used in step S57
may be read from the storage 14 into the RAM 13 anytime during
estimation of the present position, more specifically, after once
step S57 executed. Also note that, as stated above, the
cartographic file F.sub.CART read at one time preferably covers an
area larger than that displayable on the screen of the output
device 16 at one time.
[0078] The scaling factor SF.sub.2 of the read cartographic file
F.sub.CART for off -vehicle mode is predetermined. In most cases,
the walking speed of the user is lower than the vehicle speed.
Therefore, the scaling factor SF.sub.2 is so selected as to be at
least smaller in value than the scaling factor SF.sub.1 for
on-vehicle mode. With such scaling factor SF.sub.2, the output unit
16 can display a map covering a relatively small area on the
screen.
[0079] Then, the CPU 11 operates as one example of the navigation
processing part in Claims. Further, the CPU 11 makes the output
unit 16 display the estimated present position and its adjacent
area map represented by the cartographic file F.sub.CART (scaling
factor SF.sub.2) (step S58). Thus, the user can visually recognize
the present position of the vehicle. Also in this case, the output
unit 16 can display the map with a scaling factor except the
scaling factor SF.sub.2 based on an operation of the input unit 15
by the user. In off-vehicle mode, the above steps
S52.fwdarw.S57.fwdarw.S58 are repeated.
[0080] Here, in the present embodiment, the present position is
estimated in off-vehicle mode based on only the positional data
D.sub.P received from the artificial satellite. Therefore, the
estimated present position contains a considerable amount of
errors. To correct the errors, the navigation device N.sub.1
preferably receives radio waves carrying error correction
information from a base station within a system called D-GPS
(Differential GPS).
[0081] The navigation device N.sub.1 also carries out route
search/guide shown in FIG. 6 as required. This is started by the
user operating the input unit 15. In FIG. 6, the CPU 11 first sets
a starting point SP and a destination point DP for route search
(step S61). More specifically, for example, the user operates the
input unit 15 to specify the starting point SP and the destination
point DP. In response to such operation, the input unit 15 sends
the CPU 11 an operation signal S.sub.1 indicating the specified
starting point SP and the destination point DP, for example, by
latitude and longitude. Alternatively, the CPU 11 may receive the
positional data D.sub.P from the receiver 17 as the starting point
SP, while receiving the destination point DP from the input unit
15. The CPU 11 then stores the received starting point SP and
destination point DP in the RAM 13.
[0082] After step S61, the CPU 11 operates as the determination
part in Claims, determining whether the operation mode is
"on-vehicle mode" or not (step S62), in a similar manner to that in
step S52. If "on-vehicle mode", the CPU 11 operates as a navigation
processing part in Claims, searching for a route in on-vehicle mode
(step S63). FIG. 7 is a flow chart showing the detailed procedure
of route search in on-vehicle mode. In FIG. 7, the CPU 11 reads the
road network data D.sub.NET specifying the road network of a
predetermined range R.sub.PRE required for route search (step S71).
The predetermined range R.sub.PRE is a range presumably covering
the shortest route from the starting point SP to the destination
point DP set in step S61, and is preferably defined as a rectangle
including the starting point SP and the destination point DP.
[0083] Then, the CPU 11 sets a first reference node RN, a
destination node DN, and a first arrival link AL (step S72). For
the first reference node RN, a node closest to the starting point
SP is selected. For the destination node DN, a node closest to the
destination point DP is selected. For the first arrival link AL, a
link that is closest to the starting point SP and from which the
vehicle can enter the first reference node RN is selected.
[0084] Then, the CPU 11 determines whether the present reference
node RN is the destination node DN or not (step S73). The reference
node RN can be presumed at first to be the starting point SP.
Therefore, in step S73 for the first time, it is presumed that the
reference node RN does not coincide with the destination node DN.
Thus, the CPU 11 searches the road network data D.sub.NET loaded
into the RAM 13 for links to which the vehicle can exit the
reference node RN after entering it from the first arrival link AL.
The CPU 11 then selects one of the found links as the exit link PL
(step S74). Note that this selection is made by referring to the
traffic regulations, road type, and one-way traffic information for
vehicles.
[0085] The process in step S74 is specifically described. For
example, assume that the reference node RN is set to the node #2,
and the arrival link AL is set to the link #0. Under this
assumption, the CPU 11 refers to a pointer in the record NR.sub.2
to find the relevant traffic regulation record RR indicated
thereby. Now assume that the record RR.sub.0 is found. If the enter
link number "#0", the exit link number "#2", and "no left turn" are
described in the record RR.sub.0, the CPU 11 can recognize that the
link #2 is selectable as the exit link PL when the vehicle enters
the node #2 from the link #0. The CPU 11 also refers to a pointer
in the record NR.sub.2 to find the relevant record LR of the link
connected to the node #2. Now assume that the record LR.sub.1 is
found. If the road type "pedestrian-only street", the road width
"3.0 meters", or the one-way traffic "no enter from the node #2"
are described in the record LR.sub.1, the CPU 11 can recognize that
the link #1 is not selectable as the exit link. As such, based on
the road network data D.sub.NET, the CPU 11 can select the exit
link PL through which the vehicle can travel while abiding by the
traffic regulations.
[0086] After step S74, the CPU 11 calculates a passage cost PC when
the vehicle travels through the selected exit link PL (step S75).
In step S75, the link distance described in the record LR is used
as the passage cost PC. The CPU 11 then selects a node located at
the other end of the selected exit link as an arrival node AN, and
calculates an arrival cost AC from the starting point to the
arrival node AN (step S76)
[0087] The CPU 11 then determines whether the calculated arrival
cost AC is minimum or not among the arrival costs AC previously
calculated as to the selected arrival node AN (step S77). Here, if
the starting point SP is set as the reference node RN, the arrival
cost AC for each arrival node AN is first calculated. In this case,
in step S77, the CPU 11 regards initial arrival cost AC is
infinite. As a result, the CPU 11 determines the arrival cost AC is
minimum. If the arrival cost is minimum, the CPU 11 records, in the
RAM 13, the calculated arrival cost AC, and links between the
starting point SP and the arrival node AN (step S78). The procedure
then goes to step S79.
[0088] If not minimum in step S77, on the other hand, the procedure
directly goes to step S79.
[0089] After step S77 or S78, the CPU 11 determines whether any
exit link PL is left unselected or not (step S79). The exit link PL
means a link through which the vehicle can exit from the arrival
link AL via the reference node RN. If any exit link PL is left
unselected, the procedure returns to step S74. In other words, the
CPU 11 newly selects one exit link PL, and executes the process
described above such as calculation of the arrival cost AC (steps
S74 to S78).
[0090] By repeating the above steps S74 to S78, the CPU 11
calculates the arrival cost AC from the reference node RN (starting
point SP) to all relevant arrival nodes AN. If determining in step
S79 that any exit link PL is not left unselected, the CPU 11
selects, as the next reference node RN, the arrival node AN of the
minimum arrival cost AC from among the arrival nodes AN not yet
selected as the reference node RN but whose arrival costs AC have
been calculated (step S710).
[0091] The procedure then returns to step S73, wherein the CPU 11
executes steps S73 through S79 by referring to the newly set
reference node RN. Thus, the route search goes on from the starting
point SP toward the destination point DP and, in the end, the
reference node RN coincides with the destination node DN. When the
procedure goes to step S711, the RAM 13 has already stored the
minimum arrival cost AC and the links between the starting point SP
and the destination point DP. The links recorded in the RAM 13 are
combined to indicate a route connecting the starting point SP and
the destination point DP and having the minimum arrival cost AC.
Therefore, based on the information recorded in the RAM 13, the CPU
11 constructs route data D.sub.R1 indicating the route that is
optimal for the vehicle to travel from the starting point SP to the
destination point DP (step S711).
[0092] After the above step S711 ends, the procedure exits from the
flow chart of FIG. 7 (that is, step S63 of FIG. 6), and goes to
step S64. The CPU 11 makes the screen of the output unit 16 display
the adjacent area map on which the optimal route and the present
position of the vehicle are overlaid. The CPU 11 also produces
sounds from the loudspeaker as required (step S64). Thus, the
vehicle is guided from the starting point SP to the destination
point DP. Note that, similarly to step S56, the displayed map
preferably has a relatively large scaling factor SF.
[0093] The CPU 11 then determines whether the present position of
the vehicle coincides with the destination point DP or not (step
S65). If the present position does not coincide with the
destination point DP, the procedure returns to step S64, and
continues guiding the vehicle. If coincides, the procedure of FIG.
6 ends.
[0094] Referring back to step S62 of FIG. 6, if determining that
the operation mode is not "on-vehicle mode", the CPU 11 operates as
one example of the navigation processing unit in Claims, carrying
out route search in off-vehicle mode (step S66). FIG. 8 is a flow
chart showing the detailed procedure for route search in
off-vehicle mode. The procedure of FIG. 8 is different from that of
FIG. 7 only in that steps S74, S75, and S711 are replaced with
steps S81, S82, and S83. The other steps in FIG. 8 are provided
with the same reference numbers as those in FIG. 7, and not
described herein.
[0095] In step S81, the CPU 11 searches the road network data
D.sub.NET loaded into the RAM 13, and selects, as the exit link PL,
any one of the links through which the pedestrian can exit from the
reference node RN after entering it from the arrival link AL (step
S81). Note that the CPU 11 does not refer to information related to
vehicles in the road network data D.sub.NET. Such information
includes traffic regulations for vehicles, and the road type, road
width and one-way traffic information for the road only travelable
by vehicles.
[0096] The process in step S81 is now specifically described. For
example, assume that the reference node RN is the node #2, and the
arrival link AL is the link #0. Under this assumption, the CPU 11
does not refer to the traffic regulation list RL in the record
NR.sub.2. The CPU 11 does not also refer to the road width or the
one-way traffic information, if any, described in each of the
records LR.sub.0, LR.sub.1, . . . , since they are not relevant to
pedestrians. The CPU 11 selects the exit link PL from the links #0,
#1, . . . connected to the reference node #2. As such, the CPU 11
can select, based on the road network data D.sub.NET, the exit link
PL passable by the pedestrian.
[0097] After step S81, the CPU 11 calculates the passage cost PC,
which is an evaluation value for the selected exit link PL when
passed through, in a similar manner to that in step S74 (step S82).
However, the CPU 11 assumes the passage cost PC as "infinite" if
the road attribute of the selected exit link PL is "highway" or
"vehicle-dedicated road". Thus, at route search in off-vehicle
mode, a road travelable only by pedestrians (users) is
selected.
[0098] After the above procedure in FIG. 8, when the procedure goes
to step S710, the RAM 13 has already stored therein a route
connecting the starting point SP and the destination point DP and
having the minimum arrival cost AC. Therefore, based on the
information recorded in the RAM 13, the CPU 11 constructs route
data D.sub.R2 indicating the route that is optimal for the
pedestrian to travel from the starting point SP to the destination
point DP (step S711) with the minimum arrival cost AC (step
S83).
[0099] After the above step S83, the procedure exits the flow chart
of FIG. 8 (that is, step S66 of FIG. 6), and goes to step S67.
Then, with the route indicated by the route data D.sub.R2, the
pedestrian is guided from the starting point SP to the destination
point DP (step S67). At this time, the map suitable for guiding
pedestrian is preferably displayed on the screen of the output unit
16.
[0100] After step S67, the CPU 11 determines whether the present
position of the pedestrian coincides with the destination point DP
or not (step S68). If the present position does not coincide with
the destination point DP, the procedure returns to step S67, and
the CPU 11 continues guiding the pedestrian. If the present
position coincides with the destination point DP, the procedure of
FIG. 6 ends.
[0101] With the above process of FIG. 6, the route found by the
navigation device N.sub.1 differs between on-vehicle mode and
off-vehicle mode, even though the same starting point SP and the
same destination point DP are set therebetween. FIGS. 9a and 9b are
diagrams each showing an example of a route found by the navigation
device N.sub.1. FIG. 9a schematically shows an example of the road
network data D.sub.NET composed of nodes #11 to #14 and links #21
to #26. The node #1 connects the links #21, #22, and #26; the node
#12 connects the links #22 and #23; the node #13 connects the links
#23 and #24; and the node #14 connects the links #24, #25, and #26.
Assume herein that, in the road network data D.sub.NET, the traffic
regulation record RR of the node #14 describes that the vehicle
cannot exit to the link #25 from the link #26 through the node
#14.
[0102] Here, consider the case of "on-vehicle mode". Assume that
the navigation device N.sub.1 starts route search, and sets a
starting point SP.sub.1 and a destination point DP.sub.1 as shown
in FIG. 9a. Under such assumption, in the case where the reference
node RN is the node #14 and the arrival link AL is the link #26,
the link #25 is not selected in step S74 of FIG. 7 as the exit link
PL to which the vehicle can exit. Consequently, the route data
D.sub.R1 obtained in step S711 of FIG. 7 indicates, as shown by a
black arrow A in FIG. 9a, a route composed of the links #21 through
#25.
[0103] Next, consider the case of "off-vehicle mode". Under the
same assumption and the same case as the above, the CPU 11 does not
refer to the traffic regulation record RR of the node #14.
Therefore, the link #25 can be selected in step S81 of FIG. 8 as
the exit link PL to which the pedestrian can exit. Consequently,
the route data D.sub.R21 obtained in step S711 of FIG. 7 indicates,
as shown by a hollow arrow B in FIG. 9a, a route composed of the
links #21, #26, and #25.
[0104] FIG. 9b schematically shows an example of the road network
data D.sub.NET composed of nodes #31 to #34 and links #41 to #46.
The node #31 connects the link #41 and #42; the node #32 connects
the links #42 and #43; the node #33 connects the links #43 and #44;
and the node #34 connects the links #44, #45, and #46. Assume
herein that, in the road network data D.sub.NET, the road width of
the link #46 is "less than 3 meters".
[0105] Here, consider the case of "on-vehicle mode". Assume that
the navigation device N.sub.1 starts route search and set a
starting point SP.sub.2 and a destination point DP.sub.2 as shown
in FIG. 9b. Under such assumption, in the case where the reference
node RN is the node #31 and the arrival link AL is the link #41,
the link #46 is not selected in step S74 of FIG. 7 as the exit link
PL to which the vehicle can exit. Consequently, the route data
D.sub.R12 obtained in step S711 of FIG. 7 indicates, as shown by a
black arrow C in FIG. 9b, a route composed of the links #41 through
#45.
[0106] Next, consider the case of "off-vehicle mode". Under the
same assumption and the same case as the above, the CPU 11 does not
refer to the road width of the link #46. Therefore, the link #46
can be selected in step S81 of FIG. 8 as the exit link PL to which
the pedestrian can exit. Consequently, the route data D.sub.R22
obtained in step S711 of FIG. 7 indicates, as shown by a hollow
arrow D in FIG. 9b, a route composed of the links #41, #46, and
#45.
[0107] As is evident from the above description, the navigation
device N.sub.1 automatically determines whether the main device 1
is mounted on the holder 2 or not, and sets the operation mode to
"on-vehicle mode" or "off-vehicle mode" based on the determination.
In on-vehicle mode, the main device 1 refers to information such as
the traffic regulation, road type, road width, and one-way traffic
information described in the road network data D.sub.NET for
searching a route suitable for the vehicle. In off-vehicle mode, on
the other hand, the main device 1 does not refer to such
information, and therefore can search a route suitable for the
pedestrian.
[0108] In the above description, route search clearly differs
between on-vehicle mode and off-vehicle mode depending on whether
or not the information only related to vehicles such as the traffic
regulation and road width is considered. This is not restrictive,
and the present embodiment can be achieved as long as what is
searched for in on-vehicle mode is a route only passable by
vehicles, and what is searched for in off-vehicle mode is a route
only passable by pedestrians.
[0109] Next, a navigation device N.sub.2 according to a second
embodiment of the present invention is described. The navigation
device N.sub.2 is similar in structure to the navigation device
N.sub.1 shown in FIG. 1, but is different therefrom in that it
executes route search/guide shown in FIG. 10, which is described
below.
[0110] In FIG. 10, similarly to steps S61 and S62 of FIG. 6, the
CPU 11 sets the starting point SP and the destination point DP for
route search, and then operates as the determination part in
Claims, determining the present operation mode is "on-vehicle mode"
or not (steps S101 and S102). If "on-vehicle mode", the CPU 11
carries out a route search in on-vehicle mode (step S103). The
detailed process in step S103 is similar to that shown in FIG. 7,
which has been described in the first embodiment.
[0111] After step S103, similarly to step S64 of FIG. 6, the CPU 11
uses the generated route data D.sub.R1 to guide the vehicle from
the starting point SP to the destination point DP (step S104). The
CPU 11 then estimates the present position of the vehicle, and
determines whether the present position coincides with the
destination point DP or not (step S105). If the present position
coincides the destination point DP, the CPU 11 determines that the
route guide is over, and the procedure of FIG. 10 ends.
[0112] On the other hand, if not coincide, the CPU 11 receives the
detection signal S.sub.2 from the detector 19 and, based thereon,
determines whether the main device 1 has been removed from the
holder 2 or not (step S106). If not removed, the CPU 11 regards
that the operation thereof has to be continued in "on-vehicle
mode", and the procedure returns to step S104 for vehicle
guidance.
[0113] On the other hand, if determining in step S106 that the main
device 1 has been removed from the holder 2, the CPU 11 regards
that the operation mode has to be changed from "on-vehicle mode" to
"off-vehicle mode", and prepares for mode transition (step S107).
More specifically, the CPU 11 records, in the RAM 13, the position
indicated by the positional data D.sub.P received from the receiver
17 as a new starting point SP, while not changing the destination
point DP recorded in step S101 and holding it as it is. The CPU 11
also deletes the road network data D.sub.NET loaded for route
search in "on-vehicle mode" from the RAM 13.
[0114] Next, the CPU 11 operates as one example of the navigation
processing part in Claims, carrying out route search for
"off-vehicle mode" (step S108). The process in step S108 is similar
to that shown in FIG. 8, which has been described in detail in the
first embodiment. In short, the CPU 11 carries out a route search
based on the new starting point SP recorded in step S107 and the
destination point DP to construct the route data D.sub.R2. The CPU
11 then guides the pedestrian from the starting point SP to the
destination point DP in a similar manner to that in step S67 (step
S109). The CPU 11 then determines whether the present position of
the pedestrian coincides with the destination point DP or not (step
S1010). If the present position coincides with the destination
point DP, the CPU 11 regards that the guide is over, and the
procedure of FIG. 10 ends.
[0115] On the other hand, if not coincide, the CPU 11 determines
whether the main device 1 is mounted on the holder 2 or not based
on the detection signal S.sub.2 from the detector 19 (step S1011).
If determining that the main device 1 is not mounted, the CPU 11
regards that the operation thereof has to be continued in
"off-vehicle mode", and the procedure returns to step S109 for
guiding the pedestrian.
[0116] On the other hand, if mounted, the CPU 11 regards that the
operation mode is changed from "off-vehicle mode" to "on-vehicle
mode", and prepares for "on-vehicle mode" (step S1012). More
specifically, the CPU 11 records, in the RAM 13, the position
indicated by the positional data D.sub.P received from the receiver
17 as a new starting point SP, while not changing the destination
point DP recorded in step S101 and holding it as it is. The CPU 11
also deletes the road network data D.sub.NET loaded for route
search in "off-vehicle mode" from the RAM 13. Then, the CPU 11
returns to step S103 for further process.
[0117] Referring back to step S102 of FIG. 10, if the operation
mode is not "on-vehicle mode", the procedure goes to step S108 and
thereafter for further process, which have been described in the
first embodiment.
[0118] With the above described process of FIG. 10, the navigation
device N.sub.2 can search for a route suitable for the vehicle or
pedestrian, even though the same starting point SP and the same
destination point DP are set between the on-vehicle mode and
off-vehicle mode, which is similar to the case of first
embodiment.
[0119] Moreover, the navigation device N.sub.2 can accurately
detect the timing of mode transition in the main device 1, and
carry out route search/guide for both vehicles and pedestrians.
[0120] Now assume that, as shown in FIG. 11, a user travels by
vehicle from a starting point SP.sub.3 to an intermediate point
IP.sub.3 and then on foot from the intermediate point IP.sub.3 to a
destination point DP.sub.3, with the help of route search/guide by
the navigation device N.sub.2. In this case, the main device 1
first operates in "on-vehicle mode", generating the route data
D.sub.R1 for a route from the starting point SP.sub.3 to the
destination point DP.sub.3 for guiding the vehicle. When arriving
at the intermediate point IP.sub.3, the user removes the main
device 1 from the holder 2, and heads for the destination point
DP.sub.3 on foot. The main device 1 detects that it has been
removed from the holder 2, and changes the mode to "off-vehicle
mode". The main device 1 then generates the route data D.sub.R2 for
a route from the intermediate point IP.sub.3 to the destination
point DP.sub.3 for guiding the pedestrian (user). In this fashion,
the navigation device N.sub.2 can carry out appropriate route
search/guide even if the user changes his/her transportation on the
way from the starting point SP to the destination point DP.
[0121] In the above first and second embodiments, the CPU 11
determines whether the main device 1 has been removed from the
holder 2 or not, based on the detection signal S.sub.2 indicating
whether an electrical connection has been established between the
first terminal 18 and the second terminal 21. This is not
restrictive, and the CPU 11 may make the above determination by
using a mechanical or magnetic switch.
[0122] With reference to FIG. 12, a navigation device N.sub.3
according to a third embodiment of the present invention is
described. The navigation device N.sub.3 is different from the
navigation device N.sub.2 only in that a third terminal 31 is
further provided and a detector 32 is provided in place of the
detector 19. The other components in FIG. 12 are provided with the
same reference numerals as those in FIG. 1, and are not described
herein.
[0123] The third terminal 31 is a terminal for connecting the main
device 1 and an accessory power supply. The accessory power supply
is located outside the main device 1 and the holder 2, but fixed to
a vehicle, supplying power to various components in the
vehicle.
[0124] The detector 32 monitors the state of the third terminal 31
to detect whether the accessory power supply is powered on or off,
and transmits a detection signal S.sub.4 indicating the detection
result to the CPU 11.
[0125] With reference to a flow chart of FIG. 13, a present
position estimating process in the navigation device N.sub.3 is
described. The procedure of FIG. 13 is different from that of FIG.
5 only in that step S131 is provided in place of step S52. The
other steps are provided with the same step numbers as those of
FIG. 5, and not described herein.
[0126] In FIG. 13, after step S51, the CPU 11 operates as one
example of the determination unit in Claims, receiving the
detection signal S.sub.4 from the detector 32 to determine whether
the main device 1 operates in "on-vehicle mode" or not (step S131).
More specifically, if knowing from the detection signal S.sub.4
that the accessory power supply is powered on, the CPU 11 regards
that the main device 1 is used inside the vehicle, and determines
that it operates in "on-vehicle mode". On the other hand, if
knowing from the detection signal S.sub.4 that the accessory power
supply is powered off, the CPU 11 regards that the main device 1 is
used outside the vehicle, and determines that it operates in
"off-vehicle mode". The operation thereafter has been already
described with reference to FIG. 5.
[0127] With reference to a flow chart of FIG. 14, route
search/guide in the navigation device N.sub.3 is described. The
procedure of FIG. 14 is different from that of FIG. 10 in that
steps S141, S142, S143, S144, S145, and S146 are provided in place
of steps S101, S102, S106, S107, S1011, and S1012, respectively.
The other steps of FIG. 14 are provided with the same step number
as those in FIG. 10, and not described herein.
[0128] In FIG. 14, the user typically operates the input unit 15 to
specify the starting point SP, the destination point DP, and the
intermediate point IP for searching a route. Here, the intermediate
point IP is a point anywhere between the staring point SP and the
destination point DP, the point where the user gets off the vehicle
to travel on foot or where the user stops travelling on foot to get
on the vehicle.
[0129] In response to the user's operation, the input unit 15
transmits the operation signal S.sub.1 indicating the specified
starting point SP, destination point DP, and intermediate point IP
to the CPU 11. The CPU 11 writes the received starting point SP,
destination point DP, and intermediate point IP in the RAM 13 (step
S141).
[0130] The CPU 11 then receives the detection signal S.sub.4 from
the detector 32 to determine whether the present operation mode is
"on-vehicle mode" or not (step S142). If "on-vehicle mode", the CPU
11 carries out a route search/guide in on-vehicle mode (steps S103
and S104). Then, if the present position of the vehicle does not
coincide with the destination point DP (step S105), the procedure
goes to step S143.
[0131] In step S143, the CPU 11 determines whether the present
position of the vehicle coincides with the intermediate point IP
(more strictly, getting-off point) or not. If not coincide, the
procedure exits from step S143 and returns to step S104 for further
vehicle guidance.
[0132] Note that, if the CPU 11 determines that the present
position coincides with the intermediate point IP, the procedure
does not directly go to step S144. This is because the estimated
present position includes some errors, and the user is not
necessarily able to get off the vehicle at the estimated position
even though it coincides with the intermediate point IP. Therefore,
the CPU 11 first receives the detection signal S.sub.4 from the
detector 32 and, based thereon, determines whether the accessory
power supply is powered on or not. If powered on, the CPU 11
determines that the vehicle goes on travelling, that is, the
present position of the vehicle is not the intermediate point IP.
The procedure then exits from step S143, and returns to step S104
for further vehicle guidance.
[0133] On the other hand, if receiving the detection signal S.sub.4
indicating that the accessory power supply is powered off, the CPU
11 determines that the vehicle has been parked and the main device
1 is carried outside the vehicle, that is, the user got off the
vehicle. The CPU 11 then prepares for mode transition to
"off-vehicle mode" (step S144). More specifically, the CPU 11
records the intermediate point IP (getting-off point) set in step
S141 in the RAM 13 as a new starting point SP, while holding the
destination point DP recorded in RAM 13. The CPU 11 also deletes
the road network data D.sub.NET loaded for route search in
"on-vehicle mode" from the RAM 13.
[0134] The CPU then carries out route search/guide in off-vehicle
mode (steps S108 and S109). If the present position of the
pedestrian does not coincide with the destination point DP (step
S1010), the procedure goes to step S145. In step S145, the CPU 11
determines whether the present position of the pedestrian coincide
with the intermediate point IP (in this case, the point where the
user gets on the vehicle; hereinafter referred to as getting-on
point) or not (step S145). If not coincide, the procedure exits
from step S145, and returns to step S109 for further pedestrian
guidance.
[0135] Note that, for the same reason as that in step S143, the
procedure does not directly go to step S146 even if the present
position coincides with the intermediate point IP. In this case,
the CPU 11 receives the detection signal S.sub.4 from the detector
32. Based on the received detection signal S.sub.4, the CPU 11
determines whether the accessory power supply is powered on or off.
If powered off, the CPU 11 determines that the pedestrian is still
outside the vehicle, that is, the present position of the
pedestrian is not the intermediate point IP (getting-on point). The
procedure then exits from step S145, and returns to step S109 for
further pedestrian guidance.
[0136] On the other hand, if receiving the detection signal S.sub.4
indicating that the accessory power supply is powered on, the CPU
11 regards that the user got on the vehicle and starts driving.
Thus, the CPU 11 determines that the operation mode has to be
changed to "on-vehicle mode", and prepares for mode transition
(step S146).
[0137] More specifically, in step S146, the CPU 11 records the
intermediate point IP (getting-on point) set in step S141 in the
RAM 13 as a new starting point SP, while holding the destination
point DP recorded in step S141 in the RAM 13 as it is. The CPU 11
also deletes the road network data D.sub.NET loaded for route
search in "on-vehicle mode" from the RAM 13.
[0138] Referring back to step S142 of FIG. 14, if the operation
mode is not "on-vehicle mode", the procedure goes to step S108 for
further processing, which is clear from the above and not described
herein.
[0139] With the above described process in FIG. 14, the navigation
device N.sub.3 can achieve the similar technical effects as those
by the navigation device N.sub.2.
[0140] In the above third embodiment, the CPU 11 determines whether
the CPU 11 operates in "on-vehicle mode" or "off-vehicle mode" by
determining whether the vehicle is driven or parked (whether the
user uses the main device 1 inside or outside the vehicle) on the
basis of the intermediate point IP set by the input unit 15 and
whether the accessory power supply is powered on or off. This is
not restrictive, and the above determination may be made on the
basis of whether an ignition power supply of the vehicle is powered
on or off, or whether a parking brake system thereof is released or
not. In other words, any component that is fixed to the vehicle and
is able to specify whether the vehicle is parked or not may be used
for the above determination.
[0141] With reference to FIG. 15, a navigation device N.sub.4
according to a fourth embodiment of the present invention is
described. In FIG. 15, the navigation device N.sub.4 is similar in
structure the navigation device N.sub.1 of FIG. 1, but different
only in that the detector 19 is not provided. Also, the input unit
15 of FIG. 15 is similar in operation to that of FIG. 1, but
different in that it generates an operation signal S.sub.5, which
will be described below, for transmission to the CPU 11. The other
components in FIG. 15 are provided the same reference numerals as
those in FIG. 1, and not described herein. As to processing, the
navigation device N.sub.4 is different from the navigation device
N.sub.1 in estimation of the present position and route
search/guide.
[0142] With reference to a flow chart of FIG. 16, a present
position estimating process in the navigation device N.sub.4 is
described. The procedure of FIG. 16 is different from that of FIG.
5 only in that step S161 is provided in place of step S52.
Therefore, the steps of FIG. 16 are provided with the same step
numbers as those in FIG. 5, and not described herein.
[0143] Immediately after powered on, the navigation device N.sub.4
starts the present position estimating process shown in FIG. 16. In
other words, the navigation device N.sub.4 does not have to carry
out the mode setting process as shown in FIG. 4. In FIG. 16, after
step S51, the CPU 11 operates as one example of the determination
unit in Claims, determining whether the operation thereof is
"on-vehicle mode" or "off-vehicle mode", based on a detection
signal S.sub.5 received from the input unit 15 (step S161).
[0144] Now, step S161 is more specifically described. The
navigation device N.sub.4 is designed in advance so that the input
unit 15 is operated by the user for setting or switching the
operation mode between "on-vehicle mode" and "off-vehicle mode". In
response to the user's operation, the input unit 15 generates one
of two types of signals. One is an operation signal S.sub.51
indicating that the user is inside the vehicle. The other is an
operation signal S.sub.52 indicating that the user is outside the
vehicle. In step S161, the CPU 11 first requests the user to set
the operation mode. In response to the request by the navigation
device N.sub.4, the user operates the input unit 15 to tell that
he/she is inside or outside the vehicle. In response to the user's
operation, the input unit 15 generates either the operation signal
S.sub.51 or S.sub.52 for transmission to the CPU 11. When receiving
the operation signal S.sub.51, the CPU 11 operates in "on-vehicle
mode", executing steps S53 through S56. When receiving the
operation signal S.sub.52, the CPU 11 operates in "off-vehicle
mode", executing steps S57 through S58.
[0145] With reference to a flow chart of FIG. 17, a route
search/guide process in the navigation device N.sub.4 is described.
The procedure of FIG. 17 is different from that of FIG. 10 only in
that steps S171, S172, S173, S174, and S175 are provided in place
of steps S102, S106, S1011, and S1012, respectively. The other
steps in FIG. 17 are provided with the same step numbers as those
in FIG. 10, and not described herein.
[0146] In FIG. 17, the CPU 11 operates as one example of the
determination unit in Claims, determining whether it operates in
"on-vehicle mode" or not, based on the received operation signal
S.sub.5 (step S171). Note that the operation mode has been
specified in the present position estimating process of FIG. 16.
Therefore, unlike in step S161, the CPU 11 does not have to request
in step S171 the user to set the operation mode. In other words,
the determination in step S171 may be made on the basis of the
operation signal S.sub.5 received in step S161.
[0147] Also note that the user operates the input unit 15 at
his/her will if he/she wants to use the main device 1 outside the
vehicle. In response to such user's operation, the input unit 15
transmits the operation signal S.sub.52 to the CPU 11. If receiving
the operation signal S.sub.52 in step S171, the CPU 11 determines
to execute the following route search/guide process in off-vehicle
mode, even though the operation mode has been set in step S161 as
on-vehicle mode. Conversely, if the user wants to use the main
device 1 inside the vehicle, the user operates the input unit 15 at
his/her will, and the CPU 11 receives the operation signal S.sub.51
from the input unit 15. In this case, the CPU 11 determines to
execute the following process in on-vehicle mode, even though the
operation mode has been set in step S161 as off-vehicle mode.
[0148] If determining to operate in "on-vehicle mode", the CPU 11
carries out a route search/guide in on-vehicle mode (steps S103 and
S104). If the present position of the vehicle does not coincide
with the destination point DP (step S105), the procedure goes to
step S172. In step S172, the CPU 11 determines whether it receives
the operation signal S.sub.52 from the input device 15. If not
receive, the procedure returns to step S104 for further vehicle
guidance.
[0149] While the main device 1 operates in on-vehicle mode, the
user can operate the input unit 15 to tell that he/she got off the
vehicle. Consequently, the operation signal S.sub.52 is transmitted
to the CPU 11. If receiving the operation signal S.sub.52 in step
S172, the CPU 11 determines that the getting-off point is specified
and the operation is to be performed in off-vehicle mode, and
prepares for mode transition (step S173). More specifically, the
CPU 11 records the present point, that is, the point where the user
gets off the vehicle (getting-off point), in the RAM 13 as a new
starting point SP, while holding the destination point DP recorded
in step S141 as it is. The CPU 11 also deletes the road network
data D.sub.NET read for route search in "on-vehicle mode" from the
RAM 13.
[0150] After step S173, the CPU 11 carries out a route search/guide
in off-vehicle mode(steps S108 through S1010). If, in step S1010,
the present position of the pedestrian does not coincide with the
destination point DP, the CPU 11 determines whether it receives the
operation signal S.sub.51 from the input unit 15 or not (step
S174). If not receive, the CPU 11 determines to still operate in
off-vehicle mode. The procedure then returns to step S109 for
further pedestrian guidance.
[0151] If receive in step S174, the CPU 11 determines that the
getting-on point is specified and the operation is to be performed
in on-vehicle mode, in reverse to the above step S173, and prepares
for mode transition (step S175). More specifically, the CPU 11
records the estimated present position, that is, getting-on point,
in the RAM 13 as a new starting point SP, while holding the
destination point DP recorded in step 101 as it is. The CPU 11 also
deletes the road network data D.sub.NET loaded for route search in
"off-vehicle mode" from the RAM 13. After step S175, the procedure
returns to step S103 for route search in on-vehicle mode.
[0152] Referring back to step S171 of FIG. 17, if the operation
mode is not "on-vehicle mode", the procedure goes to step S108 for
further processing. The processing is evident from the above
description, and therefore not described herein.
[0153] With the above described process of FIG. 17, the navigation
device N.sub.4 can achieve the similar technical effects as those
by the navigation device N.sub.2.
[0154] FIG. 18 is a block diagram showing the whole structure of a
navigation device N.sub.5 according to a fifth embodiment of the
present invention. In FIG. 18, the navigation device N.sub.5
includes, like the navigation device N.sub.1, the main device 1,
the holder 2, and the sensor 3.
[0155] Like the navigation device N.sub.1, the main device 1 of the
navigation device N.sub.5 includes the CPU 11, the ROM 12, the RAM
13, the storage 14, the input unit 15, the output unit 16, the
receiver 17, and the first terminal 18. The main device 1 of the
navigation device N.sub.5 further includes an internal
communications port 51 and an internal communications controller
52.
[0156] The internal communications controller 52 controls, through
the internal communications port 51, communications with the holder
2 side. Between the main device 1 and the holder 2, infrared or
radio-wave communications take place. The internal communications
controller 52 also generates a notification signal S.sub.6 for
transmission to the CPU 11. More specifically, the internal
communications controller 52 generates and transmits, as required,
a notification signal S.sub.61 notifying the CPU 11 that infrared
rays or radio waves from the holder 2 are receivable. If these are
not receivable, that is, if the CPU 11 cannot communicate with the
holder 2 side, the internal communications controller 52 generates,
as required, a notification signal S.sub.62 indicating as such for
transmission to the CPU 11.
[0157] The holder 2 is similar to that of the other embodiments in
that the second terminal 21 and the wiring 22 are provided, but
different therefrom in that an external communications port 61 and
an external communications controller 62 are provided.
[0158] The external communications controller 62 controls, through
the external communications port 61, infrared or radio-wave
communications with the main device 1 side. More specifically, the
external communications controller 62 sends, through the external
communications port 61, infrared rays or radio waves to the
internal communications port 51. As for the radio waves, electric
power for transmission of the internal communication port 51 takes
a value capable of substantially covering inside the vehicle or its
adjacent area.
[0159] The above structured navigation device N.sub.5 executes
estimation of the present position and route search/guide as
described below, but does not have to carry out the mode setting as
the navigation device N.sub.1. First, with reference to a flow
chart of FIG. 19, a present position estimating process is
described. The procedure of FIG. 19 is different from that of FIG.
15 only in that step S191 is provided in place of step S52.
Therefore, the other steps in FIG. 19 are provided with the same
step numbers as those in FIG. 5, and not described herein. In FIG.
19, the navigation device N.sub.5 first carries out initialization
(step S51).
[0160] The CPU 11 then receives the notification signal S.sub.6
from the internal communications controller 52. Based on the
notification signal S.sub.6, the CPU 11 determines whether to
operate in "on-vehicle mode" or "off-vehicle mode" (step S191). As
stated above, the internal communications controller 52 transmits
the notification signal S.sub.61 if the main device 1 can
communicate with the holder 2 side. If receiving such notification
signal S.sub.62, the CPU 11 can regard that the main device 1 in
the vicinity of the holder 2. In other words, the CPU 11 regards
that the main device is inside the vehicle at this moment, and
determines to operate in "on-vehicle mode". Thereafter, the CPU 11
executes steps S53 through S56.
[0161] On the other hand, if receiving the notification signal
S.sub.62 indicating that the main device 1 cannot communicate with
the holder 2 side, the CPU 11 regards that the main device 1 is not
inside the vehicle, and determines to operate in "off-vehicle
mode". Thereafter, the CPU 11 executes steps S57 and S58.
[0162] With reference to a flow chart of FIG. 20, a route
search/guide process is described. The procedure of FIG. 20 is
different from that of FIG. 10 in that steps S201, S202, and S203
are provided in place of steps S102, S106, and S1011, respectively.
The other steps in FIG. 20 are provided with the same step numbers
as those in FIG. 10, and not described herein.
[0163] In FIG. 20, after step S101, the CPU 11 determines in step
S201 whether to operate in "on-vehicle mode" or not, in a similar
manner to that in step S191 of FIG. 19. If "on-vehicle mode", the
CPU 11 carries out a route search/guide in on-vehicle mode (steps
S103 and S104). If the present position of the vehicle does not
coincide with the destination point DP (step S105), the procedure
goes to step S202.
[0164] In step S202, the CPU 11 receives the notification signal
S.sub.6 from the internal communication controller 52 to determine
whether to change the mode to "off-vehicle mode" or not, in a
similar manner to that in step S191. If receiving the notification
signal S.sub.61, the CPU 11 regards that the operation has to be
continued in "on-vehicle mode". The procedure then returns to step
S104 for further vehicle guidance. On the other hand, if receiving
the notification signal S.sub.62, the CPU 11 regards that the
operation mode has to be changed from "on-vehicle mode" to
"off-vehicle mode", and prepares for mode transition (step
S107).
[0165] The CPU 11 then carries out a route search/guide in
off-vehicle mode (steps S108 and S109). In step S1010, if the
present position of the pedestrian does not coincide with the
destination point DP, the CPU 11 receives the notification signal
S.sub.6 from the internal communications controller 52 and, based
thereon, determines whether to change the mode to "off-vehicle
mode" (step S203). If receiving the notification signal S.sub.62,
the CPU 11 regards that the main device 1 still has to operate in
"off-vehicle mode". The procedure then returns to step S109 for
further pedestrian guidance. On the other hand, if receiving the
notification signal S.sub.61, the CPU 11 regards that the operation
mode has to be changed from "off-vehicle mode" to "on-vehicle
mode", and prepares for mode transition (step S1012).
[0166] Referring back to step S201 of FIG. 20, if determining to
operate in "off-vehicle mode", the procedure goes to step S108 for
further processing. Such processing is evident from the above, and
not described herein.
[0167] With the above process of FIG. 20, the navigation device
N.sub.5 can achieve similar technical effects to those by the
navigation device N.sub.2.
[0168] In the second embodiment, the storage 14 is incorporated in
the main device 1, and often implemented as a DVD-ROM drive or the
like, which is large and heavy. This leads the whole navigation
device N.sub.2 to become hardly portable for the user. Therefore,
an object of a sixth embodiment described below is to achieve a
easily portable navigation device N.sub.6.
[0169] FIG. 21 is a block diagram showing the whole structure of
the navigation device N.sub.6. In FIG. 21, the navigation device
N.sub.6 includes, like the navigation device N.sub.2, the main
device 1, the holder 2, and the sensor 3.
[0170] The main device 1 of FIG. 21 is different from that of FIG.
1 only in that an internal storage 71 and an internal interface 72
are provided in place of the storage 14. The other components of
the main device 1 in FIG. 21 are provided with the same reference
numerals as those in FIG. 1, and not described herein.
[0171] The internal storage 71 is structured by a storage which is
relatively light and small. Such storage is typically a memory card
containing a solid-state memory removable from the main device 1,
such as Smartmedia, memorystick, SD card (all of them are
trademarks).
[0172] The internal interface 72 is connected to an external
interface 82 provided on the holder 2 side so that the main device
1 can communicate with an external storage 81 provided on the
holder 2 side.
[0173] The holder 2 of FIG. 21 is different from that of FIG. 1 in
that the external storage 81 and the external interface 82 are
further provided. The other components of the holder 2 in FIG. 21
are provided with the same reference numerals as those in FIG. 1,
and not described herein.
[0174] The external storage 81 is typically implemented as a CD
drive, DVD drive, or hard disk drive, storing various data required
for navigation. The external storage 81 stores in advance the
cartographic database DB.sub.CART described in the first embodiment
and the road network data D.sub.NET.
[0175] The external interface 82 is so structured as to be able to
connect to the internal interface 72 on the main device 1 side.
With this connection, the external storage 81 can transfer data to
the main device 1 through the internal and external interfaces 72
and 82.
[0176] With reference to FIGS. 22 and 23, a present position
estimating process and a route search/guide process in the
navigation device N.sub.6 are described. First, in FIG. 22, the CPU
11 carries out initialization (step S221) in a similar manner to
that in step S51 (refer to FIG. 5). The CPU 11 then receives the
detection signal S.sub.2 from the detector 19 and, based thereon,
determines whether the main device 1 is mounted on the holder 2 or
not, thereby determining whether to operate in "on-vehicle mode" or
"off-vehicle mode" (step S222).
[0177] If operating in "on-vehicle mode", the CPU 11 accumulates
the values of azimuth and vehicle speed of the traveling vehicle
(step S223), in a similar manner to that in step S53. The CPU 11
then determines whether the predetermined time has passed since the
previous estimation of the present position (step S224), in a
similar manner to that in step S54. If passed (or if vehicle has
traveled the predetermined distance), the CPU 11 receives the
positional data D.sub.P from the receiver 17. The CPU 11 then
estimates the present position of the main device 1 based on the
accumulation results of azimuth and vehicle speed in step S223 and
the position indicated by the positional data D.sub.P, in a similar
manner to that in step S55. The CPU 11 also carries out map
matching to match the estimated present position on the road of the
cartographic file F.sub.CART read in the RAM 13 (step S225). The
CPU 11 then makes the output unit 16 display the estimated present
position and its adjacent area map represented by the cartographic
file F.sub.CART (scaling factor SF.sub.1) (step S226).
[0178] The CPU 11 then reads in advance the cartographic file
F.sub.CART representing an area adjacent to the present position
with the scaling factor SF.sub.2 from the external storage 81 into
the internal storage 71 (step S227). The cartographic file
F.sub.CART read in step S227 represents a map of a relatively small
area centering on the estimated present position, and, more
specifically, an area where people can presumably walk about within
a predetermined short time and a predetermined short distance. Step
S227 does not have to be carried out every time after step S226,
and may be skipped as required. In on-vehicle mode, the above steps
S227 through S227 are repeatedly executed.
[0179] Referring back to step S222, if the operation mode is not
"off-vehicle mode", it can be assumed that the user removes the
main device 1 from the holder 2 and uses it outside the vehicle.
Therefore, the CPU 11 receives the positional data D.sub.P from the
receiver 17, and reads the cartographic file F.sub.CART from the
external storage 71 into the RAM 13. The CPU 11 then matches the
present position of the pedestrian indicated by the received
positional data D.sub.P on the road of the map represented by the
cartographic file F.sub.CART on the RAM 13 (step S228).
[0180] The CPU 11 then makes the output unit 16 display the present
position and the map represented by the cartographic file
F.sub.CART with the scaling factor SF.sub.2 (step S229). In
off-vehicle mode, the above steps S222.fwdarw.S228.fwdarw.S229 are
repeatedly executed.
[0181] In FIG. 23, the CPU 11 sets the starting point SP and the
destination point DP (step S231), in a similar manner to that in
step S101. The CPU 11 then determines whether the operation mode is
"on-vehicle mode" or "off-vehicle mode" (step S232), in a similar
manner to that in step S102. If "on-vehicle mode", the CPU 11
carries out a route search in on-vehicle mode, and then guides the
vehicle based on the generated route data D.sub.R1 (steps S233 and
S234), in a similar manner as that in steps S103 and S104.
[0182] The CPU 11 then reads in advance the road network data
D.sub.NET representing the area adjacent to the estimated present
position to prepare for future mode transition to "off-vehicle
mode" (step S235). The road network data D.sub.NET read in step
S235 represents a relatively small area centering on the estimated
present position (an area where people can presumably walk about
within a predetermined short time and a predetermined short
distance), and corresponds to the road network represented by the
cartographic file F.sub.CART with scaling factor SF.sub.2. The CPU
11 then determines whether the estimated present position coincides
with the destination point DP or not (step S236). If coincides, the
CPU 11 determines that the guide is over, and the procedure of FIG.
23 ends.
[0183] On the other hand, if not coincide, the CPU 11 receives the
detection signal S.sub.2 from the detector 19 and, based thereon,
determines whether the main device 1 has been removed from the
holder 2 or not (step S237). If not removed, the CPU 11 regards
that the operation has to be continued in "on-vehicle mode".
Therefore, the procedure returns to step S234 for further vehicle
guidance. If removed, on the other hand, the CPU 11 prepares for
mode transition (step S238), in a similar manner to that in step
S107.
[0184] The CPU 11 then carries out a route search in "off-vehicle
mode" (step S239), in a similar manner to that in step S108. The
detailed process of step S239 is similar to that shown in FIG. 8,
but different in that the road network data D.sub.NET read into the
internal storage 71 in step S235 is further read into the RAM 13 in
step S81. After step S239, the CPU 11 carries out operation similar
to those in step S109 through S1012 (steps S2310 through
S2313).
[0185] With the above process shown in FIGS. 22 and 23, while
operating in "on-vehicle mode", the navigation device N.sub.6 reads
in advance the cartographic file F.sub.CART and road network data
D.sub.NET to be used in "off-vehicle mode" from the external
storage 81 on the holder 2 side into the internal storage 71 on the
main device 1 side. Thus, event though the external storage 81 is
incorporated in the holder 2 side, the main device 1 can guide the
pedestrian in "off-vehicle mode" without any problem. Also, the
main device 1 can be reduced in size and weight.
[0186] In the above sixth embodiment, what is used for navigation
in "off-vehicle mode" is the data read from the external storage 81
into the internal storage 71. Alternatively, if the navigation
device N.sub.6 can access to the Internet and a Web server that
provides the cartographic file F.sub.CART and the road network data
D.sub.NET exists on the Internet, for example, the navigation
device N.sub.6 may carry out navigation by obtaining these file and
data from the Web server. Note that this alternative can be applied
to the other embodiments. In other words, the main device 1
according to the first to fifth embodiments may carry out
navigation by obtaining these file and data over the Internet.
Therefore, the storage 14 according to the first to fifth
embodiments does not have to be incorporated in the main device
1.
[0187] As described above, the navigation device N.sub.6 according
to the sixth embodiment can achieve reduction in size and weight of
the main device 1 of the navigation device N.sub.2. The point in
the sixth embodiment can be also applied to the navigation devices
N.sub.3 to N.sub.5. That is, in these navigation devices N.sub.3 to
N.sub.5, the cartographic file F.sub.CART and the road network data
D.sub.NET to be used in "off-vehicle mode" may be read in advance
during "on-vehicle mode".
[0188] In the first to sixth embodiments, the route search in
"on-vehicle mode" is carried out with the procedure shown in FIG.
7, for the sake of simplifying description. Alternatively, if a
VICS (Vehicle Information and Communications System) receiver is
provided in the navigation devices N.sub.1 to N.sub.6 for receiving
traffic information, the route search may be carried out by using
the received traffic information. Such VICS receiver is often used
in "on-vehicle mode", and therefore preferable implemented outside
the main device 1.
[0189] In the first to sixth embodiments, for the sake of
simplifying description, a search is made in "on-vehicle mode"
(refer to FIG. 7) for a route abiding by the traffic regulations
for vehicles, while a search is made in "off-vehicle mode" (refer
to FIG. 8) without referring to such regulations. Alternatively, in
"on-vehicle mode", a route search may be made by referring to a
predetermined speed based on the road width and/or road type of a
road, that is, a speed at which the vehicle travels the road. Also,
in "off-vehicle mode", a route search may be made by referring to a
walking speed at which the pedestrian travels the road.
[0190] Furthermore, first road network data dedicated to route
search for vehicles and second road network data dedicated to route
search for pedestrians may be provided. Here, assume that the first
road network data is generated based on roads that can be traveled
by vehicles or sea roads that can be traveled by vehicles on ships.
Also assume that he second road network data is generated based on
roads as well as skywalks, underground passageways, bus networks,
railroad networks, air routes, sea routes, passageways in buildings
and others that can be passed by pedestrians. Each of the
navigation devices N.sub.1 to N.sub.6 is so structured as to use
the first road network data for route search in "on-vehicle mode",
and the second road network data for route search in "off-vehicle
mode".
[0191] In the first to sixth navigation devices N.sub.1 to N.sub.6,
for the sake of simplifying the description, an antenna for
receiving radio waves from artificial satellites through the air
has not been mentioned. At least one such antenna is provided for
the main device 1. Alternatively, two such antennas may be provided
for each of the navigation devices N.sub.1 to N.sub.6. In this
case, one antenna is incorporated in the main device 1, functioning
when the main device 1 operates in "off-vehicle mode". The other is
mounted on the vehicle and connected to the main device 1 via a
cable. The other antenna functions when the main device 1 operates
in "on-vehicle mode".
[0192] Furthermore, in the above first and second embodiments, the
main device 1 operates in on-vehicle mode while mounted on the
holder 2 and in off-vehicle mode while removed therefrom. However,
the navigation devices N.sub.1 and N.sub.2 may be used inside the
vehicle without being mounted on the holder 2. For example, the
main device 1 may be used by a person in a passenger seat or rear
seat. In this case, an auxiliary technique is incorporated into the
navigation devices N.sub.1 and N.sub.2 for determining the
operation mode based on the detection signal S.sub.4 (refer to the
third embodiment), the operation signal S.sub.5 (refer to the
fourth embodiment), and the notification signal S.sub.6 all
together. Thus, the main device 1 can operate in on-vehicle mode
even though it is used inside the vehicle without being mounted on
the holder 2.
[0193] Still further, in the third to fifth embodiments, the
navigation devices N.sub.3 to N.sub.5 each include the holder 2 for
holding the main device 1, enabling the user to easily view the map
and route from a driver's seat. However, the user may sit in a
passenger seat and operate the main device 1 without mounting it on
the holder 2. Therefore, the holder 2 is not necessarily required
in the navigation devices N.sub.3 to N.sub.5.
[0194] While the invention has been described in detail, the
foregoing description is in all aspects illustrative and not
restrictive. It is understood that numerous other modifications and
variations can be devised without departing from the scope of the
invention.
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