U.S. patent application number 11/162170 was filed with the patent office on 2007-03-22 for power saving system for navigation device.
This patent application is currently assigned to NAVICORE LTD.. Invention is credited to Niko Haatainen.
Application Number | 20070067097 11/162170 |
Document ID | / |
Family ID | 37808488 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070067097 |
Kind Code |
A1 |
Haatainen; Niko |
March 22, 2007 |
POWER SAVING SYSTEM FOR NAVIGATION DEVICE
Abstract
A navigation system using a mobile terminal, GPS receiver and
navigation software, wherein the navigation software is arranged to
switch the mobile terminal into a power saving mode if there are no
further instructions needed for a determined period of time or
distance. The power saving functionality comprises turning the
backlight off and changing the visualization of the display for
better readability without the backlight.
Inventors: |
Haatainen; Niko; (Nilsia,
FI) |
Correspondence
Address: |
ARTZ & ARTZ, P.C.
28333 TELEGRAPH RD.
SUITE 250
SOUTHFIELD
MI
48034
US
|
Assignee: |
NAVICORE LTD.
Tekniikantie 14
Espoo
FI
|
Family ID: |
37808488 |
Appl. No.: |
11/162170 |
Filed: |
August 31, 2005 |
Current U.S.
Class: |
701/532 |
Current CPC
Class: |
G01C 21/3626
20130101 |
Class at
Publication: |
701/208 |
International
Class: |
G01C 21/32 20060101
G01C021/32 |
Claims
1. A method for power saving in a navigation device comprising a
display, the device being capable of acquiring the current location
of the device and a user specified desired destination, the method
comprising the steps of: requesting navigation information for a
route based on the acquired current location and the desired
destination; displaying said requested route on said display of
said navigation device and guiding a user along said route;
determining a span value for the next expected guiding information;
determining a threshold value for power saving management; and
comparing said span value to said threshold value and activating
the power saving mode if said span value exceeds said threshold
value.
2. A method according to claim 1, wherein the power saving mode
further comprises turning off the background light of the display
of said navigation device.
3. A method according to claim 1, wherein the power saving mode
comprises changing a display color.
4. A method according to claim 1, wherein the power saving mode
comprises changing a font size.
5. A method according to claim 1, wherein the power saving mode
comprises changing a size of guidance icons of the displayed
information.
6. A method according to claim 1, wherein the power saving mode is
an independent feature of said navigation device that activates
after a certain time of inactivity and the step of comparing said
span value to said threshold value sends an activity signal when
said threshold value exceeds said span value.
7. A method according to claim 1, wherein the next expected guiding
information comprises a junction requiring instruction.
8. A navigation device for guiding the user from the current
location to a destination, the portable device being capable of
executing a software application and arranged to communicate with a
positioning module for receiving the current location of the
device, which navigation device is further arranged to: request
navigation information for a route based on the acquired current
location and the desired destination; display said requested route
on said display of said navigation device and guiding a user along
said route; determine a span value for the next expected guiding
information; determine a threshold value for power saving mode; and
compare said span value to said threshold value and activating the
power saving if said span value exceeds said threshold value.
9. A navigation device according to claim 8, wherein the power
saving mode is further arranged to turn off the background light of
the display of said navigation device.
10. A navigation device according to claim 8, wherein the power
saving mode changes a color of guidance icons of the displayed
information.
11. A navigation device according to claim 8, wherein the power
saving mode changes a font size of guidance icons of the displayed
information.
12. A navigation device according to claim 8, wherein the power
saving mode changes a size of guidance icons of the displayed
information.
13. A navigation device according to claim 8, wherein the power
saving management is an independent feature of said navigation
device that activates after a certain time of inactivity and the
step of comparing said span value to said threshold value sends an
activity signal when said threshold value exceeds said span
value.
14. A navigation device according to claim 8, wherein the
navigation device comprises a built-in GPS receiver.
15. A navigation device according to claim 8, wherein the
navigation device is coupled to a separate GPS receiver.
16. A navigation software application for a mobile device
comprising a display, the device being capable of acquiring the
current location of the device and a user specified desired
destination, the software application, when executed in a
navigation device, arranged to perform the following steps of:
requesting navigation information for a route based on the acquired
current location and the desired destination; displaying said
requested route on said display of said navigation device and
guiding a user along said route; determining a span value for the
next expected guiding information; determining a threshold value
for power saving mode; and comparing said span value to said
threshold value and activating the power saving if said span value
exceeds said threshold value.
17. A navigation software application according to claim 16,
wherein the power saving mode further comprises turning off the
background light of the display of said navigation device.
18. A navigation software application according to claim 16,
wherein the power saving mode further comprises changing the colors
of guidance icons of the displayed information.
19. A navigation software application according to claim 16,
wherein the power saving mode further comprises a font size of
guidance icons of the displayed information.
20. A navigation software application according to claim 16,
wherein the power saving mode further comprises a size of guidance
icons of the displayed information.
21. A navigation software application according to claim 16,
wherein the power saving mode is an independent feature of said
navigation device that activates after a certain time of inactivity
and the step of comparing said span value to said threshold value
further comprises sending an activity signal when said threshold
value exceeds said span value.
Description
FIELD OF THE INVENTION
[0001] The invention relates to power management of navigation
devices. Particularly the invention relates to portable navigation
devices that have a display device and a low capacity battery.
BACKGROUND OF THE INVENTION
[0002] Published US application No. 2004/0048600, assigned to
Hitachi Ltd., discloses a power saving management for a
navigational device. The system according to said application
discloses a system comprising a mobile device with navigation
software and a receiver for receiving location information from
Global Positioning System (GPS). Furthermore, the mobile device has
telecommunication means for contacting the navigation server for
downloading navigation information. The user of the disclosed
system inputs the desired destination to the mobile device. As on
response the system requests the current location coordinates of
the mobile device from the GPS receiver and sends the coordinates
and the destination to the navigation server. The navigation server
calculates the route from the current location to the destination
and sends the route information back to the mobile device. The
route information is constructed from the map information
comprising a road network. The road network is modeled as a
weighted graph that includes further information depending on
traffic rules, for example, prohibited directions. Besides the
weight that typically is a classification for a road or street, the
edges of the graph have a length that equals to the length of a
road or street segment between two junctions.
[0003] A common problem with the implementations as described above
is that mobile devices do have restricted time of operation because
of high power consumption and low power capacity. The application
mentioned above suggests a solution wherein the display device of
mobile device is turned off when there is no need for further
navigation information. For example, if further information is
required only after 15 minutes of driving, the display device can
be turned off until the next instructions. This allows major power
saving as the display device is typically the most power demanding
unit in a mobile device.
[0004] The problem with the above mentioned solution is that when
the display is turned off, the user does not have any information
about the route. The user does not know the distance to the next
turn nor has any other information about the route. This can be a
major drawback if the navigation system does not have all the
information of the route and the user has to cope with this by
making the right decisions. This is common, for example, in the
case of road construction. Furthermore, usually the drivers are
willing to consult a map and obtain other information about the
route.
SUMMARY OF THE INVENTION
[0005] The invention discloses a power efficient navigation method,
system and software for navigation devices, particularly for mobile
phones that are equipped with navigation software and positioning
means. Furthermore, the navigation device has common means required
for executing a program, such as a central processing unit and a
memory. However, these are common features in mobile devices and
are not presented herein they are well known to a person skilled in
the art.
[0006] In the implementation according to the present invention,
the navigation is initiated by requesting a route. For requesting
the route the navigation software requests the desired destination
from the user. Furthermore, the navigation software requests the
current location of the navigation device. Typically a GPS receiver
is used for providing accurate location coordinates. The GPS
receiver can be a built-in receiver or external receiver that has
been connected to the navigation device. The connection between the
navigation device and the GPS receiver may be wireless.
[0007] With the current location and the destination information a
route is computed. The route can be computed in the navigation
device or by an external server. The computed route is displayed to
the user and driving instructions to the destination are given on
the display and/or in the form of speech. A power saving function
is initiated if there is no need to display information for
predetermined threshold time or distance, for example two minutes.
The navigation software computes a span value required to reach the
next point where guidance is needed. If the span exceeds the
threshold value of time or distance, the device can be switched
into the power saving mode. Typically the device has an independent
power saving function similar to screen savers in computers. If
there is no user activity for a certain period time, the power
management mode is activated even if the information on the display
changes during this time. This can be avoided by sending an
activation signal to the power management at regular intervals. If
the span value exceeds the threshold value, the activation signal
is not sent and the device goes into the power saving state after a
period of time determined by the operating system of the
device.
[0008] In a further embodiment the colors of the display and other
visualization can be changed when the device is switched into power
saving. This is because the regular visualization is designed for
the backlight and is not readable when the backlight is turned off
in the power saving mode. Thus, there is a need for a change, for
example, in the coloring, font size and/or size of visual guidance
icons so that it can be read better without the backlight. The
invention discloses an implementation that is particularly
beneficial in small navigation devices that have low power
capacity. Compared to the prior art solution a similar power saving
is gained while still maintaining the visual information
available.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings, which are included to provide a
further understanding of the invention and constitute a part of
this specification, illustrate embodiments of the invention and
together with the description help to explain the principles of the
invention. In the drawings:
[0010] FIG. 1 is an example embodiment of the system according to
the invention.
[0011] FIG. 2 is a flow chart of a method according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Reference will now be made in detail to the embodiments of
the present invention, examples of which are illustrated in the
accompanying drawings.
[0013] In FIG. 1 an illustration of a navigation system according
to the invention is provided. In the embodiment of FIG. 1 there is
no need for external servers but the navigation device 14 comprises
all the information and software required for computing the route
even if the navigation device is, in most cases, a cellular phone
or PDA device that has network connectivity means. This kind of
implementation is known as on-board design. In off-board
implementations the route is computed in a separate navigation
server that sends the information back to the navigation device.
Both of the implementations have their benefits and most likely a
hybrid-implementation with combination of on-board and off-board
characteristics will be implemented in the future.
[0014] In the example of FIG. 1 the navigation device 14 does not
have a built-in positioning device but is connected wirelessly to a
GPS receiver 13 that computes the exact location of the receiver 13
from the observations received from the GPS-satellites 10, 11 and
12. The GPS system is used in this example because it is most
commonly used, exact and because there are plenty of hardware
implementations. However, for the power saving features according
to the present invention any kind of positioning system is
acceptable.
[0015] The present invention relates to power saving in a
navigation system according to FIG. 1. The user of the navigation
device 14 starts navigation by entering the desired destination of
the route. The navigation device 14 requests the exact location of
the device from the GPS receiver 13. Based on the map information,
the navigation device 14 computes the route between the origin and
the destination and controls a display 15 based thereon. The
display 15 uses display indicia such as various colors, front size
and size for the icons to display the map information. A background
light (backlight) 16 may be used to illuminate the display 15. The
map information can be an on-board implementation or retrieved from
a server. Practically, the map information comprises nodes and
edges that represent junctions and road and/or street segments
between the junctions. The nodes and edges can have additional
information, such as speed limits, other traffic rules and other
related information. When the user arrives at a junction the
navigation device instructs how the user should continue. Typically
in most of the junctions there is no need for further instructions
as the user continues straight forward. Thus, a method according to
FIG. 2 is used for power saving when there are no instructions
needed. In power saving mode the display indicia and backlight may
be controlled. Furthermore, the navigation device has common means
that are required for executing a program, such as a central
processing unit and memory. However, these are common features in
mobile devices and are not presented herein they are well known to
a person skilled in the art.
[0016] In FIG. 2, the user first starts the navigation by choosing
the destination. The route is computed on-board or off-board, step
20. When the guiding is started the navigation device is typically
active and the backlight is on. However, it might be beneficial to
adjust the inactivity timeout a bit longer when starting the route,
step 21. This is to guarantee that the user of the device has time
to start driving and actually starts moving on the route. While
moving on the route, the navigation device continuously receives
the new location of the device, step 22. This moving is shown on
the route display and further instructions may be given for
following the route, step 23.
[0017] While moving on the route the navigation device computes a
span value, step 24. The span value corresponds with the distance
to the next junction that requires further instructions. This can
be measured as a distance or as a time if the average speed and
speed limits are known. The span value is then compared to a
threshold value, step 25. The threshold value may be user
determined. For example, if a driver wishes to have a warning of
further instructions one minute before the actual instructions, the
navigation device approximates the distance the user travels in one
minute time and then compares the actual distance to the computed
one. The threshold value may be different during the route
depending on the road classification. Thus, in the cities the
warning can come later and in highways earlier as also the traffic
signs appear earlier along the highways.
[0018] If the span value exceeds the threshold value, the
navigation procedure continues by jumping back to step 21. First
the navigation device checks the visualization. If the navigation
device has been inactive and switched into power saving mode, the
visualization parameters should be changed. This is because the
normal colors and font size are hard to see when the backlight is
turned off. The font size and actual colors depend on the display
of the navigation device and may be implemented so that the user
may tune them according to their own preferences.
[0019] If the span value is less than the threshold the next
junction requiring guidance is close. Thus, an activity signal must
be sent to the power saving management of the device, step 27.
Similarly, if the power saving visualization has been activated,
the colors and font sizes are changed back to normal. In the normal
visualization mode more information can be presented on the display
while maintaining the readability. If the next guidance point is
the final destination the navigation procedure can be ended, step
28. If the next guidance point is a junction requiring further
instructions, the procedure is continued by jumping to step 21.
[0020] In a preferred embodiment the implementation comprises a
cellular phone that is capable of executing a navigation software
application. The navigation device has been connected to a GPS
receiver with a wireless connection, such as Bluetooth.RTM., or has
been built into the navigation device. The navigation database is
typically stored on a memory card but can be downloaded by using
the data communication features of the cellular phone. Data
communication features, that are typically packet switched, can be
used for retrieving the additional information even if the
navigation database is on the memory card.
[0021] In the preferred embodiment the actual power saving
functionality is implemented as software features. During the
guidance the software controls the power saving management of the
navigation device. If the next guiding point is not close enough,
the power saving mode is turned on. This is achieved by computing a
span value to the next guidance point and comparing it to a
predetermined threshold value. If the span value exceeds the
threshold value, the software can activate the power saving mode.
The activation can be a call signal for activating the power saving
but normally the power saving management is independent and
activates itself after certain time of user inactivity. In this
case, the normal mode is maintained by sending an activity signal
to power saving management and the power saving is turned on by
stopping said sending. Thus, after a certain time of inactivity,
the navigation device automatically goes into power saving mode.
Later when the threshold value exceeds the span value the activity
signal is sent again and the navigation device is turned on.
Furthermore, it is possible to configure the application so that
during the power saving mode the visualization of the map is
changed so that it can be better seen from the display without the
backlight. This means that the colors of the map, font size and/or
size of visual guidance icons have to be changed when the power
saving mode is activated.
[0022] It is obvious to a person skilled in the art that with the
advancement of technology, the basic idea of the invention may be
implemented in various ways. The invention and its embodiments are
thus not limited to the examples described above; instead they may
vary within the scope of the claims.
* * * * *