U.S. patent application number 11/712564 was filed with the patent office on 2007-12-06 for portable navigation device.
Invention is credited to Pieter Geelen.
Application Number | 20070282522 11/712564 |
Document ID | / |
Family ID | 38335541 |
Filed Date | 2007-12-06 |
United States Patent
Application |
20070282522 |
Kind Code |
A1 |
Geelen; Pieter |
December 6, 2007 |
Portable navigation device
Abstract
A navigation device is configured to allocate display setting
such as color schemes and screen contents to at least one ambient
lighting condition, monitors and evaluates a signal indicative of
ambient lighting conditions and determines whether display settings
for the current ambient lighting conditions are already in use and
to change display settings so that they suit current ambient
lighting conditions if needed.
Inventors: |
Geelen; Pieter; (Amstardam,
NL) |
Correspondence
Address: |
Tom Tom International;IP Creation Department
Rembrandtplein 35
CT 1017
Amsterdam
NL
|
Family ID: |
38335541 |
Appl. No.: |
11/712564 |
Filed: |
March 1, 2007 |
Current U.S.
Class: |
701/532 ;
340/995.1 |
Current CPC
Class: |
G06Q 30/0601 20130101;
H04L 67/325 20130101; G01C 21/367 20130101; G06Q 20/102 20130101;
G09B 29/102 20130101; G01C 21/3697 20130101; H04L 63/12
20130101 |
Class at
Publication: |
701/200 ;
340/995.1 |
International
Class: |
G01C 21/00 20060101
G01C021/00; G01S 13/00 20060101 G01S013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2006 |
GB |
0604709.6 |
Mar 8, 2006 |
GB |
0604708.8 |
Mar 8, 2006 |
GB |
0604710.4 |
Mar 8, 2006 |
GB |
0604704.7 |
Mar 8, 2006 |
GB |
0604706.2 |
Claims
1. A method for automatically adjusting visibility of a portable
navigation device display, the method comprising the steps of:
allocating display settings for at least one ambient lighting
condition, monitoring a signal indicative of current ambient
lighting condition, evaluating said signal, selecting a display
setting allocated to said current ambient lighting condition,
determining if a current display setting is the selected display
setting, and changing said current display setting to said selected
display setting if said current setting is not said selected
display setting.
2. The method according to claim 1, wherein said at least one
ambient lighting conditions comprises at least two ambient lighting
conditions.
3. The method according to claim 1, wherein said step of allocating
display view settings comprises selecting at least one of an
appropriate view, a backlight level, and a color scheme.
4. The method according to claim 3, wherein one of said display
settings is a day view.
5. The method according to claim 3, wherein one of said display
settings is a night view.
6. The method according to claim 3, wherein one of said display
settings comprises a three dimensional view of a map; and schematic
representation of the sky at daytime.
7. The method according to claim 3, wherein one of said display
settings comprises a three dimensional view of a map; and a
schematic representation of the sky at nighttime.
8. The method according to claim 3, wherein one of said display
settings comprises a high backlight level and a color scheme using
brighter colors.
9. The method according to claim 3, wherein one of said display
settings comprises a low backlight level and a color scheme using
darker colors.
10. The method according to claim 3, wherein one of said display
settings comprises a color scheme using inverted colors.
11. The method according to claim 3, wherein said color scheme is
stored as a plugin.
12. The method according to claim 1, wherein the step of changing
further comprises gradually changing backlight levels from a
current backlight level to a level allocated to said selected
display setting.
13. The method according to claim 12, wherein the step of gradually
changing backlight level comprises a predefined number of
incremental jumps ranging from a backlight level for current
display mode to another backlight level for said selected display
mode.
14. The method according to claim 13, wherein said gradually
changing backlight level comprises five incremental jumps.
15. The method according to claim 1, wherein said step of
monitoring further comprises receiving a signal from a light
sensor.
16. The method according to claim 15, wherein said step of
monitoring further comprises buffering said signal to filter
temporary changes in ambient lighting conditions.
17. The method according to claim 16, wherein said light sensor is
located on a printed circuit board of said portable navigation
device.
18. The method according to claim 1, wherein said step of
monitoring further comprises receiving a signal from a headlight
sensor.
19. The method according to claim 18, wherein said headlight sensor
is wired to said portable navigation device directly or through its
docking unit.
20. The method according to claim 19, further comprising the step
of confirming connection of said portable navigation device to said
signal.
21. The method according to claim 18, wherein said headlight sensor
is wirelessly connected to said navigation device.
22. The method according to claim 1, wherein said step of
monitoring further comprises receiving a signal from a map matching
function.
23. The method according to claim 22, wherein said map matching
function indicates current location of said navigation device is in
a tunnel.
24. The method according to claim 22, wherein said map matching
function indicates loss of positioning signal.
25. The method according to claim 1, wherein said display is a
touch screen display with light emitting diode backlight.
26. The method according to claim 1, wherein said step of changing
further comprises presenting a confirmation dialog to the user of
said portable navigation device.
27. The method according to claim 26, wherein said step of changing
is delayed until a confirmation is given by the user of said
navigation device.
28. The method according to claim 1, wherein said step of selecting
a display setting is performed manually by the user of said
navigation device.
29. The method according to claim 1, wherein said step of changing
comprises the step of enabling or disabling at least one function
of said navigation device.
30. The method according to claim 29, wherein said at least one
function comprises one of a star map, points of interests,
information relating to map items or a planned route, warning about
speed limits, warning about driving breaks, displaying traffic
information, displaying weather information, menu items, and menu
color schemes.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from UK patent applications
with serial numbers 0604709.6, 0604708.8, 0604710.4, 0604704.7, and
0604706.2. The aforementioned patent applications are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a portable navigation
device, including functionality for automatically adjusting display
settings to suit various ambient lighting conditions.
[0004] 2. Description of the Prior Art
[0005] Global Positioning System GPS based navigation devices are
well known and are widely employed as in-car navigation devices.
Reference may be made to devices that integrate a GPS receiver into
a computing device programmed with a map database and that can
generate navigation instructions on a display, such as the TOMTOM
GO device. These portable, integrated devices are often mounted on
or in the dashboard of a vehicle using a suction mount or a docking
mechanism.
[0006] Reference may also be made to the Navigator series software
from the present assignee, TomTom International B.V. This software,
when running on a Personal Digital Assistant PDA with GPS receiver
(such as a COMPAQ IPAQ) or connected to an external GPS receiver,
enables a user to input to the PDA a start and destination address.
The software then calculates the best route between the two
end-points and displays instructions on how to navigate that
route.
[0007] The term `navigation device` refers to a device that enables
a user to navigate to a pre-defined destination. The device may
have an internal system for receiving location data, such as a GPS
receiver, or may merely be connectable to a receiver that can
receive location data. The device may compute a route itself, or
communicate with a remote server that computes the route and
provides navigation information to the device, or a hybrid device
in which the device itself and a remote server both play a role in
the route computation process. Portable GPS navigation devices are
not permanently integrated into a vehicle but instead are devices
that can readily be mounted in or docked or otherwise used inside a
vehicle. Generally (but not necessarily), they are fully
self-contained--i.e. include an internal GPS antenna, navigation
software and maps and can hence plot and display a route to be
taken.
[0008] By using the positional information derived from the
integrated or external GPS receiver, the software can determine at
regular intervals the position of the navigation device or PDA
(typically mounted on the dashboard of a vehicle) and can display
the current position of the vehicle on a map and display (and
speak) appropriate navigation instructions (e.g. `turn left in 100
m`) on the screen.
[0009] Graphics depicting the actions to be accomplished (e.g. a
left arrow indicating a left turn ahead) can be displayed in a
status bar and also be superimposed over the applicable
junctions/turnings etc in the roads shown in the map itself. The
display of the navigation device may consist of a liquid crystal
display LCD for showing user location on a map and any information
related to surroundings and a planned route. One example is the
SAMSUNG LTE400WQ-E01 active matrix LCD module with integrated touch
panel and backlight.
[0010] The set of colors for displaying a map or showing menu items
on the screen of the navigation device might be pre-defined and
various sets of colors might be stored as color schemes. The user
may also control the backlight level of the display, which might
range from full backlight level to switching off backlight
completely.
[0011] One common approach is for a user to manually change the
brightness settings of the display when ambient lights change, e.g.
to increase brightness when using the navigation device or PDA
under direct sunlight or decrease background illumination in low
light situations, e.g. during the night or when driving in a
tunnel. In these situations, the default brightness setting might
not be appropriate because the display might be either too dark or
too bright for the given lighting conditions. Lower backlight
levels might also be desired for lower power consumption and an
extended battery life.
[0012] It is also possible to configure a navigation device or PDA
to use pre-defined color schemes for menus, maps and navigation
screens. Some color schemes utilize colors with high contrast that
remain visible even under direct sunlight, other color schemes are
suitable for color-blind persons, and it is also known to utilize
color schemes that are more suited for low light environments or
when using the navigation device or PDA during the night.
[0013] However, it is not known to gradually change display
brightness of a portable navigation device depending on current
ambient lighting conditions and user selectable options. It is also
not possible to make automatic adjustments to display brightness
and/or color schemes without user interaction where and when it is
most desired.
[0014] The present invention provides means for changing display
settings to suit current ambient light levels and for providing
user selectable preferences for automatic adjustment of display
settings when ambient light levels change.
SUMMARY OF THE INVENTION
[0015] The invention is a navigation device comprising a processor
arranged to monitor signals indicative of ambient lighting
conditions and to select display settings allocated to current
ambient lighting conditions. The invention is also a method for
automatically adjusting display settings of a portable navigation
device in accordance to current ambient lighting conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention will be described with reference to
the accompanying drawings, in which FIG. 1 is a block diagram
depicting elements of a navigation device implementing the present
invention;
[0017] FIG. 2 is a screen shot from a navigation device; the screen
shot shows a three dimensional like navigation view appropriate for
daytime usage and a status bar running along the bottom of the
display;
[0018] FIG. 3 is a screen shot from a navigation device; the screen
shot shows a three dimensional like navigation view appropriate for
nighttime usage and a status bar running along the bottom of the
display;
[0019] FIG. 4 is a flowchart illustrating an implementation of the
invention,
[0020] FIG. 5 is a screen shot from a navigation device, the screen
shot shows a preferences screen with buttons for changing map
colors and display brightness,
[0021] FIG. 6 is screen shot from a portable navigation device, the
screen shot shows a brightness preferences screen,
[0022] FIG. 7 is a screen shot from a portable navigation device,
the screen shot shows a preferences screen with a button to
manually switch between day and night views,
[0023] FIG. 8 is a diagram for transition between day and night
views according to one embodiment of the invention,
[0024] FIG. 9 is a diagram for transition between day and night
views according to another embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] An embodiment of the present invention will be described
below in detail with reference to the accompanying drawings.
[0026] FIG. 1 is a block diagram showing various elements of a
navigation device according to the invention. The main components
of the navigation device are enclosed in a portable housing 1. The
navigation device comprises a memory 10, the type of which might be
internal (such as a hard disk, flash memory, random access memory,
read only memory or similar) or removable (such as a memory card,
memory stick, compact disc, digital versatile disc or similar). The
navigation device may comprise both internal and removable memories
at the same time.
[0027] Location of the navigation device is calculated using
position (e.g. GPS) data 9 that is obtained from a GPS receiver 12.
The GPS receiver 12 might be internal or external, connected to the
navigation device with wires or wirelessly.
[0028] The navigation device contains a processor 4 for carrying
out navigation related tasks according to programmed instructions
and user interaction. The processor 4 communicates with various
elements of the navigation device through a data bus 6. Map data 7,
user data 8, GPS data 9 can be accessed by the processor 4 through
the data bus either directly or through other elements that are
outside the scope of the present invention.
[0029] The navigation device comprises a display 2 showing a map
and navigation instructions, and providing user access to various
functions of the navigation device via a graphical menu system. The
colors and the contents displayed on the screen are controlled by
the processor 4 in accordance with the programmed functions,
planned route and location of the navigation device. In other
implementations, a separate image processor might be utilized for
graphical tasks.
[0030] The display 2 comprises a light source 3 for backlight. The
light source 3 might provide different output levels such as light
emitting diodes with pulse width modulation. Backlight levels are
controlled by the processor 4 or the separate image processor.
[0031] Color schemes 11 are also stored in the memory 10 or in
other dedicated areas of the navigation device. A color scheme
might be stored as a plug-in file. A plug-in file is a special
piece of software that interacts with a main application, in this
case with the main software of the navigation device, for
performing a specific task. The plug-in file may implement (e.g.
store, retrieve, control) color association and color
conversion.
[0032] The user of the navigation device may control the navigation
device using various buttons (not shown) or a tactile user
interface such as a touch screen or touch pad or via spoken
instructions. In this example, the user may interact with the
navigation device using the touch screen display 2, which is also
connected to the data bus 6.
[0033] The navigation device might comprise an onboard light sensor
5a or might have an interface to an external light sensor 5b. A
light sensor is a specially constructed diode or transistor
producing an output signal in accordance with current ambient
lighting conditions. The processor 4 receives a signal indicative
of ambient lighting conditions from sensors 5a or 5b. The signal
from the sensor 5a or 5b is taken into account by the processor 4
for selecting and changing display settings of the navigation
device. The signal indicative of ambient lighting conditions may
not be taken into account immediately in order to filter sudden,
temporary changes in ambient lighting conditions. A buffer between
10 seconds and 150 seconds might be used to prevent unwanted
changes between display modes due to temporary changes in ambient
lighting conditions.
[0034] FIG. 2 is a screen shot from a personal navigation device.
The screen shot shows a typical three dimensional navigation view 1
and a status bar 2 along the bottom of the screen. Roads, blocks of
buildings, parks, and water areas are shown using various colors.
The overall appearance is hence similar to a paper map. An arrow 3
indicating the current position of the device is shown in the
center of the screen. As the user of the navigation device or a
vehicle wherein the navigation device is mounted, travels along a
route 4, the navigation view 1 is regularly updated by map
scrolling and turning such that the arrow 3 indicating the current
position remains in a center area of the screen, pointing upwards.
A center area of the screen is located at the lower half of the
screen; at equal distance from the left and right edge of the
viewable map area. The user of the navigation device follows route
4 in order to reach a desired destination (not shown in the
figure).
[0035] The status bar 2 provides information on the details of the
journey in area 7. The next instruction icon 8 indicates what the
next maneuver is that the user should make and how far the current
location from the place of the maneuver is, so that the user has
enough time to prepare for a next maneuver. The next instruction
icon 8 may be accompanied by appropriately timed voice instructions
played through a speaker of the navigation device or via external
audio playback devices such as headphones or a car audio
system.
[0036] It is to be noted that in the status bar 2, character types
with appropriate size, color, and placement are used over a
background of contrasting color to facilitate reading of the
contents under most lighting conditions. In this example, white
fonts are used over a dark blue background. Alternatively,
different combinations of colors may be used providing sufficient
legibility for the user of the navigation device. Such combination
of colors include yellow, white, green, or light grey text over a
black, dark grey, brown, or dark blue background. Optionally, text
and background colors might be swapped or inverted.
[0037] Streets 5 and main roads 10 are drawn using light colors,
such as white and yellow, while street names 6 are displayed in
black to ensure a sufficient contrast. Further color combinations
might be possible, as discussed above. The next action is also
marked on the map with an arrow 9. In this example, arrow 9 is
drawn in green color that remains visible when superimposed over
the streets 5 and main roads 10. It is also possible to use any
other color, which is different than the colors below arrow 9.
[0038] A set of colors to be used in navigation view is called a
color scheme. A color scheme contains information regarding types
of map elements and colors associated with them. Beside map
elements, a color scheme might also contain information regarding
colors to be used in the status bar 2 and colors to be used for
other elements, shown in the navigation view 1, such as: zoom
buttons 11 and 12; current position marker 3; street names 5; water
6; arrow 9 for next action; and any other elements on screen, also
the ones not shown on FIG. 2 such as tunnels, bridges, highways,
pedestrian streets, railways, private roads, service roads,
roundabouts, bus lanes, etc.
[0039] It is also possible to increase the backlight of the display
of the navigation device, especially when it is used under direct
sunlight, and to decrease the backlight when used in a dark
environment to provide good readability in various lighting
conditions in addition to using various sets of colors.
[0040] FIG. 3 is a screen shot from a navigation device. The screen
shot shows the same three dimensional navigation view 1 and status
bar 2 as in FIG. 2 but using a different color scheme that is
suited for dark environments, where the harsh, contrasting colors
on FIG. 2 might be disturbing for the user of the navigation
device. In this example, the brightest color is used to indicate
the planned route 4, while the other elements are drawn using
relatively dark colors. Some elements such as the river 12 shown in
FIG. 2 are almost completely dissolved in the background of the
image, and the greens of the park area 13 at the top edge of the
screen are completely dark, to represent an almost realistic
nighttime view of the environment surrounding the navigation
device.
[0041] It is also possible to draw a schematic representation of
the night sky at the area close to the top of the screen where
relevant map and routing information is not displayed. This would
compensate for the loss of details compared to the view on FIG. 2.
Stars on the night sky might be rendered using white, yellow or
light grey colored dots of the size of 1 or 2 pixels in the upper
third of the viewable area in order to create a better feeling of
space even though fewer details are shown than on the view depicted
on FIG. 2.
[0042] The color scheme used in FIG. 3 helps the user of the
navigation device identify those elements that are more likely to
be relevant during the night. Additionally, there is less variation
of colors compared to FIG. 2, hence street names 6, route 4, and
information 9 on next action stand out from an almost even colored
background consisting of other map elements. Such a color scheme
would result in a lower amount of screen flickering and less
distraction to a user of the navigation device during the night
while it would still allow sufficient visibility as opposed to
color schemes with brighter, more varied and more vivid colors. The
same or a similar color scheme might be advantageous when the user
of the device enters a tunnel or other areas with considerably
lower lighting conditions than during normal day use.
[0043] FIG. 4 is a flowchart illustrating the present invention.
The navigation device stores in its memory various data that is
required to perform navigation related functions. The data might
comprise map data, satellite data, user data, sound and text files,
software for navigation and related operations, also configuration
files, preference settings and operating system files. The memory
can be one of a random access memory, a hard disk, a flash memory,
a removable memory card, and any suitable volatile or non-volatile
storage means. The processor of the navigation device is connected
to the memory and performs various operations as and when they are
required based on programmed instructions and/or user interaction.
The processor may carry out read and write operations. The
processor is able to delete, move and modify data in any manner
that is required for the operation of the navigation device.
[0044] In the first step of FIG. 4, the processor of the navigation
device monitors for a signal indicative of ambient lighting
conditions. In this embodiment, the signal is received from a light
sensor mounted on a printed circuit of the navigation device.
[0045] A light sensor is a photosensitive diode or transistor
producing an output signal that is a function of the amount of
light impinging the surface of the diode. When the relation between
the amount of light on the diode and the corresponding output
signal is known, it is possible to reliably distinguish between
various lighting conditions such as daylight and night or,
optionally, to use a finer granularity for further distinguishing
between an arbitrary number of transitional lighting conditions
between daylight and night. Manufacturers of light sensors publish
respective operating characteristics of diodes such as the TOSHIBA
TPS851 model, which may be used in this implementation of the
invention. In other implementations, it is also possible that the
light sensor is coupled externally to the navigation device, and it
is also possible that the sensor is only capable of distinguishing
between two conditions and providing an output signal indicating
one of the two conditions. Other sensors indicative of current
lighting conditions might be used, such as a headlight status
indicator to give a good estimation that outside light levels have
decreased when the vehicle headlights are on.
[0046] In the first step, the processor of the navigation device
monitors a signal indicative of current lighting conditions. In the
next step, the processors performs an evaluation of the signal and
then proceeds to selecting an appropriate display setting that has
been allocated for the current lighting condition. The processor
proceeds to changing current display settings to the selected
display setting after it has determined that the current display
setting differs from the setting allocated to the current lighting
condition.
[0047] The allocated display setting might comprise one of the
color schemes that has been discussed above, and might also
comprise pre-set backlight levels, and optionally showing or hiding
details on the screen.
[0048] A display setting suited for daylight conditions may
comprise a screen backlight level set to a maximum value, and a
color scheme using realistic day-like colors, and showing map
information in a similar fashion than on paper maps.
[0049] Another display setting for use during the night may
comprise a lowered backlight level which can be in the lower half
of the backlight range, e.g. set to 15 percent, in combination with
the same color scheme as above or another color scheme using colors
that are similar to a view of the area surrounding the user at
night. It is also possible that the color scheme for nighttime
usage employs inverted colors of the color scheme for daytime
usage.
[0050] It is also possible that a night view indicates objects that
are not visible during the day, e.g. stars, streetlight, and it is
also possible to configure a night view to disable some objects or
functions that are more likely to be relevant during the day and
enable functions that might be relevant to the user of the
navigation device during the night or in dark environments. Thus,
besides using a pre-defined set of colors for displaying screen
contents, a day or night view might show different pieces of
information, which might include at least one of a star map, points
of interests, information on map items or planned route, and menu
items. A day or night view might also enable or disable some
functions of the navigation device, which might be at least one of
a speed limit warning, a driving break warning, and updating of
traffic or weather information. Therefore, when switching to a day
or night view, the navigation device will retrieve information on
road conditions, such as congestion or road temperatures and
similar.
[0051] In the following, attention is drawn to FIGS. 4, 5, and 6
that describe various configuration options for the user of the
navigation device.
[0052] FIG. 5 is a screen shot from a preferences menu of a
navigation device. The menu is based on various icons and text
labels, each of the icons representing a different configuration
option. On some navigation devices, configuration options can be
reached through a menu based purely on text.
[0053] Icon 51 in the lower left hand corner is labeled "Change map
colours" and by selecting it, the user of the navigation device can
select map colors that are most appropriate for the current
operating environment or other parameters, like the personal
preference of the user. Some color schemes have been designed to
create a more realistic representation of the actual view, while
others are adopted for color blind persons, and still others are
designed around various themes, such as the official colors of a
country's national soccer team. Certain color schemes conform to
regional differences in color coding of paper maps and road
infrastructure objects.
[0054] It is common in color schemes of the present invention that
any objects that might be displayed on the screen have an
association with a color. The color associations in a color scheme
might be pre-defined and fixed, or it might be possible for the
user of the navigation device to select colors for individual map
objects and elements displayed on the screen.
[0055] According to this embodiment of the invention, certain map
colors are more suited for daytime use, and others are suited for
nighttime use. The user can manually link one color scheme to
daytime use and link a different color scheme to nighttime use, or
the appropriate day and night color schemes can be stored as a
factory preset in the memory of the navigation device. Icon 52 in
the lower center area of the preferences menu opens up a brightness
preferences screen that will be described in more detail in FIG.
6.
[0056] FIG. 6 depicts a screen shot of a brightness preferences
menu of a navigation device according to the invention. The screen
shot indicates a first slider 61 for selecting a backlight level to
be used during daytime, and slider 62 for selecting another
backlight level to be used during nighttime. The backlight levels
can be selected independently from each other or as a ratio of each
other. In the example shown on FIG. 6, daytime backlight level is
at 90 percent of the available range, and nighttime backlight level
is at 15 percent of the range. Alternatively, the user may indicate
a desired ratio, e.g. daytime brightness 90 percent of the
available range, and a nighttime brightness being 15 percent of
selected daytime brightness. It is also possible that the user of
the navigation device wishes to use a higher backlight level during
the night than during the day. It is possible by setting sliders 61
and 62 accordingly.
[0057] On the lower part of FIG. 6, checkboxes 63 and 64 have been
indicated. Checkbox 63 is marked when the user wishes to rely on
the navigation device to adjust backlight of the display between
the two levels as may be selected by sliders 61 and 62. When
checkbox 63 is deselected, the user will be able to set backlight
levels manually. Checkbox 64 is marked when the user of the
navigation device wishes to rely on the navigation device to switch
between day and night color schemes according to a mechanism
illustrated in FIGS. 8 and 9. When the user deselects checkbox 64,
the navigation device keeps using the current color scheme
independently of the lighting conditions.
[0058] FIG. 7 illustrates the configuration menu of a navigational
device, wherein the user can manually switch between day and night
colors using button 71. When a nighttime display setting is
selected by pressing this button, checkboxes 63 and 64 (of FIG. 6)
will not be taken into account by the navigation device.
[0059] FIG. 8 is a transition diagram illustrating various display
settings of the navigation device in response to different lighting
conditions. The horizontal axis 1 represents the level of the input
signal received from a light sensor. When the input signal
indicates low ambient lighting conditions, i.e. the input is below
a threshold 2, the navigation device uses a night color scheme and
a nighttime display setting. When the input from the light sensor
indicates daytime lighting conditions, i.e. signal level is higher
than threshold 2, the navigation device uses a day color scheme and
a daytime display setting. Threshold 2 has been set to a value
corresponding to an ambient light level, below which the average
user would be using a night color scheme. Threshold 2 can be
factory preset or it can be set by the users of the navigation
device according to their personal preferences.
[0060] The vertical axis 4 represents the screen brightness between
0 to 100 percents. In this example, daytime brightness 5 is set to
100 percent, and nighttime brightness 6 is set to approximately 25
percent. Nighttime brightness 6 is used as long as the light sensor
input is below threshold 2, and daytime brightness 5 is used when
the light sensor input is above threshold 3.
[0061] In another embodiment, threshold 2 and threshold 3 are
identical, i.e. co-located at a point on horizontal axis 1. In this
case, the display settings instantly change from nighttime
brightness to daytime brightness when the signal indicative of
ambient lighting conditions rises above the combined threshold 2
and 3. Similarly, when the signal indicative of ambient lighting
conditions falls below the combined threshold 2 and 3, display
settings instantly change from daytime brightness to nighttime
brightness.
[0062] FIG. 8 depicts a smooth transition along line 7 between
levels for nighttime brightness 6 and daytime brightness 5 while
the light sensor input is between threshold 2 and threshold 3 that
are set to different values of the horizontal axis 1. In this case,
further display settings might be allocated to different parts of
the transition line 7. The further display settings might be
created using daytime color schemes and gradually changing
backlight levels; or nighttime color schemes and gradually changing
backlight levels.
[0063] In the preferred implementation, 5 different backlight
levels are allocated evenly between the levels for nighttime
brightness 6 and daytime brightness 5, without changing the color
scheme. This arrangement provides a gradual dimming of display
backlight in response to the decreasing ambient light levels. In
this example, four points 2-A, 2B, 2C, and 2D are shown on the
horizontal axis 1 between threshold 2 and threshold 3. There might
be a different number of points, the points might be placed
arbitrarily between thresholds 2 and 3 or they may be evenly
distributed.
[0064] When the signal indicative of ambient lighting conditions
falls to threshold 3 on the horizontal axis 1, screen brightness is
decreased to a value associated with threshold 2D, which lays
proportionally between the value of daytime brightness 5 and
nighttime brightness 6 (in this example, 100 and 25 percents
respectively). Screen brightness remains at the value associated
with threshold 2D until the decreasing signal actually reaches
threshold 2D. At threshold 2D, screen brightness changes to the
value associated with threshold 2C; and screen brightness remains
unchanged until the decreasing signal actually reaches threshold
2C. Similarly, at threshold 2C, screen brightness changes to the
value associated with threshold 2B; and at threshold 2B, screen
brightness changes to the value associated with threshold 2A.
Finally, at threshold 2A, screen brightness changes to the value
associated with threshold 2, which is the value of nighttime
brightness 6; and screen brightness remains unchanged as long as
the signal is below threshold 2. Changing from daytime colors to
nighttime colors can occur at one of thresholds 2, 2A, 2B, 2C, 2D,
and 3, depending on factory or user configuration.
[0065] Similarly, when the signal level on the horizontal axis 1
rises in response to increasing ambient light levels, the
navigation device is configured to change from nighttime color
schemes to daytime color schemes at threshold 2, and to gradually
increase display backlight from nighttime brightness level to
daytime brightness level along line 7 until light sensor input
indicative of ambient lighting conditions reaches threshold 3. The
detailed procedure is the following.
[0066] Screen brightness remains at the level of nighttime
brightness 6 as long as the signal indicative of ambient lighting
conditions is below point 2A, or alternatively threshold 2. When a
raising signal reaches threshold 2A, screen brightness changes to a
level allocated to this given point, which is a proportional value
and can be read from the vertical axis 2, somewhere between
nighttime brightness 6 and daytime brightness 5 (in this example,
25 and 100 percents respectively). At threshold 2B, screen
brightness increases to a level allocated to this given point and
thereafter it remains unchanged until the signal reaches threshold
2C. Screen brightness keeps changing in a similar manner at
thresholds 2C and 2D. Finally, at and above threshold 3, daytime
brightness 5 is used, which is equal to 100 percent in this
example.
[0067] In the above examples, there are four transition points
between nighttime brightness 6 and daytime brightness 5, providing
a good granularity without the need to store a high number of
settings. In other implementations, any larger or smaller number of
transitional steps can be used or there can be a step less,
continuous transition as well.
[0068] Above threshold 3, daytime display settings are used unless
the user of the navigation device manually selects a different
display setting, e.g. by pressing button 1 on FIG. 7 to use night
colors, or by disabling checkboxes 3 and 4 on FIG. 6. In other
implementations, different configuration options might be available
for manually disabling the switching between day and night color
schemes. The user might simply select the same color scheme and
same backlight level for daytime and nighttime usage in order to
disable any automatic change.
[0069] FIG. 9 indicates an altered transition diagram compared to
FIG. 8. On FIG. 9, the level of daytime brightness 5 has been
lowered to a new daytime brightness 5', the difference is indicated
by arrow 9. Nighttime brightness 6 has been changed to a new
nighttime brightness 6', the difference is indicated by arrow 10.
The new configuration can be compared to the previously discussed
transition line 7 as seen on new transition line 7'. Using new
transition line 7', the steps between new nighttime brightness 6'
and new daytime brightness 5' are smaller but the transition is
still a smooth, gradual one as long as threshold 2 and 3 are not
the same.
[0070] In the above examples, ambient lighting conditions are
measured using a light sensor coupled to the processor of the
navigation device. The light sensor can be an integral part of the
navigation device or it may be an external sensor attached to a
suitable connector of the navigation device or its docking
unit.
[0071] In other arrangements, the external sensor might transmit
radio signals such as Bluetooth or Infra-Red signals indicative of
ambient lighting conditions. For example, a radio signal
transmitter might be directly or indirectly connected to an
in-vehicle light sensor or headlight sensor and configured to
transmit radio signals to the navigation device, the signals being
indicative of ambient lighting conditions. The proper installation
of a Bluetooth or Infra-Red transmitter unit is known to a person
skilled in the art and it is outside the scope of the invention. A
Bluetooth or Infra-Red enabled navigation device may monitor radio
signals indicative of ambient lighting conditions and implement the
invention according to the appended claims.
[0072] In the absence of a signal from a light sensor or a similar
hardware component, or in addition to it, the software on the
navigation device may also monitor the current position of the
navigation device and compare it to the map data for the purposes
set out above. By matching map data to current position, the
software of the navigation device may indicate that the current
position is in a tunnel or in an underground car park, which is
interpreted as a signal indicative of low ambient lighting
conditions. Lack of position data (i.e. loss of GPS signal) might
also indicate that the current location is in a tunnel or
underground car park.
[0073] In that case, indication of ambient lighting conditions does
not require a hardware component implemented on or coupled to the
navigation device. The signal indicative of lighting conditions can
be generated using software means such as at least one of a map
data, user data, time data and configuration data.
[0074] In a further embodiment, the navigation device might ask for
a confirmation from the user before or after changing between day
and night color schemes upon determination that current display
setting is not the display setting allocated to current ambient
lighting conditions. A selection screen or a confirmation dialog
may be presented to the user of the navigation device for changing
display settings.
[0075] When the navigation device is removed from the vehicle, i.e.
when it is detected that the device has been undocked, the user may
select further options, which comprise at least one of a
confirmation of undocking, a selection whether or not to monitor a
signal indicative of lighting conditions, selection of color scheme
to be used, and selection of backlight level to be used. A similar
selection is possible when docking the navigation device in the
vehicle.
[0076] The invention has been described with reference to certain
preferred embodiments. It will be understood, however, that
modifications and variations are possible within the scope of the
appended claims.
* * * * *