U.S. patent application number 13/619306 was filed with the patent office on 2013-01-10 for dual-function light guide for lcd backlight.
This patent application is currently assigned to RESEARCH IN MOTION LIMITED. Invention is credited to Marc A. Drader, Robert J. Lowles, James Robinson.
Application Number | 20130009927 13/619306 |
Document ID | / |
Family ID | 36931548 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130009927 |
Kind Code |
A1 |
Lowles; Robert J. ; et
al. |
January 10, 2013 |
DUAL-FUNCTION LIGHT GUIDE FOR LCD BACKLIGHT
Abstract
A light emitter/sensor includes a lamp, a light sensor, a light
guide, and a light controller. The light guide has a pair of
opposite ends and is optically-coupled to the lamp and the light
sensor at one of the ends. The light guide is configured to convey
light emitted from the lamp to the other end of the light guide,
and from that other end to the light sensor. The light controller
is coupled to the lamp and the light sensor and is configured to
flash the lamp and to determine the intensity of light at that
other end of the light guide, via the light guide and the light
sensor, during an interval between the flashes.
Inventors: |
Lowles; Robert J.;
(Waterloo, CA) ; Drader; Marc A.; (Kitchener,
CA) ; Robinson; James; (Elmira, CA) |
Assignee: |
RESEARCH IN MOTION LIMITED
Waterloo
CA
|
Family ID: |
36931548 |
Appl. No.: |
13/619306 |
Filed: |
September 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12731842 |
Mar 25, 2010 |
8289271 |
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13619306 |
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11066451 |
Feb 28, 2005 |
8279158 |
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12731842 |
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Current U.S.
Class: |
345/207 |
Current CPC
Class: |
H04M 1/22 20130101; H04M
19/048 20130101; H04M 19/04 20130101; G09G 3/3406 20130101; H04M
2250/12 20130101; G09G 2360/144 20130101; G09G 2320/0626
20130101 |
Class at
Publication: |
345/207 |
International
Class: |
G06F 3/038 20060101
G06F003/038 |
Claims
1-10. (canceled)
11. A handheld communications device, comprising: a display device,
comprising: a display panel; a light guide coupled to the display
panel; a light sensor, the light sensor configured to measure an
intensity of ambient light, the light guide configured to direct
light between the display panel and the light sensor; and a light
source, optically coupled to the light guide, the light guide
configured to direct light between the display panel and the light
source; and a light controller coupled to the display panel and
configured to adjust an intensity of light emitted by the light
source in accordance with the measured ambient light intensity.
12. The handheld communications device of claim 11, wherein the
light sensor and the light source are provided at a common end of
the light guide.
13. The handheld communications device of claim 11, further
comprising an event notifier, wherein the event notifier comprises
the light sensor.
14. The handheld communications device of claim 11, further
comprising a user data input device coupled to the light
controller, the user data input device comprising a keyboard and a
keyboard backlight, wherein the light controller is configured to
adjust an intensity of light emitted by the keyboard backlight in
accordance with the measured ambient light intensity.
15. The handheld communications device of claim 11, further
comprising a housing, wherein the light guide is configured to
convey light between the light source and an external surface of
the housing.
16. The handheld communications device of claim 15, wherein the
light sensor is configured to measure the intensity of light at the
external surface via the light guide, and the light controller is
configured to adjust the intensity of emitted light in accordance
with the measured external light intensity.
17. The handheld communications device of claim 11, wherein the
light source comprises a plurality of backlight LEDs.
18. The handheld communications device of claim 11, wherein the
light guide is a planar light guide.
19. A method of illuminating information rendered on a display
device of a handheld communications device, the display device
comprising a display panel, a light guide coupled to the display
panel, a light sensor, the light sensor configured to measure an
intensity of ambient light, the light guide configured to direct
light between the display panel and the light sensor, and a light
source, optically-coupled to the light guide, the light guide
configured to direct light between the display panel and the light
source, the method comprising the steps of: measuring an intensity
of ambient light using the light sensor; and adjusting an intensity
of light emitted by the light source in accordance with the
measured ambient light intensity.
20. The method of claim 19, wherein the light sensor and the light
source are provided at a common end of the light guide.
21. The method of claim 19, wherein the handheld communications
device further comprises an event notifier, wherein the event
notifier comprises the light sensor.
22. The method of claim 19, wherein the handheld communications
device further comprises a user data input device, the user data
input device comprising a keyboard and a keyboard backlight, and
wherein the intensity adjusting step further comprises adjusting an
intensity of light emitted by the keyboard backlight in accordance
with the measured ambient light intensity.
23. The method of claim 19, wherein the handheld communications
device further comprises a housing, and wherein the intensity
measuring step further comprises measuring the intensity of light
external to the housing via the light guide and the light
sensor.
24. The method of claim 23, wherein the intensity adjusting step
further comprises adjusting the intensity of emitted light in
accordance with the measured external light intensity.
25. The method of claim 19, wherein the light source comprises a
plurality of backlight LEDs.
26. The method of claim 19, wherein the light guide is a planar
light guide.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 11/066,451, entitled Dual-Function Light Guide
for LCD Backlight", filed Feb. 28, 2005, the contents of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention described herein relates to a mechanism for
controlling visualization of information rendered on the display
device of a portable computing device. In particular, the invention
described herein relates to a method and apparatus for controlling
the backlight intensity of a liquid crystal display (LCD), based on
the intensity of ambient light detected at the portable computing
device.
BACKGROUND OF THE INVENTION
[0003] The conventional portable computing device, such as a
personal data assistant (PDA) or wireless telephone, has a liquid
crystal display (LCD), a LCD backlight, and a keyboard/keypad.
Typically, the display backlight is enabled when the device is
powered on or when a key on the keyboard/keypad is depressed. The
intensity of light produced by the backlight is factory set to a
fixed level that allows the information displayed on the LCD to be
viewable in moderate ambient light levels. However, the backlight
tends to be excessively bright at dim ambient light levels, and
insufficiently bright at very bright ambient light levels. In both
of these situations, the clarity of the information displayed on
the LCD is comprised. Accordingly, attempts have been made to make
the information displayed on a LCD more readily viewable over a
wider range of ambient light levels.
[0004] For instance, Keiji (Patent Abstracts of Japan, Pub. No.
11-260572) describes a lighting system that changes the
illumination level of the LCD, based on the intensity of ambient
light detected. In one embodiment, the lighting system comprises a
liquid crystal display having a Light Emitting Diode (LED)
backlight and a light guide; a light sensor disposed at an end face
of the light guide; and control means for varying the intensity of
light emitted by backlight. The light sensor measures the luminous
energy at two or more wavelengths. The control means determines the
energy of light measured by the light sensor, while momentarily
setting the radiant output energy of the backlight to zero. The
control means then sets the radiant output energy of the backlight
based on the energy of light so measured.
[0005] Since the light sensor is disposed within the LCD, the light
sensor is not prone to erroneous intensity measurements resulting
from dirt contaminating the optical surface of the sensor. However,
incorporating the light sensor into the LCD increases the
manufacturing cost of the LCD. Therefore, there remains a need for
an improved mechanism for rendering the information displayed on a
LCD more readily viewable over a wide range of ambient light
levels.
SUMMARY OF THE INVENTION
[0006] In accordance with one aspect of this disclosure, there is
provided a light emitter/sensor that comprises a lamp, a light
sensor, a light guide, and a light controller. The light guide has
a pair of opposite ends and is optically-coupled to the lamp and
the light sensor at one of the ends. The light guide is configured
to convey light emitted from the lamp to the other end of the light
guide, and from that other end to the light sensor. The light
controller is coupled to the lamp and the light sensor and is
configured to flash the lamp and to determine the intensity of
light at that other end of the light guide, via the light guide and
the light sensor, during an interval between the flashes.
[0007] In accordance with another aspect of this disclosure, there
is provided a portable computing device that comprises a housing
(that includes an external surface), and a display device supported
by the housing. The display device includes illumination means for
improved visualization of information rendered on the display
device. The portable computing device also comprises a lamp, a
light sensor and a light guide that are disposed within the
housing. The light guide has a pair of opposite ends, and is
optically-coupled to the lamp and the light sensor at one of the
ends and terminates at the external surface at the other end of the
light guide. The light guide is configured to convey light emitted
from the lamp to the external surface, and from the external
surface to the light sensor. The light controller is coupled to the
lamp, the light sensor and the illumination means. The light
controller is configured to flash the lamp, to determine the
intensity of ambient light at the external surface via the light
conduit and the light sensor during an interval between the
flashes, and to adjust an intensity of light emitted by the
illumination means in accordance with the determined ambient light
intensity.
[0008] The light guide may have a substantially Y-shape. In one
implementation, the light guide has a pair of branches that
terminate at the one end of the light guide, and a trunk that
terminates at the other end of the light guide, the branches being
optically-coupled to the trunk. The lamp may be optically-coupled
to one of the branches at the one end of the light guide, and the
light sensor may be optically-coupled to another of the branches at
that one end of the light guide. The light emitter/sensor may also
comprise a lens that is optically-coupled to the trunk at the other
end of the light guide. The lens may be secured to the housing and
optically-coupled to the trunk at that other end of the light
guide.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will now be described, by way of example only,
with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a front plan view of the portable computing
device, according the invention described herein;
[0011] FIG. 2 is a schematic view of the portable computing device,
depicting the communication pathways existing between the data
processing means, the event notifier, the LCD display, and the data
input means of the portable computing device depicted in FIG.
1;
[0012] FIG. 3 is a schematic view of the interior of the portable
computing device, depicting the event notification lamp, the light
conduit and the light sensor of one embodiment of the event
notifier;
[0013] FIG. 4 is an exploded perspective view of another embodiment
of the invent notifier, in which the light conduit and the light
sensor of the event notifier are integrated with the light guide of
the LCD display;
[0014] FIG. 5 is a schematic view depicting functional details of
the portable computing device;
[0015] FIG. 6 is a schematic view depicting the communication
pathways existing between the light controller, the event notifier,
the display device backlight and the keyboard backlight of the
portable computing device;
[0016] FIG. 7 is a flowchart depicting, by way of overview, the
method of controlling the illumination of the display device
implemented in the portable computing device;
[0017] FIG. 8 is a a flowchart depicting, in detail, the method of
illumination control of the display device implemented in the
portable computing device having a transmissive LCD display;
and
[0018] FIG. 9 is a flowchart depicting, in detail, the method of
illumination control of the display device implemented in the
portable computing device having a reflective, trans-reflective or
transmissive LCD display.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Referring now to FIG. 1, there is shown a portable computing
device, denoted generally as 100, provided according to one aspect
of the invention. The portable computing device 100 includes a
display 122, a function key 146, and data processing means 102 (not
shown) disposed within a common housing 101. The display 122
comprises a backlit display having a variable-intensity backlight,
and the data processing means 102 is coupled to the backlight of
the display 122 and controls the intensity of light produced by the
backlight.
[0020] In one embodiment, the backlit display 122 comprises a
backlit transmissive LCD display, and the function key 146 operates
as a combination power on/off switch and display backlight on/off
switch. Alternately, in another embodiment, the backlit display 122
comprises a backlit reflective or trans-reflective LCD display, and
the function key 146 operates as a master backlight on/off
switch.
[0021] As shown in FIG. 2, the data processing means 102 of the
portable computing device 100 is in communication with the display
122 and the event notifier 162. As will be described, the data
processing means 102 comprises a microprocessor 138, and a memory
124, 126 (disposed within the housing 101). The memory 124, 126
carries computer processing instructions which, when accessed from
the memory 124, 126 and executed by the microprocessor 138, cause
the data processing means to perform the method which will be
described in further detail below.
[0022] In addition to the display 122 and the event notifier 162,
the portable computing device 100 includes user data input means
for inputting data to the data processing means. Further, the data
processing means 102 is in communication with the function key 146
and the user data input means. Preferably, the user data input
means includes a keyboard 132, a thumbwheel 148 and an escape key
160. Preferably, the keyboard 132 includes a keyboard backlight.
Further, preferably the backlight for the keyboard 132 is operable
independently of the backlight for the display 122.
[0023] In a first embodiment, the portable computing device 100
includes a cavity (not shown) opening into the interior of the
housing 101 from the exterior surface of the housing 101.
Preferably, the cavity terminates at the exterior housing surface
proximate the display 122. In addition, if the portable computing
device 100 has telephony capabilities, preferably the portable
computing device 100 includes a speaker grille 134 and a microphone
grille 136, as shown in FIG. 1. Typically, the speaker and
microphone grilles 134, 136 each comprise one or more apertures
formed in the housing 101.
[0024] Further, as shown in FIG. 1, preferably the portable
computing device 100 includes a translucent lens 164 secured to the
exterior housing surface and enclosing the cavity. As shown, the
lens 164 is disposed proximate the display 122. As will be
explained, this position allows the data processing means 102 to
detect the intensity of ambient light falling on the display 122.
Preferably, the lens 164 is disposed above the display 122,
adjacent the uppermost end of the portable computing device 100.
Optionally, the lens 164 may be disposed below the display 122,
between the lowermost end of the display 122 and the uppermost end
of the keyboard 132.
[0025] As shown in FIG. 3, in the first embodiment the event
notifier 162 comprises an event notification lamp 166 and a light
conduit 168 disposed within the housing 101. Typically, the event
notification lamp 166 comprises a light emitting diode (LED). The
light conduit 168 is typically disposed within the aforementioned
cavity. Further, the light conduit 168 is optically-coupled at one
end to the event notification lamp 166, and terminates at the
external surface of the housing 101 in order to convey light
between the event notification lamp 166 and the external surface.
Preferably, the light conduit 168 comprises a light guide that
extends between the event notification lamp 166 and the lens 164.
Alternately, the light conduit 168 may simply comprise the
aforementioned cavity, and extends between the event notification
lamp 166 and the speaker or microphone grille 134, 136.
[0026] In addition to the event notification lamp 166 and the light
conduit 168, preferably the event notifier 162 also includes an
ambient light sensor 170 optically-coupled to the light conduit 168
for measuring the intensity of the light in the light conduit 168.
As will be appreciated, since the light conduit 168 terminates at
the external surface of the housing 101, the light sensor 170 is
able to provide an indication of the intensity of ambient light
external to the housing 101. Further, since the light conduit 168
typically terminates at the exterior housing surface proximate the
display 122, the light sensor 170 is able to provide an indication
of the intensity of ambient light falling on the display 122.
[0027] It should be understood, however, that the light sensor 170
of the foregoing embodiment is not an essential feature of the
invention. Rather, in one variation, the light sensor 170 is
eliminated, and the intensity of ambient light is measured via a
suitable event notification lamp 166.
[0028] A second embodiment of the invention is depicted in FIG. 4,
in which the event notifier 162 is integrated with the display 122.
As shown, the display 122 comprises a planar light diffusing film
176, a planar light reflecting layer 172, a planar light guide 174
disposed between the light diffusing film 176 and the light
reflecting layer 172, a planar liquid crystal module 180, a planar
light intensifying layer 178 disposed between the light diffusing
film 176 and the liquid crystal module 180, and a plurality of
backlight LEDs 182 optically-coupled to one edge of the light
guide. The light reflecting layer 172, the light guide 174, the
light diffusing film 176, the light intensifying layer 178, the
liquid crystal module 180, and the backlight LEDs 182 are all
retained within and supported by the housing 101 of the portable
computing device 100. The liquid crystal module 180 is
electrically-coupled to the data processing means 102 to thereby
allow the data processing means 102 to present information on the
display 122.
[0029] In the second embodiment, the event notification lamp 166
and the light conduit 168 of the event notifier 162 are not
required. Although, in the second embodiment, the event notifier
162 includes the ambient light sensor 170, the ambient light sensor
170 is optically-coupled to the light guide 174 of the display 122.
As shown, preferably the ambient light sensor 170 is coupled to the
same edge of the light guide 174 as the backlight LEDs 182,
although other orientations/configurations are intended to be
encompassed by the invention described herein. The light guide 174
acts as a light conduit that not only directs light from the
backlight LEDs 182 to the liquid crystal module 178 (thereby
illuminating the information depicted on the liquid crystal module
178), but also directs the ambient light that falls on the display
122 towards the ambient light sensor 170. As will become apparent,
this embodiment allows the data processing means 102 to more
accurately detect the intensity of ambient light falling on the
display 122.
[0030] Typically, the portable computing device 100 is a two-way
wireless communication device having at least voice and data
communication capabilities. Further, preferably the portable
computing device 100 has the capability to communicate with other
computer systems on the Internet. Depending on the exact
functionality provided, the wireless portable computing device 100
may be referred to as a data messaging device, a two-way pager, a
wireless e-mail device, a cellular telephone with data messaging
capabilities, a wireless Internet appliance, or a data
communication device, as examples.
[0031] FIG. 5 depicts functional details of the portable computing
device 100. Where the portable computing device 100 is enabled for
two-way communication, it will incorporate a communication
subsystem 111, including both a receiver 112 and a transmitter 114,
as well as associated components such as one or more, preferably
embedded or internal, antenna elements 116 and 118, local
oscillators (LOs) 113, and a processing module such as a digital
signal processor (DSP) 120. As will be apparent to those skilled in
the field of communications, the particular design of the
communication subsystem 111 will be dependent upon the
communication network in which the device is intended to operate.
For example, the portable computing device 100 may include a
communication subsystem 111 designed to operate within the
Mobitex.TM. mobile communication system, the DataTAC.TM. mobile
communication system, GPRS network, UMTS network, EDGE network or
CDMA network.
[0032] Network access requirements will also vary depending upon
the type of network 119. For example, in the Mobitex and DataTAC
networks, the portable computing device 100 is registered on the
network using a unique identification number associated with each
portable computing device. In UMTS and GPRS networks, and in some
CDMA networks, however, network access is associated with a
subscriber or user of the portable computing device 100. A GPRS
portable computing device therefore requires a subscriber identity
module (SIM) card in order to operate on a GPRS network, and a RUIM
in order to operate on some CDMA networks. Without a valid SIM/RUIM
card, a GPRS/UMTS/CDMA portable computing device may not be fully
functional. Local or non-network communication functions, as well
as legally required functions (if any) such as "911" emergency
calling, may be available, but the portable computing device 100
will be unable to carry out any other functions involving
communications over the network. The SIM/RUIM interface 144 is
normally similar to a card-slot into which a SIM/RUIM card can be
inserted and ejected like a diskette or PCMCIA card. The SIM/RUIM
card can have approximately 64K of memory and hold many key
configuration 151, and other information 153 such as
identification, and subscriber related information.
[0033] When required network registration or activation methods
have been completed, the portable computing device 100 may send and
receive communication signals over the network 119. Signals
received by antenna 116 through communication network 119 are input
to receiver 112, which may perform such common receiver functions
as signal amplification, frequency down conversion, filtering,
channel selection and the like, and in the example system shown in
FIG. 5, analog to digital (A/D) conversion. A/D conversion of a
received signal allows more complex communication functions such as
demodulation and decoding to be performed in the DSP 120. In a
similar manner, signals to be transmitted are processed, including
modulation and encoding for example, by DSP 120 and input to
transmitter 114 for digital to analog conversion, frequency up
conversion, filtering, amplification and transmission over the
communication network 119 via antenna 118. DSP 120 not only
processes communication signals, but also provides for receiver and
transmitter control. For example, the gains applied to
communication signals in receiver 112 and transmitter 114 may be
adaptively controlled through automatic gain control algorithms
implemented in DSP 120.
[0034] The portable computing device 100 preferably includes a
microprocessor 138 which controls the overall operation of the
device. Communication functions, including at least data and voice
communications, are performed through communication subsystem 111.
Microprocessor 138 also interacts with further device subsystems
such as the display 122, flash memory 124, random access memory
(RAM) 126, auxiliary input/output (I/O) subsystems 128, serial port
130, keyboard 132, speaker 134, microphone 136, a short-range
communications subsystem 140 and any other device subsystems
generally designated as 142.
[0035] Some of the subsystems shown in FIG. 5 perform
communication-related functions, whereas other subsystems may
provide "resident" or on-device functions. Notably, some
subsystems, such as keyboard 132 and display 122, for example, may
be used for both communication-related functions, such as entering
a text message for transmission over a communication network, and
device-resident functions such as a calculator or task list.
[0036] Operating system software used by the microprocessor 138 is
preferably stored in a persistent store such as flash memory 124,
which may instead be a read-only memory (ROM) or similar storage
element (not shown). Those skilled in the art will appreciate that
the operating system, specific device applications, or parts
thereof, may be temporarily loaded into a volatile memory such as
RAM 126. Received communication signals may also be stored in RAM
126.
[0037] As shown, the flash memory 124 can be segregated into
different areas for both computer programs 158 and program data
storage 150, 152, 154 and 156. These different storage types
indicate that each program can allocate a portion of flash memory
124 for their own data storage requirements.
[0038] Microprocessor 138, in addition to its operating system
functions, preferably enables execution of software applications on
the portable computing device. The operating system software and
the software applications comprises computer processing
instructions which, when accessed from the flash memory 124 and the
RAM 126 and executed by the microprocessor 138, define the
aforementioned data processing means 102. A predetermined set of
applications that control basic operations, including at least data
and voice communication applications for example, will normally be
installed on the portable computing device 100 during
manufacturing.
[0039] Another such software application comprises a light
controller 184 that controls the backlight 182 of the backlit
display 122. As shown in FIG. 6, the light controller 184 is in
communication with the light sensor 170, and the display backlight
182 and the keyboard backlight 183. Also, in the first embodiment
of the event notifier 162, the light controller 184 is in
communication with the event notification lamp 166. The light
controller 184 uses the light sensor 170 to determine the intensity
of ambient light external to the housing 101. Also, the light
controller 184 is configured to adjust the intensity of light
emitted by the display backlight 182 and the keyboard backlight 183
in accordance with the determined ambient light intensity.
[0040] The light controller 184 also controls the illumination of
the event notification lamp 166 in accordance with one or more
predefined events. For instance, the light controller 184 may be
configured to flash the event notification lamp 166 when the data
processing means 102 is in a sleep state. The light controller 184
may be configured to flash the event notification lamp 166 when an
e-mail message or a telephone call is received at the portable
computing device 100. Other suitable events are intended to be
encompassed by the invention described herein.
[0041] Returning again to FIG. 5, another software application may
be a personal information manager (PIM) application having the
ability to organize and manage data items relating to the user of
the portable computing device such as, but not limited to, e-mail,
calendar events, voice mails, appointments, and task items.
Naturally, one or more memory stores would be available on the
portable computing device to facilitate storage of PIM data items.
Such PIM application would preferably have the ability to send and
receive data items, via the wireless network 119.
[0042] In a preferred embodiment, the PIM data items are seamlessly
integrated, synchronized and updated, via the wireless network 119,
with the user's corresponding data items stored or associated with
a host computer system. Further applications may also be loaded
onto the portable computing device 100 through the network 119, an
auxiliary I/O subsystem 128, serial port 130, short-range
communications subsystem 140 or any other suitable subsystem 142,
and installed by a user in the RAM 126 or preferably a non-volatile
store (not shown) for execution by the microprocessor 138. Such
flexibility in application installation increases the functionality
of the device and may provide enhanced on-device functions,
communication-related functions, or both. For example, secure
communication applications may enable electronic commerce functions
and other such financial transactions to be performed using the
portable computing device 100.
[0043] In a data communication mode, a received signal such as a
text message or web page download will be processed by the
communication subsystem 111 and input to the microprocessor 138,
which preferably further processes the received signal for output
to the display 122, or alternatively to an auxiliary I/O device
128. A user of the portable computing device 100 may also compose
data items such as email messages for example, using the keyboard
132, which is preferably a complete alphanumeric keyboard or
telephone-type keypad, in conjunction with the display 122 and
possibly an auxiliary I/O device 128. Such composed items may then
be transmitted over a communication network through the
communication subsystem 111.
[0044] For voice communications, overall operation of the portable
computing device 100 is similar, except that received signals would
preferably be output to a speaker 134 and signals for transmission
would be generated by a microphone 136. Alternative voice or audio
I/O subsystems, such as a voice message recording subsystem, may
also be implemented on the portable computing device 100. Although
voice or audio signal output is preferably accomplished primarily
through the speaker 134, display 122 may also be used to provide an
indication of the identity of a calling party, the duration of a
voice call, or other voice call related information for
example.
[0045] Serial port 130 in FIG. 5, would normally be implemented in
a personal digital assistant (PDA)-type portable computing device
for which synchronization with a user's desktop computer (not
shown) may be desirable, but is an optional device component. Such
a port 130 would enable a user to set preferences through an
external device or software application and would extend the
capabilities of the portable computing device 100 by providing for
information or software downloads to the portable computing device
100 other than through a wireless communication network. The
alternate download path may for example be used to load an
encryption key onto the device through a direct and thus reliable
and trusted connection to thereby enable secure device
communication.
[0046] Other communications subsystems 140, such as a short-range
communications subsystem, is a further optional component which may
provide for communication between the portable computing device 100
and different systems or devices, which need not necessarily be
similar devices. For example, the subsystem 140 may include an
infrared device and associated circuits and components or a
Bluetooth.TM. communication module to provide for communication
with similarly enabled systems and devices.
[0047] FIG. 7 is a flow chart that depicts, by way of overview, the
sequence of steps performed by the light controller 184 according
to the invention. Initially, the portable computing device 100 is
in an inactive state, and the display backlight 182 and the
keyboard backlight 183 are at a minimum/off intensity. Typically,
the light controller 184 flashes the event notification lamp 166 to
notify the user that the portable computing device 100 is not off,
but is instead inactive. The portable computing device 100 remains
in the inactive state until the data processing means 102 detects a
data event. Suitable data events include activity at the data input
means (pressing a key on the keyboard 132, rotating the thumbwheel
148 or depressing the escape key 160), an incoming message (such as
a telephone call or e-mail message), or a predetermined event (such
as a scheduled meeting or task).
[0048] When the portable computing device 100 exits from the
inactive state, at step 400 the light controller 184 determines the
ambient light level at the computing device 100, via the ambient
light sensor 170. The light controller 184 determines the ambient
light intensity by measuring the intensity of the light in the
light guide 168, 174 with the light sensor 170.
[0049] Preferably, the light controller 184 is configured to
determine the ambient light intensity during an interval when the
intensity of the light emitted by the display and keyboard
backlights 182, 183 is at a minimum. Further, preferably the light
controller 184 is configured to determine the ambient light
intensity during an interval when the light controller 184 has
extinguished the event notification lamp 166, for example between
flashes of the event notification lamp 166.
[0050] At step 402, the light controller 184 sets the intensity of
the display backlight 182 to an intensity level that is sufficient
for viewing information on the display 122 under the determined
lighting conditions. Typically, this latter step involves
automatically setting the intensity of light to a first intensity
when the determined light level is greater than a first level, and
automatically setting the intensity of light to a second intensity
less than the first intensity when the determined light level is
less than the first level.
[0051] In one embodiment, the backlit display 122 is a transmissive
LCD display, and the intensity adjusting step also involves setting
the intensity of light to a third intensity less than the second
intensity when the determined light level is less than a second
level, the second level being lower than the first level. In
another embodiment, the backlit display 122 is a reflective or
trans-reflective LCD display, and the intensity adjusting step also
involves setting the intensity of light to a third intensity less
than the second intensity when the determined light level is
greater than a second level, the second level being greater than
the first level.
[0052] In one variation of these embodiments, the intensity
adjusting step involves illuminating the keyboard 132 at a first
candela level when the determined light level is greater than the
first level, and illuminating the keyboard 132 at a second candela
level less than the first candela level when the determined light
level is less than the first level. Further, the intensity
adjusting step involves illuminating the keyboard 132 at a third
candela level less than the second candela level when the
determined light level is greater than the first level.
[0053] FIG. 8 is a flow chart that depicts, in detail, the sequence
of steps performed by the data processing means 102 on a portable
computing device 100 having a transmissive LCD display 122.
[0054] Initially, at step 500, the portable computing device 100 is
in an inactive state, such as a sleep state; and the display
backlight 182 and the keyboard backlight 183 are at a minimum
intensity, such as off. Typically, the light controller 184 flashes
the event notification lamp 166 to notify the user that the
portable computing device 100 is not off, but is instead
inactive.
[0055] At step 502, the data processing means 102 waits for
activity on the data input means, such as a depression of a key on
the keyboard 132, rotation of the thumbwheel 148 or depression of
the escape key 160. If the user of the portable computing device
100 activates the data input means, the data processing means 102
exits the inactive state, and processing transitions to step
504.
[0056] Alternately, in one variation, the data processing means 102
exits the inactive state in response to activity occurring on one
of the computer programs 158. For instance, the data processing
means 102 may exit the inactive state when an e-mail message or a
telephone call is received on the portable computing device
100.
[0057] Typically, when the user depresses a key on the keyboard 132
or the escape key 160, the data processing means 102 processes the
activity as a key stroke, and uses the key stroke as a data input
to one of the computer programs 158. Further, typically when the
user rotates or depresses the thumbwheel 148, the data processing
means 102 processes the activity as a navigation input to the
operating system or one of the computer programs 158. However, at
step 502, since the activity on the data input means is used to
exit the portable computing device 100 from the inactive state, the
data processing means 102 suppresses the normal effect (data input,
navigation input) of the activity.
[0058] At step 504, the light controller 184 determines the ambient
light level at the portable computing device 100. The light
controller 184 determines the ambient light intensity by measuring
the intensity of the light in the light guide 168, 174 with the
light sensor 170. Preferably, the light controller 184 determines
the ambient light intensity during the interval between flashes of
the event notification lamp 166, i.e. when the light controller 184
has momentarily extinguished the event notification lamp 166.
[0059] At step 506, the light controller 184 compares the
determined light level against a first predetermined threshold
level. Typically, the first predetermined threshold level is
intermediate an illumination level corresponding to exposure to
sunlight, and an illumination level corresponding to dusk.
[0060] If the determined light level is greater than the first
predetermined threshold level, at step 508 the light controller 184
sets the intensity of the display backlight 182 to a first
intensity level. Typically, the first intensity level is the
maximum display backlight intensity. In addition, preferably the
light controller 184 keeps the keyboard/keypad backlight 183
off.
[0061] If the determined light level is not greater than the first
predetermined threshold level, at step 510 the light controller 184
compares the determined light level against a second predetermined
threshold level. Typically, the second predetermined threshold
level is intermediate the illumination level corresponding to dusk,
and an illumination level corresponding to night.
[0062] If the determined light level is less than the second
predetermined threshold level, at step 512 the light controller 184
sets the intensity of the display backlight 182 to a third
intensity level. Typically, the third intensity level is a dim
backlight intensity that is slightly greater than the minimal/off
intensity level. The dim backlight intensity is sufficient to allow
the information displayed on the display 122 to be viewed at night,
without "blinding" the user of the portable computing device
100.
[0063] In addition, preferably the light controller 184 sets the
intensity of the keyboard/keypad backlight 183 to a dim keyboard
intensity (brighter than off). As above, the dim keyboard intensity
is sufficient to allow the key identifier information printed on
the keys to be viewed at night, without "blinding" the user of the
portable computing device 100.
[0064] However, if the determined light level is not less than the
second predetermined threshold level (but is less than the first
predetermined threshold level), at step 514 the light controller
184 sets the intensity of the display backlight 182 to a second
intensity level. Typically, the second intensity level is a level
intermediate the first (maximum) backlight intensity and the third
(dim) backlight intensity. The second backlight intensity is
sufficient to allow the information displayed on the display 122 to
be viewed at dusk, again without "blinding" the user of the
portable computing device 100.
[0065] In addition, preferably the light controller 184 sets the
intensity of the keyboard/keypad backlight 183 to a bright
backlight intensity (typically the maximum backlight
intensity).
[0066] Thereafter, at step 516, the data processing means 102 waits
a first predetermined time period for activity at the data input
means (eg. pressing a key on the keyboard 132, rotating the
thumbwheel 148 or depressing the escape key 160) or for an e-mail
message or a telephone call being received on the portable
computing device 100. If the data processing means 102 detects such
activity within the first predetermined time period (typically
about 10 seconds), processing returns to step 504.
[0067] However, if the first predetermined time period expires
without any such activity, at step 518 the light controller 184
begins to gradually reduce the intensity of the display backlight
182, so as to provide a warning to the user of the portable
computing device 100 that the display backlight is about to be
turned off. In addition, preferably the light controller 184 also
turns off the keyboard backlight 183.
[0068] Thereafter, at step 520, the data processing means 102 waits
a second predetermined time period for activity at the data input
means or for an e-mail message or a telephone call being received
on the portable computing device 100. If the data processing means
102 detects such activity within the second predetermined time
period (typically about 15 seconds), processing returns to step
504.
[0069] However, if the second predetermined time period expires
without any such activity, at step 522 the light controller 184
turns off the display backlight 182.
[0070] Thereafter, at step 524, the data processing means 102 waits
a third predetermined time period for activity at the data input
means or for an e-mail message or a telephone call being received
on the portable computing device 100. If the data processing means
102 detects such activity within the third predetermined time
period (typically about 60 seconds), processing returns to step
504.
[0071] However, if the third predetermined time period expires
without any such activity at the data input means, processing
returns to step 502 and the portable computing device 100 returns
to the inactive/sleep state.
[0072] FIG. 9 is a flow chart that depicts, in detail, the sequence
of steps performed by the light controller 184 on a portable
computing device 100 having a reflective, trans-reflective or
transmissive LCD display 122.
[0073] Initially, at step 600, the portable computing device 100 is
in an inactive state, such as a sleep state; and the display
backlight 182 and the keyboard backlight 183 are at a minimum
intensity, such as off.
[0074] At step 602, the data processing means 102 waits for
activity on the data input means, such as by pressing a key on the
keyboard 132, rotating the thumbwheel 148 or depressing the escape
key 160. If the user of the portable computing device 100 activates
the data input means the portable computing device 100 exits the
inactive state, and processing jumps to step 604.
[0075] Typically, when the user depresses a key on the keyboard 132
or the escape key 160, the data processing means 102 processes the
activity as a key stroke, and uses the key stroke as a data input
to one of the computer programs 158. Further, typically when the
user rotates or depresses the thumbwheel 148, the 1 data processing
means 102 processes the activity as a navigation input to the
operating system or one of the computer programs 158. However, at
step 602, since the activity on the data input means is used to
exit the portable computing device 100 from the inactive state, the
data processing means 102 suppresses the normal effect (data input,
navigation input) of the activity.
[0076] At step 604, the light controller 184 determines the ambient
light level at the portable computing device 100, via the ambient
light sensor 170. At step 606, the light controller 184 compares
the determined light level against a first predetermined threshold
level. Typically, the first predetermined threshold level is
intermediate an illumination level corresponding to dusk, and an
illumination level corresponding to night.
[0077] If the determined light level is less than the first
predetermined threshold level, at step 608 the light controller 184
sets the intensity of the display backlight 182 to a second
intensity level. Typically, the second intensity level is a dim
backlight intensity that is slightly greater than the minimal/off
intensity level. The dim backlight intensity is sufficient to allow
the information displayed on the display 122 to be viewed at night,
without "blinding" the user of the portable computing device
100.
[0078] In addition, preferably the light controller 184 sets the
intensity of the keyboard/keypad backlight 183 to a dim keyboard
intensity (brighter than off). As above, the dim keyboard intensity
is sufficient to allow the key identifier information printed on
the keys to be viewed at night, without "blinding" the user of the
portable computing device 100.
[0079] If the determined light level is not less than the first
predetermined threshold level, at step 610 the light controller 184
compares the determined light level against a second predetermined
threshold level. Typically, the second predetermined threshold
level is intermediate an illumination level corresponding to
exposure to sunlight, and the illumination level corresponding to
dusk.
[0080] If the determined light level is greater than the second
predetermined threshold level, at step 612 the light controller 184
sets the intensity of the display backlight 182 to a third
intensity level. Typically, the third intensity level is the
minimal/off intensity level. In addition, preferably the light
controller 184 turns off the keyboard/keypad backlight 183.
[0081] However, if the determined light level is not greater than
the second predetermined threshold level (but is not less than the
first predetermined threshold level), at step 614 the light
controller 184 sets the intensity of the display backlight 182 to a
first intensity level. Typically, the first intensity level is the
maximum backlight intensity. The first backlight intensity is
sufficient to allow the information displayed on the display 122 to
be viewed at dusk, again without "blinding" the user of the
portable computing device 100.
[0082] In addition, preferably the light controller 184 sets the
intensity of the keyboard/keypad backlight 183 to a bright
backlight intensity (typically the maximum backlight
intensity).
[0083] Thereafter, at step 616, the data processing means 102 waits
a first predetermined time period for activity at the data input
means (eg. pressing a key on the keyboard 132, rotating the
thumbwheel 148 or depressing the escape key 160) or for an e-mail
message or a telephone call being received on the portable
computing device 100. If the data processing means 102 detects such
activity within the first predetermined time period (typically
about 10 seconds), processing returns to step 604.
[0084] However, if the first predetermined time period expires
without any such activity, at step 618 the light controller 184
begins to gradually reduce the intensity of the display backlight
182, so as to provide a warning to the user of the portable
computing device 100 that the display backlight is about to be
turned off. In addition, preferably the light controller 184 also
turns off the keyboard backlight 183.
[0085] Thereafter, at step 620, the data processing means 102 waits
a second predetermined time period for activity at the data input
means or for an e-mail message or a telephone call being received
on the portable computing device 100. If the data processing means
102 detects such activity within the second predetermined time
period (typically about 15 seconds), processing returns to step
604.
[0086] However, if the second predetermined time period expires
without any such activity, at step 622 the light controller 184
turns off the display backlight 182.
[0087] Thereafter, at step 624, the data processing means 102 waits
a third predetermined time period for activity at the data input
means or for an e-mail message or a telephone call being received
on the portable computing device 100. If the data processing means
102 detects such activity within the third predetermined time
period (typically about 60 seconds), processing returns to step
604.
[0088] However, if the third predetermined time period expires
without any such activity, processing returns to step 602 and the
portable computing device 100 returns to the inactive/sleep
state.
[0089] Variations on the foregoing embodiments are envisaged. For
instance, in one variation, rather than the first, second and third
intensity levels being fixed, the data processing means 102 allows
the user of the portable computing device 100 to set the intensity
levels through the data input means (such as through the thumbwheel
148). In another variation, rather than the first and second
threshold levels being fixed, the data processing means 102 allows
the user of the portable computing device 100 to set the threshold
levels through the data input means (such as through the thumbwheel
148).
[0090] In yet another variation, the light controller 184 allows
the user to turn the display backlight 182 on (maximum intensity)
or off, by momentarily depressing and releasing the function key
146. In still another variation, the light controller 184 allows
the user to cycle through each combination of display backlight
intensity level and keyboard backlight intensity level by
momentarily depressing and releasing the function key 146. In other
variation, the light controller 184 allows the user to terminate
the automatic dimming (at steps 518, 618) by momentarily depressing
and releasing the function key 146.
[0091] In another variation, the event notifier 162 includes the
event notification lamp 166 and the light conduit 168 (of the first
embodiment), and the light guide 174 (of the second embodiment),
with the ambient light sensor 170 being coupled to both the light
conduit 168 and the light guide 174. With this variation, the
ambient light sensor 170 is able to measure the ambient light
proximate the lens 164 and the display 122, thereby providing a
more accurate assessment of the ambient light level.
* * * * *