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Digital Camera Patent Abstract
A digital camera includes a photoflash lamp, an ambient light sensor
generating a signal representative of an ambient light level proximate
the digital camera, and a photoflash controller. The photoflash
controller may be capable of receiving the signal from the ambient
light sensor and a host signal from a main controller of the digital
camera. The photoflash controller may also be capable of being enabled
by the host signal, and, when enabled, the photoflash controller
may be capable of controlling a light output of the photoflash lamp
in response to at least the ambient light level when a user of the
digital camera utilizes a shutter-release button of the digital
camera to instruct the digital camera to take a picture.
Digital Camera Patent Claims
1. A digital camera comprising: a photoflash lamp; an ambient light
sensor generating a signal representative of an ambient light level
proximate said digital camera; and a photoflash controller capable
of receiving said signal from said ambient light sensor and a host
signal from a main controller of said digital camera, said photoflash
controller capable of being enabled by said host signal, and, when
enabled, said photoflash controller capable of controlling a light
output of said photoflash lamp in response to at least said ambient
light level when a user of said digital camera utilizes a shutter-release
button of said digital camera to instruct said digital camera to
take a picture.
2. The digital camera of claim 1, wherein said photoflash controller
is further capable of directing charging and discharging of an energy
storage element, said photoflash lamp being provided energy by said
energy storage element to provide said light output.
3. The digital camera of claim 2, wherein said photoflash controller
is further capable of directing charging of said energy storage
element if said digital camera is in a power on state and if said
ambient light level is less than a threshold level so that said
energy storage element is at least partially charged if said user
of said digital camera utilizes said shutter-release button to instruct
said digital camera to take said picture.
4. The digital camera of claim 1, wherein said photoflash controller
is capable of analyzing data representative of said ambient light
level and data representative of a light output capacity of said
photoflash lamp and controlling said light output of said photoflash
lamp in response to said analysis.
5. The digital camera of claim 4, further comprising a capacitor
coupled to said photoflash lamp to provide energy to said photoflash
lamp, said photoflash controller further capable of controlling
discharging of said capacitor to stop discharging of said capacitor
when a combined light output level of said photoflash lamp and said
ambient light level reaches a desired level for an image sensor
of said digital camera.
6. The digital camera of claim 1, wherein said photoflash lamp
comprises a white light emitting diode and wherein said photoflash
controller is capable of controlling said light output of said white
light emitting diode.
7. An apparatus comprising: a photoflash controller capable of
receiving a signal from an ambient light sensor of a digital camera
and a host signal from a main controller of said digital camera,
said photoflash controller capable of being enabled by said host
signal, and, when enabled, said photoflash controller capable of
controlling a light output of a photoflash lamp of said digital
camera in response to at least said ambient light level when a user
of said digital camera utilizes a shutter-release button of said
digital camera to instruct said digital camera to take a picture.
8. The apparatus of claim 7, wherein said photoflash controller
is further capable of directing charging and discharging of an energy
storage element of said digital camera, said photoflash lamp being
provided energy by said energy storage element to provide said light
output.
9. The apparatus of claim 8, wherein said photoflash controller
is further capable of directing charging of said energy storage
element if said digital camera is in a power on state and if said
ambient light level is less than a threshold level so that said
energy storage element is at least partially charged if said user
of said digital camera utilizes said shutter-release button to instruct
said digital camera to take said picture.
10. The apparatus of claim 7, wherein said photoflash controller
is capable of analyzing data representative of said ambient light
level and data representative of a light output capacity of said
photoflash lamp and controlling said light output of said photoflash
lamp in response to said analysis.
11. The apparatus of claim 10, wherein said photoflash controller
is further capable of directing charging and discharging of a capacitor
of said digital camera, said photoflash lamp being provided energy
by said capacitor to provide said light output, said photoflash
controller further capable of controlling discharging of said capacitor
to stop discharging of said capacitor when a combined light output
level of said photoflash lamp and said ambient light level reaches
a desired level for an image sensor of said digital camera.
12. The apparatus of claim 7, wherein said photoflash lamp comprises
a white light emitting diode and wherein said photoflash controller
is further capable of controlling said light output of said white
light emitting diode.
13. A method comprising: generating a signal representative of
an ambient light level proximate a digital camera; providing a host
signal from a main controller of said digital camera to a photoflash
controller of said digital camera; enabling said photoflash controller
via said host signal; and controlling a light output of a photoflash
lamp with said photoflash controller in response to at least said
signal representative of said ambient light level when a user of
said digital camera utilizes a shutter-release button of said digital
camera to instruct said digital camera to take a picture.
14. The method of claim 13, wherein said controlling operation
controls said light output of said photoflash lamp by controlling
charging and discharging of an energy storage element of said digital
camera, said photoflash lamp being provided energy by said energy
storage element to provide said light output.
15. The method of claim 13, wherein said photoflash lamp comprises
a white light emitting diode and wherein said controlling operation
controls said light output of said white light emitting diode by
controlling a current level supplied to said white light emitting
diode.
16. The method of claim 13, wherein said photoflash lamp comprises
a white light emitting diode and wherein said controlling operation
controls said light output of said white light emitting diode by
controlling a time interval a fixed current level is supplied to
said white light emitting diode.
17. The method of claim 13, further comprising: charging a capacitor
capable of providing energy to said photoflash lamp, said charging
occurring if said digital camera is in a power on state and if an
ambient light level is less than a threshold level so that said
capacitor is at least partially charged if said user of said digital
camera utilizes said shutter-release button to instruct said digital
camera to take said picture.
18. The method of claim 13, further comprising charging a capacitor
capable of providing energy to said photoflash lamp; discharging
said capacitor; and stopping said discharging of said capacitor
when a combined light output level of said photoflash lamp and said
ambient light level reaches a desired level for an image sensor
of said digital camera.
Digital Camera Patent Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of
U.S. Provisional Application Ser. No. 60/605,560, filed Aug. 30,
2004, the teachings of which are incorporated herein by reference.
FIELD
[0002] This disclosure relates to digital cameras and more particularly
to a digital camera with a photoflash controller.
BACKGROUND
[0003] Digital cameras are typically equipped with a photoflash
lamp to provide light to the subject of a picture. As ambient light
levels change, the digital camera may adjust the amount of light
provided by the photoflash lamp, e.g., to provide more light in
relatively darker ambient light conditions and to provide less light
in relatively lighter ambient light conditions. Most digital cameras
also have a main controller or processor that performs a variety
of functions. One of the functions that the main controller may
perform is to control how much light is emitted from the photoflash
lamp. The main controller may also control the shutter of the camera
based on the ambient light conditions.
[0004] The main controller of digital cameras, especially mid and
low end digital cameras, consumes a relatively significant amount
of power to process the information needed to make a decision on
how to adjust the photoflash lamp. Any excessive power consumption
adversely affects battery life of the battery of the digital camera
and associated performance of the digital camera. In addition, the
main controller may take considerable time to process the information
needed to make a decision on how to adjust the photoflash lamp.
Accordingly, this slows down the speed with which the user may take
pictures when using the photoflash lamp. Furthermore, a complex
and expensive main controller is needed to perform all its functions
including the photoflash lamp control function.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Features and advantages of embodiments of the claimed subject
matter will become apparent as the following Detailed Description
proceeds, and upon reference to the Drawings, where like numerals
depict like parts, and in which:
[0006] FIG. 1 is a diagram of a system embodiment including a digital
camera;
[0007] FIG. 2 is block diagram of components of the digital camera
of FIG. 1 including a photoflash controller consistent with an embodiment;
[0008] FIG. 3 is a block diagram of the photoflash controller of
FIG. 2; and
[0009] FIG. 4 is a flow chart of operations consistent with an
embodiment.
[0010] Although the following Detailed Description will proceed
with reference being made to illustrative embodiments, many alternatives,
modifications, and variations thereof will be apparent to those
skilled in the art. Accordingly, it is intended that the claimed
subject matter be viewed broadly.
DETAILED DESCRIPTION
[0011] FIG. 1 illustrates a system embodiment 100 that may generally
include a digital camera 114. The digital camera 114 may comprise
a still image camera, a digital video camera, or both combined.
The digital camera 114, as provided in this embodiment, may include
a photoflash lamp 118, an ambient light sensor 112, a power button
102, a user interface control button 106, an optical viewfinder
108, a liquid crystal display (LCD) panel 110, and a shutter-release
button 122. Other components, not illustrated in FIG. 1, may also
be included in the digital camera 114.
[0012] The photoflash lamp 118 may comprise a variety of lamps
and lamp types or light sources to provide illumination for the
subject of a picture taken by the digital camera 114. The ambient
light sensor 112 may be capable of generating a signal representative
of an ambient light level proximate the digital camera 114. The
light sensor 112 may comprise a photo-diode, photo-transistor (bipolar
or MOS type), photo-cell, and/or a photo-resistance type of light
sensor. The power button 102 may be utilized by a user of the digital
camera to turn the digital camera on and off, e.g., to enter into
a power on state and a power off state. The user interface control
button 106 may be utilized by a user to enter a variety of modes
and perform a variety of functions. The optical viewfinder 108 may
provide the user with a view of the subject. The LCD panel 110 may
provide the user with a variety of information including, but not
limited to, a view of the subject area, stored pictures, and stored
video. The shutter-release button 122 may be utilized by a user
to instruct the digital camera 114 to take a picture. The shutter-release
button 122 may be a two stage shutter-release button where the digital
camera 114 sets its focus and exposure when the button 122 is pressed
halfway and takes a picture when depressed completely.
[0013] It should be understood that certain components of the digital
camera 114 set forth above may comprise conventional, custom, and/or
proprietary components. For example, power button 102 may represent
a conventional on/off switch which may be provided on a digital
camera. Likewise, the user interface control button 106 and/or the
optical viewfinder 108 and/or the LCD panel 110 and/or the shutter-release
button 122 may represent conventional configurations. Alternatively,
in other embodiments any or all of these components may be substituted
for currently available and/or after-developed equivalent structures,
and/or equivalent functional objects (such as may be implemented
in firmware) without departing from the present disclosure. Further,
it is to be understood that the present disclosure is of broad scope
and it is fully contemplated herein that such equivalents may be
used in any embodiment described herein.
[0014] FIG. 2 is a block diagram of some components 200 of the
digital camera 114 of FIG. 1. These components 200 may include a
main controller 201, the ambient light sensor 112, a photoflash
controller 202 consistent with an embodiment, charging circuitry
204 which may include an energy storage element 215 to store electrical
charge, discharging circuitry 206 which may include an Insulated
Gate Bipolar Transistor, an image sensor 238, and the photoflash
lamp 118. As used herein, "circuitry" may comprise, for
example, singly or in any combination, hardwired circuitry, programmable
circuitry, state machine circuitry, and/or firmware that stores
instructions executed by programmable circuitry.
[0015] The main controller 201 may include circuitry capable of
performing almost all of the operating tasks associated with the
digital camera 114. Advantageously, the main controller 201 may
be relieved of auto adjustment flash duties that may now be more
efficiently carried out by the photoflash controller 202. As such,
the main controller 201 may be simplified compared to a conventional
main controller 201 and may consume less power in an environment
where there is a premium on reducing power consumption.
[0016] The digital camera 114 may operate in a variety of flash
modes. In a flash disable mode, the flash function may be disabled
such that the photoflash lamp 118 does not illuminate when a user
instructs the digital camera 114 to take a picture. In an automatic
flash mode, the photoflash controller 202 may be enabled by a host
signal from the main controller 201. When enabled in this automatic
flash mode, the photoflash controller 202 may generally control
a light output of the photoflash lamp 118. The photoflash controller
202 may receive a signal from the ambient light sensor 112 representative
of an ambient light level proximate the digital camera 114. The
photoflash controller 202 may control a light output of the photoflash
lamp 118 in response to at least the ambient light level proximate
the digital camera when a user of the digital camera utilizes the
shutter-release button 122 to instruct the digital camera to take
a picture. As such, the photoflash controller 202 may adjust the
light output provided by the photoflash lamp 118 when taking a picture
to provide more light in relatively darker ambient light conditions
and to provide less light in relatively lighter ambient light conditions.
[0017] In one embodiment, the photoflash controller 202 may control
the light output from the photoflash lamp 118 by controlling the
charging and discharging of the energy storage element 215. The
energy storage element 215 may be a capacitor, e.g., a high voltage
capacitor. The energy storage element 215 may provide energy to
the photoflash lamp 118 when discharging to enable the photoflash
lamp 118 to provide its light output.
[0018] The digital camera 114 may be in a power on state but a
user may not yet be depressing the shutter-release button 122 to
instruct the digital camera to take a picture. The photoflash controller
202 may also be enabled via a host signal from the main controller
201 to provide an auto adjust feature. In this instance, the ambient
light level sensed by the ambient light sensor 112 may be lower
than a low threshold level indicating relatively darker ambient
light conditions. In response, the photoflash controller 202 may
advantageously start direct charging of the energy storage element
215 via instructions to the charging circuitry 204. Therefore, if
the user of the digital camera 114 would depress the shutter-release
button 122 to take a picture, the energy storage element 215 would
be at least partially charged. In some instance, the energy storage
element 215 may be fully charged enabling the user to immediately
take a picture with the photoflash lamp 118 rather than waiting
for the energy storage element 215 to charge.
[0019] The photoflash controller 202 consistent with an embodiment
may comprise, for example, an application specific integrated circuit
(ASIC), a microprocessor integrated circuit and/or a digital signal
processing unit integrated circuit. The functionality of the photoflash
controller 202 may also be implemented in software. As used in any
embodiment herein, an "integrated circuit" means a semiconductor
device and/or microelectronic device, such as, for example, a semiconductor
integrated circuit chip. Of course, the digital camera 114 may also
comprise memory (not shown) which may comprise one or more of the
following types of memory: semiconductor firmware memory,..programmable
memory, non-volatile memory, read only memory, electrically programmable
memory, random access memory, flash memory, magnetic disk memory,
and/or optical disk memory. Either additionally or alternatively,
memory may comprise other and/or later-developed types of computer-readable
memory. Machine-readable firmware program instructions may be stored
in memory. These instructions may be accessed and executed by the
photoflash controller 202, and these instructions may result in
the photoflash controller 202 performing the operations described
herein as being performed by the photoflash controller 202.
[0020] FIG. 3 is a block diagram of the photoflash controller 202
of FIG. 2 in more detail. The photoflash controller 202 may include
host interface circuitry 302, light sensor interface circuitry 304,
ambient light processing circuitry 306, photoflash charge control
unit circuitry 308, and photoflash discharge control unit circuitry
310. The host interface circuitry 302 may provide an interface to
the main controller 201 enabling the main controller 201 and photoflash
controller 202 to exchange data and/or commands with each other.
The light sensor interface circuitry 304 may provide an interface
to the ambient light sensor 112 to enable the ambient light sensor
112 to provide data to the ambient light processing circuitry 306.
The ambient light processing circuitry 306 may perform a variety
of functions in response to ambient light conditions and/or commands
from the main controller 201 via the host interface circuitry 302.
These functions may include controlling the charging and discharging
of the energy storage element 215 for the photoflash lamp 118 via
the photoflash charge control unit circuitry 308 and the photoflash
discharge control unit circuitry 310.
[0021] In addition, if the digital camera is in a power on state
and the ambient light level is less than a low threshold level,
the ambient light processing circuitry 306 may instruct the photoflash
charge control unit circuitry 308 to start charging the energy storage
element 215 for the photoflash lamp 118. Again therefore, if a user
of the digital camera 114 would depress the shutter-release button
122 to take a picture, the energy storage element 215 would be at
least partially charged, and in some instances fully charged.
[0022] The ambient light processing circuitry 306 may also analyze
data representative of the ambient light level as detected by the
ambient light sensor 112, analyze data representative of the light
output capacity of the photoflash lamp 118, and control the light
output of the photoflash lamp 118 in response to that analysis.
In one embodiment, the ambient light processing circuitry may control
the photoflash discharge control unit circuitry 310 to control discharge
time of the energy storage element 215 for the photoflash lamp 118
to effectively control the light output of the photoflash lamp 118.
[0023] For example, in relatively low ambient light level conditions
the ambient light processing circuitry 306 may increase discharge
time and in relatively high ambient light level conditions may decrease
discharge time. To accomplish this, the ambient light processing
circuitry 306 may integrate, for example, light intensity information
from the ambient light sensor 112 to determine the total light flux
capable of being produced by the photoflash lamp 118 together with
the ambient light levels. The ambient light processing circuitry
306 may then stop discharging of the energy storage element 215
into the lamp when this flux reaches a desired level for the camera's
image sensor 238. The desired flux level may be an optimal flux
level for a particular picture type.
[0024] In addition, the discharge time interval may be selected
to keep the energy storage element 215 at least partially charged
to enable the next charge cycle to become shorter than if the energy
storage element was completely discharged. In turn, this may then
allow the user of the digital camera to take the next picture faster.
This may be done in some instances where the ambient light level
is great enough that energy storage element 215 does not need to
be completely discharged to produced a combined light flux from
the photoflash lamp 118 together with ambient light levels that
is high enough to reach a desired level for the camera's image sensor
238. Other methods of control based on the light data are also possible.
[0025] If other features such as red-eye reduction features are
available in the digital camera, the main controller 201 via the
host interface circuitry 302 may utilize the photoflash controller
202 to perform pre-flash control. The main controller 201 may have
full control over the photoflash controller 202 through the host
interface circuitry 302. For example, it may instruct the photoflash
controller 202 to stop or to start charging for the photoflash lamp
118. This host control may also allow the digital camera to be able
to take different types of pictures with different special effects
by changing the charge and discharge time settings inside the ambient
light processing circuitry 306 of the photoflash controller 202.
[0026] In one embodiment, the photoflash lamp 118 may be a white
light emitting diode (WLED). In this instance, no energy storage
element 215 may be necessary and the photoflash controller 202 may
be capable of controlling the light output of the WLED. In one instance,
the photoflash controller 202 may control the light output of the
WLED by controlling a current level provided to the WLED. For example,
the photoflash controller 202 may direct a reduction in current
to the WLED to reduce light levels emitted by the WLED and may direct
an increase in current to the WLED to increase light levels emitted
by the WLED. In another instance, the current level provided to
the WLED may be a fixed current level and the photoflash controller
202 may control the light output of the WLED by controlling a time
interval the fixed current level is supplied to the WLED. For example,
the photoflash controller 202 may direct a decrease in the time
interval the fixed current is supplied to the WLED to reduce light
levels emitted by the WLED and may direct an increase in the time
interval the fixed current is supplied to the WLED to increase light
levels emitted by the WLED. In yet another instance, both the current
level supplied to the WLED and time interval the current level is
provided to the WLED may be adjusted by the photoflash controller
202 to control the light output of the WLED.
[0027] FIG. 4 illustrates operations 400 according to an embodiment.
Operation 402 may include generating a signal representative of
an ambient light level proximate a digital camera. Operation 404
may include providing a host signal from a main controller of the
digital camera to a photoflash controller of the digital camera.
Operation 406 may include enabling the photoflash controller via
the host signal. Finally, operation 408 may include controlling
a light output of a photoflash lamp with the photoflash controller
in response to at least the signal representative of the ambient
light level when a user of the digital camera utilizes a shutter-release
button of the digital camera to instruct the digital camera to take
a picture.
[0028] Thus, in summary, there is provided a digital camera. The
digital camera may comprise a photoflash lamp, an ambient light
sensor generating a signal representative of an ambient light level
proximate the digital camera, and a photoflash controller. The photoflash
controller may be capable of receiving the signal from the ambient
light sensor and a host signal from a main controller of the digital
camera. The photoflash controller may also be capable of being enabled
by the host signal, and, when enabled, the photoflash controller
may also be capable of controlling a light output of the photoflash
lamp in response to at least the ambient light level when a user
of the digital camera utilizes a shutter-release button of the digital
camera to instruct the digital camera to take a picture.
[0029] In another embodiment, there is provided an apparatus. The
apparatus may comprises a photoflash controller capable of receiving
a signal from an ambient light sensor of a digital camera and a
host signal from a main controller of the digital camera. The photoflash
controller may also be capable of being enabled by the host signal,
and, when enabled, the photoflash controller may be capable of controlling
a light output of a photoflash lamp of the digital camera in response
to at least the ambient light level when a user of the digital camera
utilizes a shutter-release button of the digital camera to instruct
the digital camera to take a picture.
[0030] Advantageously, in these embodiments, the main controller
of conventional digital cameras may be simplified since the photoflash
controller displaces some functionality that may normally provided
by the main controller. Power consumption, complexity, and costs
for the main controller may therefore be lowered compared to conventional
main controllers. The photoflash controller may increase the speed
in which a user of the digital camera may take pictures with the
auto flash function. One reason for this improvement may be because
the photoflash controller may start to charge an energy storage
element that provides energy to the photoflash lamp when the digital
camera is in a power on state and a sensed ambient light level is
below a threshold level. As such, the energy storage element may
be at least partially charged, and in some embodiments, may be fully
charged before a user of the digital camera utilizes a shutter-release
button to instruct the digital camera to take a picture with an
auto flash feature enabled.
[0031] The terms and expressions which have been employed herein
are used as terms of description and not of limitation, and there
is no intention, in the use of such terms and expressions, of excluding
any equivalents of the features shown and described (or portions
thereof), and it is recognized that various modifications are possible
within the scope of the claims. Other modifications, variations,
and alternatives are also possible. Accordingly, the claims are
intended to cover all such equivalents.
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