Patent Application
20050219394
The present disclosure relates to a digital camera capable of brightness and contrast control.
The handheld consumer devices are mainly powered by the battery. The power consumption of the system will affect the battery life. In the DSC case, the power consumption will limit how many pictures can be taken by that camera; this is one of the key parameters for the digital camera design. There are many power management techniques used to reduce the total power consumption of the digital camera. For example, improve the efficiency of the DC/DC converter or shut down power for the circuits which is not needed. The LCD panel on the digital camera is almost always turned on when the digital camera is ON. For example, it is used as the view finder when the user needs to take picture. It is also required when the user reviews pictures taken with the digital camera. At the same time the LCD panel is consuming about 15% of the total power consumption. A conventional digital camera does not include a mechanism to reduce power consumption by adjusting power to the LCD panel based on ambient light conditions.
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, wherein like numerals depict like parts, and in which:
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, and be defined only as set forth in the accompanying claims.
It should be understood at the outset 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 switch which may be provided on a digital camera. Likewise, operating mode selection button 104 and/or user interface control button 106 and/or optical viewfinder 108 and/or LCD panel 110 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.
In this embodiment, controller 202 may be capable of generating one or more signals to adjust the brightness of the LCD panel 110, in a manner described herein. Ambient light sensor 112 may be capable of generating signal 203 indicative and/or proportional to ambient light conditions. Such ambient light conditions may be ambient light conditions in the vicinity of the LCD panel (such as alluded to above with reference to
LCD panel 110 may comprise, for example, a white light emitting diode (WLED) that may be capable of lighting the LCD panel 110. Alternatively, the LCD panel may comprise a fluorescent lighting system and/or other light source to light the panel. In this embodiment, control signal 205 may be capable of controlling the amount of light produced by the LCD panel. Control signal 205 may be capable of adjusting the amount of power delivered to the light. For example, control signal 205 may supply a controllable current to WLED that lights the LCD panel. Alternatively, camera 114 may comprise DC/DC converter circuitry capable of generating a DC signal to the light, and control signal may comprise a pulse width modulated (PWM) signal capable of controlling the output of a DC/DC converter circuitry (for example, by controlling the pulse width of the PWM signal).
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 capable of generating a signal 203 indicative of or proportional to ambient light conditions.
In this embodiment, controller 202 may receive signal 203 and generate control signal 205 to adjust the brightness of the lamp based on ambient light conditions. Additionally or alternatively, controller 202 may be capable of generating signal 205 to adjust the contrast of the LCD panel 110 based on ambient light conditions. Thus, for example, if ambient light in the vicinity of the LCD panel 114 increases, controller 202 may generate control signal 205 to increase the brightness of the panel 114. Conversely, if ambient light in the vicinity of the LCD panel 114 decreases, controller 202 may generate control signal 205 to decrease the brightness of the panel 114. Thus, signal 203 may be used by controller 202 as a feedback signal.
The controller 202 may also be capable of receiving a preset value signal 207. Signal 207 may represent a preset LCD panel brightness value, as may be provided by a user of the camera 114. In this embodiment, controller 202 may be capable of receiving signal 203 as another feedback input. Signal 203 may operate as a command signal that sets a threshold level for the controller 202. Thus, for example, the preset value signal 207 may be used by the controller 202 to set a desired brightness value which, in turn, may cause controller 202 to override signal 203, or provide a threshold to limit a range of brightness variations, thus permitting a user to operate the panel display at a desired brightness level. Alternatively, and without departing from this embodiment, signal 207 may operate as a “ceiling” or “floor” value. In this instance, controller 202 may be capable of comparing signal 207 with signal 203 to ensure that the panel brightness does not exceed or fall below the brightness level indicated by signal 207, in addition to the comparison of signals 207 and 203 described above.
Preset value signal 207 may be generated by, for example, a variable resistor (e.g., user controlled potentiometer) located on the external housing of camera 114. Alternatively, user input circuitry may comprise a specified computer operation, which may include a selected button operations and/or menu selections. Such an implementation may include, for example, software and/or firmware instructions, executed by the camera. Alternatively, preset value signal 207 may be generated by preprogrammed and/or user programmable circuitry that is capable of generating a preprogrammed (or user programmable) preset value signal 207.
The x-axis 302 represents ambient light intensity and the y-axis 304 represents brightness and/or contrast of the LCD panel 114. In this embodiment, ambient sensor 112 may have a maximum detectible light intensity level, as may be represented by the substantially vertical line 306. Also, the LCD panel 114 may have a maximum viewable brightness and/or contrast level, as may be represented by an asymptote 308, and a minimum viewable brightness and/or contrast level, as may be represented by an asymptote 310. In operation, controller 202 may adjust the brightness/contrast of the LCD panel 114 based on the ambient light detected from sensor 112. This operation is depicted as a linear relationship 312 between levels 310 and 308. Of course, controller 202 may be capable of generating other relationships between ambient light levels and LCD panel brightness/contrast, for example, logarithmic, quadratic, and/or other non-linear relationships.
In this embodiment, if the ambient light level is equal to, or exceeds a maximum viewable brightness and/or contrast level 308, controller 202 may be capable of generating a control signal 205 to power down the LCD panel. Thus, battery power may be saved by powering off the LCD panel 110 under circumstances where the user could not view the LCD panel.
In alternative embodiments, and referring again to the system embodiment of
Thus, in summary, at least one embodiment herein provides a brightness/contrast control system for an LCD panel display comprised in a digital camera. The system may include an LCD panel and an optical sensor generating a signal indicative of ambient light around the LCD panel. The system may also include a controller capable of generating at least one of a power and contrast control signal to control at least one of the brightness and contrast of the LCD panel based at least in part on the signal indicative of ambient light around the LCD panel. Advantageously, a digital camera according to at least one embodiment herein may be capable of using ambient light information to close the loop on the feedback information supplied to a controller. Additionally, a digital camera according to at least one embodiment herein may be capable of automatically adjusting the LCD panel brightness and/or contrast based on ambient light conditions. Advantageously, these features may permit the digital camera of these embodiments to exhibit enhanced versatility and utility compared to the prior art, and may reduce design costs and power requirements by employing the brightness and/or contrast control system described herein compared to the prior art. Further, although specific utility for the present disclosure has been described with reference to a digital camera, it is equally contemplated herein that the present disclosure may find utility in any hand-held or portable electronic device where brightness and/or contrast control of an LCD display may be desired.
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.
