Electronic device with optoelectronic input/output compensation function for a display
View Patent ↗Portable devices ( 100 ) that include displays ( 102 ) and are used in widely ranging ambient light conditions use selectable or adjustable optoelectronic input/output compensation functions to drive their displays. According to certain embodiments, a camera ( 122 ) or a light sensor ( 120 ) is used to measure the ambient light level, and an optoelectronic input/output compensation function that is specifically chosen based on the measured ambient light condition is used to drive the display. Furthermore, according to certain embodiments, the optoelectronic input/output compensation function is selected based on whether a display backlight ( 230 ) is turned on or off.
1. An electronic device comprising: a display; a light sensor for measuring an ambient light level and outputting a light level signal; and an electronic circuit coupled to said display and said light sensor, wherein said electronic circuit is adapted to receive said light level signal and to select an optoelectronic input/output compensation function from a set of optoelectronic input/output compensation functions that is used in driving said display based, at least in part, on said light level signal, and drive said display using said optoelectronic input/output compensation function, wherein each optoelectronic input/output compensation function of the set of optoelectronic input/output compensation function is predefined for a range of ambient light levels wherein:
said display comprises a transflective liquid crystal display comprising a plurality of pixels wherein each of said plurality of pixels comprises a pixel electrode comprising a reflective part and a transmissive part that is in electrical contact with said reflective part;
said electronic device further comprises a backlight optically coupled to said transflective liquid crystal display; and
said electronic circuit comprises:
a backlight driver coupled to said backlight; and a display driver that includes a plurality of drive signal sources that are selectively coupled to said pixel electrode in accordance with pixel brightness data, and wherein voltage levels of said plurality of drive signal sources are chosen to implement the optoelectronic input/output compensation function; wherein:
said transflective liquid crystal liquid crystal display exhibits a first BV function for transmitted light and a second BV function for reflected light wherein said first BV function is substantially different from said second BV function; and
wherein, said electronic circuit is adapted to determine which of a plurality of ranges includes said ambient light level, and to select said optoelectronic input/output compensation function from the set of optoelectronic input/output compensation functions based on which said plurality of ranges includes said ambient light level;
wherein said plurality of ranges comprises:
at least one closed range having an upper bound and a lower bound, and wherein, at ambient light levels in said at least one closed range, both reflected light and transmitted light make substantial contributions to illuminating said transflective liquid crystal display, and wherein the optoelectronic input/output compensation function selected when said ambient light level falls within said at least one closed range is a composite function of an inner function that is substantially a power law overall input/output function and an outer function that is an inverse of an effective BV function that is a weighted average of said first BV function and said second BV function wherein a first weight on said first BV function quantifies a first contribution of transmitted light to illuminating said display and a second weight on said second BV function quantifies a second contribution of reflected light to illuminating said display at a predetermined light level in said at least one closed range.
2. The electronic device according to claim 1 wherein:
said display comprises a transflective liquid crystal display; and
said electronic device further comprises:
a backlight optically coupled to said transflective liquid crystal display and electrically coupled to said electronic circuit.
3. The electronic device according to claim 2 wherein said electronic circuit is further adapted to selectively power said backlight and to select said optoelectronic input/output compensation function from the set of optoelectronic input/output compensation functions also based on whether said backlight is being powered.
4. The electronic device according to claim 3 wherein:
said electronic circuit is adapted to selectively power said backlight based, at least in part, on said light level signal.
5. The electronic device according to claim 4 wherein:
said light sensor comprises a camera integrated into said electronic device.
6. The electronic device according to claim 5 comprising a wireless communication device.
7. The electronic device according to claim 1 wherein:
said transflective liquid crystal display comprises a first transparent substrate, a second transparent substrate, a liquid crystal material disposed between said first transparent substrate and said second transparent substrate, wherein a space available for said liquid crystal material between said first transparent substrate and said second transparent substrate has a substantially uniform thickness proximate said reflective part and said transmissive part of said pixel electrode.
8. An electronic device comprising: a transflective display; a display driver coupled to said transflective display; a backlight optically coupled to said transflective display; a backlight driver coupled to said backlight; an ambient light sensor;
a processor coupled to said display driver and to said ambient light sensor, wherein said processor is programmed to:
read said ambient light sensor to obtain a measure of an ambient light level; and based on said measure of said ambient light level, select an optoelectronic input/output compensation function from a set of optoelectronic input/output compensation functions and configure said display driver to effect said optoelectronic input/output compensation function, wherein each optoelectronic input/output compensation function of the set of optoelectronic input/output compensation functions is predefined for a range of ambient light levels;
wherein: said transflective display exhibits a first BV function for transmitted light and a second BV function for reflected light wherein said first BV function is substantially different from said second BV function;
wherein: said optoelectronic input/output compensation function is selected to yield an overall optoelectronic input/output function that substantially equals a power law function;
wherein: for intermediate ambient light levels at which light from said backlight and ambient light reflected by said transflective display both make substantial contributions to a brightness of said transflective display, said processor is programmed to select an optoelectronic input/output compensation function that is a composite function of an inner function which is said overall optoelectronic input/output function and an outer function which is an inverse of an effective BV function that is a weighted average of said first BV function and said second BV function wherein a first weight on said first BV function quantifies a first contribution of transmitted light to illuminating said display and a second weight on said second BV function quantifies a second contribution of reflected light to illuminating said display.
9. The electronic device according to claim 8 wherein said power law function has an exponent of 2.2.