Light sensor within display

A mobile communication device with a display may be configured to apply pulse width modulation (PWM) signals to light emitting diodes (LEDs) for providing backlighting for the display, monitor ambient light conditions during off periods of PWM signals applied to the LEDs and adjust the PWM signals based the monitored ambient light conditions.

TECHNICAL FIELD OF THE INVENTION

The invention relates generally to displays on communications devices and, more particularly, to displays with light sensors.

DESCRIPTION OF RELATED ART

Displays used in communications devices, such as liquid crystal displays (LCDs), require backlighting for image generation on the LCD. In addition, the ambient lighting conditions may also be sensed to adjust the backlighting. Existing, ambient light sensors are located adjacent to the LCD display. Sensing light conditions adjacent to the display may not provide an accurate indication of ambient light that reaches the display surface.

SUMMARY

According to one aspect, a method is provided. The method may comprise providing backlighting to a display; sensing ambient light conditions during off periods of the backlighting; and adjusting a brightness of the backlighting based on the sensed ambient light conditions.

Additionally, the adjusting the brightness of the backlighting may further comprise adjusting the sensed ambient light conditions based on an image on the display.

Additionally, the adjusting the brightness of the backlighting may further comprise changing a duty cycle of a pulse width modulation (PWM) signal.

Additionally, the sensed ambient light conditions may be sensed by light sensors, wherein the light sensors are located adjacent to backlighting LEDs.

Additionally, the light sensors and the backlighting LEDs are located adjacent to a light guide.

Additionally, the display may be a liquid crystal display (LCD).

According to another aspect a mobile communication device is provided. The mobile communication device may comprise a display, the display including: backlighting light emitting diodes (LEDs), light sensors, a liquid crystal display (LCD), and logic configured to: apply pulse width modulation signals to the LEDs, monitor lighting conditions received from the light sensors during off periods of the PWM signals, adjust the monitored intensity based on a currently displayed image, and adjust the PWM signals based on the adjusted monitored intensity.

Additionally, the light sensors may be located adjacent to the LEDs.

Additionally, the light sensors and the LEDs may be located adjacent to a light guide.

Additionally, the known light values are produced by the LCD.

Additionally, the adjusting the PWM signals based on the adjusted monitored intensity may further comprise changing a duty cycle of the PWM signals.

Additionally, the adjusting the PWM signals based on the adjusted monitored intensity may further comprise changing the duty cycle of the PWM signals based on a stored value of the adjusted monitored intensity signal.

Additionally, the light guide is located underneath the LCD.

According to another aspect, a method may be provided. The method may comprise applying pulse width modulation (PWM) signals to light emitting diodes (LEDs) for providing backlighting for a display; monitoring ambient light conditions during off periods of PWM signals applied to the LEDs; and adjusting the PWM signals based the monitored ambient light conditions.

Additionally, the method may further comprise adjusting the monitored ambient light conditions with known lighting values.

Additionally, the adjusting the PWM signals based the monitored ambient light conditions may further comprise changing a duty cycle of the PWM signals.

Additionally, the known light conditions are associated with an image on the display.

Additionally, the adjusting the PWM signals based the monitored ambient light conditions may further comprise changing the duty cycle of the PWM signals based on a stored value of the adjusted monitored intensity signal.

Additionally, the ambient light conditions are monitored by a light sensor, wherein the light sensor is located adjacent to the LEDs.

Additionally, the light sensor and the LEDs are located adjacent to a light guide.

Other features and advantages of the embodiments will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The embodiments are capable of modifications in various obvious respects, all without departing from the embodiments. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive.

DETAILED DESCRIPTION

The following detailed description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Also, the following detailed description does not limit the embodiments. Instead, the scope of the embodiments is defined by the appended claims and equivalents.

FIG. 1is a diagram of an exemplary mobile terminal100in which methods and systems described herein may be implemented. The invention is described herein in the context of a mobile terminal. As used herein, the term “mobile terminal” may include a cellular radiotelephone with or without a multi-line display; a Personal Communications System (PCS) terminal that may combine a cellular radiotelephone with data processing, facsimile and data communications capabilities; a personal digital assistant (PDA) that can include a radiotelephone, pager, Internet/Intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and a conventional laptop and/or palmtop receiver or other appliance that includes a radiotelephone transceiver. Mobile terminals may also be referred to as “pervasive computing” devices. Mobile terminal100may also include media playing capability. It should also be understood that systems and methods described herein may also be implemented in other devices that include displays, with or without including various other communication functionality. For example, mobile terminal100may include a personal computer (PC), a laptop computer, a PDA, a media playing device (e.g., an MPEG audio layer 3 (MP3) player, a video game playing device), etc.

Referring toFIG. 1, mobile terminal100may include a housing110, a speaker120, a display130, control buttons140, a keypad150, and a microphone160. Housing110may protect the components of mobile terminal100from outside elements. Speaker120may provide audible information to a user of mobile terminal100.

Display130may provide visual information to the user. For example, display130may provide information regarding incoming or outgoing telephone calls and/or incoming or outgoing electronic mail (e-mail), instant messages, short message service (SMS) messages, etc. Display130may also display information regarding various applications, such as a phone book/contact list stored in mobile terminal100, the current time, video games being played by a user, downloaded content (e.g., news or other information), etc.

In an exemplary implementation, display130may be a transflective LCD that includes a light guide and an adjustable or switchable reflector located on the backside of display130. The adjustable reflector may allow display130to be efficiently backlit during low ambient lighting conditions, such as when mobile terminal100is being used indoors. The adjustable reflector may also allow ambient or external light with respect to mobile terminal100to be efficiently reflected back through the LCD during high ambient lighting conditions to illuminate the LCD. The reflective/transmissive quality of the adjustable reflector may be adjusted or switched based on the particular environment in which mobile terminal100is operating.

Control buttons140may permit the user to interact with mobile terminal100to cause mobile terminal100to perform one or more operations, such as place a telephone call, play various media, etc. For example, control buttons140may include a dial button, hang up button, play button, etc. In an exemplary implementation, control buttons140may include one or more buttons that controls various illumination settings associated with display130. Further, one of control buttons140may be a menu button that permits the user to view various settings associated with mobile terminal100.

Keypad150may include a standard telephone keypad. Microphone160may receive audible information from the user.

FIG. 2is a diagram illustrating components of mobile terminal100according to an exemplary implementation. Mobile terminal100may include bus210, processing logic220, memory230, input device240, output device250, power supply260and communication interface270. Bus210permits communication among the components of mobile terminal100. One skilled in the art would recognize that mobile terminal100may be configured in a number of other ways and may include other or different elements. For example, mobile terminal100may include one or more modulators, demodulators, encoders, decoders, etc., for processing data.

Processing logic220may include a processor, microprocessor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA) or the like. Processing logic220may execute software instructions/programs or data structures to control operation of mobile terminal100.

Memory230may include a random access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processing logic220; a read only memory (ROM) or another type of static storage device that stores static information and instructions for use by processing logic220; a flash memory (e.g., an electrically erasable programmable read only memory (EEPROM)) device for storing information and instructions; and/or some other type of magnetic or optical recording medium and its corresponding drive. Memory230may also be used to store temporary variables or other intermediate information during execution of instructions by processing logic220. Instructions used by processing logic220may also, or alternatively, be stored in another type of computer-readable medium accessible by processing logic220. A computer-readable medium may include one or more memory devices and/or carrier waves.

Input device240may include mechanisms that permit an operator to input information to mobile terminal100, such as microphone160, keypad150, control buttons140, a keyboard, a mouse, a pen, voice recognition and/or biometric mechanisms, etc. Input device240may also include one or more sensors that enable mobile terminal100to identify various external conditions. For example, input device240may include a light sensor that detects and/or measures ambient light conditions in the environment in which mobile terminal100is operating, as described in detail below.

Output device250may include one or more mechanisms that output information to the user, including a display, such as display130, a printer, one or more speakers, such as speaker120, etc. Power supply260may include one or more batteries or other power source components used to supply power to components of mobile terminal100. Power supply260may also include control logic to control application of power from power supply260to one or more components of mobile terminal100.

Communication interface270may include any transceiver-like mechanism that enables mobile terminal100to communicate with other devices and/or systems. For example, communication interface270may include a modem or an Ethernet interface to a LAN. Communication interface270may also include mechanisms for communicating via a network, such as a wireless network. For example, communication interface270may include one or more radio frequency (RF) transmitters, receivers and/or transceivers. Communication interface270may also include one or more antennas for transmitting and receiving RF data.

Mobile terminal100may provide a platform for a user to make and receive telephone calls, send and receive electronic mail, text messages, play various media, such as music files, video files, multi-media files, games, and execute various other applications. Mobile terminal100may perform these operations in response to processing logic220executing sequences of instructions contained in a computer-readable medium, such as memory230. Such instructions may be read into memory230from another computer-readable medium via, for example, communication interface270. A computer-readable medium may include one or more memory devices and/or carrier waves. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement processes consistent with the embodiments. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software.

FIG. 3is a functional diagram illustrating certain components of mobile terminal100. The illustrated components include display control logic310, light sensor320and power supply260. Light sensor320may be included within display130. Display control logic310may be included in processing logic220and light sensor320may be included in input device240.

Display control logic310may switch or change the power applied to one or more components of display130. For example, display control logic310may apply power to components for providing a display and may apply power to components for providing backlighting for display130. Display control logic310may also control and/or adjust the power applied to one or more components of display130by using ambient light conditions received (and adjusted) from light sensors. For example, display control logic310may access stored values of sensed ambient lighting conditions that may be associated with an appropriate power signal to be applied to backlighting components in display130.

In one implementation for example, display control logic310may signal or instruct power supply260to provide power to components in display130via pulse width modulation (PWM) signals. For example, the “on” and “off” durations of the PWM signals (pulses) may be changed, based on the sensed ambient or external lighting conditions in order to provide the highest quality image on display130. Further, the “on” and “off” durations of the PWM signals (pulses) may be changed, based on a predetermined stored values relating the optimum amount of backlight versus the amount of sensed ambient light, as shown and described below with reference toFIGS. 5-6. Display control logic310may also add/subtract known light signals (based on the image displayed by LCD cells410) from sensed light signals and use the remaining signal to obtain an optimum amount of backlighting. Display control logic310may then adjust PWM signals by increasing or decreasing a length of an off period of the PWM signals accordingly. In other examples, display control logic310may provide power to components in display130via direct current (dc) signals, or other types of signals and may adjust these signals in an appropriate manner in order to provide the desired intensity of backlighting.

Light sensor320may be a sensor that receives ambient light and generates a signal representing the ambient light conditions. Light sensor320may continuously or periodically monitor the ambient light conditions and may automatically provide this signal/information to display control logic310. In other embodiments, light sensor320may continuously monitor ambient light conditions without detecting backlight produced by backlighting components (such as LEDs420) within display130. For example, light sensor320may be configured to monitor light at frequencies different than the frequency of backlight produced by backlighting components.

Display130, as will be described in more detail below, may be a transflective LCD display. In an exemplary implementation, display130may include one or more films/layers and/or other components that may provide an image via display130.

FIG. 4Aillustrates components of display130according to an exemplary implementation. Referring toFIG. 4A, display130may include LCD cells410, LEDs420, light guide430, light sensors440, reflective layer450and display housing460. Although not shown, display130may include protective layers above LCD cells410and film layers between LCD cells410and light guide430that may act to increase viewing angles and to spread light.

LCD cells410may be any type of liquid crystal display used to display information. LCD cells410may receive signals from display control logic310to provide an image. LCD cells410may require additional light to generate images as may be provided using reflected ambient light and/or light generated from LEDs420.

LEDs420may be any type of light emitting diode used to provide backlighting for display130. The backlight may be produced by periodically turning on/off LEDs420. The duty cycle for controlling the on/off of LEDs420may be controlled via PWM signals or direct current signals from display control logic310. Backlighting produced by LEDs420(shown by arrows inFIG. 4A) may be directed into light guide430.

Light guide430may be a transparent material or transparent film layer that may receive light (backlight) from LEDs420and direct this light up through LCD cells410. For example, light guide430may evenly spread and direct light from LEDs420to provide uniform backlighting of display130. Similarly, light guide430may receive ambient light that may have passed through LCD cells410and may direct this ambient light toward light sensors440located at the edge of light guide430(as shown inFIG. 4B). In other embodiments, light guide430may direct backlight produced by LEDs420up through LCD cells410without directing backlight into light sensors440. In this embodiment, ambient light may be continuously monitored by light sensors440without interference from LEDs420.

Light sensors440may be any type of device capable of sensing light. For example, light sensors440may be a photo-electric cell or any other type of photo-electric device that produces an electrical signal based on an amount of light received. Light sensors440may be located at the edge of light guide430and may transmit signals corresponding to an amount of received light to display control logic310.

Reflective layer450may include a layer or layers of material that partially reflects light. For example, reflective layer450may include a transition metal, such as iron, nickel, copper, cobalt, or any other of the transition metals. In addition, reflective layer450may include a combination of various transition metals and/or one or more alloys including one or more transition metals. The reflective quality of reflective layer450may also be changed by applying power (from power supply260) to reflective layer450.

Display housing460may include structures or housings used to mount display130within mobile terminal100. For example, display housing460may be a hard plastic material that mounts components410-450within display130. Display housing460may be contained in housing110, for example.

FIG. 4Billustrates another view of an exemplary implementation of display130.FIG. 4Bincludes the same components as described above with reference toFIG. 4A. As shown inFIG. 4B, LEDs420and light sensors440located at the edge of light guide430. Small arrows shown in4B indicate light being emitted from LEDs420and directed upward from light guide430(that will provide backlighting for display130). Large arrows shown inFIG. 4Bindicate ambient light received by light guide430that may be directed to light sensors440.

FIG. 5is a flow diagram illustrating processing by mobile terminal100in an exemplary implementation. Processing may begin by applying PWM signals to the backlighting LEDs (block510). For example, display control logic310may provide signals to power supply260to control the pulse widths (on and off periods) to LEDs420. Display control logic310may provide PWM signals based on a standard backlighting value, a last used backlighting value and/or based on sensed ambient light. In other examples, power may be applied to LEDs420via direct current signals from power supply260, as controlled by display control logic310.

Processing may continue by monitoring ambient light conditions during the off periods of the PWM (block520). For example, light guide430may receive ambient light and guide this light to sensors440as shown inFIG. 4B. Display control logic310may then receive signals from light sensors440during the off periods of the pulses applied to LEDs420. In this manner, the ambient lighting conditions may be sensed without receiving the light being generated from LEDs420. In other examples, if power is applied to LEDs420via dc signals, the dc signals may be turned off for short periods of time, in order to allow light sensors440to sense ambient light without receiving light from LEDs420. In these examples, it should be understood that the “off” periods during which ambient light may be sensed may be provided by display control logic310in any number of ways (i.e., regular or irregular intervals, once per duty cycle or once every 100 cycles, etc.) and may be provided so as to not effect the quality (i.e. be detectable by a user) of backlighting provided to display130. In still further embodiments, if light sensors440are configured to sense light at frequencies other than the frequency of backlight produced by LEDs420and/or light guide430may direct all backlight produced by LEDs420away from light sensors440, ambient light may be monitored on a continuous basis using light sensors440.

Once ambient lighting conditions have been detected, processing may continue by adjusting monitored lighting values based on the current image shown by the LCD cells (block530). For example, display control logic310may provide signals to LCD cells410to generate and display an image. Using the known signals used to produce the image on LCD cells410, these known signals may be used to adjust the light signals received from light sensors440to give a more accurate signal that relates to ambient light. For example, if most of the LCD cells410are displaying black pixels, not much ambient light may be transmitted through LCD cells410and be received by light sensors440. In this example, display control logic310may add appropriate lighting values as necessary to ambient light signals received from sensors440. Conversely, if very few LCD cells410are displaying images, the sensed ambient light received by light sensors440may be an accurate indication of ambient light intensity, and the sensed ambient light signal may not be adjusted, for example.

Processing may continue by adjusting power to the LEDs420based on this adjusted signal (block540). For example, display control logic310may adjust the duty cycle of the PWM signals to control LEDs420. For example, display control logic310may adjust the PWM signals by increasing or decreasing a length of an off period of the PWM signals based on predetermined stored values relating an optimum value of backlighting with the amount of sensed ambient light. These stored values of backlight and associated ambient light may be stored in a look-up-table within display control logic310, for example. These stored and associated values of backlight and ambient light may form a relationship as shown graphically inFIG. 6. Referring toFIG. 6for example, if the adjusted signal relating to the sensed amount of ambient light is 0.4, the backlighting power signal may be 0.8 for example. In another example, if the adjusted signal of ambient light is 0.2, the backlighting power signal may be 0.6. In one example, a backlighting power signal of 0.6 (60%) may correspond to PWM duty cycles, where the PWM signal has an “on” period 60% of the time and an “off” period for 40% of the time. In other examples, it should be understood that the values shown inFIG. 6are relative values and may not directly correspond exactly to a duty cycle. For example, a backlighting intensity signal of 1.0 may correspond to a PWM duty cycle of 50% “on” and 50% “off.” In other examples, the type of signal applied to LEDs420may not be PWM signals, therefore the relative values shown inFIG. 6may be used to appropriately adjust the type of driving signal accordingly.

As shown inFIG. 6, the amount of backlight produced by LEDs420may be increased as ambient light increases up to a certain value (approximately 0.5). At levels of ambient light between 0.5 and 0.8 a full amount of backlighting may be applied by LEDs420. At some point (approximately 0.8) the amount of ambient light is so intense that the backlighting produced by LEDs420may be turned off, as it does not effect the quality of the image provided on display130. Using these stored values based on the predetermined relationship (as shown inFIG. 6) between sensed ambient light and backlighting, display control logic310may increase or decrease the length of an off period of the PWM signals to LEDs420to provide the desired amount of backlighting to enhance viewing of the image provided on display130.

CONCLUSION

Implementations described herein provide light sensors within a display, where ambient lighting conditions may be sensed during periods when the backlighting is off. The backlighting LEDs may be adjusted based on the sensed ambient light conditions. Advantageously, this may more accurately adjust backlighting based on sensed ambient lighting conditions.

The foregoing description of the embodiments of the embodiments provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the embodiments.

For example, aspects of the embodiments have been mainly described in the context of a mobile terminal. The embodiments, however, may be used with any type of device that includes a display.

Further, while series of acts have been described with respect toFIG. 5, the order of the acts may be varied in other implementations consistent with the embodiments. Moreover, non-dependent acts may be performed in parallel.

It will also be apparent to one of ordinary skill in the art that aspects described herein may be implemented in methods and/or computer program products. Accordingly, aspects of the embodiments may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, aspects described herein may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. The actual software code or specialized control hardware used to implement aspects consistent with the principles of the embodiments is not limiting of the embodiments. Thus, the operation and behavior of the aspects were described without reference to the specific software code—it being understood that one of ordinary skill in the art would be able to design software and control hardware to implement the aspects based on the description herein.

Further, certain aspects described herein may be implemented as “logic” that performs one or more functions. This logic may include hardware, such as a processor, microprocessor, an application specific integrated circuit or a field programmable gate array, software, or a combination of hardware and software.

The scope of the embodiments is defined by the claims and their equivalents.